Based on outcrops，cores and geochemistry analytical data，the lithologies，sedimentary paleoenvironment，the evaluation and distribution characteristics of source rocks of Permian Lucaogou Formation in the hanging wall of Fukang fault zone in Junggar Basin were analyzed，and the hydrocarbon accumulation model was discussed. The results show that： （1）There were sandstone，shale and carbonate rocks developed in Lucaogou Formation in Fukang fault zone，and they were dominated by gray-black and black oil shale with thickness of 200- 600 m. The carbonate rocks and shale were interbedded，and asphalt and oil traces can be seen in carbonate interbeds.（2）The Lucaogou Formation in the study area was deposited during the semi-deep lake to deep lake facies，the climate was mainly dry and hot，with intermittent warm and wet climate，and the ancient water body was brackish-saline water. The northern foot of Bogda Mountain was the center of the sedimentary lake basin， which has better deposition and preservation conditions.（3）It was a high mature and high-quality hydrocarbon source rock with abundance of organic matter in the study area，with outcrops R_o of 0.74%-1.28% and drilling core TOC of 0.92%-4.48%. They are mainly typeⅠ and Ⅱ₁ and have high hydrocarbon potential，with S₁+S₂ greater than 20 mg/g. The hydrocarbon source rocks at the northern foot of Bogda Mountain has a larger scale of development and higher maturity than that in the western side，and the chloroform asphalt “A” content is greater than 1 200× 10^-6.（4）The reservoirs of Lucaogou Formation in the study area are controlled by traps and faults. The reservoirs in the northern high steep zone are mostly exposed on the surface，damaged，and dominated by thick oil. The central nasal ridge zone is tectonically stable，with eight traps developed. The reservoirs in the central nasal ridge zone are characterized by self-generation and multi-phase filling. The southeastern part can be designated as the sweet spot area for shale oil exploration.

The Lower Cambrian Niutitang Formation in the western Hunan and Hubei is an important target for shale gas exploration in southern China. Two profiles，Guchengcun in western Hubei and Yanwutan in western Hunan，were selected to carry out petrological and geochemical analysis of the black shale series of Lower Cambrian Niutitang Formation，so as to find out the provenance and tectonic background of the black shale，and analyze the sedimentary environment. The results show that：（1）The black shale deposits of Niutitang Formation in the two profiles are obviously different. The shale of Niutitang Formation in Guchengcun profile is mainly argillaceous shale with small thickness，and a small amount of siliceous shale is developed at the bottom，while the shale of Niutitang Formation in Yanwutan profile is mainly siliceous shale with large thickness，and the bottom is rich in silicophosphorous nodules，nickel，cobalt，vanadium and other metals. The quartz content of Yanwutan profile is much higher than that of Guchengcun profile，and pyrite is also more abundant.（2）There are obvious differences in the sedimentary environment，provenance background and tectonic background between the black rock series in the two profiles. The provenance of Guchengcun profile is mainly felsic igneous rocks and quartz sedimentary rocks，which were deposited in a weak reduction and weak oxidation environment on the continental shelf of the passive continental margin. The provenance of Yanwutan profile is mainly felsic igneous rocks， quartzitic sedimentary rocks and continental tholeiites， and with the input of hydrothermal provenance， it was deposited in a reducing environment on the continental slope of the passive continental margin.（3）In the Early Cambrian，the sediments of Hefeng Guchengcun in western Hubei were mainly black carbonaceous shale and limestone，with low contents of organic matters and silica，the water body was relatively shallow，and it was obviously affected by sea level fluctuations，so it was a shelf environment. However，the sedimentary thickness in western Hunan was large，with high content of organic matters，and it was close to deep faults，the source of hydrothermal silicon was abundant， which is a continental slope environment.

Based on the model of a single-seam fractured-vuggy reservoir between wells in Tahe Oilfield，a physical simulation and displacement experiment of water plugging by rubber particle flow regulating agent was designed， the law of water flooding was analyzed，and the effects of different blocking locations，rubber particle dosage， particle size，density and injection rate on the displacement effect were discussed. The results show that：（1）The model length is 40 cm， the width is 30 cm， the thickness is 5 cm， the crack opening to is 4-20 mm， the cave diameter is 2-4 cm，the width of the wellbore is 10 mm，the crack volume of the model is 175 mL. At a temperature of 25 ℃ and atmospheric pressure，and at a water injection rate of 10 mL / min，the final degree of recovery is 43.83% when the water content of the production well reaches 98% by water injection at the rate of 10 mL/min. Due to gravity differentiation， there is a large amount of attic oil and bypass oil after water flooding， attic oil is mainly concentrated in the transverse top channel，bypass oil is mainly concentrated in the high position of the transverse middle channel and the transverse bottom channel，and the oil-water interface is flush with the high seam of the transverse middle channel.（2）In the simulation experiment，the transverse bottom channel and the transverse middle channel were blocked at the same time. The rubber particles were mixed in particle size，and the particle density is consistent with the density of the simulated formation water. The larger the amount，the greater the injection rate，and the better the flow regulation effect. When the amount of rubber particles was 0.04 PV，the particle size was less than 1 mm and 2-4 mm， and the injection rate was 15 mL/min， the recovery rate increased by 18.45%. Rubber particles with the same density as formation water can be carried and transported to the desired blocking position by injecting water，and the water blocking effect is better.（3）In the field experiment of rubber particle profile control and water plugging in well TH25X，The rubber particle size of the front section plug is 2-4 mm，the rubber particle size of the rear section plug is less than 1 mm，and the particle density is 1.13 g/cm³. Water and rubber particles were injected simultaneously at the rate of 50 m³/d， and the total amount is 920 m³. After water plugging， the cumulative oil increase is 1 200 t， and the water content decreases by 15%， achieving good plugging effect.

Based on the analysis of structural characteristics，reservoir accumulation stages and conditions，the distribution characteristics and main controlling factors of Cretaceous tight volcanic reservoirs in Yingshan-Shuangcheng fault depression of Soliao Basin were determined by using the data of seismic，inclusions，source rocks and production test. The results show that：（1）Yingshan-Shuangcheng fault depression has experienced threestage extension and compression tectonic activities. During the late sedimentary period of Qingshankou Formation（84-88 Ma）which was the main reservoir accumulation stage，the study area was in a stable depression period with weak tectonic activities，which was conducive to the formation and preservation of gas reservoirs.（2）The volcanic reservoirs in the study area are dominated by pyroclastic rocks and lava，with porosity and permeability of 9.6% and 0.93 mD. The source rocks of Shahezi Formation have high organic abundance，TOC（total organic carbon content）and S₁+ S₂（hydrocarbon generation potential）are 2.61% and 0.62 mg/g respectively，and the average vitrinite reflectance R_o is 3.26%，which is in an over-mature stage. The gas migrated into volcanic rocks of the first member of Yingcheng Formation through faults and unconformities.（3）The natural gas accumulation in Yingshan-Shuangcheng fault depression is controlled by hydrocarbon source rocks，faults，unconformities，volcanic bodies and their coupling relations. The differential activities of faults control the development and superposition of the first member of Yingcheng Formation and Shahezi Formation. The source rocks of Shahezi Formation are developed locally in the northern Yingshan fault depression，while the source rocks of the first member of Yingcheng Formation are mainly developed Sizhan-Taipingzhuang fault. The gas reservoirs are concentrated near the high-over mature source rocks with R_o greater than 3.0%，and the high yield gas wells are distributed circularly around the hydrocarbon generation center. The reservoirs of explosive facies and overflow facies near faults and unconformities that connected source have good physical properties and are important gas enrichment areas.（4）There are two accumulation models of natural gas reservoirs in the study area： “lower generation and upper reservoir， fault matching，near source and vertical migration” in Yingshan fault depression and “lateral generation and lateral reservoir，fault associated with unconformity，far source lateral migration and accumulation” in Shuangcheng fault depression. The structural-lithologic gas reservoirs in Yingshan fault depression are the most favorable exploration area in the study area.

Based on the analysis of cores，logging and seismic facies，the lithofacies of Carboniferous in Fudong slope of Junggar Basin was divided and the distribution of volcanic rocks was predicted，and the favorable exploration direction was pointed out. The results show that： （1）There are five lithofacies of Carboniferous developed in Fudong slope： volcanic vent facies，explosive facies，overflow facies，argillaceous tuff facies，sedimentary pyroclastic facies，among which the explosive facies and overflow facies are favorable reservoir facies.（2）The volcanic vent facies in the study area is characterized by medium-low frequency，medium-strong amplitude，disordered funnel-shaped or columnar reflection， the explosive facies is characterized by medium-low frequency， mediumweak amplitude and disordered mound reflection，the overflow facies is characterized by low frequency，strong amplitude and continuous reflection，the argillaceous tuff facies is characterized by low frequency，mediumstrong amplitude and continuous reflection，and the sedimentary pyroclastic facies is characterized by medium frequency，medium-strong amplitude and continuous reflection.（3）The overflow facies of section b of Songkaersu Formation is mainly distributed in the southeast of the study area，the north of well XQ11 and the west of well XQ17 to XQ11，and the explosive facies of section a of Songkaersu Formation is mainly distributed in the main part of Xiquan nose-uplift.（4）Explosive facies and overflow facies are developed on a large scale in Xiquan nose-uplift of the study area，and they are close to hydrocarbon generation center of Carboniferous，with developed fractures and superior reservoir accumulation conditions， so it is a favorable area for natural gas exploration.

