, Volume 31 Issue 2
    

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  • DAI Jinxing; HU Jianyi; JIA Chengzao; FANG Yisheng; SUN Zhidao; WEI Linghua; YUAN Jinping and YANG Wei
    , 2004, 31(2): 783-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The gas with over 2% H2S is named as a high H2S gas that is highly toxic, and one must die in seconds in case of breathing 1g/m3 H2S that means 0.063% H2S of natural gases. High H2S gas was generated in carbonate reservoirs only. The content of H2S in natural gas is very low in clastic reservoirs, which is mostly under civil standard (20mg/m3) and can be utilized without de-sulfurization. All the high H2S gas fields are distributed in systems of carbonate-sulfate strata, and generated because of high temperature-reduction, biologic de-acidizing and cracking. We emphasizes here that the researches about to explore and develop high H2S gas fields must be enhanced scientifically and safely since the Chinese are lack of the necessary researches in high H2S geology and geochemistry, H2S gas engineering and exploitation technology, H2S prevention and remove of large-scale H2S pollution.
  • ZHAO Wenzhi; ZOU Caineng; WANG Zecheng; LI Jianzhong; LI Ming and NIU Jiayu
    , 2004, 31(2): 784-0.
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    A hydrocarbon-rich depression means one developed in the terrestrial sedimentary basins, with the source rocks of high TOC, large scale and suitable thermal evolution as well as huge amount of hydrocarbon generation and migration. The conditions of sag-wide oil-bearing formation in such depressions should be: ① massive hydrocarbon generation provides sufficient source for accumulation in all kinds of sand bodies; ② large scale effective source kitchens usually occupy larger portion of the sags, which offer more opportunity for direct contact between source and reservoirs; ③ lake vibration through time causes frequent alternation and variation of sandstone and mudstone in vertical and lateral directions, which provides suitable condition for formation of different kinds of lithostratigraphic traps. The formation of sag-wide distributing lithostrigraphic traps is mainly controlled by max lake flooding surface, unconformities and fault surface. And hydrocarbon accumulations are dominantly located in favorable sedimentary facies zones, lithological or stratigraphic pinch out belts, slope-breaks at syndepositional stages, fracture zones and secondary pore zones, which are usually called “sweet points”. The “sweet points” are more likely to occur in the major sand bodies and sandstone noses with structural background. Sag-wide oil-bearing theory could develop the theories of “Source Control Accumulation” and “Composite Zones of Hydrocarbon Accumulations”, which can expand the plays beyond sub-structure zones and widely enlarge the target scope.
  • ZOU Caineng; XUE Shuhao; ZHAO Wenzhi; LI Ming; LIANG Chunxiu; ZHAO Zhikui and ZHAO Zhanyin
    Petroleum Exploration and Development, 2004, 31(2): 785-0.
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    The Cretaceous Songliao Lake was developed in a humid climatic zone and near off-shore depressed basin. The proved oil reserves in the southern Songliao Basin are distributed in four giant fluvial-deltaic depositional systems. The oil-bearing intervals are mainly developed in the lacustrine transgressive systems tract and high-stand systems tract of the second-order and third-order sequences. The structural and composite types of oil reservoirs are mainly formed. With the advance of hydrocarbon exploration, the stratigraphic and lithologic oil reservoirs are becoming important play targets. The stratigraphic and lithologic oil reservoirs could be formed on the West Slope Area.
  • 石油地质研究
  • WANG Guangfu; WANG Duanping and SHAN Jiazeng
    , 2004, 31(2): 786-0.
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    The Xinzhen structure is an oblong graben in the central uplift zone of Dongying Sag, consisting of two parallel sub-faults. The low-grade fracture in the graben controls the oil and water distributions in the complex fault block oil pool. For understanding objectively the geometric relation between low-grade fault and high-grade fault, and the formation and evolution of complex low-grade fault, the new structural modeling experiments are conducted, which are significant for promoting further hydrocarbon exploration and development in the complex fault block of Shengli Oilfield. The experiments are conducted under similar geological conditions of Xinzhen structure. The experiments prove that low-grade arc-like fractures, including single arc, wave arc, multi-arc, etc, may form between two parallel high-grade fractures under extension stresses. Geometric characters of arc-like fractures are in close relationship with inhomogeneous particle displacement of rock grains.
