, Volume 32 Issue 6
    

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  • State of the art, challenges and countermeasures of natural gas development in China
    YUAN Shiyi; HU Yongle and LUO Kai
    , 2005, 32(6): 1192-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The prospect natural gas resources are 48 TCM in China. As of December 31, 2004, the cumulative proved gas in place amounts to 4.41 TCM with 70% PGIP distributed in Midwest China including Tarim, Sichuan, Ordos and Qaidam basins. The successful developments of major gas fields such as Sichuan, Changqing, Kela-2 and Sebei fields have led to the establishment of onshore four big gas exploration/production areas. In 2004 the national gas production volume reached 40.8 BCM. In last decades, the continuous advancements of gas field development technology have contributed to the establishment of the major development technologies for different types of gas reservoirs including carbonate, low permeability, low-to-moderate H2S content, geopressured, gas condensate, etc. However, the gas reservoirs newly discovered in recent years are very complex. Their cost-effective/efficient development and the stable production including developed gas fields face challenges. Thus, the efficient development of these gas fields requires further advancement, improvement application of technologies focusing on safe and efficient development of HPHT gas reservoirs, massive hydraulic fracturing or horizontal well technology for low permeability reservoirs, sand control and water management for multi-layered loose sand reservoirs, safety and antisepsis and purification for sour gas reservoirs and gas cycling for gas condensate reservoirs.
  • Connotation of "Facies Control Theory" and its significance for exploration
    ZOU Caineng; TAO Shizhen and XUE Shu-hao
    , 2005, 32(6): 1193-0.
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    The viewpoint and basis of "Facies Control Theory" whose focus is reservoir facies are brought forward on the base of reviewing development course for exploration theory and analyzing the formation and occurrence rule of a variety of oil and gas reservoirs, and the formation and occurrence of every kind of oil and gas reservoirs with the regulation of "facies controlling" are indicated on the premise of possessing the basic geological conditions of reservoir-forming. "Reservoir facies" that control the petroleum reservoir-forming and accumulation mainly include, sedimentary facies, diagenetic facies and so on, and the"selecting depression and determining facies" are emphasized in exploration. The "facies controlling" features and rules in the litho-stratigraphyic traps, foreland basins,lower-middle combination of superimposed basin are mainly explained.
  • Petroleum generation theory deserves to be reconsidered-Reply to HUANG Di-fan and LIANG Di-gang's argument about theory of petroleum genesis
    LI Qingzhong
    , 2005, 32(6): 1194-0.
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    The paper is supposed to be a reply information to Mr. HUANG Di-fan & LIANG Di-gang's deliberating paper titled "Basic theoretical questions of oil generation in petroleum plays: discussing with oil inorganogenic theorists". The author stress that although the organic petroleum generation theory may help to find oil & gas in most cases, it doesn't answer the origin of petroleum genesis itself, and it seems to be more doubtful. From author's point of view, the indexes of organic source oil generation theory in present time are merely some kinds of sealing bed index and similar to oil seep show index. Up to now, no one can prove that organic material can produce petroleum in laboratory at low temperature (50-100℃). Author realizes even if abiogenic doctrine to be accepted, people will still explore petroleum in sediment rocks under sealing rock. After unbinding from the old theory, people will be brave to attempt searching petroleum in new frontier area and in new deep formations, and people will pay more attention to explore oil fields related to deep fault. Recently, accompanying with deep drilling exploration in China, people realize that under the old oil field, in most cases, there still exist deep oil pays or oil seeps in deep formations down to fundament. If a person's thought being restricted in old hypothesis, some kinds of oil field will not be found due to the obsolete idea.
