, Volume 31 Issue 6
    

  • Select all
    |
    专家论坛
  • Return to petroleum geology of Ordos Basin
    LI Desheng
    , 2004, 31(6): 942-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Ordos Basin, a polycyclically superimposed basin, covered about 32×104km2. Thick Phanerozoic sediments generally maintained sub-horizontal strata. The four petroleum systems explored and developed in the basin are all stratigraphic-lithologic reservoirs: super-low-permeability sandstone reservoirs of Yanchang Formation, Upper Triassic; middle-low permeability sandstone reservoirs of Yan'an Formation, Lower Jurassic; low-permeability carbonate gas reservoirs of Majiagou Formation, Lower Ordovician; and low-permeability fluvial sandstone gas reservoirs of Shanxi and Lower Shihezi Formation, Lower Permian. Since the drilling of the first onshore production well in western Yanchang City in 1907, the Yanchang Oilfield has been explored and developed for about 100 years. Due to the exploration and development progress for the shallow super-low permeability reservoirs, the crude oil production of Yanchang Oilfield reached 230×104t/a and its cumulative oil production reached 1321×104t by the end of 2003. The oil production of 14 drilling-production companies under the Yan'an and Yulin local county reached 330×104t/a and its cumulative oil production reached 1301×104t. The oil output of Changqing Petroleum Exploration Bureau, CPNC, was 701×104t in 2003 and its cumulative oil production reached 6489×104t. By the end of year 2003, there are 2×104 oil wells in the Ordos Basin, the oil production rate reached 1262×104t/a and its cumulative oil production was 9121×104t.
  • Oil and gas accumulation in craton basins of China and exploration strategy
    ZHANG Kang
    , 2004, 31(6): 943-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The craton basins in China had been reconstructed by multiple structural cycles，including the Late Cenozoic violent structural movement with strong fragmentation, causing the multi-source and multi-period hydrocarbon generation and the late hydrocarbon accumulation and the progenic and hypo-progenic and deuterogenic oil reservoirs compose a complicated spatial combination system in these basins. So the hydrocarbon generating depressions, palaeohigh, palaeoslope, unconformity surfaces, palaeo-karst, faults and framework of fault as well as the conservation conditions in late period become primary factors for controlling the formation of hydrocarbon pools. In consequence, an adaptive exploration strategy for the craton basins of China could be proposed as to identify the effective source rock, attach importance to palaeohigh and late reconstruction and deuterogenic reservoirs, pay attention to the exploration of lithologic deposit and natural gas pool, approach the targets that are closer to the source rocks from the deuterogenic oil pools self-consciously as well as build up a complete set of technologies and techniques.
    • 石油地质研究
  • Progress of basic theory and accumulation law and development technology of coal-bed methane
    WANG Hongyan; LI Jingming; LIU Honglin; LI Guizhong and LI Jun
    , 2004, 31(6): 944-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Coal bed methane (CBM) is different from conventional natural gas as it exists in coal reservoir in adsorption status, which leads to the great difference in formation mechanism and development theory. Focused on basic geology theory, accumulation law and exploration technology of CBM, the study of the CBM formation, theory and condition of reservoir formation was carried out to conclude the accumulation law represented by the enrichment of high coal rank anthracite. The prediction technology of target areas and enhanced recovery technology of low permeability reservoir are presented. The researches on CBM formation, reservoir heterogeneity, hydrocarbon accumulation and reservoir formation mechanism, and effective exploration and development technology are effective way to achieve breakthrough of national CBM industry.
  • Detachment structure in the Raonan area, Jizhong Depression
    ZHENG Dahai; LIU Chiyang; CUI Yongqian and LUO Xiaorong
    , 2004, 31(6): 945-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The interface between Member 3 and 4, Shahejie Formation in Raonan area of south Jizhong Depression is developed by a lower detachment surface but a sedimentary surface. The top boundary of Member 4 of Shahejie Formation-Kongdian Formation is the upper surface of detachment in Raonan area. The stratigraphy of Member 4 of Shahejie Formation-Kongdian Formation is a sheared belt in the basement of basin. Part of Member 3 and basement stratum are involved in the sheared belt. In the sheared belt, the deformation is quite complex. The evidences for detachment are described. The area that detachment movement has extended is controlled by the Cangxi fault on east, west slope, and the Liucun lower uplift. The mechanism of detachment deformation movement is described.