  • ZHOU Xinyuan and LUO Jinhai
    , 2004, 31(2): 787-0.
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    The unconformities in the north and south fold-thrust belts of the Kashi Sag are diachronous and are of different intensity. Development of the south fold-thrust belt took place slightly earlier than that of the north fold-thrust belt. Presence of multiple unconformities further indicates pulses of thrust faulting. The hydrocarbon accumulation in the fold-thrust belts is secondary in nature because that the traps were formed after the major release of hydrocarbon from the source rocks.
  • XIAO Kunye; DENG Rongjing; YANG Hua; XIAO Dunqing; WEI Ajuan; XU Bei; LI Jianying and GAO Hua
    , 2004, 31(2): 788-0.
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    The extreme gravity trending east to west caused by tertiary basalt and diabase rocks in Xin′gang region, north of Huanghua Depression was ever interpreted as Paleozoic buried hills. Magma intrusion and volcanism during late Oligocene to early Miocene occurred in response to massive extension of east China, causing the formation of igneous diapirism structure traps, improving maturity of source rock. Katathermal fluid of mantle origin extracted and enriched dispersed organic material and speeded source rock transformation rate by catalytic action and hydrogenation. Magma upflowing channels, which were also the channels of oil and gas migration, caused reservoir distribution either in Es3 as found in other Beitang areas and in Es1, Ed and even in the Neogene system. The seismic data below igneous rocks are very poor and always image the pseudo-morphic deep structure, so the variable velocity mapping method should be used in the process of seismic interpretation.
  • DOU Lirong
    , 2004, 31(2): 789-0.
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    Interior rift basins are one of the very important petroliferous basins. Based on the analyses of origins, structural style and sedimentary systems of rift basins and the differences of oil accumulation formation between the active and passive rift-type petroleum systems, active rift-basins are characterized by the gentle boundary fault, high sedimentation rate, more volcanic activities, and high thermal gradient. The multi-phase thermal perturbation caused several secondary cycles within the first-order course-fine-course sedimentary cycle, forming excellent source-reservoir-seal combination. Rollover-anticlines, drape-anticlines and buried-hill traps are the main types of oil accumulations. Oil and gas reserves are mainly located in the syn-rift sequence. Passive rift-basins are featured by the steep boundary fault, low extension rate and sedimentation rate, few volcanic activities, and low thermal gradient. Braided-river sandstones in the post-rift sequence are the main reservoir rocks, and the littoral-shallow lake shale within the newly developed syn-rift sequences act as the regional seal, thus forming an excellent source-reservoir-seal combination. Antithetic fault-block is the main type of oil accumulations where the oil and gas are mainly enriched in post-rift sequence.
  • CHANG Junhe; YUE Yushan; Lü Hongyu; REN Zhanli and SHAO Yongxuan
    , 2004, 31(2): 790-0.
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    Relationship between thermal evolution history and stage of hydrocarbon generation of Upper Paleozoic in the Dongpu Sag
  • XIAO Zhongyao; HUANG Guanghui; LU Yuhong; WU Yi and ZHANG Qiucha
    , 2004, 31(2): 791-0.
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    The oils from the Quele 1 Well are identified as from terrestrial source rocks based on the following characters: ① Abundant occurrence of rearranged hopanes; ② An unknown C30 terpane compound; and ③ the distribution of the C19-C26 tricyclic terpanes peaks at C19 and declines with increasing carbon number. Hydrocarbons from the mudstones in the Qakemake Formation (J2q) are the only sources that possess such unique characteristics, indicating the very source for the oils in the Quele 1 Well. Apparently, the Mesozoic lacustrine sediments in the Quele 1,Kuche Depression serve as the single most important source rocks and the depression is of significant exploration potential.
