, Volume 33 Issue 3
    

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  • Hydrocarbon formation and distribution of rift basins in Sudan—A comparative analysis of them with rift basins in East China
    DOU Lirong; PAN Xiaohua; TIAN Zuoji; XIAO Kunye and ZHANG Zhiwei
    , 2006, 33(3): 1278-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Rift basins in Sudan are the passive rifts which are formed and controlled by the Central African Strike-slip Zone triggered by the opening of Atlantic Ocean in Late Mesozoic. The three rifting sequences of Lower Cretaceous, Upper Cretaceous, and Paleogene are superimposed vertically, ranging from passive rift in Early Cretaceous to active rift in Paleogene. The sub-basins typically have a half-graben geometry characterized by steep planar boundary faults and a low extensional factor. Trace volcanic activities and continuous tectonic subsidence result in a complete sedimentary cycle during Early Cretaceous and a set of excellent source rocks. The major pay zones are composed of quartzose and feldspathic-quartzose sandstones, featured by high porosity and high-permeability. Oil reserves are mainly accumulated in the post-rift and overlying younger rift sequences. The major oil reservoirs are antithetic fault blocks and large drape-anticlines in the younger rift sequences. The transfer zones control the oil and gas accumulation and distribution. The characteristics of rift basins in Sudan are much different from those in the active rift basins of East China.
  • Practice and understanding on tertiary recovery in Shengli Oilfield
    SUN Huanquan
    , 2006, 33(3): 1279-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The tertiary recovery has become the dominant technique for the stable production of old oilfields in the Shengli Oilfield. The cumulatively incremental oil was up to 11.50 million tons by the end of Mar. 2006. Chemical flooding has developed from single polymer flooding to multiple compound flooding systems in the oilfield, and a complete set of chemical flooding with the oilfield's characteristics was formed. The tertiary recovery is facing some major problems, such as inadequate high-quality resources of the polymer flooding, replacement difficulty and unbalanced development of the tertiary recovery technology, and great resulted differences among the chemical-flooding implemented units, etc. The chemical flooding technology and the ability to innovate new products should be strengthened. The developmental space of tertiary recovery should be widened through continuously extending technical storage. The polymer-injection project should be well managed so as to enhance the effect of water decreasing and oil increasing. The intensive pilot study will make the tertiary recovery technology replacement faster.
    • 油气勘探
  • Current situation of natural gas exploration and its countermeasures in Junggar Basin
    YU Yuanjiang; ZHANG Yijie; DONG Dazhong and HAN Yongke
    , 2006, 33(3): 1280-0.
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    Owing to the historical reason, the exploration and study of natural gas were at a low level in the past 50 years of the Junggar Basin. The natural gas is in an early and fast-growing stage with the explored reserves increasing in skip-style and its yearly output rising continually and stably. The wide distribution of natural gas and large numbers of residual gas wells in the basin promise a good development prospect. Gas/oil ratios of wells go up from the margin to the central region and from the shallow layer to the deep zone in the basin, showing that there are big gas fields in the central region and lower compounding. The residual gas resources are abundant and mainly distributed in four big exploring areas. Three main problems of natural gas exploration are pointed out and countermeasures and suggestions are brought forward.
  • Exploration scheme of gas in deep-seated volcanic rocks in Songliao Basin
    YANG Hui; ZHANG Yan; ZOU Caineng; WEN Baihong; LI Jianzhong and LI Ming
    , 2006, 33(3): 1281-0.
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    Based on the similarity between the hydrocarbon generation intensity of source rocks and the formation thickness of faulted depression in the Xujiaweizi faulted depression in Songliao Basin, an exploration scheme of superposition of magnetic anomaly on thickness of source rocks to choose matched faulted depressions and prospective volcanic rock formations in other depressions with less study degree is proposed. With the geological and logging data, Changling and Gulong Depressions are believed to be the most prospective gas reservoirs in volcanic rocks in Songliao Basin. According to the viewpoint that the vicinities of magnetic gradient belts close or connected to source rocks are the most promising areas for gas exploration, some prospective volcanic rock belts are predicted in the Changling and Gulong Depressions. From the preliminary evaluation of the wildcat wells, Changshen 1 in Changling Depression is recommended to drill. A volcanic structure, 6 km north to Gushen 1 in Gulong Depression, is believed to be more favorable to drill. With the purpose of exploring gas in volcanic rocks, a 1:50 000 high-resolution aeromagnetic survey to cover the entire basin is suggested.
