, Volume 38 Issue 6
    

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    油气勘探
  • Zou Caineng; Xu Chunchun; Wang Zecheng; Hu Suyun; Yang Guang; Li Jun; Yang Wei and Yang Yu
    , 2011, 38(6): 1985-0.
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    The large gas province of platform margin reefs and shoals of the Permian Changxing Formation and Triassic Feixianguan Formation in the Sichuan Basin are studied to describe the forming conditions and geological characteristics of large strip-like gas provinces of platform margin reefs and shoals. The Sichuan Basin experienced cratonic rifting and basement faulting during the Late Permian. Within a widespread regional ramp, a paleogeomorphology pattern of “three highs and three depressions” were formed. The three negative relieves are, respectively, Chengkou-E’xi trough, Kaijiang-Liangping trough, and Nanchong-Mianyang intraplatform depression, and the three topographic highs are Fengjie-Zhenba platform flat, Shizhu-Yilong platform flat, and Suining-Moxi platform flat. In the transitional areas between platform flats and troughs, large-scale platform margin reef-shoal complexes were developed under high energy environment. Diagenetic processes, such as early stage solution, seepage-reflux dolomitization and burial solution, contributed to high-quality dolomite reservoirs along platform margins. High mature source rocks and faults were developed within the platform margin reef-shoal complexes, forming better hydrocarbon accumunation conditions than intraplatform reefs and shoals. Therefore, the distribution of platform margins controlled that of gas accumulation zones. Paleogeography background of large platform, extensive dolomitization and solution in reef-shoal reservoirs, advantageous underlying and lateral adjacent source rocks, strip assemblages of lithological, structural, and litho-structural oil and gas traps are the four basic elements that determine the formation and distribution of large strip gas provinces. The configuration of the four elements in the studied area shows promising exploration prospects of large platform margin oil and gas provinces.
  • Du Jinhu; Zhou Xinyuan; Li Qiming; Wu Guanghui; Pan Wenqing and Yang Tao
    , 2011, 38(6): 1986-0.
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    A comprehensive analysis of hydrocarbon accumulation conditions and typical reservoirs reveals that a large carbonate petroleum province is formed around the Manjiaer depression in the Tarim Basin and it is consisted of Ordovician non-structural petroleum reservoirs. Multi-type litho-stratigraphic reservoirs are stacked vertically and connected laterally along the paleo-uplift slopes, with a large area. Reservoirs are intensively heterogeneous, extensively developed and distributed in layers along the top of different-scale sequence boundaries. Hydrocarbon phase and physical properties are diverse and the distribution pattern is “lower gas, upper oil”. The oil/gas/water output alters and declines quickly, and 20%–30% high-efficiency wells provide more than 70% of the production. The stable paleo-uplift, widely developed heterogeneous reservoir, multi-stages of hydrocarbon accumulation are the basic forming and distribution conditions of the large carbonate petroleum province. The paleo-uplift near the hydrocarbon kitchen is developed stably and controls the reservoir distribution, migration and accumulation. The special characteristics of carbonate reservoirs result in the wide and discontinuous distribution of irregular fracture-cavity hydrocarbon pools. The enrichment of hydrocarbon is controlled by reservoirs, which are the main controlling factor of the formation and distribution of the large petroleum province. Multi-stages of accumulation and adjustment of hydrocarbon are universal and result in the large area and diversity of the oil and gas.
  • Li Wei; Qin Shengfei; Hu Guoyi and Gong Yanjie
    , 2011, 38(6): 1987-0.
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    In recent years, a lot of lithologic/structural-lithologic gas reservoirs were found in the Xujiahe Formation, Upper Triassic, Sichuan Basin, and most of the reservoirs contain water. We have carried out the study of the properties and characteristics of the fluid, and found the changes of natural gas components and carbon isotope which can confirm the accumulation of water-soluble gas with degasification, namely, such accumulation far away from gas source features high methane, high drying factor, high ratio of isoalkane to normal paraffin hydrocarbons, and heavy carbon isotope in methane and ethane. Accumulations of water-soluble gas with degasification with reduction of pressure & temperature for strata uplift and with reduction of pressure & temperature for lateral migration of soluble gas along layer are the main forming mechanisms. The strong ground uplift, fluid decompression and reduction of temperature, local concentration of water salinity, and a wealth of water-soluble gas resources are the favorable conditions for the accumulation. We conclude that the accumulation of water-soluble gas with degasification is not only one of the important mechanisms of development of large lithologic gas reservoirs and large gas accumulations in Central Sichuan, but also a key reason for poor source rocks in the Xu1 Member but large gas accumulation in the Xu2 Member in the Hechuan-Anyue areas.