  • Pool formation mechanism of medium shallow layer in south Songliao Basin
    ZHAO Zhanyin; LI Hongge; WANG Xingguang; MIAO Hongbo and MAO Chaolin
    , 2004, 31(6): 946-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Based on the latest data, combined with the present exploration, some new ideas are raised for the pool formation mechanism of south Songliao Basin. Although two groups of hydrocarbon source rocks are developed in south Songliao Basin, the Qingshankou Group is the main source rock and its abrupt hydrocarbon generation is mainly concentrated in the late of Mingshui Group. The first hydrocarbon filling period is in the late deposition of Nenjiang Group, and the main filling period is in the late deposition of Mingshui Group. Many faults developed in T2 reflection horizon, which are main paths for the vertical migration of hydrocarbon from the source rock of Qingshankou Group up to Fuyang, Putaohua and Saertu Reservoirs. The shale in Nenjiang Group results in few fractures in seismic reflection, improving the enclosing ability of Nenjiang Group, and is a key reason of abundant oil and gas combination in central part.
  • Structural segmentation and reservoir-formation along the Qiulitage anticline belt of Kuche thrust belt, Tarim Basin
    MIAO Jijun; JIA Chengzao; WANG Zhaoming; ZHANG Junfeng and ZHAO En-hong
    , 2004, 31(6): 947-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The Qiulitage anticline belt lies in the front of the Kuche thrust-and-fold belt along the south piedmont of the Tianshan Mountains. The major controlling factors of structural deformation and the effect of structural segmentation on reservoir formation were investigated based on the combined information of drilling, outcrop, seismic and non seismic. The results suggest that the deformation is controlled by basement, stratigraphy and the stress state. And the deformation style is mainly controlled by the cap structure.The combination, distribution and rheology of detachments as well as the thickness of deformed strata are controlled by stratigraphy varied along the belt, resulting in the superposition of shallow structures over deeper ones. The structural features of the Qiulitage anticline belt control the formation of hydrocarbon reservoirs, causing the quick pool formation in the east since there are close to sources and the accumulation in the west is from flank in a long period of time.
  • Oil accumulation history in Tadong 2 oil reservoir in Tarim Basin, NW China—A case study of oil stability and cracking
    ZHANG Shuichang; WANG Zhaoming; WANG Feiyu; LIANG Digang; XIAO Zhongyao and HUANG Haiping
    , 2004, 31(6): 948-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The oil from the Well Tadong 2 (TD2) in the Cambrian reservoir in eastern Tarim Basin contains high concentration of 4-methyl steranes, dinosteranes and their aromatic dinosteroids,which is different from heavy oils discovered in the Lunnan area and their Middle-Upper Ordovician source rocks, suggesting a clear affinity with the Cambrian source rock extracts but distinctly. Present maturity of the Cambrian source rocks is as high as 2.67%-2.75% VRE. Burial history and hydrocarbon generation history analysis suggest that major liquid hydrocarbon generation time from this source rock suite was in the Middle and Late Ordovician and petroleum generation process was rapidly completed within 10 Ma. All these indicate that the oil accumulation has been severely affected by high temperature processes, which caused oil densification and cracking to gas.During subsequent stratigraphic elevation after the Devonian, TD2 oil pool was uplifted to 1730m undersurface and reservoir temperature dropped to about 70℃ (brine inclusion homogenization temperature of 50-90℃). Newly formed fractures and tectonic fissures linked up early accumulated oil and gas in the Cambrian fissure system, leading to oil and gas diffusion upward and biodegradation. High concentration of 25-norhopanes occurrence in oil is one obvious result of biodegradation, which causes further oil densification. Discovery of TD2 heavy oil inspire some new considerations. An oil pool formed more than 400Ma ago, which has experienced paleotemperature of higher than 200℃, can be preserved till present, indicating much higher oil stability than previously believed.