  • Water-soluble gas accumulation process of Hetianhe gas field in Tarim Basin，NW China
    QIN Shengfei; ZOU Caineng; DAI Jinxing; LI Mei; HU Jianfeng; ZHANG Qiucha and LU Yuhong
    , 2006, 33(3): 1282-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The Hetianhe gas field of Tarim Basin has excellent geological conditions for water-soluble gas accumulation. The gases exhibit very good water-soluble characteristics. The traps were formed during the Late Himalaya orogeny,when the gases generated by highly mature Cambrian source rock were largely dissolved in water. Subsequent faulting allowed the gas charged water to migrate towards Ordovician and Carboniferous traps in the eastern part of the field. As the pressure and temperature decreased, some gases were released from water and gas reservoirs were formed. The water beneath the gas-water interface subsequently migrated along the unconformity for a long distance from the eastern high-pressure part towards the western low-pressure part of the field. During the horizontal migration, the gases were gradually released as pressure decreased. A chain-like cluster of gas pools was formed. The migration history has made the migration parameters of the water soluble gases increase significantly from west
  • Leading effect of high-class source rock of Chang 7 in Ordos Basin on enrichment of low permeability oil-gas accumulation——Hydrocarbon generation and expulsion mechanism
    ZHANG Wenzheng; YANG Hua; LI Jianfeng and MA Jun
    , 2006, 33(3): 1283-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Based on geochemical testing, hydrocarbon-generation thermal simulation experiment, and the basin petroleum geologic characteristics, the paper analyzes the hydrocarbon-expulsion and mechanism of the high-class source rock in Chang 7 oil-shale section, and calculated the hydrocarbon expulsion rate. The yield of Chang 7 is up to 400kg/t. TOC and its increasing pressure action from hydrocarbon-generation expanding can offer enough energy for oil primary migration (hydrocarbon-expulsion). The kerogen network system and the pore-fracture system constitute a three-dimensional network system for the migration. The continuous oil phase is the main phase of primary migration. The intense compaction before the oil shale section matured and generated oil do not have any effect on the hydrocarbon-expulsion efficiency, on the contrary, the lower residual porosity reduces the capacity to occlude hydrocarbon, which is helpful to enhance hydrocarbon-expulsion efficiency (the average reaches 72%) and makes the high-class source rock have the good quality fluid with high hydrocarbon and low water. This provides advantageous conditions for crude oil concentration of low permeability reservoir.
  • Oil sources of Fuyang oil formation in Qijia Sag and Daqing Placanticline, Songliao Basin
    WANG Xue
    , 2006, 33(3): 1284-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Qijia Sag is one of the important petroleum generative depressions in the Songliao Basin, and the Fuyang oil formation is the main oil-bearing formation. Different opinions existed on oil sources of the Fuyang oil formation in the northern Qijia Sag. By means of oil population division and oil-source correlation, it is showed that the crude oil of the formation originated from the local Qingshankou No.1 Formation. It negates the viewpoint of migration. In the past 40 years, it was believed that the sags on both sides supplied the oil of Daqing Placanticline. Oil-oil and oil-source correlations reveal that there is low mature authigenic oil in the placanticline，which proves that low mature source rocks have the genetic potential in Daqing Placanticline.
  • Lithology prediction by Poisson’s ratio—An example from Junggar Basin, NW China
    FAN Changjiang and WANG Xian
    , 2006, 33(3): 1285-0.
