By investigating a large number of domestic and foreign literatures on casing deformation in shale gas wells，the types of casing deformation in shale gas wells were summarized，the differences and problems of influencing factors of casing deformation in deep and shallow shale gas wells were discussed，and the corresponding prevention measures and the main research directions in the next step were put forward. The results show that：（1）The types of casing deformation in shale gas wells mainly include squeezing diameter deformation and shear deformation. The probability of casing deformation in deep shale gas wells is greater than that in middle and shallow layers，and is mainly shear deformation.（2）The engineering factors that cause casing deformation include wellbore cooling，cementing quality，casing fatigue，casing quality and wellbore dogleg degree. The geological factors include rock mechanical properties，non-uniform in-situ stress stress and natural fracture/fault slip. The casing deformation of deep shale gas wells is mainly affected by natural fracture/fault slip.（3）Measures can be taken to reduce the risk of casing deformation，such as controlling wellbore temperature and injection strength，using cement with lower mechanical properties of cement sheath for cementing operation，appropriately reducing the outer diameter of casing，increasing wall thickness，improving steel grade，to improve casing quality，and smoothing well trajectory as far as possible. For deep shale gas wells，the risk of casing shear deformation can also be reduced by designing the extension direction of the horizontal section of the wellbore to be consistent with the bedding direction of the rock formation，mastering the fracture distribution，avoiding the high-risk shear slip section as much as possible，reasonably reducing the fracturing scale for different levels of slip risk sections，and adjusting the wellbore orientation.（4）The research directions of casing deformation prevention and control of shale gas wells mainly include four aspects：optimizing fracturing layers with good rock mechanical properties，analyzing the relationship between optimal well trajectory and in-situ stress，identifying and evaluating fractures，calculating fault slip and casing variables.

In order to standardize overseas oil reserves evaluation,a method for classifying and categorizing overseas lithologic reservoir reserves,determining lithologic boundary,o il bearing area and effective thickness was proposed. The results show that:（1）Reserves classified as P generally require a development plan approved by the company or the government of the resources country. P1 reserves are calculated based on wells with commercial production or commercial test flow rates,and their area is usually determined by the drainage area of the production wells and the range limited by the known gas bottom or the known oil top and oil bottom. The reserves within half the distance from the P1 reserves boundary to lithologic boundary are P2 reserves,and the reserves within the range from P2 reserves boundary to lithologic boundary are P3 reserves. If there is no oil water contact within the trap or cannot be determined yet,P3 reserves should be determined based on the spill point of the trap. If there are significant changes in lithologies or reservoir physical properties,P2 reserves can be determined by extrapolating one development well spacing based on P1 reserves,and P3 reserves can be determined by extrapolating one development well spacing based on P2 reserves.（2）When the distance from a class P reserve well to the pinchout line of a permeable reservoir is no more than 3-4 times the development well spacing,for medium to high porosity and permeability reservoirs,the pinchout line can be directly determined as the lithologic boundary,while for low porosity and permeability reservoirs,the minimum effective thickness contour line that can meet the class P reserve standard is determined as the lithologic boundary. The oil and gas bearing area should be comprehensively delineated by lithology boundaries,oil（gas）water contact,tight layer sealing zones,etc,the wells within the area should meet the class P reserve standard. For oil and gas reservoirs with identified fluid interfaces,the fluid interfaces used to delineate oil and gas bearing area should be confirmed by drilling and coring data or testing data. For oil and gas reservoirs with unidentified fluid interfaces,the oil and gas bearing area should be determined by extrapolating the lowest confirmed bottom boundary of the oil and gas producing layer or the effective thickness value through testing.（3）The determination of the effective thickness of P1 reserves should have reliable formation testing data or sufficient logging data and have demonstrated its production capacity. The determination of the effective thickness of P2 reserves usually lacks conclusive testing data and has not confirmed its production capacity. Due to the uncertainty in rock physical interpretation,there is significant uncertainty in the effective thickness of P3 reserves.（4）It is recommended to use the volumetric method for evaluating lithologic reservoir reserves. The application example in TP oilfield in Ecuador has confirmed the effectiveness of the classification and categorization of lithologic reservoir reserves and reserves evaluation method.

In order to solve the problems of low opening rate caused by directional gas channeling in the middle and later stages of CO₂ flooding development in low permeability reservoirs, poor overall development results and potential safety issues, numerical simulation and laboratory experiments were used to analyze the effects of anti-controlled gas channeling, to ensure the production rate of oil wells and other technical methods. The results show that the CO₂ of water-gas alternating is more uniform and the oil recovery efficiency is better than that of gas injection, wheel injection and continuous gas injection. When the monthly CO₂ injection-production ratio is 1.7 to 1.8, it can simultaneously maintain the mixing capacity and prevent gas channeling, so as to decrease water cut and increase oil production. In view of gas channeling characteristics of oil well, different flow pressure control standards were formulated to maximize the CO₂ flooding effect. The pressure field changes can be adjusted by periodic oil recovery, which can increase the frequency of oil and gas contact to promote mixed phase and expand the volume of CO₂. The periodic oil recovery effect of typeⅠgas wells is better than that of type Ⅲ gas wells and the continuous oil recovery. The safety production is effectively guaranteed by adjusting the injection production ratio and controlling the reasonable production pressure difference, installing the wellhead control valve and setting up wellhead single well tank regular pressure relief. The results can provide technical reference for the development of CO₂ flooding test and promotion in Jilin Oilfield and the same kind of oil reservoirs in China.

