, Volume 32 Issue 1
    

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    石油地质研究
  • Prediction of favorable reservoir sand in Tuo-71 Block of Dongying Depression
    WU Junchang; WU Shenghe; GAO Zhiyong and FU Guo-you
    , 2005, 32(1): 1026-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Stochastic modeling based on well logs and seismic data of Tuo-71 Block in Dongying Depression indicates that favorable reservoir sand bodies of un-drilled areas can be predicted. In statistical and probability analyses of permeable sands modeled in several realizations, uncertainty evaluation was applied for the modeling results. According to the thickness of the permeable sands with probability greater than 0.5 and 0.7, as well as the structure and distribution of the oil-bearing formation in the well nearby, two favorable reservoir sand bodies are predicted to occur in the area, on east of well Tuo-71, and the other southeast of well Tuoshen-1.
    • 专家论坛
  • Chinese great advance: from a gas-shortage country to a giant gas-producer
    DAI Jin-xing
    , 2005, 32(1): 1031-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Based on the gas yield, the country whose annul gas yield is up to 5×1010m3 is called as a giant gas-produced country. There are 11 this side countries on the world, among which Russia ranks number one. Two conditions are important for a "gas-rich" country: the recoverable gas resources are higher than 13×1012 m3, and remaining recoverable gas resources is over 1.246×1012 m3. China possesses these two conditions since 2003. It is estimated that Chinese gas production in 2004 will achieve over 4.05×1010m3, and about 6.2×109 m3 more than that of 2003. The gas yield shall get close to or achieve 5×1010 m3 and China will become a real giant gas-yield producer.
    • 石油地质研究
  • Control of basement fault minor-activity on gas pool formation of Upper Paleozoic, Ordos Basin
    WANG Zecheng; ZHAO Wenzhi; MEN Xiangyong; ZHENG Hongju and LI Xizhe
    , 2005, 32(1): 1032-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Large amount of fractures developed in tight reservoir rock in Upper Paleozoic in Ordos Basin. Based on the frequency analysis of abnormal value of permeability from a lot of data, the distribution of fractures in the central-east part of this basin is forecast which trend to NE, located mainly in area of NE basement faults. The heterogeneity of basement in Ordos Basin has led to the activity with minor scale of basement faults in the dominant NE orientation in particular since Mesozoic, which had given strong influence not only on the fracture forming, but also the gas pool forming. The secondary gas pool is believed to be discovered in the future exploration in the NE basement fault area.
  • Vitrinite reflectance modeling in the over-pressured formations
    XIAO Lihua; MENG Yuanlin; ZHANG Lianxue; WEI Ajuan; LI Jun; ZHANG Wencai; YIN Xiulan and WANG Zhiguo
    , 2005, 32(1): 1033-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The studies indicated that overpressure could retard vitrinite reflectance and increase activity energy. Using the vitrinite reflectance from both the overpressure well and the normally pressured well, a new vitrinite reflectance kinetic model Pa%Ro incorporating overpressure retardation is developed, in which overpressure modifies activity energy. The model was tested in Qibei Sub-sag of Huanghua Depression. The results suggest that the maturity and timing of the onset of hydrocarbon generation is different significantly from those predicted by EASY%Ro. The vitrinite reflectance values are retarded by 0.1%-0.3% in the overpressure formations with the pressure coefficient of 1.2-1.6, and the time of source rocks entry into oil generating threshold is delayed by 1-4.4Ma.