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    This paper puts forward a new method of identifying lithology of high-speed mudstone layers by using Poisson's ratio, in which, the Poisson's ratio calibration template is set forth based on lab data and full-wave log data, and the Poisson's ratio data volume is calculated through the AVO inversion technology. The Poisson's ratios of sandstone and mudstone are obviously different and that difference between calcareous mudstone and sandstone is even greater, showing that the method is better in predicting lithology than P-wave impedance. The Poisson's ratio calibration template analysis shows that the method can effectively distinguish between sandstone and mudstone, and between sandstone and high-speed mudstone. It can effectively predict the hydrocarbon of formations within 3000m. In the Poisson's ratio inversion of the Junggar basin, sandstone and high-speed mudstone can be clearly identified in the Poisson's ratio profiles, while it is impossible in P-wave impedance. The predicted sandstone and reservoir boundary match the real drilling and production test, suggesting the method can offset the shortcomings of P-wave impedance inversion, enhance the prediction accuracy, and reduce the lithologic exploration risk.
  • Syngenesis relationship between abnormal overpressure and gas pool formation—With Kuqa Depression as an example
    SONG Yan; HONG Feng; XIA Xinyu; GAO Gang and FU Guoyou
    , 2006, 33(3): 1286-0.
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    The paper analyzes the relationship between abnormal overpressure and gas pool formation in the tectonic compression environment, taking the Kela 2 gas field of Kuqa Depression as an example. In the earlier cosmic elevating, most gas is injected into pool and the pressure of gas accumulation rises rapidly. The hydrocarbon accumulation model of Kela 2 is that the reservoir and source rocks are communicated by faults, and oil and gas driven by superpressure migrate into reservoir and accumulate. In the earlier accumulation, the reservoir has no strong superpressure and is not closed. The fluids can outflow from it. With the natural gas replacing water in the structural trap and the diagenesis, the liquid pressure of gas accumulation rises and the overpressure pool is formed no more than 2 Ma ago. Abnormal overpressure and gas accumulation are the results of structural event and conservation condition; there is not a cause-effect connection between them. The perfect match between gas source and seal is the key factor of gas accumulation.
  • Exploration of Paleogene lithostratigraphic reservoir in western steep slope of Damintun Sag，Liaohe Oilfield
    ZHAO Limin and SUN Hui
    , 2006, 33(3): 1287-0.
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    The margin fault controlled the formation of the western steep slope in the Damintun Sag during the early Paleogene, and two fracture slope break zones including salient-steep slope margin and steep slope-subsag margin were developed. The source supply of western steep slope was the important condition for forming the lithostratigraphic reservoir. In terms of sequence stratigraphical principles, the Paleogene can be divided into one 2-order sequence and 3-order sequences. The 3-order sequence can be further divided into deep-faulted sequence and shallow-faulted sequence, with the former one having excellent reservoir conditions. The sandstone body of low-stand system and the sandbody of lake transgression under the control of the fracture slope break zones are important targets for the lithostratigraphic reservoir exploration. Drilling proves the predicted spacial distribution characteristics of sandstone body.
  • Distribution and genesis of secondary pores in Tertiary clastic reservoir in Southwestern Qaidam Basin
    LIU Wei and ZHU Xiaomin
    , 2006, 33(3): 1288-0.
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    The sedimentological and petrologic researches in the southwestern Qaidam Basin indicate that the reservoir spaces in Tertiary clastic rocks are mainly primary pores and secondary pores. Secondary pores exist from 1700 m to 3900 m in the study area. Two secondary pore belts are developed in the Yuejin area, and one in the Lcaotan-Wunan-Wanxi area. The genesis of the secondary pores is the dissolution of carbonate cement, feldspar and lithoclast caused by organic and carbonic acids, which are generated during the evolvement of source rock. The development and distribution of secondary pores are controlled vertically by the maturity time of source rock and horizontally by the location of acidic water. They are also related to the sedimentary facies zone where the sandstones exist and the development of fault zone.
  • Origins of interlayer and permeability barrier and their controlling function on reservoir—With Sangonghe Formation of Moxizhuang in Junggar Basin as an example
    WANG Yanzhang; LIN Chengyan; DONG Chunmei and LOU Guoquan
    , 2006, 33(3): 1289-0.