  • Fu Xiaodong; Qin Jianzhong; Tenger and Wang Xiaofang
    , 2011, 38(6): 1988-0.
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    The mineralogical composition and its influencing factors of three sets of excellent Paleozoic source rocks are analyzed to discuss the geological significance of mineralogical composition in the Middle-Upper Yangtze Region (MUYR). The source rocks in the Lower Cambrian Niutitang, Upper Ordovician Wufeng – Lower Silurian Longmaxi, and Upper Permian Dalong Formations are similar in mineralogical compositions, which are siliceous shale of low clay mineral average content. Mineral contents of the Upper Permian Longtan Formation source rocks show much variation and 65% of source samples have over 70% quartz content., Clay shale is found in the Longtan Formation. The difference of mineral components in shale is mainly caused by the sedimentary environment, and it is also greatly influenced by the bioclastic sedimentation and thermal maturity. Mineral composition is a cause of the difference in hydrocarbon-generating model and hydrocabarbon expulsion rate of source rock. The source rocks of the Niutitang,Wufeng-Longmaxi and Dalong Formations are rich in brittle minerals and lower in clay mineral, which is favorable for exploiting shale gas, but lower clay mineral is a disadvantage factor for gas adsorption in shale. And it is necessary to differentiate shale source rocks according to the mineral components in the Longtan Formation in the shale gas exploration.
  • Liang Xing; Ye Xi; Zhang Jiehui and Shu Honglin
    Petroleum Exploration and Development, 2011, 38(6): 1989-0.
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    Forming conditions of the shale gas reservoir of the Weixin Sag in the Dianqianbei depression are studied and preferable sweet spots for shale gas exploration are proposed based on the results of geologic survey, drilling and seismic exploration in the shale gas region. The black shales of Cambrian Niutitang Formation and Silurian Longmaxi Formation are the two principal exploration targets in the Weixin Sag, having the characteristics of high single layer thickness(>50m)and abundant organic matter, low porosity and permeability. Those two formations have favorable conditions for the formation of shale gas reservoirs and also can be easily hydraulic fractured in the later stages of production. The coexistence of the clastic rock layer on the top, shallow entire seal, and the absence of exposed faults are the three desirable factors for the preservation of shale gas reservoir. The shale core analysis shows that the major composition is methane, the content of which increases as the preservation conditions become better and the shale TOC abundance and formation pressure increase. After integrated evaluation and optimized selection of shale gas exploration zones, it is determined that the Junlian-Luobu zone located in the north of the sag is the most favorable sweet spot for shale gas exploration in the overlapping target layer of the Longmaxi Formation and Niutitang Formation, and the Huani-Weixin zone in the middle of the sag is proposed to be the sweet spot for shale gas exploration in the Niutitang Formation. It is recommended that importance be attached to the evaluation of shale gas exploration in Lower Carboniferous Jiusi Formation and Upper Permian Leping formation.
  • 油气勘探
  • Sun Tongwen; Lü Yanfang; Liu Zongbao; Fu Xiaofei and Fu Guang
    , 2011, 38(6): 1990-0.
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    To clarify the hydrocarbon migration, accumulation and enrichment features of the Fuyu oil layer to the east of the Daqing placanticline, the hydrocarbon migration conditions of the Fuyu oil layer are studied in detail using the performance data of oilfields. In the area to the east of the Daqing placanticline, dual modes of vertical–lateral migration are available. Vertical migration mainly happens where vertical hydrocarbon expulsion takes place in upper source rocks.. Hydrocarbon is poured into the underlying Fuyu oil layer along the open T2 source fault under overpressure. Lateral migration has three types: hydrocarbon within source rocks migrates laterally in short distance into the uplifted wall of source faults along sands; hydrocarbon near source rocks migrates laterally into successive local uplifts along tectonic axis in short distance; hydrocarbon far from source rocks migrates laterally in long distance into the Chaoyanggou Terrace along Type II fault concentration belts connected by sands. Oil-rich zones are places where source faults are developed and nose-structures around vertical hydrocarbon expulsion of source rocks with tectonic axis being nearly the same with the trend of faults. Because of the different features, the fault concentration belt in the Sanzhao sag is not oil-enriched, but the Chaoyanggou Terrace is the favorable oil-accumulation structure.