  • Tectonic evolution and its controlling on petroleum generation in Weibei Basin
    CHENG Youyi; LI Xiao-qing; WANG Zecheng and TANG Zewei
    , 2004, 31(6): 949-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Weibei Basin is a Mesozoic-Cenozoic basin developed in the Tanlu fault zone. Based on interpretation of large amount of seismic data and structure mapping, the basin is proved to be a typical slip-extensional basin according to structure and sedimentation analysis. The basin experienced 3 stages of evolution, slip-compressing movement in the end of Cretaceous, slip-extensional movement during the deposition of Kongdian Formation and depression and slip-compressing movement in Neogene. Structure styles include flower structure, extensional structure and fault nose caused by slip-compression. Favorable source-reservoir-caprock association and multi-type traps were developed in Weibei Basin and that should be a favorable area for petroleum play.
  • Hydrocarbon generation from Paleogene deep source rocks in Huanghua Depression
    LI Huijun; WU Tairan; MA Zongjin; HAO Yinquan and ZHANG Wencai
    , 2004, 31(6): 950-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    :Overpressure developed in the Paleogene of Huanghua Depression. Obvious overpressure constraint of deep source rock evolution was found through high temperature and pressure simulation experiment, natural thermal evolution and geological case studies. The Ro profile in Well BS35 is discontinuous with 5 nonparallel segments situated in over-pressured system, low Ro gradients coincide with high TOC, S2 and/or S1 contents, high Ro gradients coincide with low TOC, S1 and S2 contents. This demonstrates that early developed overpressure, high original TOC contents of source rocks and the retention of the pore fluids, are the 3 important factors affecting overpressure constraint of organic-matter maturation, which is quite important for clearly understanding petroleum exploration.
  • Sulfur isotopic composition and its geological significance of the Paleogene sulfate rock deposited in Dongpu Depression
    SHI Zhongsheng; CHEN Kaiyuan; SHI Jun; HE Hujun and LIU Baojun
    , 2004, 31(6): 951-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The sulfur isotopic composition of the Paleogene sulfate rock deposited in Dongpu Depression and the relationship between the sulfur isotopic composition and the sedimentary environment suggest that the δ34S values changed with the climate, sedimentary environment, tectonic subsidence and so on. The sulfur isotopic development matched the sequence development. The comparison between the evaporite δ34S values of Dongpu Depression and that of marine facies reveals that Dongpu salt-lake was a continental brackish lake and the sedimentary environment was closed to sulfate.
  • Reservoir character of pelitic dolostone in the Xiagou Formation, Lower Cretaceous, Qingxi Oilfield, NW China
    YANG Hongmei; WANG Manfu; YANG Linke; WANG Rong and LI Yulan
    , 2004, 31(6): 952-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Pelitic dolostone, including argillaceous dolostone, dolomitic mudstone, and dolostone, in the Xiagou Formation, Lower Cretaceous，Qingxi Oilfield，is of reservoir with lowest permeability and porosity, which has been buried beneath 3600m with abundant felsic micrograin, its matrix porosity is less than 5% and matrix permeability less than 0.5mD. The analyses of sedimentary facies zone, rock components, pore types and matching features have been used for forecasting the distribution of favorable reservoirs and a better exploration effect is attained
  • Water-rock interaction in the Shiwu Depression, Songliao Basin, NE China
    XIANG Caifu; XIA Bin and XIE Xinong
    , 2004, 31(6): 953-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Space distribution and evolution of the formation water chemistry in Shiwu Depression and its indication for the water-rock interaction processes were discussed based on the 199 data collected from the Shiwu Depression, Songliao Basin, NE China. The space distribution of the water geochemistry was controlled by the hydrological conditions, the penetration of the meteoric water decreased the salinity at the basin margin and the severely faulted central ridge (below 4.5g/L) and the salinity increased toward basin center to 7-10g/L. And the vertical change can be obviously subdivided into 3 zones: the free replacing zone (<1250m) with the NaHCO3 type fluid, the obstructive replacing zone (1250-1650m) with the Na2SO4 type fluid and the lagged zone (>1650m) with the CaCl2 type fluid. The time evolution of the formation water is governed by the water-rock interaction, the relationship between Cl－and HCO3-and relationship between Na++K+ and Ca2+ suggests that the initial water-rock interaction was the dissolution of NaCl and calcium-bearing carbonate, resulted in the increasing of ions and salinity. The succeeding water-rock interaction was albitization, which led to the decreasing of Na+ and the increasing of Ca2+ simultaneously and CaCl2 type fluid was formed. The analyzed water-rock interaction process has been proved by other geological observations.