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    Aimed at the complicated distribution of oil and water in the thick sandbody and the difficulty of identifying the trap type in Moxizhuang, Junggar Basin, the heterogeneity of the reservoir was studied and the origins of interlayer and permeability barrier and their function on the oil and gas distribution were discovered. The interlayer blocks off the oil and gas not only at the reservoir top, but also, if the oil column height is short, on the side. These cause the situation of water-up and oil-down in vertical and the tilted oil/water contact. The diagenesis-formed lateral permeability barrier zone provides the necessary condition for the side block, leading to the different oil/water contacts on both sides of the zone and controlling the distributions of oil, gas and water.
  • Tracing interpretation and prediction for geological structures of the well location during drilling using logging and seismic data and its application
    LI Jun; SHI Zejin; CHEN Qiang; CHEN Weizhong and WANG Huanzeng
    , 2006, 33(3): 1290-0.
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    The extremely complicated geological conditions in the Kuqa foreland basin, Tarim have brought great difficulties in seismic prospecting and resulted in a high risk in oil and gas exploration. Aimed at the difficulties, a new method is put forward which include the following steps: determining geological structures based on the appropriate data-processing and geological interpretation of Dip Log and Borehole Imaging Log in the course of drilling, performing interpretation while drilling for the geological structures of the well location, predicting the well-reached local structural position by integrating logging and seismic data, analyzing the contradiction between logging well-bore and seismic structures, and timely optimizing the parameters for seismic data processing or adjusting the well position to reduce the exploration risk to the minimum level.
  • Origin of Member 2 sandbodies of Lower Jurassic Sangonghe Formation in the area of Well Zhuang 1, Junggar Basin
    LI Dejiang; ZHU Xiaomin; ZHANG Xiaojing; KONG Xianglin and HUANG Wensong
    , 2006, 33(3): 1291-0.
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    Sandbodies of Member 2 of Lower Jurassic Sangonghe Formation are the important reservoirs in the Junggar Basin. At present, there are different understandings to the sandbodies. Understanding the origin of the sandbodies and establishing a sedimentary facies model of the area will shed light on the petroleum exploration and development. The analysis of the core, lithofacies and lithofacies sequence of the wells around Well Zhuang 1 indicates that J1s21(the Upper Second Member of Sangonghe Formation of the Lower Jurassic) belongs to the deposition of meandering stream deltaic front; J1s22(the Lower Second Member of Sangonghe Formation of the Lower Jurassic) belongs to the deposition of braided stream deltaic front and is with the slump turbidite facies at the front of it.
  • Physical simulation of the control of source rock oil saturation on forming lithological oil pools
    WANG Yongzhuo; DONG Chunhui; JIANG Zhenxue and LI Hongyi
    , 2006, 33(3): 1292-0.
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    The lithological oil pools discovered in Dongying Sag are distributed under the depth of hydrocarbon expulsion threshold of Es3 and Es4, and the formation of the oil pools is controlled by hydrocarbon expulsion scopes and intensity distinctly. The control of oil saturation in shoulder-bed on formation of lithological oil pools was studied by using the three-dimensional high-temperature and high-pressure simulation. The relationships between resistance and oil saturation and water saturation were acquired by calibration experiment. The resistance data of simulation experiments were transformed to oil saturation data. The control of oil saturation on formation of lithological oil pools can be demonstrated. The results showed a non-linear decrease of shoulder-bed resistance and a non-linear increase of sandbodies resistance, and the rate of resistance is fast initially, slow afterwards, and steady finally. With a certain pressure, the higher shoulder-bed oil saturation is, the higher oil saturation in sandbodies is, and the more favorable it is for the sandbodies to accumulate oil.
  • Control of sedimentary facies on reservoir quality—An example from Zao Ⅱ and Ⅲ oil sets in Wangguantun Oilfield, Huanghua Depression
    SONG Kun; JIN Zhenkui; WANG Xiaowei; ZHANG Aihong; DUAN Zhiqiang; WANG Chunsheng and ZHANG Guo-hua
    , 2006, 33(3): 1294-0.