    • 石油地质研究
  • Reservoir characteristics and development controlling factors of JZS Neo-Archean metamorphic buried hill oil pool in Bohai Sea
    ZHOU Xinhuai; XIANG Hua; YU Shui; WANG Gang and YAO Changhua
    , 2005, 32(6): 1195-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    JZS is the biggest buried hill oil pool in the Liaoxi uplift of Bohai Sea area, with dominated light grey gneiss and cataclasite. The laboratory test reveals that reservoir properties of JZS buried hill are reasonably good, but still very heterogeneous. Reservoirs in this area can be classified into 4 types with FMI and porosity log information:①network-dissolved fracture reservoir;②cataclasite reservoir; ③dissolution fraction reservoir and ④micro-fracture tight reservoir. The Neo-Archean metamorphic buried hill reservoir in the JZS underwent diagenetic period→pre-buried→erosion-deformation→hypergenesis→post-buried period. The key controlling factors in JZS pool are Cenozoic palaeo-geomorphology and tectonic stress of Mesozoic and Cenozoic. The weathered eluvium is distributed in flat slopes of different highlands. Tectonic stress, weathering and dissolution during catagenesis, and organic acid dissolution during oil and gas infilling are the key to affect the evolution of metamorphic reservoir of the JZS oil pool. The evolutionary pattern of Neo-Archean metamorphic reservoir of the JZS oil pool can be applied to similar buried hills in the Bohai Sea area.
  • Differences for geochemical controlling factors between coal-bed and conventional natural gases
    ZHAO Mengjun; SONG Yan; SU Xianbo; LIU Shaobo; QIN Shengfei and HONG Feng
    , 2005, 32(6): 1196-0.
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    Contrasting the coal-bed thermal evolution and the coal-bed gas geochemical characteristics in the Jincheng area of south Qinshui Basin and in the Huozhou area, western Qinshui Basin, central China, suggests that the geochemical characteristics of coal-bed gas, such as components and carbon isotopic compositions, are controlled by the key geological period, when the coal-bed reached the highest mature rank. Whereas the components and carbon isotopes of the coal-bed gas could reflect the coal-bed thermal evolution. Because the coal-bed gas is very different from conventional natural gas in storage mechanism, the effect on the geochemical characteristics of coal-bed gas by thermal evolution is different from stage and consecution accumulation processes for the conventional natural gas. The storage mechanism difference has obvious effects on the geochemical characteristics of coal-bed gas, which is different from that of the conventional natural gas.
  • Relationships between dynamic conditions of effective hydrocarbon expulsion and critical abundances of organic matter in carbonate source rocks
    HUANG Zhilong; ZHONG Ningning and ZHAO Zhe
    , 2005, 32(6): 1197-0.
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    In the possible dynamic models for hydrocarbon expulsion in carbonate rocks, the formation of micro-fractures is very important as the increased pressure can be released through these fractures. It is difficult to observe the formation of micro-fractures directly in the hydrocarbon generation process in carbonate source rocks, but the amount of the pressure increase resulting from hydrocarbon generation could be estimated by measurements of the generated products in experimental simulations and certain mathematical models. The temperature and pressure conditions for the formation of the effective hydrocarbon expulsion pathways in carbonate source rocks could be determined based on the obtained values of the theoretical pressures for rock cracking, suggesting that the driving force for effective hydrocarbon expulsion is relative to organic matter abundance in carbonate rocks. At normal subsurface temperatures, hydrocarbon generation by carbonate rocks with very low abundances of organic matter can hardly create enough additional pressures to result in the formation of cracking fractures, which constitute effective hydrocarbon expulsion pathways. The total organic carbon content of 0.2%-0.3% is determined to be the critical organic matter abundance for the dynamic conditions for effective hydrocarbon expulsion.
  • Denudation ridges and erosion flutes in the central gas field, Ordos Basin
    DAI Jinyou; ZHANG Yiwei; SHI Ruoheng and HE Shunli
    , 2005, 32(6): 1198-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The gas field in the center of Ordos Basin is formed in the eastern central paleo-uplift of the stable craton. They are of weathering crust and related to Ordovician marine carbonate. Due to obvious paleo-karst, erosion flutes and platform co-exit at the top of the weathering crust. According to the previous studies, the erosion flutes on the eastern and western borders are of the same origin,the latest data show that there are clear differences between them. The western ones are denudation ridges, which are the extension of the planar denudation during the change from central paleo-uplift to paleo-marine basin. Stratum lacuna of the Ordovician top in the western ones are caused by wind action, chemical corrosion, and leach; whereas that in the eastern ones by linear erosion and chemical erosion.