  • Mesozoic-Cenozoic five tectonic events and their petroleum geologic significances in west Tarim Basin
    LUO Jinhai; ZHOU Xinyuan; QIU Bin; YIN Hong and LI Jianli
    , 2005, 32(1): 1034-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The new achievements about the strata, structure, paleo-magnetism, geochemistry and oil-gas-bearing basins of the west Tarim Basin, west Kunlun Mountains, Middle Asia Tianshan and Pamir orogens suggest that structural features, origins and their petroleum geologic significances of the five fateful events play an important role in the west Tarim Basin since Mesozoic. The five events could be identified as: ①evolution closing of the west segment of the south Tianshan (or Turkestan) ocean in the end of Early Permian and exhumation of the west part of the Tarim Basin in the early Mesozoic; ②Jurassic strike-slipping of the Talas-Ferghana fault and the formation of the Early-Middle Jurassic Kuzigongsu pull-apart basin; ③Cretaceous-Paleogene regional descension and ingression; ④the formation of the Pamir arc during Neogene-Quaternary and S-N regional compression; ⑤Early Cretaceous and Paleogene basaltic volcanisms in the Tuoyun and the Middle Asia Tianshan. All of the five events have important significances for the exploration of the west parts of the Tarim Basin.
  • Jurassic sequence stratigraphic frames in the Middle Junggar Basin
    WANG Jufeng; DENG Hongwen and CAI Xiyuan
    , 2005, 32(1): 1035-0.
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    The identification signs of the Jurassic sequence boundary are determined and two kinds of sequence boundaries, unconformity and shift surface of deposition, are identified according to drilling, logging and seismic data in the middle Junggar Basin. Five Jurassic sequence boundaries are developed as four long-term base level cycles further in the middle basin. Stratigraphic frames are built on the basis of well and seismic data calibration. It is confirmed that the Sangonghe Formation is the key target series for exploration in the middle basin where reservoir sands are the river mouth bar and distributary channel sandstones of delta front. The distribution of advantaged reservoir facies is closely related to their position in the sequence and mainly developed at the half cycle of increasing A/S conditions.
  • Division of the sequence boundaries and system tracts in deep-water environment—A case study on the Lower Cretaceous in Chagan Sag, Yin'gen Basin
    CHEN Jianping; LIU Mingming; LIU Chuanhu and GUO Yanru
    , 2005, 32(1): 1036-0.
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    The abrupt changes in spore-pollen species and in the content of reduction sulfur are sensitive to water depth, and can be used as indicators for sequence boundaries and system tracts. The Lower Cretaceous strata in Chagan Sag were deposited in a deep-water lacustrine environment. Based on geochemical and paleontological data, the Lower Cretaceous is divided into three sequences, which correspond to the Upper, Middle and Lower members of the Lower Bayingebi Formation. The system tracts of each sequence are also identified. From the lacustrine lowstand system tracts, lacustrine transgression system tracts to lacustrine contraction system tracts, the content of reduction sulfur changed from low, high, to low, and reached a peak in the condensed section; and the number of spore species decreased rapidly in lacustrine extension system tracts and showed an increasing trend in contraction system tracts.
  • Origin and characteristics of quartz-sandstone reservoir of the Yulin gas field, Ordos Basin
    FU Jinhua; WANG Huaichang; WEI Xinshan and QIN Baiping
    , 2005, 32(1): 1037-0.
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    Yulin gas field is one of the large gas fields in the middle-east part of the Ordos Basin. Its reservoir strata, mainly tight quartz-sandstone of the Shan-2 Member of the Shanxi Formation, show a positive correlation between porosity and permeability, with mainly intergranular porosity，low drainage and median pressures, coarse pore throats, and a homogeneous pore structure, suggesting a high water-energy depositional environment. Chemical weathering and mechanical sorting through long distance transportation may have played an important role in forming the reservoir characteristics of the quartz-sandstone.
  • Structure evolution and sedimentary filling of Jiuquan Basin in Mesozoic-Cenozoic period, NW China
    WANG Chongxiao; MA Guofu and ZHOU Zaihua
    , 2005, 32(1): 1038-0.