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    Wangguantun Oilfield is located in the southern Huanghua Depression. The Zao II and III Paleogene oil sets are the major production beds, and the reservoirs are mainly sandstones with different quality. The study shows that the difference results from the different sedimentary environments. The sandstones with oil and good reservoir quality are deposited in high-energy channels of braided river. They are low in mud content, good in sorting and relatively coarse in grain size. Primary porosity is developed. The sandstones with no oil and poor reservoir quality are deposited in low-energy channels. They are high in mud content, poor in sorting and relatively fine in grain size. Porosity is not developed. High-energy channels are favorable facies for good reservoirs.
  • Sequence stratigraphy and the distribution of natural gas enrichment and high production area in Lower Shihezi Formation, Sulige gas field, Ordos Basin
    LI Hongwei; FAN Junxia; YUAN Shiyi; TIAN Changbing and ZHENG Xiaodong
    , 2006, 33(3): 1295-0.
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    The gas reservoirs in the Lower Shihezi Formation of Sulige gas field are typical lithological reservoirs. They are very subtle and controlled by lithology. In order to reveal the gas reservoirs distribution rule, the sequence stratigraphy and reservoirs overlap and distribution of Lower Shihezi Formation were studied. A key sequence boundary which is an unconformity is recognized in the formation. Below the unconformity are the prograding lobes of fluvial delta which were developed during the base-level fall. Above the unconformity is the incised valley-filled channel sandbodies developed during the base-level rise. The incised valley cut downward into the prograding lobes of fluvial delta, and the incised valley-filled channel sandbodies overlapped over the prograding delta sandbodies. The prograding lobes of fluvial delta acted as the main channels for hydrocarbon migrating from the lower source rocks to the upper incised valley-filled channel sandbodies. The favorable gas accumulation areas and the promising gas production areas lie on the overlapping sites of the incised-valley-filled channels and the prograding delta.
  • Detective ability and data processing method of the MPR logging
    KANG Junzuo; XING Guanglong and YANG Shande
    , 2006, 33(3): 1296-0.
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    The detective ability and data processing method of the MPR (multiple propagation resistivity) logging were studied by using the thinly laminated sequence and the low resistivity annulus formation models. The MPR tool of Baker-Hughes INTEQ provided four phase difference curves and four amplitude ratio curves. The radial integral response curves of some probes of MPR crossed each other, suggesting that there was much repeated information among MPR data. The sensitivity of amplitude ratio curve to formation resistivity was much lower than that of phase difference curve. In this paper, three phase difference curves and two amplitude ratio curves are selected out from the eight logging curves for the MPR data processing. Based on the selected five curves, the thin interbeds and the low resistivity annulus can be identified through the senses. However, the true value of formation resistivity cannot be obtained from these apparent resistivity curves. The two-dimension inversion of MPR synthetic data are carried out by using an improved damping regularized Gauss-Newton optimization algorithm. Satisfying inversion results are obtained for thin interbeds and low resistivity annulus formation models.
  • Reservoir formation process in the Changchunling anticline of Songliao Basin
    WEI Zhaosheng; MIAO Hongbo; WANG Yanqing; LI Jianchen; WANG Maojie and DING Ye
    , 2006, 33(3): 1297-0.
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    A group of oil and gas pools have been found in the Changchunling anticline,southeastern Songliao Basin. Predecessors thought that gas from deep formation occupied upper zone of the structure, and oil from upper source rock only filled the down-zone of the structure. Through researching the reservoir formation, the paper indicates that oil and gas from the K1qn1 section source rock migrated downward with abnomal pressure and passed through fault to the structure. When the basin evolution was in the extruding-shrivel period, the Changchunling anticline had taken shape. Gas in deep formation passed through fault, migrated upward and accumulated in the structure. Then oil was expelled to the down-zone of the structure, the oil displayed a "gas-washing" character. Because the gas in deep formation was abundant and several destruction of the reservoir caused original gas reservoir to be substituted by the gas in deep formation, the mixed gas was with little associated gas. It is such a process that leads to gas reservoir locating at the upper of the structure and oil ring appearing in the down of the structure.