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.

On the basis of clarifying the conception of reservoirs, according to the history of the research on reservoirs, it is an inevitable course of history that stratigraphic-lithologic reservoirs are regarded as an important part in the petroleum prospecting. The category, genesis and prospecting features of stratigraphic-lithologic reservoirs are summarized, and three typical examples are analyzed.

Three oil-gas bearing regions have been proved in Qaidam Basin since the 1950’s, including Tertiary oil filed in west, Jurassic oil field in north and the Quaternary gas field in east. It is a problemconcerned by the petroleum geologists where the new targets are for the further exploration. The discoveries of eclogite, ultramafite and gold mine in the periphery of the basin and gypsum-salt, dolomite, illite and strontiummine in the basin indicate the existence of mantle fluid activity. The seismic sounding result shows that low velocity-high conductive layers widely developed in the mid-crust of Qaidam Baisn. The analyses of the relationships between the low velocity-high conductive layers and discordogenic fault, between the fault and the unconformity and between the shallow fault and the reservoir take a significant part in looking for large oil and gas fields. The research shows that the further exploration should be stressed in deep granite and weathered crust in Chaixi area, and the deep of Sanhu area is the favorable target for looking for large gas fields.

Based on the analysis of distribution characteristics of proved reserves of low abundance reservoirs in Daqing peripheral oilfield, the main principles and methods for determining oil-bearing area of proved reserves of low permeability reservoirs in northern Songliao Basin are summarized. According to the change of area after the exploitation in typical blocks, the influence of wells per square kilometer on the determination of oil-bearing area is analyzed. The quantity of drilling wells per square kilometer is considered to be controlled by the size and shape of sand and the type of reservoir in northern Songliao Basin. It should be increased to 0.5 to 1.0 per square kilometer in the evaluation stage for lithologic reservoirs.

Aiming at the problem of ineffective circulation of injected water caused by fixed streamline in the late stage of water drive development of Paleogene fault block reservoirs in Dongying Sag, Jiyang Depression, Bohai Bay Basin, based on seepage mechanics and reservoir engineering principles, the injection-production coupling development adjustment technology of“subdividing development layers, rotating injection and production”was proposed by means of indoor physical model simulation and reservoir numerical simulation, and the mechanism of enhancing oil recovery by this technology was clarified. The results show that:（1）The water absorption ratio model between high permeability channel and low permeability channel during injection and the oil production ratio model of mainstream line and non-mainstream line during oil production established by the injection-production coupling development technology reveal the injection-production coupling seepage mechanics mechanism of“changing pressure field to promote the adjustment of seepage field, achieving balanced injection and production, expanding sweep efficiency of water drive and increasing the oil displacement efficiency”. （2）The injection-production coupling technology can achieve remarkable development effect of“expanding sweep efficiency and increasing oil displacement efficiency”, that is, it plays a similar role of“profile control”. During the high water cut period, this technology can increase the diversion rate of low permeability cores from 1.0% to 18.6%, and the model displacement is more balanced. After two rounds of injection-production coupling adjustment, the oil recovery of high and low permeability cores increased by 10.3% and 16.1%, respectively. （3）The numerical simulation results of injection-production coupling development of Es₂3⁶ oil-bearing sublayer of Paleogene Shahejie Formation in fault block D of the study area show that the displacement of mainstream line and non-mainstream line was more balanced, and the pressure gradient range between them decreased from 2.3 to 1.4. After three rounds of injection-production coupling development and adjustment, the average comprehensive water cut of the reservoirs in the third to the sixth sand layers of the second member of Shahejie Formation decreased by 3.2%, and the cumulative oil production increased by 1 760 t, which improved the oil recovery by 2.1%, and the effect of increasing oil production and dewatering was remarkable.

Aiming at the current status that low salinity water flooding has been applied to pilot test abroad while in China there is little research, this paper analyzed the current research status and existing problems, and proposed prospects for low salinity water flooding. It is concluded that for sand reservoirs, the main mechanisms of low salinity water flooding are similar to alkaline flooding, fines migration and the wettability alteration caused bymulti-component ion exchange, while for carbonate reservoirs, the mechanismof lowsalinitywater flooding is wettability alteration caused bymulti-component ion exchange. Crude oil properties, reservoir rock properties, formation and injected water salinity and reservoir temperature can all influence the effects of low salinity water flooding. The main problems lie in the unclear mechanisms, low salinity water source limitation and reservoir adaptability. Finally, it is pointed out that low salinity water flooding can be combined with current oilfield development techniques, coal bed methane production techniques, development techniques for low permeability oilfield and high water-cut oilfield, which will form new economical, environmental-friendly and great potential techniques for enhanced oil recovery.

Based on the analysis of lithostratigraphic gas reservoirs exploration course in China from initially discovery to development, lithostratigraphic gas reservoirs are considered to take a significant contribution to the reserves increase. According to the study on the distribution characteristics, the lithostratigraphic gas reservoirs in China mainly distribute in large palaeohigh and slope in craton basin and special lithosome in fault depression, which will be the main fields for searching for large lithostratigraphic gas reservoirs.

