Lithologic Reservoirs

In viewof the problem that the relation between oil and water is complicated in oil and gas exploration, by dissecting oil and gas reservoirs and analyzing the matching relationship between oil and gas distribution and reservoir forming conditions, this paper studied the oil and gas enrichment rule and its controlling factors of Shahejie Formation in Qijia-Yuanyanggou area. The result shows that hydrocarbon mainly distributed in Sha 2 member in profile and step Ⅲ in plane, and most of the reservoirs are fault-lithologic reservoirs. The enrichment of oil and gas is mainly controlled by the development of sand reservoir and traps, lateral sealing of faults and fault activity during late period. The enrichment of oil and gas in different layers has different controlling factors. The nondevelopment of traps of Sha 2, submember 1 of Sha 3 and Sha 4 member is the main cause for failure wells, while the nondevelopment of sand reservoir of sub-member 2 and sub-member 3 of Sha 3 member is the main reason for failure wells.

Characteristics of buried hill reservoir in Jizhong Depression

GAO Changhai， ZHANG Xinzheng， ZHA Ming， WANG Xiaoyan

2011, Vol.23(6): 6–12 Abstract ( 483 ) PDF (832 KB) ( 664 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.002

It is difficult to explore the buried hill reservoir in Jizhong Depression because of the strong heterogeneity of carbonate reservoirs and the complex hydrocarbon distribution. The theories and methods of petroleum geology, geophysics and organic geochemistry, combined with exploration practice, were applied to systematically study the characteristics of buried hill reservoir in Jizhong Depression. The result shows that the hydrocarbon in buried hill mainly came fromthe source rocks of Eogene and Permo-Carboniferous system. The reservoir is composed ofMiddle-Upper Praterozoic and Lower Paleozoic carbonate rocks, and pores, caves and fractures are the main reservoir spaces. The cap rocks are composed of argillaceous rocks of Eogene, coal measure strata of Permo-Carboniferous system and interlayers of inner buried hills, and there developed eight sets of reservoir-cap rocks assemblage. The faults and unconformities are the main hydrocarbon migration pathways of buried hills. The buried hill reservoirs can be divided into hilltop type, hillside type and inner buried hill type. The buried hill reservoirs are mainly located in eastern depressed areas, and distributed close to fractural belts near source rocks, forming the complex hydrocarbon accumulation belts. These research results will be helpful for the disclosure of hydrocarbon accumulation rules, and provide guidance for the target evaluation and favorable zone selection.

Diagenesis and its influence on reservoir properties in Qie 6 well area of Kunbei Oilfield

LI Wenlong， MU Zhonghai， QU Xinzhong， TENG Xianqing， HUANG Jing

2011, Vol.23(6): 13–17 Abstract ( 517 ) PDF (974 KB) ( 451 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.003

Based on the analysis of ordinary thin sections, cast thin sections, scanning electron microscope and X-ray diffraction, this paper studied the diagenesis types, evolutionary phase, evolutionary series and influencing factors of reservoir properties of E1+2 and E31 in Qie 6 well area ofKunbei Oilfield. The result shows that the sandstone of E1+2 and E31is in the late stage of middle diagenetic stage A, and the main diagenesis types are compaction, cementation, dissolution, metasomatism and cataclasis. The experienced compaction, quartz secondary enlargement and cementation of calcite and anhydrite are the main destructive factors of reservoir properties, while the dissolution of feldspar, detritus and calcite and cataclasis are the constructive factors of reservoir properties.1

Origin and carbon isotope geochemistry characteristics of middle-shallow natural gas in the middle part of Western Sichuan Depression

ZHU Jinli, ZOU Yue，CHEN Dongxia

2011, Vol.23(6): 18–23 Abstract ( 494 ) PDF (545 KB) ( 597 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.004