    • 油气田开发
  • 16S rRNA genes comparative analysis of microbial community in nutrient-injected oil reservoir by the T-RFLP method
    CHENG Haiying; XIAO Shengke; MA Guangdong; WANG Weidong and WANG Xiulin
    , 2006, 33(3): 1298-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    For monitoring the dynamics of microbial community under simulated oil reservoir conditions, the effect of nutrient injection on the structure of oil reservoir microbial community was investigated by applying a cultivation and clone independent molecular technique—terminal restriction fragment length polymorphism (T-RFLP). With the bacterial and archaeal primer pairs in which forward primers were fluorescently labeled, 16S rRNA genes were amplified from total community DNA by polymerase chain reaction (PCR). The PCR products were digested by the restricted endonucleases Rsa I and Msp I. The labeled terminal restriction fragments were efficiently separated by capillary gel electrophoresis and sensitively detected by the laser-induced fluorescence detector for determining the length and abundance of each T-RF. The T-RFLP pattern comparisons between samples with different incubation time showed that the number and abundance of T-RF were significantly increased after incubation and that the structures of microbial communities were different, suggesting that T-RFLP is a powerful tool for studying the dynamics of oil-reservoir microbial communities and analyzing their structures.
  • Impact of perforation parameters on the flow efficiency of water injection wells
    ZHAO Min; ZHOU Wanfu; XIONG Tao and LIU Wenping
    , 2006, 33(3): 1299-0.
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    The authors analyzed factors of influencing the flow efficiency during the process of perforation completion in water injection wells. The relational expressions of flow efficiency with factors under the following three conditions are given: the hole depth doesn't perforate the polluted area, the hole depth perforates the polluted area, and the ideal perforated hole with perforation compaction and without drilling pollution. The efficiency influencing factors in order of importance are: hole depth, hole density, compaction damage degree, hole diameter, phase angle, formation heterogeneity and compaction thickness when perforation doesn't penetrate polluted zone. When perforation penetrates polluted zone, the order is hole density, hole length, compaction damage degree, formation heterogeneity, compaction thickness, phase angle and hole diameter.
  • Technique of exceptionally low abundance oil reservoir development by horizontal wells and its application
    JIANG Hongfu; SUI Jun; PANG Yanming; ZHANG Guoliang and LIU Yuetian
    , 2006, 33(3): 1300-0.
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    A horizontal well development test of exceptionally low abundance formations was conducted in the Daqing Oilfield. The formations are thinner than 1m. The seismic interpreting and geologic modeling were utilized to describe the structure and faults of the formation where the horizontal wells were to be located. The target-based geological statistics method of sandbody modeling was selected for lithology interpolation and providing foundations for the design and geological guide of horizontal wells. The well network with producing horizontal wells and both injecting and producing vertical wells was selected as the optimal well network, and the production capacity was forecasted by simulation. The electric test and well track were obtained and imaged at real time. The geological model was modified also at real time and used to guide the drilling direction in the sand. The sand oiliness was estimated by the drilling returns analysis and gas logging, providing the basis for geological guide and later perforation. The actual average sand ratio drilled along horizontal well bores is 55%, with the highest ratio of 75%. The average stable production rate of the 10 horizontal wells which have been producing for over 6 months is 8.9t/d per well. The average initial production rate of the 10 horizontal wells is 19.5t/d per well. They are three times more than those of vertical wells.
  • Application of foam combination flooding in Shengli Oilfield
    ZHOU Guohua; SONG Xinwang; WANG Qiwei; GUO Ping; LI Xiangliang and LI Xuesong
    , 2006, 33(3): 1301-0.
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    An experimental study about polymer-surfactant foam combination flooding was done in the reservoir conditions of the central part of Block 2 in central Gudao Oilfield and the western Chengdong Oilfield. The blocking ability of the flooding system rises with the increasing core permeability. The resistance factor of gas and liquid commingled injection grows with the injection rates rising while that of gas and liquid alternative injection wavily rises with the injection rates rising, however both the methods can produce better blocking effect. When it is injected alternately with a low gas/liquid ratio, the blocking effect is generated more slowly; when it is alternately injected at big-size slug, the blocking effect is worse than at small-size slug. The oil recovery factor increases by over 20% than that of water flooding. The foam agent is not sensitive to salinity, temperature and oil, and has a stable displacement effect. In the field test in Gudao Oilfield, production wells got obviously increased oil with less water, and water injection wells had the input profiles greatly improved.