Despite technological advances in lab instruments, grain-size analysis has many limitations, such as low speed. A theoretical method of determining grain size based on spatial autocorrelation coefficient of simulated rock section was proposed. Firstly, spatial autocorrelation coefficient was obtained from a group of known distribution grain size of rock section. Secondly, an unknown distribution grain size of rock section was used to calculate spatial autocorrelation coefficient. Finally, linear least squares method about spatial autocorrelation coefficient was solved with constrains. In order to show the feasibility and availability of this method, a serial theoretical rock sections were simulated by random ellipse process. Relationship between spatial autocorrelation coefficient and grain size of simulated rock section was analyzed. With the decrease of offset or increase of grain size of rock section, spatial autocorrelation coefficient is increasing. Grain size distribution of simulated rock section was determined accurately. For example, gritstone was separated into 0.5～1.0 mm, 1.0～1.5 mm and 1.5～2.0 mm, whose computed percentages are respectively 55.8%, 24.6% and 20.2% by the proposed method, closing to the actual values, and the variation trend is same as the actual.

Reservoir microscopic pore structure directly affects the reservoir storage and permeability, so the research on reservoir microscopic pore structure characteristics can help to carry out reasonable classification evaluation of reservoir, and find out reservoir distribution law, improve the productivity and recovery ratio of oil and gas. Based on a large number of relevant literatures, this paper summarized and expounded the origin, test methods, theory research progress and comprehensive evaluation of reservoir microscopic pore structure, analyzed the main existing problems in the research of domestic reservoir microscopic pore structure, and pointed out that the research of the domestic micro structure is mainly based on traditional methods, having the problem of insufficient combination with domestic actual geological condition and lack of quantitative research.

Undergoing an evolution cycle of Palaeozoic “block-trough” andMesozoic “basin-orogenic belt”, Qaidam Basin developed four different types of source rocks, including Carboniferous marine-continental transitional facies, Jurassic limnetic facies, Tertiary saline facies and Quaternary salt lake facies, and formed a compound oil/gas system of “multisource, multi-depression, and multi-kitchen”, which has a characteristic of “multi-factor controlling hydrocarbon-charging, multi-structure and multi-type-trap reservoir formation, multi-layer oiliness”. Based on the research of reservoir forming mechanism, it is revealed that different types of reservoir can form outside the source rock, on slope, in late Himalayan traps and deep layer, which can guide the exploration and bring newdiscoveries and progress.

Helium resource in Weihe Basin is abundant and holds great potential for exploration and development. Based on the research process related to helium resource in Weihe Basin，the exploration history，helium source rock，helium carrier and groundwater system，theoretical models of helium accumulation，resource quantity forecast，and prospect priority were summarized，and the existing issues and countermeasures for key techniques in helium exploration and development were discussed. Research findings show that：（1）Helium resource in Weihe Basin was discovered in 1970s，including methods of gravity，magnetics，geochemistry，seismics，and drilling，as well as the latest deployed five helium exclusive exploration wells. However，the exploration level remains low.（2）Helium source rocks widely distributed in the basement and south margin of Weihe Basin show significant potential for helium generation. The effectiveness is closely related to key factors，such as the content of radioactive elements of Th and U，formation age and characteristics of geological structure. The Late Paleozoic coal-bearing strata may remain in the deep basin，providing a carrier gas source for the upward migration of deep helium. Helium-rich natural gas is closely associated with groundwater，and the carrier gas and formation pore-pore water are important carriers for helium migration and enrichment. Based on the genetic method，the effective helium resources in Weihe Basin are estimated to be 33.8×10⁸ m³. Considering the overlapping characteristics of geothermal energy，biogenic gas and helium resource in Weihe Basin，Huazhou-Tongguan area is identified as an important target area for comprehensive exploration and development of multiple resources.（3）The helium exploration well drilled into Archean metamorphic rock basement and IndosinianYanshannian granite. Formation conditions of helium-rich natural gas in Huazhou exploration area are controlled by various factors，such as helium source rock，deep faults，and effective sealing conditions.（4）The exploration and development of helium resource in Weihe Basin still faces several problems and challenges，such as inability to accurately assess helium reserve，significant difficulties in exploration，need for improvement in key engineering technologies，and the requirement for further study of economic sustainability. In response，the related countermeasures have been proposed，including strengthening seismic data processing and technology research of helium downhole engineering，optimizing the matching technique of safe drilling，and trying to carry out the related work about extraction and concentration of helium at wellhead.