The middle part of Western Sichuan Depression is one of the major gas-producing areas in Sichuan Basin. However, there still exist some different opinions on the genesis and origin of middle-shallow natural gas in this area. In order to get a better understanding of the issues, the authors selected 56 gas samples and analyzed their carbon isotope compositions of C1 - C4, which were collected from producing wells in Xiaoquan-Xinchang-Hexingchang, Luodai-Xindu and Majing gas fields, and analyzed the origin of the middle-shallow natural gas combining with the natural gas composition and the source rock geochemistry characteristics. The population distribution of the methane carbon isotopes indicates a normal pattern of δ13C1<δ13C2<δ13C3<δ13C4. And the carbon isotopes showan obvious decrease vertically from the deeper Xu 4 member, Shaximiao, Suining and Penglaizhen formations until the shallower Lower Cretaceous gas reservoirs, reflecting the origin and migration characteristics of the natural gas. By means of calculating differences between δ13C2 and δ13C1, it could be concluded that the gas maturity increases from deep to shallow. In addition, the paper illustrated that the natural gas of Shaximiao, Suining and Penglaizhen formations in the study area behaves a type of pyrolysis gas and are mainly fromXu 5 and Xu 4 members, partly from Ziliujing Formation.

Quantitative study on Triassic diagenetic facies in Wuxia area, Junggar Basin

TAN Kaijun，XU Duonian，YIN Lu，DAI Dongdong，QI Wen

2011, Vol.23(6): 24–29 Abstract ( 517 ) PDF (997 KB) ( 723 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.005

Reservoir properties are closely related to the burial diagenesis. By studying diagenetic facies, we can effectively determine the favorable reservoir which is directly related to reservoir properties. On the basis of reservoir characteristics and diagenesis analysis, by recovering the original porosity, we quantitatively calculated the visible compaction rate, visible cementation rate and dissolution rate of Triassic reservoir in Wuxia area. According to the calculation results, we made classification criteria for reservoir compaction, cementation and dissolution rate, and described the diagenetic facies characteristics of nine types. By quantitative evaluating the diagenetic facies, it is considered that the favorable reservoirs mainly distribute in the area ofWuerhe nose uplift and Xiazijie fault zone with mediumcompaction, weak cementation and strong dissolution.

Sandstone component of outcrops of Yanchang Formation in the margin of Ordos Basin and its geological significance

HE Jing，FENG Shengbin，YUAN Xiaoqi，HAN Peng，XIE Guwei，ZHANG Caili

2011, Vol.23(6): 30–36 Abstract ( 459 ) PDF (533 KB) ( 880 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.006

Outcrops of Yanchang Formation in the margin of Ordos Basin are widely spread with abundant strata. It is favorable area for research of sedimentary and hydrocarbon generation characteristics in lacustrine basin. According to systematic sampling and measurement of the outcrops of Yanchang Formation, combining with sandstone detrital component analysis, this paper discussed the provenance of Yanchang Formation. It is considered that there exist several provenances from different orientation in Late Triassic in Ordos Basin, including east-north, eastsouth, west-south, west, west-north and north, and sedimentary systems which dominated by the east-north, west and west-north proveniences spread widely. There are great differences of detrital components, heavy mineral assemblages, and interstitial material components and assemblages of sandstones under different sedimentary systems that dominated by different provenances or different depositional stages in the same sedimentary system. Comprehensive studies indicate that the research of sandstone component characteristics of outcrops has great significance for provenience analysis, sedimentary systems division, sand body distribution and favorable reservoir prediction, stratigraphic correlation between outcrops and cores, exploratory well deployment and reservoir reconstruction.