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    Jiuquan Basin has experienced two major tectonic cycles that are stages of the expanding rifting in the Early Cretaceous and the compressing depression in Tertiary, which means the basin was developed by the evolution phase of rifted basin in the early Cretaceous and the evolution phase of the foreland basin in Cenozoic. From the Middle to Late Mesozoic Period, Jiuquan Basin was in the expanding and splitting environment, however, the basin was in the compression and convergent environment in Cenozoic period. Therefore, the sedimentary cap formations have bilayer structure of superposed sag and depression from Mesozoic to Cenozoic. In the Early Cretaceous, Jiuquan Basin experienced three evolution stages, which are the halfgraben-like depression, the expanding depression and the dished depression. From Late Tertiary, the Late Mesozoic rift-subsidence basin has been dismembered and transformed by the fierce thrusting and shearing action.
  • Gas migration and accumulation and the exploration of the middle-deep layers in Yinggehai Basin, Offshore South China Sea
    HE Jiaxiong; XIA Bin; LIU Baoming; LIU Quanwen and ZHANG Shulin
    , 2005, 32(1): 1039-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The middle-deep beds are very important new hydrocarbon exploration area in the Yinggehai Basin where there are some mud diapir belts with abnormal high temperature and pressure. The migration and generation of hydrocarbon and hydrocarbon trapped system with the abnormal temperature and pressure in the middle-deep beds are comprehensively studied based on the data of the geophysical explanation and well logging in two new exploration wells (Well X and Well Q). There is a relative good mud cover system with high broken pressure and a good reservoir combination. The geochemistry analysis suggests that the source rocks in the middle-deep beds are good at generating hydrocarbon, which shows a potential for oil and gas exploration in the basin.
  • Determination of Mesozoic tectonic heat event in Qinshui Basin
    REN Zhanli; XIAO Hui; LIU Li; ZHANG Sheng; QIN Yong and WEI Chongtao
    , 2005, 32(1): 1040-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    A tectonic heat event happened in Late Mesozoic era in 100-150Ma ago and the main peak values are 130-140Ma.The time of the event is revealed by the analyses of tectonic evolution, paleogeothermal gradient, paleogeothermal flux, fission track age, magmatic activity and hydrothermal activity in the Qinshui Basin. Thermal maturation of Permo-Carboniferous coal seams were mainly controlled by geothermal anomaly of Late Mesozoic, on the basis of this geothermal anomaly, different structural units has different metamorphic rank due to plutonic metamorphism and regional magmatic metamorphism. The determination of the existence and timing of the tectonic heat event shows that the Huabei Mass lithosphere had been thinned in Mesozoic, the boundary of thinning might at least extend to the west of Qinshui Basin. Peak generation of hydrocarbon of Permo-Carboniferous coal series in Qinshui Basin happened between Late Jurassic and Early Cretaceous, which was controlled by the tectonic heat event in Late Mesozoic. The large scale uplift in Qinshui Basin happened from Miocene, the stratigraphic temperature dropped down
  • Chemical features of extracts from source rocks in coal measures with different polarity solvents
    DENG Chunping; WANG Huitong; CHEN Jianping and ZHANG Dajiang
    , 2005, 32(1): 1041-0.
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    The extracting experiment of source rocks with four different polarity solvents, hexane, benzene, dichloro-formethane and chloroform, shows that polarity of solvents controls the content and chemical composition of extracts. The chemical composition of the hexane extracts is the most similar to that of the oils from coal-measures basins in the four kinds of solvent extracts. The proportion of saturated hydrocarbons in the chloroform extracts is obviously lower than that in the hexane extracts and the oils, while the proportion of resins and asphaltenes in the chloroform extracts is obviously higher than that in the hexane extracts and the oils. Quantitative calculation reveals that the majority of saturated hydrocarbons in source rocks can be extracted by hexane solvent, and the solvents with strong polarity are not able to extract more saturated hydrocarbons from the source rocks than hexane solvent does. It may imply that the difference of chemical composition between chloroform extracts from coals and the oils derived from coal measures does not affeet the correlation of the extracts and biomarkers of the coal measures
  • Feldspar corrosion and secondary pore formation in the Upper Paleozoic gas reservoir, Ordos Basin
    ZHAO Guoquan; LI Kaiming; ZHAO Hailing; LIU Ruie; SUN Fenjin; DI Yongjun and LI Yongtao
    , 2005, 32(1): 1042-0.