The Middle Jurassic Toutunhe Formation is an important exploration target zone in the southern margin of Junggar Basin. Based on the field survey of southern Anjihai river outcrops in the southern margin of Junggar Basin，combined with thin section identification of rock samples and geochemical analysis data，the lithologies and sedimentary structure of Toutunhe Formation were descried，and the sedimentary environment，sedimentary facies types and depositional evolution were analyzed. The results show that：（1）The Middle Jurassic Toutunhe Formation in the study area experienced a semi-arid，arid and humid climate evolution during the sedimentary period. The lacustrine basin was shallow，the lake bottom was gentle，and shallow delta deposits were developed.（2）Six types of sedimentary microfacies were developed in the study area，including distributary channel，inter-distributary depression，underwater distributary channel，inter-distributary bay，sheet sand and beach bar. The shallow water delta of Toutunhe Formation was affected by rivers and lake waves，forming a river-dominated shallow water delta in the stable period of lacustrine basin，and wave-dominated shallow water delta was developed.（3）From the early stage to the late stage of Toutunhe Formation，the lake level generally decreased and then increased. Riverdominated shallow water delta was developed in the first member of Toutunhe Formation，the distributary channel had strong hydrodynamic force. The river was frequently diverted and bifurcated，and continuously accumulated towards the lacustrine basin. The multi-stage channels were spliced. At that time，it was dominated by distributary channel and underwater distributary channel. Subsequently，the climate was further dry，wave-controlled shallow water delta was developed in the second member of Toutunhe Formation. The river action was weakened，and the wave action was enhanced. The delta plain was dominated by the development of a folded distributary channel. The sand bodies of underwater distributary channel of the delta front were transformed by wave scouring，forming strip-shaped sheet sand. During the deposition of the third member of Toutunhe Formation， due to the continuous subsidence of the Junggar Basin and the lateral migration of delta lobes，the surface of delta lobes in the shallow lacustrine basin was covered by lake water，and part of the clastic materials in the front of the shallow delta were reconstructed by lake waves， forming beach bar deposits parallel to the lake shore.

Based on the data of 3D seismic，mud-logging，wire-logging and core observation，the sedimentary characteristics and main controlling factors of the sublacustrine fan of the first member of Eocene Liushagang Formation in Weixinan Sag of Beibuwan Basin were studied，and the lithologic trap development model and hydrocarbon accumulation model were determined. The results show that： （1） The sublacustrine fans are developed in lowstand systems tract（LST）and transgressive systems tract （TST）of the first member of Liushagang Formation in subsag A of Weixinan Sag. The sublacustrine fans in LST are developed near the No. 1 fault，which is characterized by continuous and strong seismic reflection，while the sublacustrine fans in TST are distributed in the sag，and have obvious mound reflection.（2）Controlled by two major factors of source supply and paleogeomorphology，the first member of Liushagang Formation in subsag A developed two stages of sublacustrine fans. During the period of LST，there was little source supply in short axis direction，the footwall of No. 1 fault was the accumulation center of the sag，small scale nearshore submarine fans that directly enter the lake were developed，and lithologic traps that dip upward and pinch out toward the source area were formed. During the period of TST，the source supply gradually increased，the activity of No. 1 fault weakened，and the accumulation center of subsag A gradually migrated to the sag. The loose sediments in the fan delta front transported again into the middle of the sag and developed sublacustrine fans. Lithologic traps that dip and pinch out toward the south slope，and structurallithologic traps shielded by No. 2 fault were formed.（3）Vertical migration conditions are the key factors for lithologic reservoir accumulation in the study area. Microfractures controlled by early faults and late structural differential settlement developed in the upper part of the hydrocarbon source layer of subsag A，providing a good migration path for oil and gas to vertically migrate through mudstone caprocks to the lithologic trap above the source and accumulate to form reservoirs. This area has a reservoir accumulation model of “overpressure driving，microfractures provide migration path， and accumulation in low potential areas”.

The tectono-sedimentary differentiation through geologic history has an important influence on the tectonicsedimentary filling processes of the carbonate strata and the geological conditions for hydrocarbon accumulation in large petroliferous basins. Through the high-density 2D seismic data and logging-drilling data covering the whole area，the uplift and sag patterns and paleogeographic evolution of eastern Sichuan Basin during the depositional period of Triassic Jialingjiang Formation were described in detail. The results show that: (1) Linshui-Fengdu intra-platform depression was identified from the characteristics of seismic section，stratigraphic and lithological combination. Its slope is about 1°-2°，and the slope on the left is greater than the slope on the right. (2) LinshuiFengdu intra-platform depression and other paleogeological units jointly controlled the paleogeographic pattern and tectono-sedimentary differentiation during the depositional period of the second member of Triassic Jianglingjiang Formation (T₁ j²). The intra-platform depression controlled the distribution of shoal around it during the early and middle period of T₁ j²，and a large area of gypsum lagoons developed in the intra-platform depression during the late period. (3) The Linshui-Fengdu intra-platform depression，with around micro-paleo-geomorphology， controlled the distribution of grain shoals during the early depositional period，and high-quality dolomite reservoirs were more likely to be formed in the high parts of the peripheral structure. The continuous arid and evaporative environment formed a regional cap layer. (4) In general，the T₁ j² has good reservoir-forming geological conditions and is expected to be a strategic exploration area for searching as shoal-facies monoblock gas reservoirs. It is recommended that the high-energy intra-platform shoal facies development belt around the Linshui-Fengdu intraplatform depression should be the key exploration area of Jialingjiang Formation in eastern Sichuan Basin in the future.

The Longtan Formation is a new important layer for shale gas exploration and development in Sichuan Basin. The shale reservoirs of Permian Longtan Formation in southern Sichuan Basin was comprehensively studied by means of polarizing microscope identification，field emission scanning electron microscope analysis，X-ray diffraction test，organic carbon content determination，high-pressure mercury injection analysis and on-site analytical gas experiment. The results show that: (1) The Permian Longtan Formation in southern Sichuan Basin is a set of continental meandering river deposits，and shale is developed in fluvial deposits. Its minerals are mainly quartz and clay minerals，with a small amount of carbonate minerals. (2) There are mainly intergranular (marginal) pores and microfractures developed in the shale reservoirs in the study area，intragranular pores and dissolved pores are locally developed，and organic pores are rarely developed，among which microfractures between clay minerals are the most developed. The pore structures are mainly microporous，followed by mesoporous (with pore size of 2-50 nm). The pore size is generally small，with poor sorting，the radius difference between pore and throat is large，and the heterogeneity is strong. (3) In the shale reservoirs in the study area，the gas content in coal rock is the highest，followed by carbonaceous mudstone and mudstone，and the gas content in argillaceous siltstone，siltstone and fine sandstone is the lowest. Compared with the shale reservoir of Longmaxi Formation，the mudstone of Longtan Formation has better porosity and total gas content and poor permeability，and the porosity and total gas content of carbonaceous mudstone are the best. (4) The Permian Longtan Formation in the study area has great exploration potential. The organic matter in the source rocks is mainly type Ⅲ，followed by typeⅡ₂. The average value of R_o is about 2.8%，reaching the stage of high maturity. TOC content varies widely， and TOC content in carbonaceous mudstone is generally greater than 15%. (5) Alluvial plain is developed in Permian Longtan Formation in southern Sichuan Basin，being rich in organic shale，with good shale gas formation conditions. The estimated natural gas resources are about 2.4×10¹² m³，and the favorable exploration area is mainly located in Gulin-Xuyong area in southern Sichuan Basin.