  • Physical modeling experiments of structural deformation under shear stresses
    SHAN Jiazeng
    , 2004, 31(6): 954-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    On the base of results of physical modeling, processes of structural deformation have been given under simple shear stresses. Strain circle deforms strain ellipsoid under shear stresses, in which the angle between strain major axis and horizontal axis has been increased by degrees. Major displacement zone parallels with direction of shear loading. An echelon shear fractures have angle of 45° with direction of shear loading. Following zigzag shear fracture has been deformed. An echelon shear fractures, zigzag shear fracture and major displacement zone made up the shear fracture system. Shear fracture system is characterized by tensile-shear, which provide a powerful pathway to migration and storage conditions of hydrocarbon.
    • 综合勘探开发技术
  • Technique and application of precise seismic interpretation in the later development stage of oilfields
    WANG Xi-wen
    , 2004, 31(6): 955-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    In the later period of oilfield development, oil productivity decreases progressively. To stabilize oil productivity, some new oil pools including structural and lithologic oil pools must be discovered. With the conventional interpretation of either seismic or log data separately, the correct structure of oil pools would be hardly achived. A new technique of true 3D seismic interpretation in the oilfield development stage is presented, including log structure research, log layer depth modeling, precise seismic interpretation, various velocity modeling, precise structure map, good structure appraising and well position locating. A well was drilled in G388-2 fault block as an application of this technique in Tangjiahe Oilfield and greater amount of oil has been obtained.
  • Intricate 3-D seismic interpretation in shallow water area of Huanghua Sag, Dagang transition zone
    FAN Zheqing; LIANG Huilan and ZHAO Chunduan
    , 2004, 31(6): 956-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Intricate seismic 3D interpretation technology is used in shallow water area in Huanghua Sag, Dagang transition zone, in which a time-variable wavelet along the seismic profile of deviation borehole survey and geologic surface synthetic calibration is used based on the true track of borehole. The existence of faulted geologic structural model which is steep in north but lenitive in south around Qikou Depression is proved by the stress field analyses. The fault scale and structure evolvement is determined by using the moving-block of seismic profile along the fault slice, and seismic horizon flatten and the plain and space connection of faults is identified by using coherent slice and visualization. These technologies have been applied in this area and better results were obtained.
  • Numerical simulation of clastic diagenesis and its application
    HE Dongbo; YING Fengxiang; ZHENG Junmao; GUO Hongli and ZHU Rukai
    , 2004, 31(6): 957-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Based on the diagenetic stage division theory and the effect-oriented modeling method, the diagenetic stages are used to describe the modified results of reservoirs due to different diagenesis. The diagenesis study is carried on in two domains of time and space by establishing the diagenetic parameter evolution models to reverse diagenetic history, and by simulating the spatial distribution of diagenetic parameters to build the spatial sketch of diagenetic stages, which supports the basin or sag wide reservoir evaluation and prediction. In the diagenetic modeling of the Lower Jurassic reservoir in the eastern Kuche Sag, considering the integrated effects of burial and tectonic compaction,the tectonic compaction is the major factor controlling the distribution of reservoir quality.