  • XIE Wenyan; JIANG Jianqun; ZHANG Zhanwen and QIU Fang
    , 2004, 31(2): 792-0.
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    Based on the detail oil-source correlation, two petroleum systems of high waxy oil and normal oil are identified. Four elements and petroleum-accumulated dynamics for both systems are analyzed. There also exist similarities and dissimilarities in reservoir rock, cap rock, trap and reservoir forming feature except the source. Therefore, the two systems share something in common in vertical and plane distribution. The accumulated episode of the high waxy oil pool is a little earlier than that of normal one. The exploration of high waxy oil should focus on the distribution of oil shale.
  • XIAO Lihua; MENG Yuanlin; LI Chen; YIN Xiulan; YANG Hui; FENG Wenyan; QI Jincheng and QU Aiying
    , 2004, 31(2): 793-0.
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    The analyses of homogenized temperature of fluid inclusion, Roman, salts and the K-Ar age dating of authigenic illite within the reservoirs suggest two stages of the Paleozoic coal-derived reservoir-forming in the Wen'an slop of the Jizhong Depression, Bohai Gulf Basin, including at the end of the Mesozoic era and in the Paleogene, respectively, in which the first one had been destroyed by the Yanshan movement and the another one was formed in Paleogene, a major stage of reservoir-forming in the studied area. The plays in the Jizhong Depression should be focused on the traps formed during the Himalayan episode, and where would be the secondary hydrocarbon generation areas.
  • ZHANG Shouren and WAN Tianfeng
    , 2004, 31(2): 794-0.
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    Faulting and other tectonic activities in the Northwest Qaidam Basin are widespread and characterized by shearing and compression. Based on depositional history and regional stress analysis, the Cretaceous-Quaternary tectonic history is subdivided into four phases: ① Subsidence from the middle part of the Early Cretaceous to the Paleocene; ② Extension and shearing in the Eocene-Oligocene; ③ Intensive compression and shearing from Miocene to early Pleistocene; and ④ Relative quiescence since the middle Pleistocene. Miocene was a period of intensive faulting and fracturing, apparently affected by surrounding orogenic activities.
  • ZHAO Xianzheng; WU Yinye; SHAO Wenbin; GUO Bincheng and YU Huilong
    , 2004, 31(2): 795-0.
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    Major Tertiary reservoirs in the southwest Qaidam Basin are lowstand to early transgressive turbidities deposited in lacustrine deltaic front setting. The most prolific reservoirs are delta front, marginal lacustrine deposits and turbidities in Dongchaishan and southwest Qiekelike Sag. These deltaic sediments are more likely to accumulate hydrocarbon because they are adjacent to the source rocks.
  • HOU Ping; SONG Yan and FANG Chaoliang
    , 2004, 31(2): 796-0.
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    The data of Keyi structure about tectonic movements during the Mesozoic-Cenozoic period was synthesized and the development history of the basin and the structure was characterized. Studies on reservoir fluid inclusions, geothermal anomaly, gas accumulation patterns and hydrocarbon expulsion from source rocks show that the gas accumulation occurred episodically in the Kela-2 Gas Field, which lies on Keyi structure. It is inferred that the episodic tectonic actions of the Keyi structure lead natural gas fill episodically in the traps of the Kela-2 Gas Field.
  • JIAO Daqing; XIE Qingbin; GENG Huiju and GUAN Shourui
    , 2004, 31(2): 797-0.
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    The Yunlong Sag is located within the east part of Chuxiong Basin, Southwest China. The Mesozoic and Paleozoic have source rocks, reservoirs and capping conditions. However, the geological features there are real complex, so the preservation of oil and gas should be the key for the petroleum plays. The several long-term meteoric filtering stages were harmful for the oil assembling and preservation. The low salinity and Cl― concentration indicates that the formation lies in the fluid freely replacing zone, which is also a bad factor for the petroleum preservation. It was proved that the erosion thickness of Ordovician, Devonian and Paleogene were tremendous through the initial thickness recovery. The two formers greatly affect the petroleum preservation conditions. By the petroleum preservation unit criterion, Yunlong Sag was divided into 3 units: the mid-north preservation unit, the southwest preservation unit and the northeast preservation unit, in which the mid-north preservation unit was assumed to be the best one.