The Permian Fengcheng Formation in the northwestern margin of Junggar Basin is enriched with shale oil resources，and a major breakthrough has been made in oil and gas exploration in Mahu Sag and Wuxia area. There is certain exploration potential in the adjacent Hasan area. Through rock thin section observation，scanning electron microscope analysis，organic geochemical test，XRD analysis and reservoir physical property analysis， the shale oil reservoir characteristics and controlling factors of Permian Fengcheng Formation in Hashan area were studied. The results show that: (1) The lithologies of shale oil reservoirs of Permian Fengcheng Formation in Hashan area are mainly composed of felsic shale，calcareous shale and mixed shale. The shale could be classified as good to best source rocks. The organic matters are mainly typeⅡ₁ and typeⅡ₂，and mainly at the immature stage. Some shale samples in the footwall of the overthrusts were involved into early mature stage. (2) The average porosity of the shale oil reservoirs in the study area is 2.32%，belonging to low porosity reservoir. The reservoir space is dominated by inorganic pores and micro-fractures，and the development degree of organic pores is relatively low. (3) The development of shale oil reservoirs of Fengcheng Formation in the study area is mainly controlled by sedimentary facies，diagenesis and tectonic activities. Sedimentary facies not only determines the rock type，but also controls the enrichment of organic matters. Compaction and cementation can play a negative role in reservoir physical properties，and dissolution can greatly improve reservoir physical properties. Micro-fractures formed by tectonic activities can not only provide reservoir spaces for shale oil，but also provide channels for oil and gas migration，thus improving the percolation condition of shale oil reservoirs.

Through low-field NMR experiments, the T₂ spectra of the Quaternary mudstone biogas reservoirs in the Sebei area of Qaidam Basin were analyzed under saturated water state and gradient drying temperature state, and the NMR response characteristics of pore fluids were clarified to evaluate the effectiveness of pores. The results show that:(1) Based on the T₂ spectrum under the saturated water state, the centrifugal bound water T₂ spectrum was constructed by fitting the normal distribution function, the T₂ cutoff values of movable fluid and capillary bound fluid were determined, the fluid types were divided, and the pore effectiveness evaluation was carried out. (2) The T₂ spectral peaks of water-saturated rock samples in the study area are small on the left and large on the right, and the amplitude of the right peak is much larger than that of the left peak, accounting for more than 90% of the T₂ spectral amplitude. With the increase of drying temperature, the amplitude of the T₂ spectrum decreases and the left shift trend is obvious. The T₂ spectrum shape of the bound water is approximately normal distribution, and the starting position basically coincides with the T₂ spectrum under the saturated water state.(3) The T₂ cutoff value(T_{2 C1}) of movable fluid in the study area is 3.3 ms on average, and the average T₂ cutoff value(T_{2 C2}) of capillary bound fluid is 1.8 ms. The pore fluids include movable water, capillary bound water and clay bound water. The clay bound water T₂ is less than T_{2 C2}, and the capillary bound water T₂ is larger than T_{2 C2} and less than T_{2 C1}, and the movable fluid T₂ is larger than T_{2 C1}. The capillary bound water content is the highest, followed by the clay irreducible water, which account for 84.43%-95.06% of the total pore fluids, and the movable water content is low.(4) The effective pores of the reservoir in the study area account for 54.99% of the total pores and are mainly capillary-bound pores, and clay-bound pores are ineffective pores. The higher the clay content, the smaller the effective porosity.

Yinggehai Basin is an important natural gas exploration area in the South China Sea. Based on detailed analysis of typical gas reservoirs and gas-bearing structures of different accumulation systems in the central depression of Yinggehai Basin，the effectiveness and controlling factors of caprocks were evaluated，and the controlling effects of caprocks on natural gas accumulation were analyzed. The results show that: (1) In the ultra-shallow and shallow accumulation systems in the central depression zone of Yinggehai Basin，the sealing of caprocks is controlled by the caprocks，the diapir structure and the faults associated with the activity of the diapir structure. In the middle-deep accumulation system，under the background of abnormally high fluid pressure and the absence of faults，hydraulic sealing of caprocks is the key factor controlling differential enrichment of oil and gas. (2) The critical juxtaposition thickness of the brittle caprocks to maintain the sealing effectiveness is 86-98 m in the ultrashallow and shallow accumulation systems. The effectiveness of the caprocks in the middle-deep accumulation system can be evaluated by the hydraulic fracturing pressure coefficient. When the value is greater than 1，it means that the caprocks have ruptured or have a strong risk of hydraulic fracturing. (3) From the overall view of the central depression，hydraulic fracturing induced by overpressure is the fundamental cause of sealing failure in mid-deep caprocks. Deep natural gas migrates to shallow layer through hydraulic fracturing channel and finally to the ultra-shallow reservoir through the faults. Therefore，under the condition of sufficient gas source，ultra-shallow and shallow gas reservoirs are mainly distributed at the top of the diapir，while middle-deep gas reservoirs are mainly concentrated in the diapir wing and slope areas.

The geochemical characteristics and sedimentary environment of the third member of Paleogene Shahejie Formation (E₂s³) in central Laizhouwan Sag of Bohai Sea were studied by means of pyrolysis，TOC，GC/MS analysis of saturated hydrocarbons，and major and trace elements analysis of source rock samples. The results show that: (1) The source rocks of E₂s³ have different organic matter abundances，they are generally good to high-quality source rocks. The organic matters are mainly type Ⅰ-Ⅱ and in the low mature to mature stage as a whole. (2) According to Pr/nC₁₇-Ph/nC₁₈ plates，C₂₄ tetracyclic terpanes/C₂₆ tricyclic terpanes (C₂₄ TeT/C₂₆ TT)， C₂₇/C₂₉ regular sterane and olliane index，it can be concluded that the organic matters of E₂s³ source rocks are derived from mixed inputs of lower aquatic organisms and terrigenous higher plants. (3) CIA，Sr/Ba，Pr/Ph，V (/V+Ni)， U/Th and gammacerane index were used to analyze the paleoenvironment of the source rocks. During the sedimentary period of E₂s³，the climate was warm and humid with abundant precipitation. The water environment was fresh-brackish water，accompanied by strong terrigenous input，with high initial productivity，and the sedimentary environment is weak oxidation and weak reduction environment with poor oxygen. The sedimentary environment of E₂s³ has little change，and the paleoclimate and water salinity are basically the same. However，terrigenous input and water oxidation conditions gradually increase with the deposition.

The eastern Lufeng 13 subsag is a key area for oil and gas exploration in the Pearl River Mouth Basin. Combined with regional tectonic background，and based on the fine interpretation of high-quality 3 D seismic data， the structure and structural features of the eastern Lufeng 13 subsag were analyzed，the tectonic evolution of the subsag was restored by using balanced section technology，and the influences of tectonic evolution on trap formation and hydrocarbon accumulation were discussed. The results show that: (1) The Cenozoic tectonic evolution in eastern Lufeng 13 subsag can be divided into three stages: Early-Middle Eocene fault depression，Late Eocene fault depression transition，Oligocene-Quaternary regional thermal subsidence depression. The fault depression stage has a complete fault depression cycle. According to the strength of the fault depression activity，it can be further divided into the initial stage，peak stage and shrinkage stage of the fault depression. The reservoirs were relatively developed in the initial stage and shrinkage stage of the fault depression，and the source rocks were relatively developed in the peak stage of the fault depression. (2) Under the influence of multi-stage tectonic activities，many types of traps were formed in Cenozoic in eastern Lufeng 13 subsag，including drape anticline traps， fault anticline traps，fault block traps，fault nose traps，structural-stratigraphic traps (truncation，overlap) and structural-lithologic traps. So many trap types show great potential for hydrocarbon exploration in this area，in particularly，the Wenchang Formation and Enping Formation，which are deposited in the fault depression stage and fault depression transition stage，have developed a large number of traps of various types. Those traps are close to high-quality source rocks and have favorable conditions for hydrocarbon accumulation，which are the key formations for oil and gas exploration in eastern Lufeng 13 subsag. In plane，the southern gentle slope zone has the most types and numbers of traps，followed by the central uplift zone and low uplift zone，which are the most important zones for hydrocarbon exploration in the study area.

Based on the description of lithofacies characteristics of fluvial outcrops，the architectural element types，distribution and stacking patterns of fluvial sand bodies of the eighth member of Permian Xiashihezi Formation in eastern Ordos Basin were studied. The results show that: (1) Braided river and meandering river are developed the eighth member of Permian Xiashihezi Formation in eastern Ordos Basin. Eight types of lithofacies were identified，including massive bedding conglomerate (Gm)，trough cross bedding gravelly sandstone (Gst)， trough cross bedding sandstone (St)，tabular cross bedding sandstone (Sp)，parallel bedding sandstone (Sh)， climbing ripple bedding sandstone (Sc)，parallel bedding siltstone (Fh) and massive bedding mudstone (M). (2) Five architectural elements are developed in the study area，including channels (CH)，channel bars (CB)， abandoned channels (ACH)，point bars (PB) and overflow (OF) deposits，and the vertical sedimentary sequences of these architectural elements are obvious differences. CH: Gm-Gst-St-M-St，CB: Gm-Gst-St-Sp，PB: St-Sp-ScSh-M or St-Sp-Sc-M，ACH: Gm-St-Sp-M，OF: Sp-Fh-M. The vertical sedimentary sequences of ACH are similar to that of CH，but featured with smaller grain size and higher mud content. (3) Nine basic combination types of architectural elements are developed in the study area，namely CH-OF，CH-ACH，CH-CB (vertically and laterally)， CH-CH (vertically and laterally)，CB-OF，CB-CB (vertically and laterally)，PB-PB (laterally)，PB-ACH and PB-OF. (4) The types，stacking pattern and distribution of architectural elements of fluvial sand bodies in the study area are affected by the distance of source and hydrodynamic force. The closer to the source，the better the hydrodynamic force，the larger the sand body scale，and the better the connectivity between the sand bodies. In the braided river near the source，the development of sand bodies at the bottom is better than that at the top，and the reservoir capability of point bars is the best. Multi-stage point bars at the bottom of meandering river in the far-source area are well developed and stack laterally with good connectivity.