  • Exploration and targets for lithologic reservoirs in Junggar Basin, NW China
    KUANG Lichun; Lü Huantong; QI Xuefeng; TANG Yong and ZHANG Xin
    , 2005, 32(6): 1199-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Twelve steep-slope fan-like reservoirs have been found in Junggar Basin. In the gentle-slope depositional system, such petroleum reservoirs as braided channel sandbody in Jurassic Toutunhe Formation in Well Feild Shinan 4, Shinan 21 and Shinan 26, and hydrocarbon reservoirs of Sangonghe Formation in Zhongguai High and Xishanyao Formation in Baijiahai High, have also been found. Having experienced polycyclic tectonic movements and multistage vibratory movements of lake planes, Junggar Basin has been provided with good bases for the formation of various lithologic traps. Multitudes of hydrocarbon sources and kitchens have provided abundant hydrocarbon sources for the formation of lithologic reservoirs. Multistage faulting activities and the development of multi-regional unconformable surfaces have constructed an excellent oil and gas transporting system for multi-stage hydrocarbon accumulation in the depositional traps. Therefore there is great potential for exploration of lithologic reservoirs. The identifying ratio of the lithologic reservoirs in Junggar Basin only accounts for about 4%. The reserves from such reservoirs account for less than 22% of the total proved hydrocarbon reserves. It is considered that there are currently mainly five provinces for the exploration of lithologic hydrocarbon reservoirs in Junggar Basin: Permian and Triassic steep-slope fan body in the NW margin, large gentle-slope delta front mouth bar and slumping fan of Jurassic Sangonghe Formation and Xishanyao Formation in the hinterland, channel sand body of Toutunhe Formation (or Shishugou Formation) in Luxi and Fudong slope, Jurassic-Cretaceous channel-incised valley stratigraphic-lithogic trap dominated by Chemo High, and stratigraphic-lithologic trap dominated by Jurassic structural slope belt in Western Slope of Mahu.
  • Helium and argon isotopic compositions of natural gases in the Tazhong area, Tarim Basin
    ZHANG Dianwei; LIU Wenhui; ZHENG Jianjing; WANG Xiaofeng and NAN Qingyun
    , 2005, 32(6): 1200-0.
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    Helium isotopic compositions in natural gases have a good relationship with geology tectonic background,which indicate the features of tectonic evolvement in a great region but don't work for a small region in the same basin. The 3He／4He ratio of natural gas in the Tazhong area, Tarim Basin,has typical crust-source characteristics, and is consistent with the tectonic background in the basin.The 40Ar/36Ar ratio of the gases in the Tazhong area is different from that in other basins with Cambrian-Ordovician source rocks, which could be caused by the low potassium abundance in Cambrian-Ordovician source rock in the Tazhong area. The calculation of potassium abundance indicates that the argillite and argillaceous stripe in Cambrian-Ordovician source rocks make significant contribution to natural gases in the study area.
  • Forming conditions of lithologic reservoir in transition zone of western Liaohe Depression
    SHAN Junfeng; CHEN Zhenyan and HUI Xuefeng
    , 2005, 32(6): 1201-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The structural hydrocarbon reservoir exploration is becoming more harder in the western Liaohe Depression. It was proved that the transition zone of slope and depression has the geologic conditions of forming a large-scale lithologic reservoir by analyzing the sedimentary system, oil sources, transport system and sealing system. It could be the main direction in the future exploration. Following this cognition and by synthetically using log, geological and seismic data, Huan 103, Qi 231 and Jin 306 traps have been found as the lithologic reservoirs, showing a great exploration potential.
  • Petroleum geological role of Paleogene overpressure reservoirs in Tanggu-Xincun of Beitang Sag, Bohai Bay Basin
    DENG Rongjing; XU Bei; QI Jiafu; XIAO Dunqing; WEI Ajuan; WANG Donglin and Li Jianying
    , 2005, 32(6): 1202-0.
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    Based on well acoustic and static pressure data, two disequilibrium compaction zones are defined vertically in the Paleogene of the Tanggu-Xincun region, Beitang Sag, with the uncompaction of the lower one stronger than that of the upper one. The overpressure reservoirs are developed beneath 3500m and their planar distribution is mainly in the east of Tanggu structure belt and the low relief of Xincun structure belt. The reservoirs' pressure coefficients are associated with the sedimentary facies and fault activities. Disequilibrium compaction and the generation of oil and gas triggered abnormal high pressure in the study area, which retarted source rock thermal evolution, prompted oil and gas migration, conduced to the preservation of reservoir primary porosity and the formation of deep fractures, and improve the well production. The overpressure mudstone could be a good cap rock.