  • Genetic analysis and evaluation of low resistivity oil formation in Tarim Basin
    ZHAO Jun and SONG Fan
    , 2004, 31(6): 958-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    With the continuous growth of exploration of Tarim Basin, some low resistivity oil formations were discovered in succession. The lowest resistivity value of the oil formations is 0.45Ω·m which is the same as the value of the water formations. It is very important for the growth of reserves and output to identify and evaluate the low resistivity oil formations. According to the different characteristics of pyrite, clay and high salinity bound water which lead to the low resistivity of formations,the relationships of reservoir properties,pay thickness and saturation are obtained using the capillary pressure data and the rock electrical parameters under high temperature and high pressure are presented,with the different evaluation methods,good results are achieved.
  • Discussion on a CO2 geological sequestration by methanogens in the biogenic gas field in China
    XIA Zunyi and BAI Zhiqiang
    , 2004, 31(6): 959-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    It is believed that 20% of the natural gas is from methanogens. Many countries suggest to sequester CO2 by methanogens to produce methane. An experiment was conducted about the biogenic gas field in China to test the possibility of sequestering CO2 by the methanogens in the strata. The experiment suggests that methanogens and the relative consortia are widespread in the field, the methanogens are adapted to the tiny salt water habitat and the methanogens in the strata can use the injected CO2 to produce methane. Therefore, it is possible to sequester CO2 in this biogas field and produce methane at the same time.
  • Evolution simulation of stress field in West Qaidam Basin, NW China
    HUANG　Ligong; ZHONG Jianhua; WANG Haiqiao; ZHAO Mifu; CHEN Hanlin and LI Yong
    , 2004, 31(6): 960-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    There is a good comparability between the period of intensity alteration of stress field and the period of hydrocarbon release, migration and accumulation, and a consanguineous relation between the distribution of hydrocarbon and the stress field of a basin. The tectonic stress, especially the tectonic stress in the reservoir-formation stage in an oilfield, is of fundamental significance on hydrocarbon migration, accumulation and reservoir formation. The stress field of a basin controls the producing, migration and accumulation of hydrocarbon by some direct or indirect mode. Numerical simulation, especially the 3D dynamic simulation, is efficient for understanding the control of stress field on the hydrocarbon distribution.
    • 油田开发与油藏工程
  • Productivity evaluation and conductivity optimization for vertically fractured wells
    WANG Xiaodong; ZHANG Yitang and LIU Ciqun
    , 2004, 31(6): 961-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Productivity evaluation is the base of optimal design for hydraulic stimulation, and is important to improve the fracturing effect. According to the theory of unsteady porous flow, the pressure behavior of a well with single finite-conductivity vertical fracture in a circular bounded reservoir is discussed, and new asymptotic solutions are obtained from the formulas for a radial flow in the middle period and a pseudo-steady state flow in the late period, a modified Dupuit-type productivity formula for vertically fractured wells is also derived, furthermore, two methods of optimal design are presented as the Prats method and the novel method. With the derivate of the specific productivity index curve, a new optimal dimensionless conductivity plot is obtained, which is a compact correlation for optimal design of conductivity. In practical stimulation, the average width of fracture is known, then the hydraulic fracturing length and scale can be quickly determined from the correlation, and the efficiency is enhanced.
  • Staged numerical simulation of Layer 3, Member 2, Shahejie Formation, in District 2 of Shengtuo Oilfield
    GAO Boyu; PENG Shimi and HUANG Shuwang
    , 2004, 31(6): 962-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    In the simulation of residual oil distribution in a high water cut reservoir, the conventional numerical simulation may distort the results for it adopts invariable geology and fluid model without considering the change of reservoir rock and fluid characteristics during the reservoir development. The results of staged numerical simulation would accord with the fact of reservoir development because it adopts staged geology and fluid model considering the variation of rock and fluid properties during the development. By the method of staged numerical simulation and PEBI gridding with black oil model of Eclipse, the residual oil distribution of Layer 3, Member 2, Shahejie Formation, in District 2 of Shengtuo Oilfield was analyzed and favorable results were achieved.