  • XU Huaixian and QIN Jianzhong
    , 2004, 31(2): 798-0.
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    The source rocks in the Qiangtang Basin, a low thermal flow basin with a paleothermal gradient of about 2℃/100m, are the best ones in Tibet residual basins, where four main source rock formations developed. Analysis of the 7761 samples, collected from the 27 petroleum geology lines in Tibet in 1994-1999, shows that the Xiaochaka Formation, Upper Triassic, is in an over maturity stage and the Middle Jurassic Sowa Formation, Xiali Formation and Buqu Formation are in a middle-late stage of oil generation, and a second oil generating process existed in Late Tertiary. All the maturity parameters decrease gradually in cycles from margin to central uplift. The main influential factors of the thermal evolution are: the highest paleo-temperature and the deepest burial depth in relative weak structure in the middle basin; the non-balance pressure in basin margin or nearby fault folder play; the local igneous rock and thermal flow in deep formation.
  • 综合勘探开发技术
  • XIE Jinzhuang and WU Xiling
    , 2004, 31(2): 799-0.
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    The empirical formulas for oil and water relative permeability in the Daqing Oilfield are obtained by analyzing the characteristics of the oil-water relative permeability curves of 128 cores from 9 sealed coring wells. The correlation between the reservoir water cut and water saturation is derived based on the percolation mechanics theory. The parameters in the empirical formulas are determined with the correlation and the oil cut, water cut and water saturation from the production logging data. The oil-water relative permeability curves obtained in this way agree with that obtained from the core analysis.
  • SONG Fuqing; ZHANG Dajiang; WANG Peirong; XU Guanjun; LI Youchuan; FU Ning and GUO Yonghua
    , 2004, 31(2): 800-0.
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    It is very important to select the effective correlation parameter with anti-biodegradation for calculating the contribution to biodegraded mixed oils. The results have been tested by artificial oil-mixing experiment. The biodegraded mixed oils in the PL 19-3 Oilfield, Bohai Bay, have been reconstructed using the triaromatic sterane/dinotriaromatic sterane parameter derived from typical oils from the Shahejie Formation (Member 3) and the lower Dongying Formation. From Well PL 19-3-4 (the closest to the Bozhong Depression) southward to Well 2, Well 8, and Well 5,the contribution from the source rock of the lower Dongying Formation shows a gradual decrease, from the highest value of about 30% in Well PL 19-3-4 to the lowest around 10%.
  • LIU Jianzhong; WANG Chunyun; LIU Jimin; ZHAO Yuwu and LIU Zhipeng
    , 2004, 31(2): 801-0.
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    The technology of observing production performance by using micro-seismic method in swept region is concerned worldwide. The overseas recognition criteria and method of micro-seismic signals are inferred to develop independent observation system and software, which have been successfully used in near 100 wells in Daqing, Huabei, Zhongyuan and Dagang Oilfield. The result of flood front observation is accordant with operation practice according to observation example of Well J344 (injector) in fault-block J11 of Huabei Oilfield. The remaining oil distribution could be estimated at any time by establishing micro-seismic net in early stage of reservoir development. The observation result may be used as a basis for water injection, profile controlling, well pattern layout and adjusting. And the micro-seismic could also be improved to monitor the micro-seismic induced by human activities.
  • LIU Baojun; CHEN Kaiyuan; SHI Zhongsheng; LIU Gang and Lü Jinbo
    , 2004, 31(2): 802-0.