  • Wang Jinghong; Jin Jiuqiang; Hou Lianhua and Zhu Rukai
    , 2011, 38(6): 1991-0.
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    Based on the newest exploration and research achievements, the paper studies the types and controlling factors of the fractures in Carboniferous igneous rocks of Northern Xinjiang, and their influences on the high-quality reservoir and high production of oil and gas. Fractures with different occurrences (oblique fracture, net fracture, horizontal fracture and vertical fracture) and geneses (autoclasic fractures, contraction fractures, dissolved fracture, joint fracture and structural fractures) were developed in igneous rocks. The ability of fluid flow and seepage radius were different in various fractures. The development degree of fractures was controlled by lithology, tectonic movement, early and late diagenesis. It was controlled mainly by lithology in the areas of weak tectonic movement; it varied in different lithologic igneous rocks with the same tectonic background. The main controlling factors of forming fractures in igneous rocks were tectonic movement, late and early diagenesis, especially hypergenesis during the stage of late diagenesis. Various lithologic igneous rocks undergoing intense tectonic movement and long-time weathering developed fractures and favorable volcanic reservoirs that were concentrated in the area no more than 3 km away from main fault zone. The closer to the fault the well is located, the easier it gains high and stable production of oil and gas.
  • Luo Chunshu; Yang Haijun; Li Jianghai; Xie Huiwen and Huang Guangjian
    , 2011, 38(6): 1992-0.
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    The exploration during recent years in the northern slope of the Tazhong area,Tarim Basin indicates that the Ordovician strata have two sets of high quality reservoir, i.e. the Upper Ordovician reef-beach body and the Yingshan Fm. weathering crust of the Lower Ordovician, which were respectively controlled by high energy facies at platform edges and early Ordovician weathering crust in the early period and modified by faulting in the later period. Comprehensive research shows that the types and distribution rules of Ordovician reservoirs in the northern slope of the Tazhong area are related to faulting. This paper demonstrates the controlling effects of three periods of faulting on above two sets of Ordovician high quality reservoirs: (1) The Early Ordovician regional extension laid the foundation for the forming of Tazhong No.1 slope break and drove the formation of the Yingshan weathering curst karst reservoirs in Lower Ordovician and the subsequent sedimentation of Upper Ordovician reef-beach bodies; (2) The intense compressions at the end of early Ordovician promoted the development of salt related structures in the northern slope (the detachment and salt arch occurred in the Middle Cambrian gypsum), and faults modified the reservoirs of reef-beach bodies and weathering crust; (3) The Late Silurian strike-slip faulting had limited modification to the Ordovician reservoir, but controlled the location with gas cutting in Ordovician reservoirs in the Tazhong area in the Himalayan period.
  • Feng Youliang; Zhang Yijie; Wang Ruiju; Zhang Guangya and Wu Wei’an
    , 2011, 38(6): 1993-0.
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    Using the data of cores, well logging interpretations, seismic sections and experimental geochemistry, this paper analyzes the sedimentary environment, genesis, and distribution of dolomites, as well as the hydrocarbon enrichment factors of dolomite reservoirs in the Permian Fengcheng Formation. According to attitude and structure, the dolomites of the Fengcheng Formation are divided into lamina dolomites, thin-bed dolomites, and spotted dolomites and they are mainly the penecontemporaneous and epigenetic dolomites. The former is deposited in a saline semi-deep lake, while the latter results from the dolomitization of lime mud that was deposited in a saline semi-deep lake during the diagenetic stage. The dolomites are distributed at the palaeoslopes formed by volcano eruption and movement of thrust faults and the main dolomite reservoir spaces are dissolved pores and fractures. The factors controlling hydrocarbon enrichment are fractures and structural background.