By means of thin section identification，scanning electron microscopy，cathodoluminescence，and carbon and oxygen isotope analysis，the diagenesis characteristics and their influence on pores of Neogene MeishanHuangliu Formation under the background of high temperature，overpressure and high CO₂ content in LD10 area of Yinggehai Basin were studied. The results show that: (1) The reservoirs of Neogene Meishan-Huangliu Formation in LD10 area of Yinggehai Basin are developed with gravity flow. The lithologies are mainly medium-fine feldspathic lithic quartz sandstones，and the reservoir physical properties are mainly characterized by ultra-low porosity and ultra-low permeability. (2) Compaction，cementation and dissolution are the main diagenesis types in the study area. Overpressure can obviously inhibit the transformation of clay minerals and the secondary enlargement of quartz，which can protect the primary pores to a certain extent. The high-temperature fluid rich in CO₂ not only causes the abnormal transformation of clay minerals，but also promotes the dissolution to increase the secondary pores. (3) The diagenetic sequence of the second member of Huangliu Formation is summarized as siderite cementation→secondary enlargement of quartz→chlorite cementation→early stage feldspar dissolution→ kaolinite formation→early stage calcite cementation→early stage dolomite cementation→feldspar dissolution→ calcite dissolution→massive illite formation→late stage iron calcite and iron dolomite formation. (4) In general， compaction reduces the porosity by 45.30%-62.93%，and cementation reduces the porosity by 1.65%-35.01%， while dissolution increases the porosity by 0.72%-8.00%. The sandstone reservoir in the middle and lower part of Huangliu Formation is affected by overpressure and CO₂ dissolution，with good physical properties，so high CO₂ risk should be considered during drilling.

Taking the sandstone reservoirs of Neogene Guantao Formation in Gudao oilfield of Shengli Oilfield as an example，based on oil-water relative permeability test and geological knowledge，the characterization model of oil-water relative permeability curves was established. The sandstone reservoir model was established by numerical simulation method，and the applicable conditions of model under different rhythms and different development methods and the influence on development results were discussed. The results show that: (1) The correlations of 7 parameters affecting relative permeability curves，such as permeability measured with gas and average pore-throat radius，with endpoints of relative permeability curves and the shape of curves were respectively fitted. Multiple regression method was carried out by using the alternate conditional expectation method，irreducible water saturation calculation model was established based on permeability measured with gas and average pore-throat radius，and residual oil saturation calculation model was established based on permeability variation coefficient and significant parameters. Based on permeability measured with gas，calculation model for relative permeability of oil phase under irreducible water was established. Based on coefficient of variation and significant parameters， calculation model for relative permeability of water phase under residual oil was also established. The absolute errors of the four endpoint characterization models are all less than 0.1. Referring to Honarpour empirical formula， relative permeability curve shape calculation model of oil phase was established based on uniformity coefficient， and relative permeability curve shape calculation model of water phase was established based on permeability variation coefficient and pore-throat ratio. The absolute errors of the two models are less than 1.7，which proves the reliability of models. (2) In the depletion development simulation of sandstone reservoirs，the production performance is mainly controlled by the relative permeability of oil phase. Normalizing curves derived from the model can eliminate the influence of reservoir heterogeneity to a certain extent. In simulated waterflood development，reservoir heterogeneity can exacerbate the impact of water phase relative permeability on production performance. In the simulation，the relative permeability curve of the reservoir that contributes the most to oil production can be closer to the actual production.

The Da’anzhai member of Jurassic Ziliujing Formation in eastern Sichuan Basin has the typical characteristics of near-source hydrocarbon accumulation. By means of source rock evaluation，fluid inclusion analysis and burial history recovery，the reservoir characteristics and hydrocarbon accumulation of Da’anzhai member of Jurassic Ziliujing Formation in eastern Sichuan were studied. The results show that: (1) The organic matters of Da’anzhai member of Jurassic Ziliujing Formation in eastern Sichuan Basin are mainly type Ⅱ. The measured residual organic carbon mass fraction is 0.67%，the hydrocarbon generation potential is 1.53 mg/g，and the thermal evolution degree of organic matter is 1.1%-1.3%. On the whole，the source rocks of Da’anzhai member have medium to low abundance of organic matters，which is at the peak of hydrocarbon generation. (2) The lithologies of the first submember of Da’anzhai member in the study area are mainly shell limestone and limestone，and the structural fractures are the main reservoir space，followed by dissolved pores (caves) and dissolved micropores developed along the structural fracture. The reservoirs have poor physical properties with ultra-low porosity and ultra-low permeability. (3) There are two stages of crude oil charging and one stage of natural gas charging in the reservoirs of Da’anzhai member in the study area. The two stages of crude oil charging time are about 140 Ma and 25 Ma respectively. The first stage is relatively low maturity crude oil charging，the second stage is relatively high maturity crude oil charging，and the latter is the main charging period. The natural gas charging time is the same as the second stage of crude oil charging，which is mainly associated gas of crude oil.

Through core observation, thin section identification and logging analysis and other geophysical technologies, the characteristics of tight sandstone reservoirs of the third member of Upper Triassic Xujiahe Formation in western Yuanba area of Sichuan Basin were studied. Combined with gas well productivity characteristics and main controlling factors in the study area, the types and causes of gas reservoir sweet spots were summarized, and the distribution of the sweet spots was predicted. The results show that:(1) There are various sandstones of the third member of Xujiahe Formation, among which medium-coarse-grained calcareous lithic sandstone and fine conglomerate are high-quality reservoirs. There are various types of fractures, mainly low angle shearing cracks and diagenetic contraction joints.(2) There are two types of sweet spots, such as medium-coarse-grained calcareous lithic sandstone type and fine conglomerate type, which can be further subdivided into six types combined with fracture characteristics. There are differences in geological characteristics, test methods and trial mining characteristics of various sweet spots.(3) The formation of sweet spots is mainly controlled by sedimentation, diagenesis and tectonism. The medium-coarse-grained calcareous lithic sandstone and fine conglomerate are mostly distributed in the distributary channel near the boundary between delta plain and front. Differential recrystallization is the reason for the formation of gravel-edge fractures. The distribution of fractures is controlled by faults and stratum flexure caused by tectonic activity.(4) The medium-coarse-grained calcareous lithic sandstone and fine conglomerate are characterized by low GR, low CNL, medium-high R_d and medium AC values. The S-wave impedance of high-quality reservoirs and μρ(μ stands for shear modulus, ρ stands for density) are medium-high, and the sweet spots of medium-coarse-grained calcareous lithic sandstone, fine conglomerate and superimposed through gravel cracks are widely distributed in strip shape, while the other four types of sweet spots are sporadically distributed.

Overpressure prediction is of great significance to the study of oil and gas accumulation. By means of logging curve combination，cross plot of acoustic velocity and vertical effective stress，cross plot of acoustic velocity and density，and overpressure comprehensive analysis，the overpressure causes of each layer in Dafengshan uplift of Qaidam Basin were analyzed，and the pressure prediction method was improved. The results show that: (1) The overpressure of Xiayoushashan Formation in Dafengshan uplift of Qaidam Basin is caused by uneven compaction and tectonic compression，and the overpressure of Shangganchaigou Formation and upper Xiaganchaigou Formation is caused by uneven compaction，tectonic compression and overpressure transmission. (2) Single methods such as equilibrium depth method or Eaton method cannot be effectively used to predict the formation pressure in the study area. Based on the difference of different overpressure genesis mechanisms，the equilibrium depth method was used to calculate the formation pressure of Xiayoushashan Formation，and the Eaton method was used to calculate the formation pressure of Shangganchaigou Formation and upper Xiaganchaigou Formation，with more accurate results. The error between the calculated pressure and the measured formation pressure in the study area is less than 7.00%，and the average error is 4.30%. (3) Overpressure prediction can provide data support for reservoir description，reserve estimation and safe drilling operation. Overpressure is the driving force of oil and gas migration. It can be used to indicate the direction of oil and gas migration and estimate the distance of oil and gas migration，which has important guiding significance for the study of oil and gas accumulation.