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    The Qianjiang Formation in the Qianjiang Sag, Jianghan Basin is a typical saline deposit where the salt are mainly developed in the early base level rise half cycle and M-L (middle-later) base level fall half cycle. The development of reservoirs is controlled by fall-rise cycle, paleo-landscape and material supply. The reservoirs could be typed as low-sand system-sandstone, saline density current sandstone, shallow shore and no-sand bodies, etc, which causes the diversity of type and distributing in the Jianghan Basin. It is well developed about high-stand deltas (or fan deltas) and low-stand deltas (or fan deltas) in QianBei fracture belt; Banghu sag's eastern and western slope fan and saline density current sandstone at the slope break belt in depress are distributed in saline abroad, which are good at forming subtle trap reservoirs.
  • CHEN Feng; LI Jinzong; LI Dongdong and CHEN Huiping
    , 2004, 31(2): 803-0.
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    According to the line-like texture characters of seismic images, an algorithm of coherence enhancing diffusion, which is a kind of nonlinear anisotropic diffusion based on partial differential equation, is proposed.The original seismic images are disposed by controlling diffusion direction by the eigenvector of the structure tensor and controlling the diffusion amount in the characteristic direction by the eigenvalue of diffusionmeasure ment. Energy spectrum analysis is used to develop the formula of the signal to noise ratio (SNR) and the ranges of the diffusion parameters are also obtained. Processing results of real seismic images show that, under the condition of constant structure relation and signal energy of 80%-90%, the SNR increases of seismic images with high SNR and low SNR are about 9dB and 15dB, respectively. Also, there won't be false images, and seismic events and important geological information are enhanced.
  • LUO Houyi; TAO Guo; SUN Yaoting; TANG Yongmei and WANG Hong
    , 2004, 31(2): 804-0.
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    The comprehensive studies are performed on metamorphic formations with the resistivity logs, ultrasonicimaging combined with temperature logs, full waveform and other conventional logs obtained from the Chinese Continental Scientific Drilling-PrePilot Ⅱ(CCSD-PPⅡ), which is the first pilot well with logging data available in China. The porosity and permeability are calculated with ELAN-Plus in conjunction with core pictures. It is acknowledged that the activity of underground water is in close relations with fracture. The pseudo geothermal gradient of Maobei region is concluded as 2.15 ℃/100m by analyzing the temperature logs. This case study demonstrated the key role of well logging data in the research on metamorphic rocks in the continental drilling program.
  • DING Baitao and LEI Lijing
    , 2004, 31(2): 805-0.
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    Eleven microstructure reservoirs have been discovered around the Gudong Oilfield, Shengli petroleum province, and the accumulated discovered reserves are up to 5.79 million tons. The microstructures are frequently distributed over the gentle structural belt of some gigantic structure or in adjacency to the big oil field, which could control the distribution of remainder oils. The microstructures could be typed as micro-anticline, micro-fault-nose and micro-block. The microstructures must be interpreted in detail by using high resolution 3-D seismic, drilling and logging information for analyzing and evaluating the formation conditions of reservoirs, including structure and fault and the oil source traps, since they have less scale of oil-bearing and lower oil column.
  • LIU Kun; HU Wangshui and LU Jian-lin
    , 2004, 31(2): 806-0.
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    The evaluation of the fault sealing ability demands of thorough anatomization of the fault by different methods. A method to systematically analyze and evaluate the fault sealing is brought up, i.e., studying comprehensively the 4 elementary parameters and their interact of fault sealing and establishing practical 4-D sealing model by the way of many disciplines, including petroleum and tectonic geology, sedimentology, reservoir geochemistry, fluid mechanics, geophysics, computer science, etc.
  • ZHU Jiajun; ZHANG Shanwen; WANG Yongshi; SHI Dishi and GU Ling
    , 2004, 31(2): 807-0.
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    The acoustic logging data could be extremely affected by borehole slump and mudstone alteration during the using of water-base mud. The use of oil-base mud would have the real information of the formation. The analysis of correlation relationship between the lithological characters and change of velocity could be used to establish a correction equation of logging. The equation has been used for over 40 wells in Shengli Oilfield, the corrected information shows a good relationship between the compound seismic record and the practical seismic information of nearby the well.