The organic-rich shales of the second member of Kongdian Formation （Ek₂） are developed very well in Cangdong Sag, Huanghua Depression. Research on geochemical characteristics of the shales is highly significant for the shale oil resource evaluation. Based on collecting and sorting the research results of predecessors, additional core samples were taken to carry out tests and analysis of organic carbon, rock pyrolysis, chloroform bitumen “A”, kerogen maceral and vitrinite reflectance. Single well numerical simulation of burial and thermal history and geochemical evolution sections were also
studied. Organic-rich shales of Ek₂¹, Ek₂² and Ek₂³ were all evaluated as the best source rocks. The types of organic matterare mainly of ⅠandⅡ₁ , with small amount of Ⅱ₂ and Ⅲ. Immature to low mature shales are mainly distributed in central uplift zone, while the organic-rich shales in slope zones are at low maturity to maturity stage. The organic-rich shales of Ek₂ began to generate and expulse immature to low mature hydrocarbon in early Eocene and reached the peak in the late sedimentary period of Guantao Formation. Then with being continuously buried deeply, the source rocks could entered into
low mature to mature hydrocarbon generation stage and the conversion rates of hydrocarbon generation is as high as 60%.

Based on experimental analysis of source rock，gas and reservoir fluid inclusions，we systematically study the geochemical properties，development environment，origin and source of natural gas，hydrocarbon accumulation period and reservoir control function of the Cretaceous source rock in the Dehui fault depression， Songliao Basin. The results show that：（1）The TOC of Cretaceous source rocks in Dehui fault Depression is generally greater than 1%，the organic matter types are mainly type Ⅲ，and type Ⅱ samples are mainly distributed in Non gannan Depression，which is generally in the mature to high mature stage of abundant gas；The source rocks of Huoshiling Formation and Yingcheng Formation were formed in the depositional environment of reduction-weak reduction and high-water salinity，and the lower biogenic sources such as plankton and algae contributed more in the source rocks of Huoshiling Formation in Nongannan Depression，and the oil generation capacity was stronger. （2）The composition of cretaceous natural gas varies greatly，with alkane gas ranging from 2.0% to 98.5% and CO₂ content ranging from 0.1% to 96.5%；The main type of gas is coal-derived gas，and some gas samples show signatures of carbon isotope inversion because of secondary gas charging at different epochs. In the Guojia Depressions，Huajia Depressions and Nongannan Depressions，the hydrocarbon-bearing rocks are mainly the Huoshiling Formation. The gas in the Baojia Sink probably comes primarily from the source rock of the Zhuocheng For mation. The genetic type of CO₂ gas is predominantly inorganic. As the burial depth increases，the carbon isotopic composition of the carbonate cement shows a positive shift，indicating the risk of drilling deep into the highly inorganic CO₂ gas layer.（3）The source rocks in Nongannan Depression are in the stage of oil generation. From the south to the north，the thermal evolution degree of the source rocks increases gradually，which controls the phase distribution of“oil from the south to the north”and controls the hydrocarbon accumulation period. Industrial oil and gas wells are mainly located near the center of the high thick source rock，which controls the distribution of oil and gas reservoirs.

The response surface regression analysis technique is an integrative method for optimization procedure. It not only can build continuous curved surface model, but also can form response surface to estimate the interaction of the influence factors, which can make up the shortage of traditional single factor experiment. This technique is firstly applied to carbon dioxide drive numerical simulation, and the influencing factors are analyzed. The good result shows that response surface regression analysis technique can be used for experiment design and analysis in petroleum research.

Shale gas is one of unconventional gas resources and stores in organic rich shales and mudstones as free gas and absorbed gas in pores developed in organic matter and mineral matrix. Shale gas accumulation is considered as a cumulative gas charging within organic rich shales, and the organic rich shales serve as gas source, reservoir and seals. The gas origin in shale gas reservoirs could be thermogenic, biogenic or the mixing of both. The feature of low porosity （<10%） and low permeability （μD～nD） in shales requires hydraulic fracturing to enhance pore connectivity for achieving commercial gas production. A success of shale gas development in the United States is a typical model of comprehensive integrating between shale gas geological characterization and petroleum engineering technologies. Shale gas exploration in China is in its early stage but shows a great resource potential. The low-level shale gas survey, immature technologies for shale gas development, unclear understanding of main controlling factors of shale gas reservoirs, the lack of the theory and model of shale gas accumulation are challenging issues for shale gas success in China.

Based on well drilling and logging, as well as core observation, the reservoir rocks in the study area are mainly cryptite in open platform facies, followed by granular limestone. Combined with well logging interpretation and statistical data of fractures and cavity of core samples， it is concluded that the main reservoir space types are dissolved cavity and low angle dissolved fracture that is semi-filled and unfilled. The thick Upper Ordovician un-karstic strata made the Ordovician reservoir obstructed from the karst alteration. The paleokarst reservoir developed mainly below Caledonian parallel unconformity, and the reservoir quality is much poorer compared with the reservoirs in the main region of Tahe Oilfield where Upper Ordovician is absent. It is well developed when closer to the host of Tahe oilfield. The paleokarst reservoir developed at the top of the Ordovician Yijianfang Formation and the reservoir development decreased with the increase of burial depth. The reservoir development is controlled by sedimentary facies, Caledonian karstification, fault and fracture. It is concluded that Ordovician Yijianfang Formation may be the main reservoir space.