The Lower Cretaceous Shushanhe Formation in Xinhe area is one of the potential fields of lithologic reservoir exploration in northern Tarim Basin. Based on the drilling data from 15 wells and 3D seismic interpretation results，the stratigraphic division of Lower Cretaceous Shushanhe Formation in Xinhe area of northern Tarim Basin was carried out，the sedimentary microfacies characteristics and plane distribution of Shushanhe Formation were studied，and the sedimentary model of thin sand bodies was established. The results show that: (1) Shushanhe Formation in Xinhe area is in conformity contact with the overlying Baxigai Formation and overlying the denuded basement of Shaya uplift，and can be divided into Shu 1 member，Shu 2 member and Shu 3 member. (2) The rock of Shushanhe Formation in the study area is mainly lithic arkose，followed by feldspathic lithic sandstone and arkose. The microfacies of shore shallow lake mud and shore shallow lake sand bar can be identified. (3) Before the deposition of Shushanhe Formation in the study area，three-level paleogeomorphology of uplift， low uplift and depression developed，which controlled the distribution of sedimentary facies. During the sedimentary period of Shu 1 member，the sedimentary range is limited to the depression area. The strata of Shu 2 member overlapped from the depression area to the east and west sides，and the sedimentary area expanded. The sedimentary period of Shu 1 and Shu 2 members presents the distribution characteristics of shore-shallow lake facies belt from the east and west sides to the middle. During the sedimentary period of Shu 3 member，the study area was further transgressive into shallow lake sediments. (4) The thin sand bodies of Shushanhe Formation in the study area are important exploration fields，and their distribution is controlled by paleogeomorphology，lake level change and paleowater depth before sedimentation.

The upper member of Oligocene Xiaganchaigou Formation (E₃²) in Yingxi area of Qaidam Basin is a self-generation and self-storage type oil and gas reservoir. By using a series of experimental means such as X-ray diffraction analysis of whole rock mineral content，thin section identification，scanning electron microscope observation，carbon dioxide adsorption，nitrogen adsorption/desorption，high pressure mercury injection，nuclear magnetic resonance and spontaneous absorption，the reservoir characteristics of E₃² in Yingxi area were systematically analyzed and the microscopic pore structure characteristics were finely characterized. The results show that: (1) The reservoirs of E₃² in Yingxi area are dominated by fine-grained sedimentary rocks. Its mineral composition is mainly carbonate such as dolomite and ankerite，containing terrigenous clasts such as feldspar and quartz，and clay minerals such as illite-montmorillonite mixed-layer and illite. (2) The reservoir rocks in the study area are relatively dense as a whole. The porosity is 1.0%-14.5%，with an average of 4.0%，while the permeability is 0.011-6.146 mD， with an average of 0.125 mD，which is characterized by low porosity and ultra-low permeability. (3) The pore types of the reservoir rocks in the study area are mainly intercrystalline pores，dissolved pores，caves and fractures， and the pores are parallel slit-shaped. (4) The average pore volume of micropores in the study area is 0.005 6 mL/g， accounting for 34.70% of the total pore volume. The average pore volume of mesopores is 0.006 6 mL/g，accounting for 40.84% of the total pore volume. The pore volume of macropores is 0.0039 mL/g，relatively small，accounting for 24.46% of the total pore volume. Therefore，mesopores contribute the most to rock reservoirs，followed by micropore.

Based on the principle of base level cycle change, the data of field outcrop, drilling, logging and seismic stratigraphic slice were used to analyze the sequence structure, river channel composition characteristics under different accommodation spaces and river type conversion model of the second member of Jurassic Shaximiao Formation in Wubaochang area of northeastern Sichuan Basin. The results show that:(1) There are mainly one third-order and three fourth-order base level cycles developed in the second member of Jurassic Shaximiao Formation in Wubaochang area of northeastern Sichuan Basin. Each fourth-order sequence is a thick layered stacked box type sand body under the low accommodation space. With the base level rising, the accommodation space increases, and it transits to a relatively isolated sand body deposition at the top of the sequence.(2) The paleoclimate of the second member of Shaximiao Formation was dry. Due to the near provenance deposition, the sandstone was coarse and the maturity was low, the strong hydrodynamic structure was developed, it was parallel reflection on seismic profile, and the fluvial facies characteristics were obvious. There are many braided river sedimentary systems with discontinuous positive rhythms superimposed on each other in low accommodation space and meandering river sedimentary systems with binary structure in high accommodation space.(3) The fluvial facies strata of the second member of Shaximiao Formation have a "braid curve" transformation law from bottom to top, which is specifically shown as follows:under the low accommodation space, sand bodies are distributed in a large area, and the seismic geomorphology is shown as mutually overlapping braided river channels. When the base level rises rapidly, the accommodation space increases, and the seismic geomorphology shows a relatively isolated meandering river channel.(4) The accommodation space and sediment supply ratio(A/S) is mainly affected by strong tectonic activity and change from warm and humid to hot and dry climate in Daba Mountain provenance area.

The dolomite-evaporite paragenetic strata are rich in oil and gas resources. Based on the principle of sequence stratigraphy, combined with drilling and thin section data, and on the basis of third-order sequence division, INPEFA and wavelet transform technologies were used to identify and divide the high-frequency sequences of dolomite-evaporite paragenetic strata of Cambrian Gaotai Formation in eastern Sichuan Basin. The results show that:(1) The dolomite-evaporite paragenetic strata of Cambrian Gaotai Formation in eastern Sichuan Basin can be divided into three third-order sequences which are respectively Sq1, Sq2 and Sq3 from bottom to top, and can be further divided into six fourth-order sequences(ssq1-ssq6). The Gaotai Formation is mainly in a carbonate platform sedimentary environment, with mixed tidal flats, confined-evaporative platforms and open platform facies deposits developed in turn from west to east.(2) There are four types of intergrowth rock assemblages of Cambrian Gaotai Formation in the study area, including:thick-layered evaporite overlying dolomite, thick-layered dolomite interbedded with evaporite, interbedded dolomite and evaporite, and thick-layered dolomite overlying evaporite. The dolomite-evaporite paragenetic strata are developed at the contact interface of the fourth-order sequence, and are mostly developed in the highstand systems tract inside the sequence, reflecting a strong disturbance of sea level, especially the relative decline of sea level, which is conducive to the deposition of dolomite and evaporite. (3) The rock assemblage sequence of the dolomite-evaporite paragenetic strata of Gaotai Formation can generate response characteristics on the GR_inpefa and wavelet transform curves. The corresponding 64-scale wavelet coefficient curve fluctuates smoothly, and the energy clusters are weak yellow-blue. The GR_inpefa curve shows lithological difference between evaporite and dolomite in the form of "notch".

Dolomites of Qixia Formation of Middle Permian in Baoxing area of southwestern Sichuan Basin display a complex diagenetic alteration and complex genesis of high-quality reservoirs. The filling characteristics of dolomite reservoirs in the study area were analyzed based on field investigation, macroscopic and microscopic petrological characteristics, cathodoluminescence and fluid inclusion measurement. The results show that:(1) The dolomites of the first member of Qixia Formation of Middle Permian are composed of subhedral medium to coarse-grained dolomites, with zebra texture and tectonic breccia developed. The reservoir spaces are mainly residual intercrystalline pores, residual intercrystalline dissolved pores and dissolved fractures, followed by expanding dissolved fractures and geodes, with porosity of 1%-4%.(2) The dolomite reservoirs in the study area are mainly filled with medium to coarse-grained saddle dolomites and bright crystal calcites, followed by a small amount of quartzs. Locally, medium to coarse-grained dolomites are distributed in the fractures together with calcites in a belt shape. In general, the distribution of dolomites is obviously controlled by faults, and the fractures and caves are relatively developed, and the filling sequence is coarse-grained saddle dolomite-quartz-calcite.(3) During the Middle-Late Triassic period, the Mg-rich thermal brine in deep basin entered the formation along faults and replaced original rock to form hydrothermal dolomites. The hydrothermal cooling effect carried out the dissolution transformation of the early reservoirs, and accompanied by the pressure reduction, led to the precipitation of coarse-grained saddle dolomite and a small amount of calcite. Under the influence of Yanshan movement at the end of Jurassic, the silicon-rich hydrothermal solution in deep basin entered the reservoir and replaced some saddle dolomites and a small amount of quartzs filled holes. In the late Yanshanian period, the carbon dioxide rich fluids with high-temperature and low salinity were supersaturated due to tectonic uplift and precipitated late calcites, which greatly reduced the reservoir space.(4) The reservoirs are intense densification after episodic fluid alteration, and part of the residual vugs or fracture networks are relative porous for hydrocarbon accumulation and migration.