Physical simulation on hydrocarbon accumulation of lithologic reservoirs and its mechanism in continental rifted basin

ZHAO Weiwei，ZHA Ming

2011, Vol.23(6): 37–43 Abstract ( 479 ) PDF (1290 KB) ( 528 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.007

As the hot spot and emphasis of petroleum exploration, lithologic reservoir is the main type of subtle reservoirs for increasing reserves in continental rifted basin, but there are many differences of cognition in the aspect of migration process and hydrocarbon mechanism. According to the hydrocarbon accumulation characteristics of lithologic reservoirs in continental rifted basin, the physical simulation on hydrocarbon accumulation process was carried out, and the accumulation mechanism of lithologic reservoirs was studied. The result shows that lithologic reservoirs have differences in accumulation process, accumulation characteristics and accumulation efficiency under different conditions. The episodic accumulation has high accumulation efficiency and high speed characteristics. Hydrocarbon source conditions, charging patterns, pressure, faults, sand bodies properties are the main controlling factors of lithologic reservoir accumulation. Among these conditions, fault connected migration pathway is the critical factor of lithologic reservoir forming. The research results may have important significance for research of hydrocarbon accumulation mechanismof lithologic reservoirs in continental rifted basin.

Diagenesis of Chang 6 oil reservoir set in Fengdikeng-Hongde area, Ordos Basin

LUO Junmei，LUO Shunshe，CHEN Xiaojun，ZHU Junqiang

2011, Vol.23(6): 44–49 Abstract ( 477 ) PDF (1054 KB) ( 463 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.008

Chang 6 oil reservoir set is the major exploration target in Fengdikeng-Hongde area of Ordos Basin. Because it has such petrological characteristics as fine grain size, low compositional maturity, poor psephicity and worse sorting, it is extremely important to carry out study on the diagenesis which controls the physical properties of reservoir. Combining with the data from plainlight microscope, scanning electronic microscope, cathodoluminescence, X-ray diffraction analysis and homogenization temperature test of fluid inclusion, the diagenesis of Chang 6 oil reservoir set was studied systematically. The result shows that the main diagenesis types include compaction, pressure solution, cementation, metasomasis and dissolution, and its diagenetic evolution lies mainly in the middle diagenetic stage A. Based on the diagenetic study and combined with clay mineral components, cement and growing situation of pores, the Chang 6 oil reservoir set is divided into five kinds of diagenetic facies, namely kaolinite cementation, chlorite cementation, ferrocalcite cementation, chlorite film plus feldspar dissolution and feldspar dissolution, among which the latter two kinds are the most favorable reservoir facies.

Sedimentary environment of Jialingjiang Formation in Danfeng-Tanghe area, southern Sichuan Basin

WANG Wenzhi，TIAN Jingchun，ZHANG Xiang，LONG Hui，LIU Dongmei，SUN Li

2011, Vol.23(6): 50–55 Abstract ( 623 ) PDF (1087 KB) ( 500 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.009

Based on core observation and rock slice identification, combined with the studies on the combination of rock types，fossils，sedimentary texture, sedimentary structure and sedimentary sequence, the Jialingjiang Formation in Danfengchang-Tanghe area is divided into two sedimentary facies including open platform and restricted platform, and further divided into five subfacies and several microfacies. The distribution of sedimentary facies of Jialingjiang Formation was studied, and the sedimentary environment and its evolution were analyzed. It is considered that the carbonate rocks of Jialingjiang Formation has frequent sea-level changes, experienced six evolution stages，and formed three times of larger transgression-regression sedimentary cycle. Each cycle is composed of small subcycles, while small subcycle is composed by a number of little rhythms. After detailed study on the lithology and sedimentary environment, it is considered that the most favorable layers for shallow particles dolomite and beach room dolomite are Jia Ⅰ-Jia Ⅱ1 member of Jialingjiang Formation in Tanghe and Danfengchang area and Jia Ⅱ3member in Tanghe and Linfengchang area.