  • EOR field test of gas-water alternative injection in Pubei Oilfield
    ZHANG Jun; ZHOU Ziwu; WANG Weisheng and TAO Linben
    , 2004, 31(6): 963-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The miscible displacement of gas-water alternative injection (WAG) has been conducted in Pubei Oilfield, Tuha Basin, which is the first field test base of the gas-water alternative drive in China. The gas injection can not be put in practice after water injection in the course of WAG in Pubei Oilfield. To solve this problem, a long core displacement test was conducted to investigate gas injection mechanism, spot acidification to remove blockage, high pressure liquid nitrogen injection and well close to reduce pressure in injection well, etc. Since miscible displacement was conducted in Pubei Oilfield, the formation pressure and flowing pressure have been hold above the pressure limit provided by miscible displacement development. The formation fluid viscosity has been reduced to 0.2mPa·s from 0.67mPa·s, the volume factor increased to 2.819 from 2.210, the saturation pressure increased to 32.86MPa at present from 29.44MPa, and the crude oil component has been changed apparently with the medium hydrocarbon content increased to 25.12% from 23.79%, showing a good effect of miscible displacement in Pubei Oilfield.
  • Problems confronted in microbial enhanced oil recovery
    WANG WeiDong; WEI Bin; TAN YunXian and WANG XiuLin
    , 2004, 31(6): 964-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The progress in microbial enhanced oil recovery (MEOR) is briefly viewed and the key problems confronted in MEOR are discussed. It is believed that the major factors retarding ongoing MEOR exist in MEOR itself other than conditions of oil reservoirs, and two matters should be especially took into account. One is the impercipient realization of microbial ecology in oil reservoirs, in which only a small part of microorganisms in oil reservoirs, approximately 0.1%-10%, was analyzed due to the traditional method of the pure culture identification, and consequently, the exact number of microbial species in production water, the amount of various microorganisms and the active communities in oil reservoirs could not be obtained by the traditional method. The other is limitation existing in core flooding procedures, in which procedures and instruments as well as man-made core samples for chemical flooding were applied to evaluate MEOR, consequently, the practical results of MEOR could not be obtained due to these procedures. The parameters from core flooding in this case, therefore, should not be directly used in field trial. The key problems existing in MEOR and the solutions are finally concluded.
  • Profile modification agent with abio-gel coating for high-temperature and high-salinity reservoir
    TANG Xiaofen; LIU Yuzhang; CHANG Zeliang; QIN He; LIU Gehui; CAI Lei and LU Wei
    , 2004, 31(6): 965-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Cross-polymer gel has limited application in profile controlling of high-temperature and high-salinity reservoirs. Reservoirs in Tarim Basin, NW China, were geologically developed in marine environment with high temperature and high salinity. To address the problem of deep profile modification in Tarim Basin, profile controlling agent with abio-gel coating (WJSTP) is developed by taking advantage of the multi-valence cations concentrated in both the formation and injection water and injects a compounded silicate to react with the cations to form abio-gel with the same density as water. Beaker test shows that the gel has desirable properties of heat resistance, salinity resistance and long-term stability. Core flood tests verify that, by slug injection, the process can gradually build long lasting residue resistance factor (RRF) for water flow in high permeability streaks, indicating a "layering" or "coating" mechanism.
  • Experiment on H2S stress corrosion of tube in deep well
    ZHANG Xing; LI Zhaomin; MA Xinzhong; ZHANG Zhihong and DONG Bin
    , 2004, 31(6): 966-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    More and more oil/gas wells contain H2S,and the corrosion has serious effect on oil/gas field production. The study on law of H2S corrosion under formation conditions is important for reservoir development. Constant load tensile tests were carried out in the laboratory to simulate the tube corrosion rules under production conditions. The results show that stress corrosion crack may occur even under the temperature and pH value not sensitive to H2S stress corrosion. Scanning electron microscope features of the fractured surface show that the corrosion crack is brittle crack. Stress corrosion crack is affected by many factors. Select appropriate material in well completion according to corrosion environment and provide correspondent completion technique, then the corrosion crack could be reduced, and oil/gas field development requirementsmet.