According to the theories of heat transfer and thermal recovery，the SAGD (steam-assisted gravity drainage) unsteady heat transfer model and the analytical solutions of key development indexes were derived， which were taken into account for boundary effect. The rapid prediction of development indexes was realized by using the program design method. The results show that: (1) The existing unsteady heat transfer models have limitations on the temperature assumption of the outer boundary of heat transfer. According to the principle of energy conservation，the outer boundary condition of heat transfer was modified，and the analytical relationship between the heat transfer depth and the accumulated heat transfer was established，which can be used to quantitatively calculate the heat loss of the overburden and underburden. (2) On the basis of Butler’s classical SAGD production model，the analytical models of water production，oil-steam ratio and steam heat utilization ratio in the steam chamber rising stage，lateral expansion stage and downward expansion stage were derived respectively，which can realize the rapid prediction of key indicators in the specific development stage or the whole life cycle of SAGD. (3) By comparing with the actual production indexes of the well group in 6.4 years，the coincidence rates of predicted oilsteam ratio and predicted water-cut are above 95%，which confirms the reliability of the analytical model and the program design. (4) According to the reservoir parameters of Zhong 32 well area in Fengcheng oilfield of Junggar Basin，the predicted and analyzed SAGD steam heat utilization rate and key development indicators under different oil layer thickness conditions show that when the steam heat utilization ratio is greater than 35% and the oilsteam ratio is greater than 0.15，the corresponding oil layer thickness should be greater than 12 m.

Based on core observation and physical property, geochemical analysis and 3D seismic data, through sedimentary facies analysis of single well and well-tie profile, fine seismic interpretation and identification of dominant sand bodies, the hydrocarbon accumulation law and model of Cretaceous clastic rocks in western Tabei uplift were studied from the aspects of oil source, oil and gas charging characteristics, transport system and reservoircap assemblage. The results show that:(1) The Cretaceous oil and gas in the study area has the characteristics of terrigenous origin. The oil mainly comes from Triassic lacustrine source rocks in Kuqa Depression, the gas mainly comes from Jurassic coal-measure source rocks in Kuqa Sag, while the deep Triassic marine source rocks contribute a little to oil and gas.(2) The Cretaceous oil and gas charging in the study area lasted for a long time, and the accumulation period was late. The accumulation can be divided into two phases:oil generation in the early period and gas accumulation in the late period. Oil accumulation occurred in the Miocene(4.0-22.0 Ma), and gas accumulation occurred in the early Pleistocene(3.5-11.0 Ma). Affected by the structural uplift of 2.6-3.5 Ma, the gas reservoir maturity was low.(3) The oil and gas transport system in the study area is well developed. Faults and unconformities are used as the main migration channels in southern Tianshan Mountains. The unconformity surface and thin sand bodies of Baxigai Formation are the migration channels in Shunbei area.(4) The reservoirs in the study area are mainly developed in Shushanhe Formation and Baxigai Formation, with sand content generally higher than 60%, which constitute a good reservoir-cap assemblage with the continuous mudstone developed in the upper part. The distribution of high-quality reservoirs is controlled by sedimentary facies. The high-quality reservoirs in southern Tianshan Mountains are mainly distributed in the front sand bar and beach-bar of fan delta, while the high-quality reservoirs in Shunbei area are mainly distributed in front lobe of braided river delta. At present, the exploration wells are not at the highest part of the lobe, and the oil and gas shows are relatively poor. the reservoir properties in Shunbei area are better.(5) Due to different fault activities and reservoir-cap assemblages, there are obvious differences in the types of oil and gas reservoirs between southern Tianshan Mountains and Shunbei area. The oil and gas reservoirs in southern Tianshan Mountains are mainly low-amplitude structural and structural-lithologic composite reservoirs. The oil and gas reservoirs in Shunbei area are mainly lithologic reservoirs with small scale.

Based on core observation, micro thin section identification and scanning electron microscope analysis, combined with sequence division, the reservoir characteristics and controlling factors of Triassic Feixianguan Formation in eastern Kaijiang-Liangping trough of Sichuan Basin were studied. The results show that:(1) The reservoirs of Triassic Feixianguan Formation are dominated by oolitic dolomite and fine silty dolomite in TieshanpoPuguang area, and oolitic dolomite(with gravel, sand and bean grains) in Dukouhe -Qilibei area, and the original structural components of oolitic rocks are better preserved.(2) The reservoirs in the study area are characterized by multi-stage development. The reservoirs in Tieshanpo-Puguang area are developed in ssq1, ssq2 and ssq3 sequences, with the characteristics of early development, large thickness and wide distribution area, and type Ⅰ, Ⅱ and Ⅲ reservoirs are developed. The reservoirs in Dukouhe Qilibei area are developed in ssq2 and ssq3 sequences, which are late developed, small in thickness and limited in distribution area, and are dominated by type Ⅱ and Ⅲ reservoirs.(3) Sedimentary palaeogeomorphology and sea-level change control the development stages and thickness of oolitic shoal reservoirs in the study area. When sea-level began to decline in the middle and late stages of ssq1, oolitic shoal reservoirs began to develop in the paleogeomorphic highlands with large thickness and obvious dolomitization.(4) The water energy in steep slope and gentle slope margin slope zones affects the types of oolitic shoal sediments, provides a material basis for diagenetic dissolution and dolomitization, and thus controls the physical properties and scale of the reservoir.

Heshui area in Ordos Basin is the main zone for the exploration and development of shale oil in Chang-qing Oilfield. Based on the data of cast thin section, physical property analysis, scanning electron microscopy, high-pressure mercury compression and nuclear magnetic resonance, the characteristics and main controlling factors of shale oil reservoirs of Triassic Chang 7 member in Heshui area of Ordos Basin were analyzed. The results show that:(1) The shale oil reservoir of Chang 7 member in Heshui area is mainly a set of dark gray-black fine siltstone, mainly lithic arkose, and the average volume fraction of fillings is 16.71%. The rock physical properties are poor, with an average porosity of 8.15% and an average permeability of 0.102 mD. It is an ultra-low porosity, extra-low porosity and ultra-low permeability reservoir.(2) The reservoir pores in the study area are mainly feldspar dissolved pores and residual intergranular pores. Sub-micron pores(0.1-1.0 μm) are the main reservoir space, accounting for 75.56% of the total pores, followed by nano pores(with diameter less than 0.1 μm), accounting for 17.94% of the total pores. The throat type is relatively complex, and the tube-shaped throats caused by dissolution and the flake and curved flake throats caused by compaction are the main throat types of the reservoir. (3) Sedimentation, diagenesis and tectonism jointly control the quality and distribution of shale oil reservoir of Chang 7 member in the study area. Sedimentation provides the material basis for the reservoir. The reservoir is mainly formed in the deep-water gravity flow sedimentary environment, which can be divided into two types:sandy clastic flow sand bodies and turbidite sand bodies. The medium-strong compaction and cementation reduce the physical properties of the reservoir. The dissolution has a certain positive effect on improving the physical properties of the reservoir. The fractures formed by tectonism improve the percolation capacity of the reservoir and are of great significance for the later fracturing and reconstruction of the reservoir.

Reservoir sensitivity analysis is an important means to evaluate the degree of reservoir damage, which is of great significance for the later efficient development and remaining oil tapping. The core samples from Neogene Guantao Formation in Kenxi oilfield of Zhanhua Sag in Bohai Bay Basin were selected to analyze the damage index and sensitivity characteristics of reservoirs of Guantao Formation in combination with thin section observation, X-ray diffraction analysis, mercury injection test and flowing water drive experiment. The results show that:(1) The Guantao Formation in Zhanhua Sag of Bohai Bay Basin is loosely cemented. The pore structure is characterized by large pore size, uniform distribution of pore throat and good connectivity. The rock minerals are mainly composed of quartz, plagioclase, K-feldspar and rock debris, and the clay minerals mainly include kaolinite, illite, chlorite and chlorite-illite mixed layer. The upper member of Guantao Formation is dominated by fine grains, while the lower member is dominated by medium grains.(2) The reservoirs of Guantao Formation are generally characterized by medium velocity sensitivity, weak alkali sensitivity and weak salt sensitivity. The acid sensitivity characteristics of the upper and lower members are quite different. The upper member has non-acid sensitivity characteristics, while the lower member has strong acid sensitivity characteristics with index of 78.25%.(3) The content of ankerite and chlorite and pore structure of Guantao Formation in the study area control the reservoir sensitivity.(4) Controlling of injection-production flow rate is an important content of the development plan in the study area, while the reservoir damage caused by acid sensitivity in the lower member of Guantao Formation should be protected and treated.