  • 油气田开发
  • Xu Changfu; Liu Hongxian; Qian Genbao and Qin Jianhua
    , 2011, 38(6): 1994-0.
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    Targeting the conglomerate reservoir of the Lower Karamay Formation in the Middle District No.6 of Karamay Oilfield, based on the research of conglomerate reservoir characteristics and flow mechanism, laboratory experiments were conducted to study the pore producing characteristics during water-oil displacement and imbibition and analyze the effect of pore structure on oil displacement efficiency, the microcosmic distribution of remaining oil and the influence of long term water flooding on reservoir pore structure. The results show that the remaining oil saturation is high, while the remaining oil is mainly in small sized pores. During the water-oil displacement, the preferential producing pores are super large pores; large and middle pores make great contributions to recovery. During the imbibition, the preferential producing pores are small pores and imbibition effect largely depends on middle and small pores. The oil displacement efficiency and microcosmic remaining oil distribution are mainly affected by pore structure. After water flooding over a long period of time, the interstitial matters expand, decentralize, move, and get eroded; large pores and throats increase; the connectivity becomes better; and the micro-heterogeneity gets more serious.
  • Lü Jing; Liu Yuzhang; Wang Jialu; Li Yikun; Gao Jian and Wei Falin
    , 2011, 38(6): 1995-0.
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    According to the concept of “gel dam” in-depth fluid diversion in horizontal wells, the EOR mechanism of “gel dam” in-depth fluid diversion technique in horizontal wells is studied by means of laboratory water flooding experiment combined with computer tomography (CT) technique. In the experiment, the artificial cementing heterogeneous model is casted with epoxy resin on surface, and the flooding process before and after the “gel dam” formed is scanned dynamically using CT technique. Through observing the distribution feature of gel dam, tracking the internal oil and water distribution in the heterogeneous model, water flooding streamline change, oil saturation distribution and its dynamic variation in real time, it is indicated that “gel dam” can effectively shut off the deep channeling in higher permeability layer, and divert the injected water to low-permeability layer to displace the remaining oil therein. After “gel dam” is formed, the oil recovery by water flooding increased by 16.7%, and the water cut ascending velocity slowed down. With “gel dam” technique, the gel can be placed in the in-depth reservoir zone to realize deep fluid diversion, which expands the water flooding sweeping volume effectively. “Gel dam” deep fluid diversion technique is a promising EOR method for positive rhythm reservoirs of great thickness.
  • Zan Cheng; Ma Desheng; Wang Hongzhuang; Shen Dehuang; Guan Wenlong; Li Xiuluan; Jiang Hang; Luo Jian and Guo Jia
    , 2011, 38(6): 1996-0.
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    In order to solve the problems of existing physical simulation experiment device for thermal recovery, such as great heat loss, low precision in internal pressure control of physical model and insufficient process monitoring, a new experiment device for high-pressure and high-temperature (HPHT) 3D scaled physical simulation is developed independently, and the relevant experiment technical route is presented. By using thermal fluid simulation, PID auto-control and 3D graphics, the following difficulties are solved: (1) the heat loss scaled simulation technology is applied for HPHT thermal recovery model, to control the heat dissipating capacity of model top and bottom and realize the continuous growth of steam chamber; (2) HPHT 3D formation temperature/pressure simulation technology is applied to control the model pressure and temperature stably, ensuring temperature difference at each point in high-pressure chamber less than ±2 ℃; (3) 3D data field on-line monitoring and visual analysis technology is applied to monitor and control the reservoir performance at real time. By using this experiment device, 3D scaled physical simulation experiment is performed for commingled thermal recovery of extremely heavy oil by horizontal/vertical wells as well as SAGD of super heavy oil by dual horizontal wells. The evolution of steam chamber is depicted and the knowledge on SAGD mechanism by dual horizontal wells and the production performance is deeply studied.
  • 石油工程
  • Liu Changsheng; Zhou Fengdao and Lin Jun
    , 2011, 38(6): 1997-0.