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    The Upper Paleozoic gas reservoir in the Ordos Basin mainly consists of Shan 2 gas layer in Shanxi Formation and He 8 gas layer in Xiashihezi Formation, Permian. The formation of secondary pore is mainly the result of feldspar corrosion according to a scanning electron microscope study. Calculation on feldspar corrosion from the perspective of thermodynamics, with reference to volume effect, proves that most secondary pore in the formation could be developed by the potash feldspar corrosion, and in this respect anorthite and albite corrosion is less effective. Analysis on possible sources of organic acid is conducted. All the studies indicate that the main cause of the formation of secondary pore in the gas reservoir is the corrosion of alkali feldspar with the effect of organic acid.
    • 综合勘探开发技术
  • Experiment and application of NMR technology on cuttings
    WANG Weimin; ZHAO Gang; GU Changchun and SUI Mingqing
    , 2005, 32(1): 1043-0.
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    A quantitative method of determination of rock properties from cuttings by using Nuclear Magnetic Resonance technology is presented, for which the rock relaxation could be achieved by using the feasibility of fluid in pore. Differences between Nuclear Magnetic Resonance cuttings analysis and Nuclear Magnetic Resonance core analysis are studied. The method to determine the rock properties such as porosity, permeability, etc, from cuttings by using Nuclear Magnetic Resonance technology is also presented. The on-site application of Nuclear Magnetic Resonance of cuttings is carried out in Qinghai, Jilin and Jidong Oilfield, suggesting that the NMR technology on cuttings and conventional core analysis matches well.
  • Formation mechanism and RRSR identification for low-resistivity oil pays, Y Oilfield
    LI Wei; TIAN Zhongyuan; YAN Weilin; LIU Zhengjun and YIN Haiying
    , 2005, 32(1): 1044-0.
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    Mechanism for low resistivity oil pays (LRP) of Y Oilfield has been deeply studied by integrating data,including well logging, master log, core and DST results. The Y Field LRP is caused mainly by high irreducible water saturation in abundant micro-porosity system in fine to very fine grain sands and shale of reservoir. LRP types are as ①caused by low porosity and permeability; ②by abundant micro-porosity system; ③by invasion of saline drilling filtrate into oil pays for the interval of bad borehole. RRSR identification is developed from mechanism of LRP and is equal to 0 for water zones, and RRSR is over 0 for LRP. It is confirmed by the practice cases in Y Oilfield.
  • Interpretation of the pinch-out belt in YW3 Well field using relative amplitude preserved high-resolution processing data
    WANG Xiaoping; CHEN Bo; SUN Weizhao; ZHANG Hongmei and ZANG Dianguang
    , 2005, 32(1): 1045-0.
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    YW3 Well field is located in the east of Hade 4 Oilfield, Tarim Basin, in which one of the target reservoirs is Carboniferous Donghe Sandstone (DHS). It is difficult to make sure the position of DHS pinch-out by using the conventional processing 3D seismic data. The relative amplitude preserved high-resolution processing technique is used to reprocess the 3D seismic data. After the process, the comprehensive interpretation is carried out based on the forward model, and reasonably described the distribution of DHS pinch-out boundary through analyzing the features in section. The relative amplitude preserved techniques is helpful to the study of lithological pinch-out.
  • Pressure-temperature coupling calculation of transient wellbore heat transfer in deep geopressured gas reservoir
    LIAO Xinwei and FENG Jilei
    , 2005, 32(1): 1046-0.
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    As fluids move through a wellbore in deep geopressured gas reservoir, there is transient heat transfer between fluids and the earch due to the difference between fluid and geothermal temperatures. Integrating the coupling influence between pressure and temperature in wellbore, a new pressure-temperature coupling calculation model, consisting of temperature calculation model and pressure calculation model, is presented, and coupling calculation method is provided incorporating analytic and numerical method. The wellbore temperature calculation model considers the heat-transmission within wellbore and from wellbore to formation as transient. The wellbore pressure calculation model considers the influence of friction resistance and dynamic energy variation. The pressure and temperature of Well YH23-1-14, Tarim Oilfield, is calculated using the new model. Comparisons of field testing data and computed data of pressure and temperature in Well YH23-1-14 indicate that the new method is of high accuracy.