Sedimentary characteristics and evolution of Paleogene Lower Xiaganchaigou Formation in northern Mahai area, northern margin of Qaidam Basin

SUN Guoqiang， XIE Mei， ZHANG Yongshu， ZHAO Mingjun， KANG Jian， SHI Jian

2011, Vol.23(6): 56–61 Abstract ( 516 ) PDF (1156 KB) ( 626 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.010

Based on the analysis of sedimentary sequence, cores, grain size, well logging data, the sedimentary characteristics and evolution of Lower Xiaganchaigou Formation of Paleogene in northern Mahai area，northern margin of QaidamBasin，were studied. The result shows that the Lower Xiaganchaigou Formation displays an obvious regression, and the sedimentary facies is mainly braided fluvial facies. The study on sedimentary systems demonstrates the sedimentary facies distribution and evolution rule more clearly, which provides reliable geologic information for the next exploration activity.

Characteristics and significance of Carboniferous volcanic rocks in Dinan uplift

XIONG Yixue，XI Aihua，RAN Qiquan，GE Yuhui，LIU Xiaohong，SUN Yuanhui

2011, Vol.23(6): 62–68 Abstract ( 492 ) PDF (976 KB) ( 474 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.011

Based on core observation, thin section identification, petrochemical analysis and reservoir property data analysis, the characteristics and significance of Carboniferous volcanic rocks in Dinan uplift were studied. The result shows that the Carboniferous volcanic rocks in Dinan uplift have the characteristics of coexistence of basic, intermediate and acidic, and intercrescence of subalkaline and alkaline series. Basic volcanic rocks mainly are alkaline series and distributed in Dixi 17 well area. Intermediate-acidic volcanic rocks can be divided into alkaline and sub-alkaline series, the former mainly distributed in Dixi 14 and 18 well areas, and the latter mainly distributed in Dixi 17, 14 and 10 well areas. The lithology distribution on the plane has obvious zonation showing the gradual transition from basic rock to acidic rock towards the southeast.Magmatic process controls the volcanic texture, structure and matrix properties, which led to a gradual deterioration of physical properties frombrecciated lava to volcanic tuff.

Characteristics and influencing factors of fractures of Chang 4+5 reservoir in southern Puziwan area, Jiyuan Oilfield

YU Lei， CHEN Jianwen， LI Yuan， LI Weihua， CHEN Zhenbo

2011, Vol.23(6): 69–72 Abstract ( 506 ) PDF (422 KB) ( 657 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.012

There are a large number of natural fractures in Triassic reservoir in Jiyuan area of Ordos Basin. Based on core, microscopic thin slice and logging interpretation, the palaeomagnetism, ground stress and homogenization temperature are applied to analyze the characteristics and forming stages of the natural fractures of Chang 4+5 reservoir in southern Puziwan area, and the influencing factors for fracture distribution are studied. The result shows that the natural fractures of Chang 4+5 reservoir developed well in the study area, and they are mainly of high-angle and effective fractures. The direction of fractures is affected by regional tectonic movement, and mainly of NE-SW. Lithology, strata thickness and sedimentarymicrofacies are the main influencing factors for fracture development.

LA-ICP-MS U-Pb dating of zircon from basement igneous rocks in Yitong Basin and its significance

ZOU Yu， CHEN Zhenlin， MIAO Hongbo， NONG Junnian

2011, Vol.23(6): 73–78 Abstract ( 510 ) PDF (766 KB) ( 411 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.013

In order to determine the formation period of Yitong basement accurately, six zircon samples are selected to carry out the study on LA-ICP-MS U-Pb dating of zircon. Zircons fromthe basement igneous rock are euhedral in shape and show the typical oscillatory zoning with magmatic origin. The dating results indicate that the biotite-monzonitic granite at the depth of 2 484.2 m in C24 well in Chaluhe fault depression formed in （176.8 ±1.7 ）Ma, the crack lithification perthitr monzonite at the depth of 3 153.0 min C17 well formed in （171.8±3.2）Ma, the basement igneous rocks in X5 and L2 wells in Luxiang fault depression respectively formed in （170.3±3.4）Ma and （169.1±4.5）Ma, and the basement igneous rocks in Y53 and Y3 wells in Moliqing fault depression respectively formed in（247.2±3.4）Ma and（186.6±2.5）Ma. In combination with other U-Pb dating, it is considered that the age of basement igneous rocks in Yitong Basin is mainly of 170～336 Ma, and the most formed in Yanshanian, and a little formed in Hercynian. The distribution of granite in each fault depression is different. The most of granites in Chaluhe and Luxiang fault depression formed in Yanshanian, while in Moliqing fault depression the granites formed in Hercynian, Indosinian and Yanshanian.