The advantages of huge carbonate reservoirs in Riphean period （1 650～800Ma） and Wendian period （670～ 590 Ma） of East Siberian platform include the following aspects: the formation of high quality source rock of dark shale during the Riphean Aulacogen evolution stage, the long-term developed paleo-uplifts within the craton basins are the major oil and gas enrichment zones, the stable distributed cap rock of gypsum is the key for the preservation of ancient reservoirs and the lithologic reservoir with structural background is the main reservoir type for petroleum accumulation. Comparing with the Sichuan, Tarim and Ordos basins in China, the common features of carbonate reservoir in these basins include strong heterogeneity and rapid lateral alternation. The differences include the significant changing of hydrocarbon generation indicators of shale source rock, the large thickness of Mesozoic to Cenozoic sedimentation and the deep burial of the lower combination within the superimposed basins. The carbonate exploration in China should comprehensively focus on the following aspects: evaluate the shale source rock of Sinian and Cambrian, evaluate the cap-rock condition of multi-phase reconstruction superimposed basin and enhance the exploration of lithology reservoir with structural background. The recent exploration should focus on great basins, seek the great structural background and develop the great combination zones of structure and lithology. Focusing on Sichuan, Tarim and Ordos basins, we should carry out structural reservoirs exploration of large-scale uplifts and buried hills and stratigraphy and lithologic reservoirs exploration of regional unconformity, slope zones of paleo-uplifts, great pinch-out zones of strata, reef on platform margin and grain banks symbiosis with evaporate rock within platform.

Based of X-ray analysis, conventional logging data combined with multielement nonlinear regression and grey theory analysis are applied to determine the clay mineral content in the area where is poor in natural gamma ray spectrometry log. The result shows that the method is accurate for determining the clay mineral content, so it can provide theory foundation for reservoir evaluation and sensitivity analysis.

A majority of oil and g as reserves have been discovered that are located in the Mesozoic a nd Cenozoic fault basins of terrestrial facies in eastern China. These basins have different sizes and types with great discrepancy of reserves, whereas most of oil and gas fields that have been discovered and developed are obvious structural trap. With the continual enhancement of Chinese hydrocarbon exploration activity,the difficult increasing and type transferring,the targets of hydrocarbon exploration have been changed to subtle li thologic and stratigraphic trap. Therefore it is much necessary to analyze and research the characteristics of depositional filling at different structural zone during different evolutive phrases in this basin in order to provide geological theories and science evidences for the exploration of lithologic and stratigraphic trap.Dongying Sag belongs to Jiyang Depression of Bohaiwan Basin, which is a typical lake basin of half-garben with the terrestrial coarse clastic deposits. The depositional filling pattern and extensional characteristic of sandstone within Dongying Sag are very representative to study this type of basin.So,the paper emphasized that Dongying Sag has been analyzed from both spatiality and timein the view of sedimentology. A set of corresponding relationship has been expatiated that structural characteristic directly controls the depositional filling characteristics,climate straightly determines the property of deposits, sediment supply and lake-level changes mainly dominate the patterns of spatial depositional filling.The depositional filling model and corresponding relationship in the v arious structural zones during each evolutive stage have finally been summed up. These results can provide help and evidences for hydrocarbon generation and distribution in faul t basin of terrestrial facies.

Using the biomarker parameters of n-alkane, the carbon isotope of full oil and the distribution pattern of single molecule, combined with the composition and carbon isotopic characteristics of natural gas, this paper discussed the oil and gas origin and genesis in Dongping area, Qaidam Basin. The results show that the n-alkane odd and even carbon number predominance of condensate oil in Dongping 1 well is equivalent （CPI =1.021, OEP =1.004）, showing the characteristic of high-mature crude oil. The Pr/Ph is 3.06, showing the pristane advantage. The carbon isotope of condensate oil（-31.25‰） is close to the carbon isotope of the Jurassic limnetic facies crude oil in the northern margin of Qaidam Basin, and the distribution characteristics of single molecule carbon isotope demonstrate the organic biological source of terrigenous higher plants. It is considered that the oil and gas in Dongping area are from Jurassic hydrocarbon source rocks, and the natural gas is a typical coal-type gas.

The reservoir classification study is important work for managing scientifically the reservoir and raising the effects of oilfield development．In view of the reservoir characteristic parameters，the reservoirs are classified by cluster analysis method on the basis of the similar relationship of the reservoir features，which overcomes the influence of human factors．According to the attribute value of each category．the discriminant functions are established．The multibank discriminant methods are applied to calculate the probability of the standard type for unknown reservoir,and then the similar degree with the standard one is decided．Thus the type of the unknown reservoir is determined accurately． The result shows that the use of these two kinds of mathematical methods can classify and manage the reservoir scientifically．

Clay mineral is an important component part of reservoir, and its content and feature have a great effect on oil field development. The identification of the clay mineral types by using natural gamma- ray spectroscopy log method was discussed. The result showed that using natural gamma- ray spectroscopy log could not only identify the types of the clay mineral, but also determine the content of the clay mineral in the reservoir, which could provide effective reference for the development plan of oil field.