  • Practice of tertiary-main layers polymer flooding in Daqing Oilfield
    ZHANG Xiaoqin; GUAN Heng and WANG Hong-tao
    , 2006, 33(3): 1302-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Based on physical simulation experiments and mathematical simulation, the paper summarizes a series of methods about tertiary-main layers polymer flooding in Daqing Oilfield, including: accurately dividing layer series of development; strictly controlling object of polymer-flooding; declining differences of formation; enhancing the degree of exploring oil-bearing formation; the injection-production well spacing should be 100m or so to enhance the controlling degree and improve injection-production connection. In selecting relative molecular weight of polymer, the oil displacement efficiency of polymer flooding, the compatibility of relative molecular weight and oil-bearing formation, and the impact of the clay swelling of low permeable formation on permeability should be considered.
    • 石油工程
  • Application of geo-steering technique of horizontal well in complex fluvial reservoir—A case from Caofeidian 11-1 Oilfield
    QIN Zongchao; LIU Yinggui; XING Weiqi; WANG Guodong and GAO Dongsheng
    , 2006, 33(3): 1303-0.
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    In the geo-steering technology, a reservoir navigation model is built, with which the anticipated formation lithology and LWD logging are simulated based on the appraisal wells data. While drilling, the modeled structure and reservoir are validated constantly from the real-time LWD and the compound logging. The model is updated repeatedly according to the penetrated information. The target depth is diagnosed and the target data is adjusted accordingly to make sure the horizontal well successful. The technology has two key steps: geo-steering to land the horizontal well and reservoir navigation to the horizontal section. Horizontal wells are applied in the development practice of the Caofeidian11-1 Oilfield. Different geo-steering rules are made for landing and horizontal section drilling based on different reservoir type, structure and container rock characteristics. They provide a powerful guarantee for perforating reservoirs and increase the success ratio of horizontal well drilling in comparison with the conventional technology.
    • 国际交流与合作
  • Sedimentary characteristics and evolution of Lower Devonian in Zarzaitine Oilfield，Eastern Algeria
    LI Shunming; DENG Hongwen; WU Xiuli and ZHANG Haina
    , 2006, 33(3): 1304-0.
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    The petrologic characteristics, sedimentary structures, well log curves and paleontology of the Lower Devonian F4 reservoir in the Zarzaitine Oilfield of Algeria were analyzed from a multi-disciplinary aspect. It shows that the sedimentary facies are submarine fans deposited by gravity flow at the bathyal depth. The mid-fan and lower-fan sub-facies of submarine fans are developed. From the proximal to the mid, the distal of the mid-fan and to the lower-fan, gravity flow evolves gradually from debris flow to grain flow, liquefied flow, low density turbidity current and finally to traction current. The planar distribution features of the reservoir sedimentary facies are that the lower part consists of predominant mid-fans and subordinate lower-fans, the mid part comprises mid-fans without lower-fans, and the upper part comprises reducing mid-fans with lower-fans expanding. The sea level changing from fall to rise is the main controlling factor of the spatial shift of sedimentary micro-facies.
  • Recommendations on strategic selection of exploration areas in Africa
    JIANG Wenrong; LI Yun; CAI Dongsheng; WANG Bruce and ZHANG Qi
    , 2006, 33(3): 1305-0.
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    The sedimentary basins in Africa are of different structure styles: Paleozoic and Mesozoic flexure basins, Mesozoic and Cenozoic continental margin rift basins, intra-plate rift basins and continental margin progradational deltaic basins. The paper categorizes the basins according to the integrated geological evaluation of the play elements, the basin analog analysis of various exploration stages and the ultimate exploration potential analysis. Based on which, the authors conclude that the selection of exploration areas in Africa should follow the following principles: for long-term the strategic exploration areas should have resources potential, low cost, high risk and high return; for mid-term the strategic exploration areas should be the hydrocarbon resources in good geological conditions, with high return in short to middle terms; for short-term the strategic exploration areas should be of middle to low cost, low risk and low return, just be favorable for petroleum discovery during a short period.
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