  • SU Aiguo; ZHANG Shuichang; HAN Dexing and WANG Yanbing
    , 2004, 31(2): 808-0.
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    A PVT experiment in which pressure-drop and gas-washing in reservoirs are simulated under subsurface temperature and pressure conditions. The molecular composition measurement (GC/MS analysis) of the products formed in the different experimental stages showing that some sterane and terpane molecular parameters in crude oils are related to evaporation fractionation. The parameters include not only light/heavy ratios of the same series compounds but also those application indexes frequently used in petroleum exploration geochemistry, such as ratios of Ts/Tm, rearrange sterane/regular sterane, C29 isosterane/ C29 sterane, and so on. Additionally, the variation in oils and their relevant condensates, and the difference between pressure-drop and gas-washing fractionations can be reflected from sterane and terpane parameters. The research is favorable for identifying different processes of formation of petroleum reservoirs, and to the scientific application of routine geochemical parameters.
  • 油田开发与油藏工程
  • YAN Cunzhang; LI Xiusheng; WU Xiaodong and LI Wenxing
    , 2004, 31(2): 809-0.
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    The level of recoverable reserves replacement has been the key factor restricting the oil production increase in China for years. The relation between the increases of reserves and production and the relation between the calibrated recoverable reserves of new oilfields and improved recoverable reserves of maturing oilfields are analyzed quantitatively from the viewpoint of oil development. It is demonstrated that oil production is mainly affected by the level of reserves replacement ratio provided that the reserve-production ratio reaches its rational lower value, while the reasonable ratio of increased reserves of new oilfields to that of maturing oilfields depends on the difference between the initial calibrated recovery and ultimate recovery of oilfields.
  • WANG Hongbao; SU Zhenge and CHEN Zhongyun
    , 2004, 31(2): 810-0.
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    To avoid the big error caused by geological statistical technique of well-point parameters and coarse grid approximation, a 3-D waterflooding streamline model is put forward to study the residual oil distribution. The flow of water and oil through porous media follows the continuum mechanics; for every point in the 3-D space, the system state is determined provided that the values of several variables are given. Definite variables at infinite number of points constitute a "field". The 4 variables composing the 3-D waterflooding streamline model include pressure field, velocity field, flow path of the fluid and time and saturation field. The pressure field and velocity field are figured out in the porous media; then the streamlines are obtained; and the residual oil saturation at every point on every streamline is acquired. The streamline model overcomes the numerical dispersion and instability,is faster than the conventional numerical simulation and allows for more nodes. From the water cut of 21 wells predicted by using the streamline model, the error of 18 wells is within 10%.
  • WANG Weihong; WANG Jingrong; LI Dang; DONG Zhengyuan; GAO Xiaotian; Ai Jingxu and LIU Xinfu
    , 2004, 31(2): 811-0.
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    The level of oil production using steam injection technique directly depends on the heat efficiency of steam injection, and the heat efficiency can be determined by injection-production parameters. By treating steam flow in surface pipeline, in the borehole, and within the rock formation as a system, this study establishes an integrated mathematical model of steam injection system, and a new method of optimization design of steam stimulation injection-production parameters. In this integrated model, the wellhead and well bottom are treated as nodes, and a nodal analysis technique is applied to integrate surface pipeline flow, well-bore flow and formation seepage flow. The optimization design method takes into consideration the cost of steam injection and fluid production in the steam stimulation well, and forms the basis of an economic evaluation model. Simulated annealing to global optimization problem is introduced to optimize the injection-production parameters. The results suggest that operations based on the optimal injection-production parameters designed by this method lead to an increase in heat efficiency and recovery rate of steam stimulation wells.
  • LI Baozhu; ZHU Yuxin; SONG Wenjie; JI Guang and XIA Jing
    , 2004, 31(2): 812-0.