Giant carbonate stratigraphic-lithologic oil and gas field is an important type of oil and gas field in the world. It has been proved to be rich in oil and gas resources and production. Ninety-four carbonate stratigraphiclithologic oil and gas fields were theoretically analyzed, including their geographical distribution, strata distribution, trap types, buried depth and reserve scale of reservoirs,and the main controlling factors of their distribution were discussed. Such oil and gas fields are mainly distributed in the North America, Middle East and Central Asia, among which North America has the most abundant oil and gas,and the oil and gas resources of carbonate reservoirs are mainly accumulated in the Ordovician, Carboniferous, Paleogene and Neogene. The traps can be classified as biological reef, grain beach, diagenetic trap, unconformity and weathering crust. The reservoir burial depth of these oil and gas fields is generally less than 5 000 m,and the oil and gas fields with reservoir burial depth of more than 5 000 m account for only 6.4%. The effects of the following five key factors on the formation and distribution of giant carbonate stratigraphic-lithologic oil and gas fields were discussed:(1) The stable and confined shallow water environment and mid-low latitude are conducive for the generation and preservation of organic matter.(2) Tectonic movement not only increases the reservoir spaces by producing a large number of faults and fracture zones, but also promotes the migration and accumulation of hydrocarbon(usually matching with the hydrocarbon generation stage), and provides a favorable background for paleo-karstification(. 3) Diagenesis such as paleo-karst improves reservoir performance.(4) Evaporite plays an important role in sealing oil and gas.(5) Trap finalization time and hydrocarbon generation and expulsion time of source rocks need to achieve a good matching relationship in time and space.

The formations from the Upper Sinian toMiddle Triassic in Sichuan Basin are marine deposits and mainly composed of carbonate rocks. Through 50 years petroleum exploration, fifteen carbonate gas-bearing beds have been found in the basin. Among them, carbonate rocks of Upper Sinian and Cambrian have been completely dolomitized, and the others also have dolomitization more or less. There are various explanations for the genetic model of dolomite in marine carbonate reservoir in Sichuan Basin, mainly including: protogene, penecontemporaneous, reflux, meteoric-seawater mixing water, burial, hydrothermal fluid, leaching of basalt and biogenesis. Dolomite reservoir is regarded as one of the most important carbonate reservoir, and the dolomitization is the prerequisite for the development of high-quality carbonate reservoirs in Sichuan Basin. The burial dolomitization and meteoric-seawater mixing dolomitization of marine carbonate rocks have been widely queried, and there are two taphrogenesis events and related extensive fluid activities in marine carbonate rocks in Sichaun Basin, so hydrothermal dolomitization could be more widespread than previously thought in Sichuan Basin.

As petroleum exploration goes into a more and more mature stage, deep clastic reservoir is becoming an important new area for exploration in the oil-gas basins. The research of deep petroleum exploration is focusing on the mechanism of the clastic reservoir evolution. The formation mechanism of the deep effective clastic reservoir is complex and closely connected to the sedimentation, diagenesis and tectonism. Sedimentary environment is the prerequisite and foundation for forming effective reservoir. Secondary pore produced by the main constructive digenesis vastly improves reservoir physical properties. Depositional environment and diagenetic conditions that can prevent or slow down diagenesis effectively is conductive to the reservoir physical properties, including low geotemperature, rapid burial history, abnormal pressure, gypsum-salt bed effect, hydrocarbon inject, grain coats and fluid activity, etc. During the evolution of deep reservoirs, tectonic compaction reduces the pore volume, while the structural fractures improve the seepage ability of the reservoir porosity, forming effective fractured reservoir. Thus, the reservoir forming mechanism was suggested with the deposition, dissolution and tectonism being fundamental, key and occasion respectively. Through using modern technology, conducting the diagenesis modeling experiments and using new methods with the inter-discipline knowledge, have already become the main development trends of the research of the forming mechanism of the deep effective clastic reservoir.

The importance of stratigraphic reservoir exploration is rising day by day on the condition that the field of national oil and gas exploration is transferred fromstructural reservoir to litho-stratigraphic reservoir. On the basis of the former research, this paper centers on the unconformity and classifies the stratigraphic trap into three types: the on- lapping typed trap above the unconformity, the barrier typed trap belowthe unconformity and the truncation type of trap between the former unconformity and the later unconformity according to the difference of trap mechanism. This paper summarizes the formation mechanism of stratigraphic reservoir from the strength and the structure of the unconformity. Furthermore, authors point out the distribution law of different type of stratigraphic reservoirs and exploration suggestion for different type of stratigraphic reservoirs. Finally, this paper points out some theories and techniques which are in great need for stratigraphic reservoir exploration.

As the key in the process of reservoir modeling, facies modeling provides reservoir framework for the simulation of the reservoir parameters. Based on the analysis of several commonly used facies modeling, it was presented that using shale content and comprehensive well log interpretation to reconfigure lithofacies in lithofacies modeling, which is available for the work area without sufficient accurate sedimentary microfacies study. The principle and importance of the variogram were expounded. A set of effective methods was suggested referred to the problems occurred in the process of variogram calculation. The effectiveness of these methods has been proved in practice.