  • Well log distinguishability visual stochastic modeling for carbonate reservoir
    LI Yuanjue
    , 2005, 32(1): 1047-0.
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    The statistical indicators of well log can be used to predict the distribution of reservoir parameters. The statistical indicators of reservoir parameters and alternate frequency of reservoir bed via interbed have been extracted from well log. Combining the statistical indicators of vertical heterogeneity with stochastic reservoir modeling and making vertical data interval of model corresponds to well log interval, a realization of reservoir model in well log distinguishability could be achieved. In the project of a carbonate reservoir description, based on well logging and 3D visualization calculating language, the characteristics of the reservoir is subtly rendered by the well log distinguishability stochastic modeling for carbonate reservoir.
  • Sensitivity of variogram in stochastic modeling
    WANG Genjiu; ZHAO Limin; LI Wei and ZHAO Guoliang
    , 2005, 32(1): 1048-0.
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    Variogram is a vital parameter in stochastic modeling. determining sand distribution, petrophysical property and volumes. Based on the measure of sand geometry in M Block and comparison of results calculated with Spherical, Exponential and Gaussian Model, it is concluded that different variogram models get very different variogram range in major and minor direction. The difference of the range in major direction can reach 15% while that in minor direction can reach 25%. The variogram is very sensitive and the volumes calculated with different models have big difference. The more developed the sand is, the less different the sand volume is. The space varying variogram, improved from normal variogram, is put forward with the varing variogram in planar view. The reliability of variogram could be improved by application of space varying variogram.
  • Calibrating fracture width using Circumferential Borehole Image Logging data from model wells
    QIAO Dexin; LI Ning; WEI Zhongliang; ZHU Shihe and WU Dong
    , 2005, 32(1): 1049-0.
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    Circumferential Borehole Image Logging (CBIL) is discussed based on model wells, which consists of a group of test wells of different rock types to simulate litology variation and structural phenomena of the well wall, and to reflect the complex geological characters of the well wall on the basis of the structural characteristics of real formation. Three models of amplitude echo-fracture width relationships are presented through integrated analysis of CBIL data from model wells and improved computing equation of fracture width is provided according to the relationship between the apparent fracture width and echo amplitude. The fractural width is calculated by using the CBIL data in model wells with the mean absolute error of less than 7%. The reliability of this method is verified in model wells and satisfactory results are obtained also from real-case test.
  • Wavelet multiscale analysis and geophysical significance of the spontaneous potential of oil and gas reservoir
    LI Yule; WANG Junheng; PAN Zhuping and HOU Zunze
    , 2005, 32(1): 1050-0.
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    Spontaneous potential of oil/gas reservoir is the cumulative effect of petroliferous beds in different depth, and can be divided into 1-n order wavelet details and n order approximation by wavelet multiscale analysis. The first order wavelet detail indicates mainly the interference of ground surface, the 2-n order wavelet details indicate the anomalies of oil/gas layers in different depth. The n order approximation indicates the background of the anomalies. The depth of 2-n order wavelet detail anomaly source (layers) can be estimated by empirical equation. This method is used in Qijiabei area,Songliao Basin,in order to study the contribution of oil/gas layers, the result suggests that there is a responsible relationship between the oil/gas reservoir and the 2-n order wavelet details.
  • Application of wavelet transform in auto-identify units of stratigraphy sequence
    ZHU Jianbing; JI Youliang; ZHAO Peikun and WANG Yonghong
    , 2005, 32(1): 1051-0.