    • 油田非注水开发
  • Parallel-column experiments for enhancing oil recovery after polymer flooding
    XU Ting; LI Xiusheng; ZHANG Xuehong and ZHAO Fulin
    , 2004, 31(6): 967-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    In order to prove the water flooding method after polymer flooding, the variations of the pressure, relative water intake, recovery efficiency of respective layers and water cut are studied in flow experiments of parallel columns simulating the real reservoir heterogeneity with high, medium and low permeability. The results show that, with polymer occupying part of the high permeability channels, direct deep profile control after polymer flooding,with the deep profile control agent of high viscosity, will do harm to the layers of low and medium permeability, then will decrease oil recovery. Injecting polymer-fixing agent after polymer flooding will cross-link and fix the high concentration polymer existing in pores of high permeability, then effectively control the water intake ability of big channels and increase the sweep efficiency of succeeding water flooding, which will make foundation for further deep profile control. Compared with the technology of injecting deep profile control agent after polymer flooding, this polymer-fixing technology is predominant in low cost, high oil recovery and utilizing extent of polymer existing in porous media as an effective treatment for improving oil recovery after polymer flooding.
    • 油藏物理
  • A novel experiment method on phase change of gas condensate in porous media
    LI Jingsong; LI Xiangfang; TONG Min; CHENG Shiqing and KANG Xiaodong
    , 2004, 31(6): 968-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The existing experiment method can't reveal the characteristics of phase change because of its lower pressure and temperature. Based on the theory of gas condensate composition change with pressure, a high temperature and pressure experiment course is designed for the research of condensate gas phase change under reservoir conditions. The fluid composition in core after the condensation of gas condensate is analyzed by chromatogram and compared with phase characteristics in PVT cell to study the influence of porous media on condensate gas phase change. The experiment results indicate that the composition of hydrocarbon in core changes with the fall of pressure under constant temperature, as the pressure reduce to upper dew point, the condensate liquid is released, and condensate liquid and gas enter two phase flow area; with the fall of pressure in the course of retrograde condensate, heavy hydrocarbon component increases and light hydrocarbon component decreases in liquid, but just the reverse in gas. As the pressure decreasing below the dew point and entering tow phase flow area, the composition of the gas-liquid system changes greatly, light hydrocarbon components increase in gas and heavy hydrocarbon components increase in liquid; but the gas composition does not change and remains in single phase at PVT cell. Comparing with current experiments, the new experiment results are more precise and credible.
    • 油层保护与改造
  • Particle migration in loose sandstone reservoirs
    YOU Qidong; LU Xianliang and LUAN Zhi-an
    , 2004, 31(6): 969-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Particle migration in loose sandstone reservoirs causes serious results in reservoir development. The sand fines are flushed out and consequent large channels may result in serious water breakthrough. The capture of sand fines may block the pores and decrease the permeability and production. A modified capillary model is developed to describe the mechanisms of particle migration. The model is a system of non-homogeneous quasi-linear equations. The analytic solution is derived by typical line method and the numerical solution is obtained by finite difference method. The analytic and numerical solutions are compared. Research of the model reveals that, for low permeability reservoirs, formation blockage occurs before the particle content reaches the peak value, and large channels tend to form in high permeability reservoirs.