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    Marine controlled-source electromagnetic method has become the research focus in subsea hydrocarbon exploration overseas. This paper studies the parameters of its survey system by simulation during instrument development and survey design. The simulations indicate that no matter in deep sea or in shallow sea, the system parameters affect the measurement results by the same way. The current of transmitter and the length of receiver antenna only affect the amplitude of electromagnetic signals and there exits a positive correlation between them. The offset and the frequency of transmitter have remarkable effects on the measurement results. When they are too small or too big, no obvious hydrocarbon anomalies can be observed. So mid value should be allotted to them. The influences on the measurement results from the length and height of transmitter antenna and the height of receiver antenna are small. The hydrocarbon anomalies gradually become small with the increase of the three parameters. Since the values of these parameters are usually not big, their influences can be neglected. In shallow sea, both the transmitter antenna and the receiver antenna could be set close to the sea surface, where small antenna height is still kept. However, this distribution manner can not be used in deep sea.
  • Geng Jiaojiao; Yan Jienian; Cao Ming; Bai Xiangshuang and Shi Haimin
    , 2011, 38(6): 1998-0.
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    Factors affecting the solubility of CO2 and CaCO3, including temperature, pressure, salinity of solutions, and pH value have been studied and then the mechanism of scale deposition in gas reservoirs with high CO2 content has been analyzed r. The solubility of CO2 reduces with the increase in temperature and salinity, whereas it increases with the increase in pressure; the solubility of CaCO3 reduces with the increase in temperature, whereas it increases with the increase in pressure and pH value. Taking the typical formations with high CO2 content in Jilin Oilfield as an example, the prediction of CaCO3 scaling was conducted, which indicated that there might be scale deposition after the drilling fluid filtrate invaded into the formations. Since the gas reservoirs was characterized by deep embedding, high temperature, low pressure coefficient, fracture developing, etc., two kinds of drilling fluids, oil-in-water drilling fluid and formate drilling fluid with no solid phase, was selected for the underbalanced drilling. The anti-pollution test and dynamic damage tests showed that they all exhibited excellent anti-pollution performance to CO2 and remarkable formation protection. The field applications in Longshen No.2 and No.3 proved that the two drilling fluid systems worked well and the returned permeability of the field drilling fluid to cores was more than 85%, which met the demands of underbalanced drilling.
  • 综合研究
  • Li Jianhua; Pang Xiong qi; Song Bing; Chen Dongxia and Ma Junbao
    , 2011, 38(6): 1999-0.
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    The regional caprock(C), favorable sedimentary facies(D), surface potential(P) and source rock(S) are 4 functional elements that control the formation and distribution of lithologic reservoirs in the Damintun sag. Based on this, this paper proposes T-CDPS model with 4 functional elements to control hydrocarbon distribution and the method of predicting the favorable areas of lithologic reservoirs. The 4 elements’ combination in vertical and superimposition on the horizon control the strata and scope of lithologic reservoir formation respectively; they jointly determine the time of reservoir formation in geohistory. The integrated probability index of the factors’ control on reservoir, calculated by the weighted mean of the probability index of single factor’s control on reservoir that is obtained by the analysis of its hydrocarbon controlling process and quantitative characteristics, can help predict the favorable area of lithologic reservoir distribution. T-CDPS model was applied to predict the favorable areas of lithologic reservoir in Paleogene Es33, Es34 and Es4 strata of the Damintun sag and has been proved feasible and effective.
  • 学术讨论
  • Wang Jiahua; Lu Tao; Chen Fengxi; Wang Xudong and Wang Yong
    , 2011, 38(6): 2000-0.
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    With a major gas reservoir of the second member of Shanxi Formation in YL gas field as an example, reservoir modeling constrained by geological conditions, including distribution of sand bodies and lateral and vertical heterogeneity, is carried out to reduce uncertainty of results of gas reservoir modeling and uncertainty of probabilistic reserves of the major gas reservoir. The geological constraints include: (1) there are almost no sand body in most of the southeastern part in the study area; (2) owing to sand bodies concentrated in the middle and bottom parts of braided channels, the proportion curves of petrophysical parameters of the gas reservoir show that porosity, permeability, and oil saturation present low values on the top and high values on the bottom of the channels. Comparison with 400 realizations obtained without any geological constraints, 100 realizations with constraint No.1, and 23 realizations with constraints No.1 and No.2, and the calculation of the probabilistic reserves P90, P50, and P10 show that owing to the geological constraints, the uncertainty of the probability reserves of the major gas reservoir is reduced significantly.