Petroleum column height is one of the important indicators to determine the degree of hydrocarbon enrichment. Based on the data of hydrocarbon accumulation in major petroliferous basins worldwide, a systematic analysis of petroliferous basins with ultra-high petroleum columns was conducted. The favorable geological conditions for the formation of ultra-high petroleum columns in petroliferous basins were analyzed in combination with hydrocarbon supply capacity, reservoir-cap assemblages and hydrocarbon migration patterns. The results show that:(1) Most of the typical oil and gas fields in the world with ultra-high petroleum columns are dominated by carbonate formations, accounting for 78% of the total. This is because carbonate formations are relatively easy to develop large-thickness stacked reservoirs, which are conducive to the formation of ultra-high petroleum columns.Typical oil and gas fields with ultra-high petroleum columns abroad are mainly distributed in Persian Gulf Basin, Pre-Caspian Basin and Western Siberian Basin, while mainly distributed in Sichuan Basin, Bohai Bay Basin and Tarim Basin in China.(2) The favorable conditions for the formation of ultra-high petroleum columns include sufficient hydrocarbon supply, vertically stacked large-thickness reservoirs, extensive overlying caprocks, vertical network transport system, favorable migration conditions and good source-reservoir configuration.(3) Many ultrahigh petroleum columns have been found in the deep strata of Tarim Basin. Taking the Fuman oilfield as an example, the sufficient hydrocarbon supply from the Lower Cambrian source rocks, the thick reef tuff reservoirs and tight mudstone caprock of Middle and Upper Ordovician, and the favorable migration conditions such as deep and large faults, are the main reasons for the formation of ultra-high petroleum columns in this area.

The fluid inclusions in shale and tight sandstone of Paleogene Shahejie Formation in Bonan sag of Jiyang Depression were tested for Paleopressure, the fluid pressure evolution process was restored, and its petroleum geological significance was discussed. The results show that:(1) The third member of Shahejie Formation(Es₃) in Bonan sag experienced four pressure field reconstruction processes in Guantao Formation and subsequent sedimentary periods. The duration of each pressure field reconstruction is 3-4 Ma, showing the characteristics of low sequence episodic pattern.(2) Different from the low sequence episodic pressure field building process of Es₃, the Es₄ has a high threshold for pressure field reconstruction under the sealing of overlying gypsum rocks. Two pressure field reconstruction processes occurred during the sedimentary period of Dongying Formation and the end of Guantao Formation, showing the characteristics of high sequence episodic pressure field.(3) The low sequence episodic pressure field building process of Es_{3 i} ndicates an open fluid environment and strong acid dissolution. The physical properties of Es_{3 r} eservoir with low sequence episodic pressure field are higher than those of the upper Es_{4 r} eservoir with high sequence episodic pressure field. The hydrocarbon source rocks of Es_{3 n} ot only discharge a large number of hydrocarbons, but also contains hydrocarbons in its own reservoir space, so as to form enrichment areas of conventional oil and shale oil.

Based on core thin section, experimental analysis, drilling, logging and seismic data, the Ordovician carbonate karst reservoirs in Tarim Basin were classified according to the reservoir genetic mechanism, and the distribution, space types and main control factors of various reservoirs were analyzed. The results show that:(1) The Ordovician fracture-vuggy karst reservoirs in Tarim Basin can be divided into five types according to their genesis:(quasi-) syngenetic karst reservoirs, interlayer karst reservoirs, bedding karst reservoirs, buried hill(weathering crust) karst reservoirs and fault-controlled karst reservoirs.(2) (Quasi-) syngenetic karst reservoirs, also known as reef-shoal karst reservoirs, are the reservoir formed by short-term(transient) exposure and leaching of reefshoal facies granular limestone at the platform edge or within the platform due to sea level drop, with matrix pores, dissolved fractures and dissolved caves being developed. They are usually superimposed with later interlayer karst or buried hill karst to form complex karst reservoirs.(3) The interlayer karst reservoirs are developed in the inner zone, and they are related to the parallel(micro-angle) unconformity surface in the carbonate strata and distributed quasi-stratified. The reservoir space is mainly cave type, followed by fracture-vuggy type and vuggy type.(4) The bedding karst reservoirs are related to the slope background, pre-existing pores and fractures around the buried hill, and the surrounding of the buried hill is distributed in a ring band, dominated by vuggy type and fracture-vuggy type, and more than 90% of the dissolved pores and caves are connected through faults and fractures.(5) The buried hill(weathering crust) karst reservoirs are developed in buried hill area. They are related to medium to long-term angle unconformity and greatly affected by faults and fractures. They are quasi-stratified and have obvious characteristics of peak and hill geomorphology. According to the lithology of the surrounding rocks, they can be divided into limestone buried hill karst reservoirs and dolomite weathering crust karst reservoirs. The limestone fracture-vuggy system is developed, the matrix pores are not developed, and the dolomite fracture-vuggy is underdeveloped, mainly consisting of dolomite intercrystalline dissolved pores and fractures.(6) Controlled by faults, karst reservoirs are mainly developed in the fault development area of inner zone. The fractures and vuggy are developed with large burial depth, large scale and long span, and they are distributed in a grid-shape along the faults, dominated by fracture-vuggy type, followed by fault-cave type. The more developed the faults and fractures are, the more developed the dissolved vuggy and caves are, and the higher and more stable the single well oil testing productivity is.(7) Karst reservoirs in the study area are largely developed in the interior area, mainly bedding karst reservoirs and karst reservoirs controlled by faults, with great exploration potential.

Under the framework of source-to-sink system, the sedimentary facies, palaeogeomorphology and seismic configuration attribute slices of Paleogene Wenchang Formation in Panyu 4 depression of the Pearl River Mouth Basin were studied based on seismic configuration analysis, the sedimentary units were divided, the boundaries of each sedimentary unit were defined qualitatively and semi quantitatively, and two exploration potential zones were selected. The results show that:(1) Three types of source-to-sink systems of Paleogene Wenchang Formation were found in Panyu 4 depression of the Pearl River Mouth Basin. A gentle slope divergent source-to-sink system is developed in the northwest, which is characterized by the dynamic evolution of fan delta, lake and braided river delta in the vertical direction, and the seismic configuration changes from medium-strong reflection sheet filling to medium-weak amplitude parallel reflection, and then to high-frequency medium amplitude progradation reflection. A long axis convergent source-to-sink system is developed in the southwest, and the braided river delta is developed stably, which is mainly wedge-shaped in configuration. A steep slope parallel source-to-sink system is developed in the hanging wall of fault controlling depression with stable multi-stage overlapped fan delta, which is generally characterized by a wedge-shaped configuration, reflecting the sedimentary characteristics of fan delta plain-front under the background of abundant sources.(2) The sedimentary palaeogeomorphology of Wenchang Formation in the study area is generally faulted in the east and superposed in the west. During the deposition of the fifth and fourth members of Wenchang Formation, it was in a strong fault depression period. Local tectonic movement raised the northwest and southeast, and a structural ridge and two sub depressions formed in the central part. During the deposition of the third and second member of Wenshan Formation, it entered fault depression period, the sedimentation center moved eastward as a whole, the lake basin shrank, and the western strata were denuded.(3) Seven sedimentary units are developed in the gentle slope divergent source-to-sink area of the study area, which are mainly superimposed underwater distributary channels and thin sheet sand in fan delta front. Four sedimentary units are developed in the long axis convergent source-to-sink area, which are dominated by underwater distributary channels and widely distributed front sheet sand in braided river delta front. In the steep slope parallel source-to-sink area, there are four sedimentary units, including underwater fan, fan delta front, turbidite fan.(4) The long axis convergent source-to-sink system in the southwest and the gentle slope divergent source-to-sink system in the northwest are the exploration potential areas in the study area.

Through the study of structural evolution characteristics, combined with the analysis of hydrocarbon inclusions and fine dissection of typical oil and gas reservoirs, the formation and evolution process of oil and gas reservoirs in the upper member of Paleogene Xiaganchaigou Formation in Yingxiongling area of Qaidam Basin were analyzed. The results show that:(1) The upper member of Xiaganchaigou Formation in Yingxiongling area experienced a semi saline lake, saline lake and salt lake environment during the Paleogene period, and formed a large area of source-reservoir type oil and gas reservoir dominated by laminated calcite dolomite which is rich in organic matters.(2) The upper member of Xiaganchaigou Formation in the study area has experienced three stages of oil and gas filling. The hydrocarbon inclusions in the first stage are single liquid oil inclusions, reflecting the migration and filling of early low mature crude oil. The hydrocarbon inclusions in the second stage are single liquid oil inclusions, which reflects the migration and filling of medium mature crude oil. The hydrocarbon inclusions in the third stage are gas-liquid two-phase oil inclusions, reflecting an episode of filling of highly mature crude oil.(3) The oil and gas in the study area are characterized by three stages of accumulation. In the middle and late stages of the deposition of Shangganchaigou Formation, reservoirs with low saturation and low maturity formed in the upper member of Xiaganchaigou Formation. In the sedimentary period of Shangyoushashan Formation, low mature to mature oil and gas accumulated to the salt reservoirs and high permeable zones, forming a high oil and gas production area. During the sedimentation period of Shizigou Formation to Qigequan Formation, maturehighly mature oil migrated to the upper member of Ganchaigou Formation and above through the transport of double layer faults to form structural oil and gas reservoirs.