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    The Kela-2 Gas Field is the main reserves supply for the West-East Gas Pipeline Project in China. Accurate forecast of the productivity of Kela-2 is the basis of development planning. The relationship of the open flow potential with respect to the flow capacity is utilized to establish the typical binomial productivity equation that is applicable field wide. The pseudo-pressure productivity equation can be used to reliably predict the individual well productivity and producing pressure drop, and the average field-scale productivity and pressure drop under various perforation degrees. The productivity can also be approximately estimated by using the pressure-squared method.
  • YANG Guangrong; YU Yuanzhou; TAO Ziqiang; LI Baorong and YANG Bo
    , 2004, 31(2): 813-0.
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    Two phases, gas and liquid, exist in the formation when the pressure drops to below the dew point pressure in the pressure depletion process of the condensate gas reservoir. For the mid-high permeability sandstone condensate gas reservoir with mid-high condensate content, when developed under depletion mode, the condensate recovery has good correlativity with original condensate content, original gas oil ratio, gas recovery and initial gas productivity index per meter of condensate gas well (reflecting the physical properties of the formation), respectively. By studying the data of condensate gas reservoirs in Dagang Oilfield, 4 empirical formulae for condensate recovery calculation are developed, providing a convenient and effective way for calculating the recoverable condensate reserves of the condensate gas reservoir.
  • ZHANG Yitang; JI Bingyu; LIAO Guangzhi; LI Xiuluan and SHEN Dehuang
    , 2004, 31(2): 814-0.
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    Economic and technological feasibilities of cyclical steam stimulation (CSS) in three types of conventional reservoirs are discussed. For waxy low-permeability reservoir, feasibility of CSS to enhance development efficiency is studied by physical and numerical simulations, the field experiment in the two production wells in the Chaoyanggou low-permeability reservoir, periphery of Daqing Oilfield, shows that CSS is an effective stimulation method. For Fuyu water-drive conventional reservoir in the Jilin Oilfield, feasibility of converting to steam displacing is investigated by using reservoir engineering method, development index and economic profit prediction of one well group are given, the study demonstrates that the increased recovery may be over 20% if water-driving changes to steam-displacing. Feasibility of changing polymer-driving of Daqing Oilfield to steam displacing is studied by physical and numerical simulations, the mechanisms of enhancing recovery by steam-displacing and polymer-driving are analyzed by comparison, elementary investigation shows that the recovery of this kind of reservoir can be increased more than 10% if it changes to steam displacing.
  • ZHU Huaijiang; ZHU Ying; SUN Shangru; LIU Yuzhang and TANG Jinxing
    , 2004, 31(2): 815-0.
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    Pre-crosslinking micro-gel dispersion, which is synthesized with inverse-phase emulsion polymerization, is a novel agent for profile control and oil displacement different from either polymers or pre-crosslinking gel particles. Its swelling process could be controlled by changing the sort and quantity of inverse-phase agent. This kind of agent possesses high chemical stability and "amoeba" character. Different from bulk gels and the pre-crosslinking gel particles, the micro-gel dispersion with a diameter of 5-13μm could be injected into porous media with a permeability of 0.4-10D with the help of oil before it swelled. The diameter of the swollen micro-gel reaches 20-60μm, and its migration ability in the porous media depends on the diameter of pore throats and the deformability of rock particles. The agent could be used to adjust the reservoir permeability and enhance oil recovery.
  • LI Zhenquan
    , 2004, 31(2): 816-0.
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    Using the existing well pattern of Guantao No.3 Formation in the central No.1 Block of Gudao Oilfield, the dry polymer powder of 8688 tons within the solution amount of 5.005 million cubic meters confected by flesh water and diluted by produced water was injected into the reservoir by two-grade plugs in a period of 33 months. The maximum water cut decrease of the whole area is 6.3% and the maximum water cut decrease in the Station 1-16 is 12.1%. The oil production increment is 690 thousand tons with the oil recovery increment of 6.4%. The water cut appeared a decreasing trend after the followed water flooding. The investment of this project has been recovered completely, which means the success of this industrial pilot test. The profit of this project is remarkable. The evaluation by the “increment method” shows that the internal rate of return is as high as 84.4% with the net present value of 3.8914 trillion RMB Yuan.