With the decarbonization of energy worldwide，natural hydrogen，as a primary energy，has gained widespread interest for its carbon-free emission and renewability. However，natural hydrogen has not yet to be explored in China. Through the review of the main geological settings and genesis of natural hydrogen with a high content（greater than 10%）discovered worldwide，the beneficial geological factors for natural hydrogen accumulation were systematically summarized，and the exploration prospects of natural hydrogen in China were evaluated based on the exploration and development status of natural hydrogen abroad. The results show that：（1）Global high content natural hydrogen is mainly developed in ophiolite belts，rift valley，and Precambrian iron-rich strata，mainly inorganic genesis，and the serpentinization process of iron-rich minerals is the most critical source of natural hydrogen，followed by degassing in the deep earth and water radiolysis.（2）High-quality hydrogen sources and good migration channels are the prerequisites for hydrogen enrichment，and the sealing ability of the cap rocks is a key element for the formation of natural hydrogen reservoirs. When natural hydrogen is used as associated gas，the traditional cap rocks can seal it，but may be difficult to form effective sealing when its content is high. The rift valley environment，ophiolite development areas，and the fracture-developed Precambrian iron-rich strata are the favorable areas for the exploration of hydrogen-rich gas reservoirs.（3）Many countries and regions abroad have formulated plans to explore，develop，and utilize natural hydrogen. Mali has realized commercial exploita‐tion of natural hydrogen，and the United States and Australia have also successfully drilled natural hydrogen ex‐ploration wells.（4）The areas with high hydrogen content in China are highly compatible with hydrogen-rich geological conditions，and the prospects of natural hydrogen exploration are good. The Tan-Lu fault zone and the peripheral rift basin areas，the Altyn fault zone and the basin areas on both sides，and the Sanjiang orogenic beltLongmenshan fault zone and peripheral basin areas have great natural hydrogen exploration potential. China should carry out the survey work of natural hydrogen as soon as possible，strengthen the research on hydrogen reservoir accumulation process and potential evaluation，and carry out research on exploration technology，ex‐traction and separation technology，and storage and transportation technology，to prepare technological reserves for large-scale development and utilization of natural hydrogen.

Based on the mercury penetration analysis of more than 300 samples and analysis result s of more than 260 casts and more than 100 image pores , and referred to the classification criterion about clastic reservoir , especially low permeability reservoir , the low permeability sandstone reservoirs in Ordos Basin were divided into four types and four sub-types. The four types include low permeability reservoir ( I) , extra-low permeability reservoir ( II) , super-low permeability reservoir ( III) and tight reservoir ( IV) . Among them extra-low permeability reservoir and super-low permeability reservoir are the main reservoir types of Triassic Yanchang Formation in Ordos Basin. According to t he characteristics of t he pore structure and petrophysics and the classification criterion of the reservoir thickness , they are divided into two
sub-types respectively.

A series of studies, such as source analysis of both the light and heave materials, tectonic modelling and hydrocarbon source rock evaluation, have been carried out to investigate the forming conditions and exploration prospect of Shuixigou group in northern piedmont belt of Turpan-Hami Basin. The research results suggest that: (1) Shuixigou group in north piedmont belt was once dominated by the south source system before the sedimentation of Xishanyao formation. Sand-bodies generated by braid delta are well developed. (2) North piedmont belt of Turpan-Hami basin can be divided into three parts: thrust belt, anticline belt, and slope belt. The thrust belt can also be further divided as a thrust-superimposed body in hanging wall and underlying belt in footwall. Underlying anticlines are developed in the thrust fault zone of footwall, distributed in both rows and belts. Piedmont belt in this area goes through multiple tectonic evolution stages, including three sliding and two thrusting phases. (3) Source rocks in Yierxitu, Taodonggou, and Sangonghe formations show the ability of hydrocarbon generation, indicating a potential in the tectonic traps such as anticlines beneath the underlying belts, faulted anticlines and et al. We finally conclude that the tectonic group of underlying anticlines in the piedmont belt can be a promising target for oil&gas exploration in Turpan-Hami Basin.

Structural belt of buried hill is a building unit which shows great concentration of hydrocarbon in eastern-China faulted basin, but the research of the relationship between buried hill and hydrocarbon trap is still weak. Taking the buried hill belt of western Liaohe Sag as a research target, this paper expounds the internal structure of buried hill and the control action of accumulation from various aspects, including structural framework and active phases of inner buried hill, formation lithology and attitude, morphological unit classification and distribution framework, trapping types and hydrocarbon source conditions，hydrocarbon migration and accumulation conditions. The hydrocarbon trap is divided into palaeogeomorphology reservoir and stratigraphic hydrocarbon reservoir of inner buried hill. It establishes the “new source and old reservoir” hydrocarbon accumulation that the hydrocarbon migrates fromtop to bottom, then parallel migrates fromlowtomediumburied hill along unconformable face, at last fills in buried hill and forms the reservoir. The hydrocarbon accumulation model provides references for deep exploration activity of buried belt in Liaohe Sag.