Based on the data of logging and oil test, the vertical sealing of Paleogene faults controlling reservoir in Chaluhe fault depression of Yitong Basin was evaluated by using the method of normal pressure of fault plane. The results show that:(1) The present normal pressure of fault plane of oil and gas reservoirs can be calculated by the data of burial depth, average density of overlying strata and fault dip angle. In the Paleogene, the present normal pressure of Paleogene reservoirs in Chaluhe fault depression of Yitong Basin ranges from 13.3 MPa to 56.0 MPa, and the normal pressure during the reservoir forming period was 3.8-13.1 MPa, showing the characteristics of "ancient opening and present closing". As the greater the pressure on the fault plane, the tighter the fault, thus forming a vertical seal, otherwise open.(2) The minimum value of present normal pressure of fault plane of the reservoirs in the study area is 13.3 MPa, which is defined as the critical value of the vertical sealing of Chaluhe fault depression, and the present critical burial depth of the faults controlling reservoir is further determined to be 2 262 m.(3) The normal pressure of fault plane is positively correlated with the fault tightness index, the vertical sealing critical pressure value, critical burial depth and fault tightness index can be used to quantitatively evaluate the sealing ability of the faults controlling reservoir in the study area.(4) The fault can not only serve as the hydrocarbon migration pathway, but also provide shelter for the formation of reservoirs. The faults controlling reservoir of C43 reservoir in the northwestern margin of Chaluhe fault depression showed a vertical opening during the accumulation period, which coincided with the period of hydrocarbon generation and expulsion, with the function of connecting oil sources and migrating oil and gas. The faults controlling reservoir in well region C43-C48 are now in a vertical sealing state, which can effectively seal oil and gas.

Based on the research progress of distributive fluvial system（DFS）， the geomorphic characteristics and main types of DFS were summarized， and the controlling factors of the formation and development of DFS were discussed. The results show that：（1）DFS is not a new or special river channel type，but a regular collection of multiple river channels. The geomorphic characteristics are shown as follows： the river network is radially distributed from one-point，various types of rivers develop together，the geometric shape of the river channel changes greatly，the sedimentary environment includes river channel and interchannel，and the sedimentary system is complex. The main types include alluvial fan，fluvial fan and megafan.（2）Based on DFS radius，area and their surface slope，DFS can be divided into three types as microDFS，macroDFS and megaDFS. The micro DFS，i.e.，alluvial fan，with a radius of less than 30 km，an area of less than 100 km² and a slope of greater than 1.0°. The macroDFS is called fluvial fan，with radius greater than 30 km but less than 100 km，their area is greater than 100 km² but less than 1000 km²，and slope is less than 1.0°. The megaDFS is megafan，which has a radius of greater than 100 km，an area of greater than 1 000 km² and a slope of less than 0.5°. The distribution ranges of the three types have certain overlap and repetition. It is also necessary to distinguish them by combining the hydrodynamic process and sedimentary characteristics of DFS.（3）Tectonic and climate are the most fundamental factors controlling the formation and distribution of DFS. Basin area and provenance may influence the total sediment supply and sediments composition of the depositional system. As an indirect factor，DFS slope may control the channel morphology and the bifurcation and crevasse of the channel together with channel flow and velocity， thus control the sedimentary environment and depositional facies distribution of the DFS.

The mature development technology and large demands of coalbed methane provide favorable conditions for the development of low rank coalbed methane in S block of eastern Australia. However,there is a lack of systematic research on the characteristics of low rank coalbed methane reservoirs. Therefore,the reservoir characteristics such as coal seam development,coal quality characteristics,reservoir physical properties,gasbearing property and preservation condition for low rank CBM were studied by using drilling,logging and core analysis data from S block,eastern Australia. On this basis,a multi-level fuzzy evaluation method was applied to predict favorable areas in S block. The results show that there are six sets of long flame coal with medium-high ash and a cumulative thickness of 25 m are developed in the study areas. Macroscopically,the coal is mainly composed of semi-bright coal and bright coal,the content of vitrinite is the highest in macerals,and vitrine is the dominated microstructure in coal. The pore structure is mainly mesopores and macrospores,cleats and fractures are relatively developed,and the permeability is 399.85 mD. The average gas content is 4.3 m³/t,and good hydrogeological conditions and temperature,pressure system also ensure the enrichment of coalbed methane to a certain extent. The distribution of favorable areas is mainly controlled by gas content,cumulative thickness and permeability. It is considered that the low rank coalbed methane resources in S block of eastern Australia have good potential for development.

Through analyzing a large number of overseas exploration cases in the past 30 years of CNPC“going out”,the current exploration status,distribution characteristics and exploration models of lithostratigraphic reservoirs were systematically summarized,and the exploration potential of global lithostratigraphic reservoirs and outlook for lithostratigraphic reservoirs of CNPC overseas were pointed out. The results show that:（1）The exploration of global lithostratigraphic reservoirs has gone through four stages,and is currently in a mature stage of development. The large-scale deep-water sediments and reefs have become the main areas for discovering giant lithostratigraphic oil and gas fields.（2）Lithostratigraphic reservoirs newly discovered by CNPC overseas exploration and global lithostratigraphic reservoirs are mainly distributed in composite traps,mainly developed in foreland,rift and passive continental margin basins,The former has the largest reserves found in rift basins,followed by foreland basin,while the latter has the largest reserves in foreland basin,rift basins was the second.（3）CNPC overseas has implemented the same deployment and integrated exploration strategy for structural and lithostratigraphic oil and gas reservoirs,forming three distinctive exploration models:Stereoscopic exploration for multiple lithostratigraphic reservoirs,discovered high abundance lithologic reservoirs in lower combination,high buried hill reservoirs and low buried hill-lithologic complex reservoirs in Bongor Basin of Chad,and channel,fan delta,subaqueous fan and buried hill reservoirs in South Turgai Basin of Kazakhstan;High resolution 3D seismic exploration for complex lithologic bodies,discovered large gentle slope reef-beach complex gas reservoirs in Amu Darya Basin of Turkmenistan,giant lacustrine reef-beach oil fields in Santos Basin of Brazil,and deep-water turbidite sandstone biogas reservoirs in Rakhine sub-basin of Myanmar;Geology and engineering integration exploration for thin layer low amplitude structural-lithologic complex,discovered low amplitude structural-lithologic complex oil reservoirs in Oriente Basin of South America and thin layer reef-beach oil reservoirs in the Oman sub-basin of Middle East.（4）The exploration of global lithostratigraphic reservoirs will expand from mature exploration areas to frontier areas with low exploration levels,and from onshore to deep-water and ultra deep-water areas. The deep-water sedimentary bodies,subaqueous fans,and reefs in passive continental margin basins will be the hotspots of lithostratigraphic reservoir exploration. Subaqueous fans and burial hills in rift basins,composite traps related to reefs in foreland and passive continental margin basins will be the main targets of lithostratigraphic reservoirs exploration for CNPC overseas,which have favorable prospects for exploration.

The distribution of hydraulic fractures is very important for the efficient development of tight conglomerate reservoirs. Through the observation of fractures in the core from the horizontal coring well MaJ02 in the fractured conglomerate oil area of Mahu Sag，the type，occurrence，formation，opening，density and proppant filling of hydraulic fractures in the tight conglomerate reservoirs of Triassic Baikouquan Formation in Mahu Sag were analyzed，their distribution characteristics were clarified，and the formation mechanism was discussed. The results show that：（1）The hydraulic fractures developed in the cores of Baikouquan Formation in well MaJ02 account for 77.6% of the total number of fractures，with a strike of 90°-110 ° and a dip angle of 70°-90°. （2）The shear fractures formed by strike-slip mechanism in the study area account for 65.8%，followed by tensile fractures formed by tensile stress，accounting for 34.2%. Most of the shear fractures are in groups with small openings and fully filled，and the fracture surface is mainly through gravel，and multiple cracks are superimposed to form a fracture network fracture zone. The tensile fractures are mostly single with relatively large openings and irregular fracture surface，which are fully or half-filled，and the fracture surface is mainly surrounded by gravel.（3）The smaller the distance between the coring well and the fractured well in the study area，the smaller the perforation cluster spacing in the fracturing section，and the greater the hydraulic fracture density. Under the same fracturing engineering conditions，the fractures of argillaceous supported floating conglomerate facies and front sheet sand microfacies are relatively developed. The higher the sand content，the greater the hydraulic fracture density.