Characteristics of reef reservoir of Changxing Formation in Wenquanjing and adjacent areas of northeastern Sichuan

JIAO Zengyu， ZHANG Fan， ZENG Deming， DU Jiangmin，ZHANG Hongxia， FENG Mingyou

2011, Vol.23(6): 79–83 Abstract ( 505 ) PDF (833 KB) ( 558 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.014

Based on core observation, thin section analysis, well logging data, the characteristics and controlling factors of reef reservoir of Changxing Formation in Wenquanjing and adjacent Huanglongchang and Wubaiti area of northeastern Sichuan were studied in detail. The result shows that the main reservoir rocks are fine-medium crystalline dolomite, clay-powder crystalline dolomite, medium-coarse crystalline dolomite and reef limestone（dolomite）, among which the fine-medium crystalline dolomite is the best. The physical property is poor, generally with porosity less than 2% and permeability less than 1.0 mD. The main reservoir spaces mainly are secondary intercrystal pores and intercrystal dissolved pores and intergranular dissolved pore, followed by small caves, and fractures developed locally. The pore structure has the characteristics of lowporosity and small throat. The main reservoir type is porosity type, and fractureporosity type is developed locally. The reservoir in the study area is mainly of type Ⅲ, and typeⅠand Ⅱ are rare. The reservoir formation and evolution are mainly affected by sedimentation, diagenesis and tectonism. Sedimentation is the foundation of reservoir formation, diagenesis is the key factor to improve the reservoir, and tectonismprovides conditions for reservoir improvement.

Seismic plane sedimentary facies interpretation method and its application

WANG Ligong， BI Jianjun， WANG Zhenhui， WANG Xuexi， GAO Xingxing， WANG Yafei

2011, Vol.23(6): 84–88 Abstract ( 434 ) PDF (1265 KB) ( 606 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.015

Traditional three-dimensional seismic interpretation has a good effect on the exploration research of structure reservoir, but it can not solve the problemin the exploration and study of lithologic reservoir. This paper proposed a new seismic interpretation method: plane sedimentary facies interpretation. Based on the method of seismic slice interpretation, it develops the key technologies such as multi-attribute fusion imaging, projection of slicing sedimentary facies and auto-tracking of plane lithofacies. These technologies fully use the characteristics of lateral continuity, and can improve the efficiency and accuracy of seismic-geologic interpretation and have recognition capability for small geologic bodies and significance for exploration and study on lithologic reservoirs.

Seismic inversion technique based on volcanic sequence and its application

HUANG Yu， BAI Xiaoyin， GUO Xuan， TAN Kaijun

2011, Vol.23(6): 89–92 Abstract ( 506 ) PDF (545 KB) ( 523 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.016

As a special type of reservoirs, volcanic reservoir is characterized by fast lithology and lateral lithofacies change, strong heterogeneity, complex geologic and seismic conditions, which makes the recognition of effective volcanic reservoir difficult in the aspects of plane distribution, burial depth, thickness and properties changes, and it is difficult to obtain accurate prediction effect by conventional seismic inversion techniques. In viewof this difficulty, this paper analyzed the high quality volcanic reservoir in Hongche fault zone in the northwestern margin of Junggar Basin, established the volcanic sequence, and predicted the high quality volcanic reservoir distribution law by using multiattribute constrained seismic inversion technique. The predicted area of favorable reservoir in the study area reaches 57.4 km2. It will promote the oil and gas exploration of volcanic reservoirs in this area.