  • Blockage mechanism and blockage reducer for polymer-injection well
    ZHENG Junde; ZHANG Yingzhi; REN Hua and LIU Ye
    , 2004, 31(6): 970-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Blockage material in polymer injection well in Daqing Oilfield is analyzed by inorganic and organic chemical methods, experiments were conducted to demonstrate the effect of sulfide, ferrum and microorganism on blockage, and slabbed core analyses of different permeability were carried out. The research shows that the main components of the blockage are infusible substance containing calcium and magnesium ions, clay and nucleus formed in sand production. Large polymer molecules wrap around nucleus and form gelatinous complex groups, whose main scale does not match with the throats of actual formation and causes formation blockage. Blockage analyses of various permeability cores show that blockage degrees of different permeability formations are different for the same polymer solution. The lower the core permeability is, the higher is the clay content in the core, and the more polymer is adsorbed on the surface of clay mineral because of electrical character, thus the more serious blockage is caused by inorganic stem. For the core of higher permeability, blockage caused by inorganic stem in sand production is much more serious than that of low permeability formation. In accordance with the blockage mechanism, 3 types of blockage reducers were developed, evaluation of the experiment results show that receipt A is the best, B is medium and C is common.
  • Fracturing technology research and test for deep heavy oil reservoirs
    ZHANG Jianping and NIU Ruiyun
    , 2004, 31(6): 971-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Block Yu 1,Tuha Oilfield, is a super heavy oil reservoir with poor reservoir properties and buried depth of 3328-3365m. Normal production cannot be maintained because of its low porosity and permeability. Based on the reservoir properties, tests of fracturing technology for heavy oil reservoirs were carried out by applying minitype fracturing and testing technology, high sand concentration and wide-short fracture fracturing technology, the technology of vertical fracture extension control using the temporary blocking agent with low-displacement pad fluid, and the technology preventing layers from water base fracturing fluid, etc. The displacement is 2.6 m3/min, pad fluid is 34.8 m3, sandcarrier is 56 m3, sand volume is 18.74 m3, the average sand ratio is 41.2%, and the maximum sand ratio is 60%. The daily production increased from 4t to 11t with no water production. The success of fracturing in Well Yu 1 improved the development effect and provided an economical and effective means for the future development of heavy oil reservoir in deep zone.
  • Eliminating condensate blocking by electromag-netic heating
    PU Chunsheng; FENG Jinde; LI Haiping and NIE Cuiping
    , 2004, 31(6): 972-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    To eliminate the condensate oil blocking which decrease the productivity of condensate gas well, the electromagnetic heating-chemistry combination block removal method is used in condensate gas wells to improve heating and block removal efficiency. In order to provide basis for well selection and heating technique optimization of electromagnetic heating, the impact of heating manner, production rate, heating power and porosity on block removal efficiency is studied by numerical simulation. The results show that well closing and heating can removal serious condensate blocking, and the production and porosity are the key factors affecting heat efficiency. When the production rate keeps constant, the increase of heating power raises the side wall temperature rapidly, but it has little effect on the increase of heating radius. Higher production decreases the heating radius, and the high temperature appears only near the well-bore. The effective heating radius is about 3m when the production is lower. The electromagnetic heating technology is applicable in low production and low porosity condensate gas wells.
  • Radius of scale removal in injectors of Yushulin Oilfield
    ZHOU Wanfu; YANG Baoquan; ZHAO Min and WANG Xin
    , 2004, 31(6): 973-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    There is a serious scaling problem (the main component is CaCO3) in both the water injection system and formation of Yushulin Oilfield, which led to formation damage, decreased absorbing ability of the injectors and worse development efficiency. The laboratory experiments show that the scaling could bring definite damage to core permeability. When the injection quantity adds up to 800 times of the pore volume, the permeability of a core could be decreased by 80％-100％. Based on experiments and quantitative analyses, it is concluded that the scaling mainly exists within 4m around the well-bore. According to the theoretical calculation, the economically optimum acidizing radius is 4m. The success ratio of field experiments in 7 wells was 100% and good effect of injection improvement was achieved.
Office Online
Included
Most Popular
Links More
Visited
    Total visitors:
    Visitors of today:
    Now online:
Copyright © Petroleum Exploration and Development
Address:P. O. Box 910, No.20 Xueyuan Road, Haidian District, Beijing 100083, China
Powered by Beijing Magtech Co. Ltd.