  • Application of stochastic simulation of reservoir parameters on heterogeneity in fan delta reservoir
    HUANG Jixin; PENG Shimi and HUANG Jianquan
    , 2005, 32(6): 1203-0.
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    Fan delta reservoirs are widely distributed in most continental basins in China, and heterogeneity of parfacies is serious. Based on the heterogeneity of fan delta reservoirs in the first and second member of Kongdian Formation in the Weibei Basin, Tanlu Fault Zone,sedimentary facies and reservoir property models were established by deterministic modeling and stochastic modeling. According to the variogram and stochastic simulation, the distribution of micro-facies was described by the sequential indicator simulation. The fractional geometry model of porosity and permeability was developed based on fractional Kriging interpolation principles. Comparing all the simulations suggests that the Kriging Model could preferably reflect the macroscopic changes of reservoir physical properties and sequential indicator simulation reproduces the heterogeneity in reservoirs. The fractional Kriging Model could reflect macroscopic physical properties and heterogeneity.
  • Jurassic stratigraphic base-level cycle and subtle oil reservoir in Baijiahai-Wucaiwan, Junggar Basin, NW China
    HU Ping; XIE Hongwei and SHI Xingpu
    , 2005, 32(6): 1204-0.
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    Baijiahai-Wucaiwan is located in the NE Junggar Basin, where the subtle oil reservoirs could be the major play targets. According to the stratigraphic base level, six mid-term base-level cycles and eleven shore-term base-level cycles can be recognized in the Jurassic. Based on the drilling，well logging, 3-D seismic data，and the base-level cycle pattern of high-resolution sequence stratigraphy，eleven transfer levels of the base-level cycle are recognized, from which the high-resolution sequence stratigraphic framework is established, suggesting that the subtle oil reservoirs are mainly developed in the sand body in front of the delta in the descending half-cycles and channel-sand in the ascending half-cycles
  • Hydrocarbon generation of laminar algal limestone of Lower Cretaceous in the Jiuxi Depression, NW China
    CHEN Jianjun; CHENG Keming; XIONG Ying and MA Liyuan
    , 2005, 32(6): 1205-0.
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    The laminar algal shaly dolomite and dolomite mudstone of Lower Cretaceous are the main source rocks in the Jiuxi Depression, NW China. Carbon isotopes and all kinds of biomarkers indicate that the main oils in the Jiuxi Depression have low maturity,and the isomerization parameter value of sterane is 0.45-0.50, and does not reach the terminal of isomerization. The oils are abundant of gammacerane, C30-methylsterane and dinosterane, but poor in diasterane, suggesting that the depositional environment is the brackish, alkalescent reducing water, in which alga developed flourishingly. This is the main feature of crude oil in the region and also one of the features of the hydrocarbon generation from carbonate rocks in the Jiuxi Depression.
    • 综合勘探开发技术
  • Application of wave impedance inversion in sequence stratigraphy and sedimentary analyses
    JI Shengzhen and LIU Zhen
    , 2005, 32(6): 1206-0.
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    Wave impedance inversion usually describes lithology. To the terrestrial petroliferous basins mainly composed of sandstone and mudstone, wave impedance inversion has good application in sequence stratigraphy and sedimentary analyses. It can be used for identifying sequence boundaries effectively according to wave impedance inversion characteristics. The informations reflected by wave impedance inversion, such as lithology, the ratio of sandstone to mudstone and the superimposition of sandy body, provide important evidence for the tract system division. Based on wave impedance inversion and lithologic information, typical sand body and the boundaries of facies can be identified.
  • Wavelet packet energy characteristic identification of water flooded layer
    WANG Renyi
    , 2005, 32(6): 1207-0.
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    The petroliferous information is disclosed by the acoustic time and resistivity logs. The energy characteristic of wavelet packet varies greatly with different swept extent,and the wavelet packet energy is an exponential decline curve along with frequency augmentation without reference to water flooded extent. Along with water flooded extent increasing, the wavelet packet energy is declining in evidence. The energy in some frequency components shows great difference for different water flooded types. The energy of the swept layer and water layer are absorbed, while the energy of oil and weak water flooded are increased. The wavelet packet energy characteristic method based on the log signal could well identify the lowly resistive oil layer, highly resistive swept layer and water layer, which are done poorly by the conventional log explanation theory.