Three-parameter AVO inversion method based on modified Cauchy distribution

YUAN Huan， WANG Yuchao， SHI Lanting， HU Ziduo，YUAN Gang

2011, Vol.23(6): 93–96 Abstract ( 608 ) PDF (468 KB) ( 500 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.017

Three-parameter AVOwaveforminversion can be used to estimate P-wave velocity reflectivity, S-wave velocity reflectivity and density reflectivity simultaneously. But the method is often ill posed and difficult to get a high resolution result. Based on Bayesian procedure, combined with seismic deconvolution frame, a priori constrained method based on modified Cauchy distribution is proposed. This method has a strong ability of antinoise. It can improve the stability of inversion, recover the sparsity of reflectivity sequence very well, protect information of weak reflection body excellently, and offer a result with high resolution. The simulation test shows that inversion parameters are almost perfectly retrieved quickly.

Prediction of Sulige gas reservoir with multi-wave pre-stack inversion based on dual γ models

ZHAO Wanjin， ZHANG Qiaofeng， ZHANG Jianxin， LI Hailiang， SUN Hui

2011, Vol.23(6): 97–101 Abstract ( 405 ) PDF (594 KB) ( 407 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.018

The He 8 member of Shihezi Formation in Sulige Gas Field of Ordos Basin mainly developed fluvial facies reservoir which is characterized by strong heterogeneity and vertically superimposed sand bodies with fast lateral variation. So, conventional inversion can not be used to distinguish the tight sand fromgas-bearing sandstone effectively. The pre-stack multi-wave inversion based on dual γ model and simulated annealing was applied to carry out the reservoir prediction. The method makes use of time-travel and amplitude energy to calculate each ratio（γ） of P-wave velocity and S-wave velocity, and then estimate the best γ by simulated annealing, making the P-wave and S-wave match the best, finally, carry out the P-wave and S-wave velocity inversion with P-wave intercept, gradient and S-wave gradient. Simulate annealing method, which uses interval quartation to determine critical temperature, can be used to obtain global optimumvalue for object function accurately and steadily. The actual data inversion result proves the validity and applicability of this method.

Study on AVO model numerical simulation based on wave equation

LV Shanshan，XIONG Xiaojun，HE Zhenhua

2011, Vol.23(6): 102–105 Abstract ( 534 ) PDF (449 KB) ( 514 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.019

The conventional AVO model numerical simulation based on convolution has some problems about wavelet settings, such as the selection of wavelet, wavelet frequency and wavelet continuity and so on. In order to overcome these disadvantages, this paper proposed a newAVOmodel numerical simulation method which is based on wave equation from the aspect of seismic numerical simulation. Based on sonic and density log data, this method uses Zoeppritz equation or approximate equation to calculate reflection coefficient of a corresponding incident angle firstly （being consistent with the conventional method）. Secondly, extend the reflectance to two-dimensional horizontal layered velocity model and reflection model, and then use the frequency-wave field offset method to calculate numerical simulation of earthquake wave field. Thirdly, extract the seismic trace as AVOnumerical simulation of a corresponding incident angle. This method has heavy computation, but it uses advantages ofwave equation numerical simulation effectively, and can obtain the same simulation records with the field observation records, so it has practical value.

Estimation of seismic wave energy attenuation gradient based on Pseudo-Margenau-Hill distribution

FU Xunxun，XU Feng，QIN Qirong，LIU Fulie，JIANG Ziran

2011, Vol.23(6): 106–110 Abstract ( 476 ) PDF (697 KB) ( 510 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.020

It is stated that the propagation of seismic wave in oil & gas reservoirs is accompanied by intense energy attenuation, and the frequency component is higher, the energywill be absorbed more. Thus energy attenuation gradient can be used to detect hydrocarbon sensitively. Conventional Fourier transformsuffers fromtime-frequency resolution problems, while Pseudo-Margenau-Hill distribution has many favorable properties, such as time-frequency marginal distribution, “weak” finite support, time-frequency location, which is one ofCohen class time-frequency distribution. The time-frequency analysis based on Pseudo-Margenau-Hill distribution is presented for energy attenuation gradient estimation, and the log of energy and frequency of higher band is used to calculate the energy attenuation gradient. The practical application shows the effectiveness of the method in hydrocarbon reservoir prediction.