  • 油藏物理
  • WU Lei; YUAN Shiyi; HU Yongle; LIU Henian and LI Haiping
    , 2004, 31(2): 817-0.
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    The liquid phase often condenses in the reservoir when the fluid pressure drops below the dew point pressure. The condensate often remains as an immobile phase in the porous media with low recovery because the saturation point of liquid condensate is usually less than that of the critical condensate and the mobility effect occurs due to larger viscosity of condensate. Due to the effect of phase equilibria, the reservoir fluid may exhibit one, or a combination, of the following three types of vaporization: ① the re-vaporization of condensate, when the pressure is below the maximum condensation pressure, ② the equilibria revaporization due to the extraction effect of lean gas during gas injection, ③ the retrograde vaporization of condensate, when the reservoir pressure builds up as a result of more voids being replaced by injected gas. With pressure depletion, the liquid volume will be reduced continuously. For rich gas condensate reservoirs, due to the component exchange between the injection gas and the condensed liquid, the re-vaporization is obvious. The tests show that the lean gas can vaporize the intermediate as well as the heavier fraction such as C20+. In the natural reservoir, under the condition of high injection-production ratio, the composition of heavy components will increase and the heavy components can be extracted to the surface through partial vaporization.
  • ZHONG Taixian; YUAN Shiyi; HU Yongle; LIU Henian and LI Haiping
    , 2004, 31(2): 818-0.
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    Gas condensate reservoirs discovered worldwide may contain a large amount of heavy molecular weight hydrocarbon components, resulting in complex gas-liquid-solid phase changes, near-critical behavior in huge condensate gas layers and even peculiar composition distribution. The experimental results show that the fluids may exhibit four regions of phase transition in pressure-temperature diagram due to the effect of wax: ① gas-solid phase in the lower temperature and high pressure; ② a gas phase only in the both high temperature and pressure; ③ gas-liquid-solid phase in the lower temperature and ④ a gas-liquid phase in the high temperature and low pressure. Under a high pressure and high temperature condition, the reservoir fluids would be large deviation factor, low IFT, etc., water is likely to be present in the form of vapor. The condensed water will heavily corrode the equipment in the presence of sour gas.
  • 国际交流与合作
  • ZHOU Wenwen; JIANG Wenrong and LIRongxi
    , 2004, 31(2): 819-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Abundant organic inclusions with different characteristics of filling were discovered from the reservoir rocks of Zhuhai and Zhujiang Formation in Zhu ⅢDepression. The organic inclusions in Wenchang Sag A and Qionghai Uplift can be divided into two phases that represent two main periods of oil and gas migration. The Phase I organic inclusions filled in the secondary pores of the inner or edge of the detrital quartz grains, with the homogenization temperature ranging from 120℃ to 140℃. The Phase II organic inclusions filled in the crack of detrital quartz grains or overgrowths on the quartz, with the homogenization temperature ranging from 150℃ to 170℃. There is only one phase of organic inclusions occurred in Wenchang Sag B, indicating only one period of oil and gas migration. The organic inclusions filled in the secondary pore and crack, with its temperature varying from 120℃ to 140℃. The measurement of homogenization temperature of organic inclusions can be used to calculate the paleo-geothermal gradient. With the paleo-geothermal gradient, the buried depths for oil/gas migration have been calculated and the time for peak oil/gas migration is inferred at Middle Oligocene to Quaternary. This paper analyzes the experimental test results of the homogenization temperature, salinity, fluorescence spectrometry, micro-Fourier transform infrared spectrometry, laser Raman microprobe, isotope and biomarker from the organic inclusions. It is suggested that the hydrocarbons within organic inclusions in Wenchang Sag A and Qionghai Uplift come from Enping Formation, and that in Wenchang Sag B from Wenchang Formation. The ancient water between Wenchang Sag A and B has different characteristics. In result, the characteristic and distribution of petroleum system in Zhu Ⅲ depression are further understood.