  • Theory of screenless fiber resin-coated sand complex fine-silty sand control
    ZHOU Fujian; XIONG Chunming; YANG Xianyou; ZHANG Shouliang; ZONG Yiping; LI Shubai; LI Xiangdong; LIAN Shengjiang and LIU Min
    , 2005, 32(6): 1208-0.
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    Severe sand production takes place in siltstone and pelitic siltstone reservoirs where conventional sand control techniques ended in low efficiency. To overcome the deficiencies of conventional sand control techniques, and according to the characteristics of siltstone, the new theory of fine-silty sand control was presented. The prepad plug remover is utilized to remove formation damage. The soft fibre with positive branch chains absorbs fine-silty grains to form bigger aggregation, and to stabilize fine-silty sand. Netted 3D hard fibre resin-coated sand complex is filled outside the cement mantle to act as an apparent screen for sand control. Frac-Pack and TOS are applied for removing the near wellbore damage, improving flow status and enhancing productivity. Experiments show that fibre may enhance the sand stabilizing ability of complex by 10 times or even more.
  • Stochastic simulating distribution of continuous reservoir attributes based on the GMRF Model
    LIU Zhenfeng; HAO Tianyao and WANG Feng
    , 2005, 32(6): 1209-0.
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    Predicting the distribution of continuous reservoir attributes is an important task in the reservoir research. Corresponding digital research methods include interpolation techniques and other stochastic simulation techniques based on geo-statistics. Different methods are used in diverse situs for their respective merits. The authors discussed at length the principle of simulating continuous reservoir attributes based on GMRF model and a corresponding algorithm. A practical model and its simulation process indicate that the method is very compact and valid and the configuration and randomicity of continuous attributes are exhibited from a series of realizations.
  • Oil saturation analysis in migration pathways with NMR imaging technique
    ZHOU Bo; HOU Ping; WANG Weimin and LUO Xiaorong
    , 2005, 32(6): 1210-0.
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    NMR imaging technique was applied to observe the oil migration pathways within a glass cylinder filled with water-wetting glass beads or sand grains. The oil saturations in the migration pathways at different stages are measured. It is found that the oil saturation may reach 83% within the initial accumulation column. The saturation is about 40%-50% within the pathway when the latter is growing. The saturation is about 20%-35% within the pathway when migration finishes. The grains' surface properties seem to influence the saturation within the pathway.
  • Forming mechanism and application of low resistivity annulus in oil reservoirs invaded by fresh drilling mud
    LI Changxi; OUYANG Jian; ZHOU Cancan and XIU Lijun
    , 2005, 32(6): 1211-0.
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    The invasion profiles of mud filtrate invading into a permeable layer was theoretically studied and numerically analyzed. By means of simulation, the radial distribution of formation water saturation, salinity and formation resistivity after invasion were computed. The forming process of the low resistivity annulus was explained on the concept of relative permeability. The effects of formation parameters, such as formation porosity, water saturation and mud filtrate salinity, on the invasion profiles were also analyzed. The existence of low resistivity annulus was proved by one dimensional oil-bearing core displacement experiment with fresh mud filtrate and by field logging data. It is found that the effect of low resistivity annulus on induction logs, such as array induction logs, is greater than that on lateral logs, and that the identification of low resistivity annulus from array induction logs can be used to classify oil pay-zone.
  • Applied seismic forward modeling (part Ⅱ): Quantitative determination of thin layer anisotropy by pre-stack seismic forward modeling
    Ben F Mclean; DAI Jinxing and YAO Pengchang
    , 2005, 32(6): 1212-0.
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    Pre-stack seismic modeling reveals information unattainable from post-stack seismic modeling, for example which can be used to refine a velocity model by the inclusion of anisotropy. The sandstone-mudstone member of the Tarim Basin is a Lower Carboniferous interbedded sandstone and mudstone, with occasional interbeds of gypsum, conglomerate, and coal. It has been suspected that the sandstone-mudstone member may be anisotropic due to the thin interbedding of contrasting velocity beds,but verifying and quantifying the anisotropy is difficult with conventional seismic techniques. Pre-stack isotropic modeling of seismic shot-gathers however proves that the sandstone-mudstone member is anisotropic. Iterative modeling whereby synthetic pre-stack shot-gathers are compared with the original shot-gather can be used to quantify the anisotropy, showing that the sandstone-mudstone member is approximately 5% transversely isotropic, with a fast horizontal plane. Figure 4 reference 9.