High rate non-Darcy flow is easier to occur in low permeability reservoirs?

LI Chuanliang

2011, Vol.23(6): 111–112 Abstract ( 391 ) PDF (293 KB) ( 474 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.021

High rate non-Darcy flow increases additional pressure drop and decreases flow efficiency in reservoirs, which is unfavorable to petroleum production.Whether high rate non-Darcy flowis easier to occur in low permeability reservoirs or in high permeability reservoirs is a problem unsolved well. Previous experiment results by several authors showthat low permeability reservoirs are more suitable for high rate non-Darcy flowto occur. However flowin low permeability reservoirs is extremely difficult and high rate can not be reached usually. According to mechanics of fluids, conditions of high rate non-Darcy flow and factors causing high rate non-Darcy flow were studied. It is considered that high rate non-Darcy flowis easier to occur in high permeability reservoir than in low permeability reservoir. So the effect of high rate non-Darcy flowcan be neglected in development of low permeability reservoirs.

Development technology with thermal recovery for horizontal well of superheavyoil reservoir in Du 84 block in Shu 1 area, Liaohe Oilfield

YU Tianzhong，ZHANG Jianguo，YE Shuangjiang，HUANG Bo，ZHOU Yuanlong，ZHI Yinmin

2011, Vol.23(6): 114–119 Abstract ( 614 ) PDF (587 KB) ( 921 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.022

Du 84 block is a super-heavy oil reservoir in the Shu 1 area, Liaohe Oilfield. When developed by the cyclic steamstimulation in vertical well patterns, the smaller drainage radius, lower oil production per period, lower oil rate per day, higher production decline rate and the inefficient displacement of the interwell remaining oil problems have been encountered. According to the study on the thermal recovery technology for horizontal well of super-heave oil reservoir, the deployment way of the horizontal wells, steam stimulation parameters and enhancing oil recovery with SAGD technology were analyzed. The result shows that the horizontal well development technology is a potential and advantageous new technology to relieve the contradictions between interlayer, endostratic and plane. Horizontal well steam stimulation and SAGD technology have more effectiveness than the vertical well, so the use of horizontal well is coming to be an effective method for enhancing oil recovery.

Reservoir properties under overburden pressure of Paleozoic in the middle area of Ordos Basin

JIANG Jihui，YANG Liqin

2011, Vol.23(6): 120–123 Abstract ( 365 ) PDF (461 KB) ( 330 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.023

The stress sensitivity of low permeability reservoir has great influence on the fluid flow capacity. The experimental study was carried out on the relationship between reservoir properties and overburden pressure of Paleozoic in the middle area of Ordos Basin. The result shows that the porosity and permeability become small with the increase of overburden pressure. The variation level and cause of reservoir properties in the low permeable sandstone and carbonate rock were analyzed, which has good effect to guide the exploitation and adjustment of oil and gas field.

Influencing factors of subsea natural gas hydrate exploitation with CO₂

REN Degang

2011, Vol.23(6): 124–127 Abstract ( 482 ) PDF (280 KB) ( 545 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.06.024

This paper introduced the crystal structure of gas hydrate, discussed the feasibility on methane hydrate exploitation with CO2 from thermodynamics, and analyzed the effects of different factors on the replacement reaction, including loricae effect, temperature, pressure, crystal structure, crystal cage fill fraction, porous media, salinity, additive and microemulsion. It is pointed out that reinforcement of the reaction procedure by multi measures is the research emphasis in the future, and the research provides a newthought for CO2 subsea preservation and natural gas hydrate expoitation.