China is rich in terrestrial shale oil resources. After more than a decade of exploration of terrestrial shale oil focusing on basic research,key areas and selection evaluation,remarkable progress has been made in technological innovation,industrial test and pilot production,large-scale development,making it a key area for future oil and gas exploration. The systematic analysis was carried out about the geological characteristics,resource potential and development status of typical terrestrial shale oil all over the world,which can provide a reference for the geological evaluation and exploration and development of terrestrial shale oil in China. The results show that:(1) It is a superiority of high organic matter abundance,overpressure,and fragile calcareous layers and porous dolomite of the Uteland Butte member,Uinta Basin,USA,providing favorable conditions for horizontal well drilling.(2) Except for the USA,of the 152 shale oil formations in 101 basins worldwide,24 are terrestrial shale oil formations,accounting for about 19% of the total terrestrial shale oil resources.(3) There are six terrestrial source rock units are developed in six petroliferous basins in Argentina where the exploration and development of terrestrial shale oil is limited by low TOC content and source rock thickness.(4) REM Formation in Cooper Basin was estimated for about 2.4×10⁸ t of technically recoverable resource according to burial depth(less than 2 000 m),vitrinite reflectance(R_o=0.7%-1.0%) and reservoir thickness(greater than 15 m).(5) The Prosopis, Mimosa and Kubla Formation in the Bongor Basin of Chad are the target formations for shale oil development, estimated a technically recoverable resource of 3.42×10⁸ t,with the characteristics of high TOC content,moderate thermal maturity(R_o=0.7%-1.2%) and shallow depth(500-3 000 m).(6) The technically recoverable resources of shale oil of Early Cretaceous in Doseo Basin are 9.77×10⁸ t.(7) The counterpart of the Brown Shale Formation and Talang Akar Formation in Sumatra Basin are 3.8×10⁸ t and 5.61×10⁸ t,respectively.(8) The terrestrial shale oil resources in Western and Northern Europe are mainly found in the Permian-Carboniferous Formation in Paris Basin,France,and the Wealden Formation in Lower Saxony Basin,Germany,and the technically recoverable shale oil resources are 4.36×10⁸ t and 0.18×10⁸ t respectively based on organic matter maturity and burial depth. The study can provide a reference for terrestrial shale oil exploration in China.

Seismite is a type of catastrophic deposits with recognizable evidence for seismic activities and sequence. According to core observation and description, many deformation structures with seismite characteristics are recognized within sandstone and shale sedimentary strata of Paleogene continental faulted basin in Yangxin Subsag, such as micro-faults, earthquake fissures, liquefaction sandstone veins, water-escape structure, vibrational liquefaction deformation structure, seismic pillow structure and associated structure, etc. The vertical sequence of seismites in Yangxin Subsag, in ascending order, is underlying unshocked layer, micro-faults layer, autoclastic shattered breccia layer, vibrational liquefaction deformation structure layer, seismic pillow structure and associated structure layer, liquefied homogeneous layer and overlying unshocked layer, which corresponds to different earthquake intensity respectively. The discovery of seismites can be used to analyze the intensive activity stages of basincontrolling boundary fault, and seismite itself is a kind of potential reservoir, so it has important geological significance for studying earthquake event deposit.

Deliverability analysis of horizontal well is the basic work of getting economic benefits, and it provides basis for horizontal well optimization, perfecting work system, production dynamic analysis and adjustment. At present, there are twomethods of deliverability calculation for horizontal well, namely analytical method and simulation method. The deliverability prediction methods for conventional horizontal well, multilateral well, fractured horizontal well and horizontal well pattern are summarized. The birth and development of deliverability analysis theory are reviewed, the new advances at home and abroad in the deliverability analysis theory and methods are introduced, the problems exists are expounded, and the development direction is pointed out, which will be helpful for improving the application of horizontal well in oilfield development.

Aimed at the shortage of classification evaluation for extra- low permeability reservoirs, several new techniques developed in reservoir research are introduced in recent years. Four classification evaluation parameters for extra-low permeability reservoir are proposed, including effective porosity, mainstream throat radius, movable fluid saturation and start-up pressure gradient. The reservoir classification evaluations are carried out to nine blocks. The results show that the seepage capacity and effective reservoir space could be effectively reflected. This classification method will be important to guide the oil/ gas field development.

For the requirement of petroleum exploration, logging techniques develop rapidly. Several logging techniques are analyzed. High resolution array induction, microresistivity image well logging, three component induction resistivity logging and cross dipole acoustic logging tool are favorable for the research on formation heterogeneity and anisotropy. Nuclear magnetic resonance logging, cable formation test and sidewall coring improve the recognition of formation fluid. Recently, new logging technique of electrokinetic logging is proposed. The measuring principle and apparatus composition of new techniques from Schlumberger, Halliburton, Atlas, Computalog and Russia are introduced, which is helpful for the development of our current scientific research and production. The current status and difference of the logging technologies in China are discussed, and the developing direction is pointed out.

Some quantifying parameters are so far unclear about water cut rising rule of reservoirs. The corresponding relationship between water cut rising features and geological features of reservoirs has not been established. Reservoir geological model and case analyses were used to define the quantifying parameters of water cut rising rate. The quantifying parameters of water flooding rate and the corresponding relationship between water breakthrough time in wells and bottom-water types were obtained. Two types of reservoir heterogeneity were defined: discrete heterogeneity and continuous heterogeneity.Discreteheterogeneousreservoirshavethestep-typecurveof water cut rising, while continuous heterogeneous reservoirs have the continuous curve of water cut rising. The relative permeability curves of porous media are not straight lines because of high capillary pressure, which results in the non-straight line type of water cut rising curves in such reservoirs. However, the relative permeability curves of fractured-vuggy media are straight lines because of low capillary pressure, which results in the straight line type of water cut rising curves in fractured-vuggy reservoirs.