    • 钻井工程技术
  • Initiation and extension of existing cracks under detonation gas loading in a high energy combined perforation
    CHEN Lijing; LI Ning and WANG Jun-qi
    , 2005, 32(6): 1213-0.
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    In a high energy combined perforation, the pressure gradient of detonation gas along cracks varies with time due to the influences of flow velocity, crack surface roughness and media permeability. Since the pressure gradient affects stress strength of crack top, it is unsuitable to judge crack initiation by the traditional breakdown pressure. A function describing gas pressure distribution along the crack is proposed to derive the corresponding stress strength of crack top, and then the conditions of crack initiation in borehole rocks are concluded. The conditions reflect that gas pressure gradient varies with time. The example analysis reveals that slower borehole pressurization gives rise to lower crack initiation and arrest pressure, greater extension of crack arrest time, and longer cracks in the formation.
    • 油田开发与油藏工程
  • Recoverable reserves calibration in the middle-late stage of reservoir development
    SU Ying-hong
    , 2005, 32(6): 1214-0.
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    In the middle-late stage of reservoir development, the water drive curves show "downward" or "upward" phenomena after the production structure adjustment of oilfields or development units. The recoverable reserves calculated from the water drive curves don′t reflect the real exploitation performance. Based on the filtration theory, the relationship between oil production rate and recovery in the middle-late stage of reservoir development, which can be used to figure out the ultimate recovery and recoverable reserves of the development units, was presented. The application indicates that the method gives rise to rational recoverable reserves and settles the difficulties brought by distortion of water drive curve.
  • Simulation model and calculation of seepage flow field for high pressure waterjet perforated wells
    LI Gensheng; SONG Jian; XIONG Wei; HUANG Zhongwei and NIU Jilei
    , 2005, 32(6): 1215-0.
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    A finite element simulation model was established, which was used to compare the seepage flow fields of open hole completion, perforation completion and high pressure waterjet perforation. The calculation in the open hole completion proved the accuracy of the model. The drilling damage zones and compacted zones of conventionally perforated wells have seriously harmful effects on the productivity. High pressure waterjet perforation can avoid the negative effects of compacted zones and decrease the the harmful effects of the drilling damage zones. At the low permeability formations, the high pressure water jet perforation should be implemented for a higher productivity.
  • Influences of sand production on permeability and experiments on sand production characters in SZ36-1 Oilfield
    ZENG Xianglin; HE Guanjun; SUN Fujie and WANG Pingshuang
    , 2005, 32(6): 1216-0.
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    Sand production brings negative influences on oilfield development, but it also increases the reservoir permeability and enhances productivity. In order to further understand the influences of moderate sand production on productivity enhancement, physical experiments were carried out to simulate the influences of sand production on permeability and to study the sand production performance. Taking the samples from the SZ36-1 Oilfield in Bohai Bay Basin as example, gravel-pack and sieve sand controlling experiments were carried out to analyze the relationship between pressure drop, sand production and productivity, and to study the formation of wormholes and their network. The results indicate that sieve or liner completion should be used for producing with controlled sand production; sand production enhances permeability of formation, creates wormholes, and thus enhances productivity; the perturbation of pressure plays an important role in sand production, and the oil production rate is directly proportional to the sand production rate.
    • 油层保护与改造
  • Study and application of deep profile controlling agent in the SZ36-1 Oilfield, Bohai Bay Basin
    TANG Xiaofen; LIU Yuzhang; XIANG Wentao; LIU Gehui; JIANG Ruyi; QIN He and PAN Weiyi
    , 2005, 32(6): 1217-0.
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    SZ36-1 is an offshore oilfield in the Bohai Bay Basin, with high water salinity, gravel pack completion and narrow platform space. As the conventional deep profile controlling agents do not meet the requirements of the reservoir, a new salt-resisting and instant-dissolving deep profile controlling crosslinked gellant, RNSTP-CTm, consisiting of pectinal salt-resisting polymer, resorcin and compound adjuvant, was developed. Lab experiments and field tests show that the gellant can disperse and dissolve in the high salinity water instantly and it is applicable in the reservoirs with a temperature of 40-70℃ and a salinity below 40,000 mg/L, and the offshore and continental oilfields with limited operation space. The pilot test was conducted in the Injector SZ36-1-A21, after that the daily production increase of the well group was 50-60t, and in one year the cumulative production increase exceeded 10,000t without considering the effect of natural production decline and other operation measures.
  • Formation damage from elemental sulfur deposition in sour gas reservoir
    ZENG Ping; ZHAO Jinzhou and ZHOU Hongbin
    , 2005, 32(6): 1218-0.
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    Reservoir pressure and temperature decrease radially to the borehole after the gas wells were put into production. Elemental sulfur is separated from gas stream and precipitate in the pores or channels if the gas stream is saturated with sulfur, which decreases the porosity and permeability or even completely plugs the flow channels of gas and leads to the closed in or abandonment of the gas wells. The paper presents a model to simulate the formation damage caused by elemental sulfur deposition, based on which the characteristics of elemental sulfur deposition and its damage to the formation properties were analyzed. The results show that the elemental sulfur mainly deposits in the near wellbore area and the deposition decreases radially from the wellbore to the formation. Formation damage is more serious in the area nearer to the wellbore and the damage increases with the production.
    • 资源评价与管理
  • Economic Evaluation and Decision System of Petroleum Exploration Targets (EDSys1.0)
    GUO Qiulin; HU Suyun; NI Heyan and CHEN Ningsheng
    , 2005, 32(6): 1219-0.
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    The Economic Evaluation and Decision System of Petroleum Exploration Targets (EDSys1.0) includes 3 models. (1) Data processing and managing model. It is the tool for selecting basic parameters such as target geological evaluationresults and resource evaluation results, and also the basis for economic evaluation and decision-making analysis. It has the functions of managing base data and common parameters, assessing exploration invest, developments invest and other invests, as well as calculating projects cost. (2) Economic model. It is the core model of the system, and covers financial evaluation, breakeven analysis, sensitivity analysis, probability analysis, and economic critical value assessment. (3) Decision model, used for decision-making analysis on exploration and development activities. It consists of 3 sub-models: single target, multi-designs optimization, multi-targets optimization, and invest portfolio optimization. This system can help a better optimization for exploration targets selection, and a better optimization for invest portfolio. The results can provide basis for decision-making on exploration and development activities.
    • 国际交流与合作
  • Pore structure characteristics analysis of the oilfield in north Melut Basin, Sudan
    MA Mingfu; LI Wei and LIU Yacun
    , 2005, 32(6): 1220-0.
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    The pore structure characteristics of reservoir in the north Melut Basin, Sudan, including the effect of lithology, diagenesis, pore types and clay minerals on pore structure, show that the reservoir's lithology is mainly lithic quartz arenite and feldspathic quartz arenite, and has middle textural and compositional maturity. It has various kinds of diagenesis types and the diagenesis stage belongs to subage of type B in an early stage. Original inter-granular pore is the major pore type along with a few secondary pores and other types of pores in the reservoir. Pore structure is mainly large pore with large throat, followed by medium pore with medium throat. The clay minerals include kaolinite, interstratified zones of illite and smectite, and illite, in which the kaolinite content is the highest and has a destructing role to pore structure because of fast water injection. To prevent from damaging pore structure and reduce the oil recovery cost in waterflooding, the flowing velocity of injected fluid should be below the threshold velocity of rocks.
  • Reservoir prediction of the retrogradation braided delta depositional system of P Oilfield in the M Basin, Sudan
    ZHAO Guoliang; MU Longxin; JI Zhifeng; LI Zhiming and WU Changji
    , 2005, 32(6): 1221-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    It is always challenging to use geophysical technology options in reservoir prediction. A set of methods which will combine various geophysical technologies have been summed up through the reservoir prediction of the retrogradation braided delta depositional system of P Oilfield in the M Basin, Sudan. According to the data of core and logging, the depositional environment can be defined and sub-facies and micro-facies can be identified; on the bases of depositional characteristics of core and log responses, delta plain, delta front and pro-delta have been classified in target formation of wells in the oilfield; and the depositional facies analysis and the technology of calibration of well and seismic are used to determine the characteristics of the reservoir, and define the seismic facies. The extension and development of different sands by the technology of impedance inversion could be used for the comprehensive reservoir evaluation.
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