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    According to the character of multi-resolution analysis, several common wavelet functions such as Harr, Daubechies, Symlet, and Dmeyer function are used to transform SP, GR and RT. It is concluded that the para-sequence units of stratigraphy sequence can be identified in certain range. By this method, the well log curves of Well T715, T711,T76,T79,T762 in Shengtuo Oilfield have been identified. The statistics suggests that the best result is the symlet wavelet.
    • 钻井工程技术
  • Suggestions on the sustainable development for drilling engineering
    LIU Guangzhi
    , 2005, 32(1): 1052-0.
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    Drilling engineering is one of the important engineering sciences with special basic theories and many applications. Drilling engineering has already played important roles in the scientific activities and will have broader application fields. And more functions of drilling will be created with the development of national economy. Four technical suggestions for the development of drilling engineering are put forward as follows: join the IODP(Integrated Ocean Drilling Program) sponsored by the Japanese Marine Science and Technologic Center (JMSTC) for training Chinese younger technicians; prepare for mining the rare mineral in the Northwestern Pacific Ocean; research for the drilling equipment and related techniques for exploration and production of natural gas hydrate; exploration and exploitation of the abiogenetic oil and gas in the pre-Cambrian bottom formations to detect new fields for oil/gas resources.
  • Development trend of the modern drilling technology
    SHEN Zhonghou
    , 2005, 32(1): 1053-0.
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    Rotary drilling has experienced 3 periods of development: elementary, development and scientific drilling period. There are 3 great achievements in the late period of scientific drilling: the realization of downhole real time signal record, transmission, treat and analysis; the development of downhole directional drilling and downhole closed loop drilling system and the development of new drilling techniques. The modern drilling technology is developing toward informatization and intelligentization, combination of multi-disciplines to improve oil production and enhance oil recovery, and effectively development of special oil & gas reservoirs. If the technology can be imported, the method of introduction-digesting-innovation should be applied to keep step with the advanced technology on drilling. If it cannot be imported, develop it by ourselves. Much basic research works should be performed on the 3 new drilling techniques as horizontal drilling techniques, multilateral drilling techniques and under balance drilling techniques. At present the development of petroleum engineering requires that the drilling engineering should not only construct the channel for the production of oil but also take the task to improve the production of single well, enhance the recovery and explore the special oil/gas reservoirs. So the drilling technicians should be familiar with the theory and techniques related to the oil reservoir engineering.
  • Geosteering drilling technology and its development in China
    SU Yinao
    , 2005, 32(1): 1054-0.
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    Characterized by decision-making and control on measurement, transmission, real-time surface interpretation of near-bit geologic and/or engineering parameters, geosteering drilling technique has been used in nearly 50 wells of 6 countries in Europe and Africa by 13 companies during the 3 years since it came out and the total drilling footage was over 32187m, which brought great technique effect and economic benefit. The structural composition and technical characteristics of Geosteering Drilling System (GDS) was introduced taking example of IDEAL system. CGDS-1, the first GDS of China, is composed of Chinese Geosteering MWD (CGMWD), CAIMS and surface software package CFDS of information processing & decision-making. CGMWD had been tested and used in 2 directional wells in field and the performance met the design requirements. A prototype of CAIMS is being manufactured and prepared for field test. NBLOG-1 has been tested by unit and integral in field wells by 7 times in total and great progress has been achieved. As a high-tech, GDS should be given an impulse to its research and application. Departments in charge should give more support to CGDS-1 so that the research could be completed and the new-tech be used in production.
  • Advances in researches and applications of water jet theory in petroleum engineering
    LI Gensheng and SHEN Zhonghou
    , 2005, 32(1): 1055-0.
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    The recent developments of high pressure water jet technology, especially its research progress in theory and applications in petroleum engineering industry, are reviewed. The study on modulation mechanism of self-resonating water jet introduced a new type, high efficiency, self-resonating cavitating jet. Wide and effective applications are found both in drilling, which invented the self-resonating cavitating jet bit, and in plug removing and formation treatment, which developed two new technologies: one is self-resonating swirling jet treating near well bore formation to enhance oil production and water injection, and the other is self-resonating pulsating water injection. The technology of rock penetrating by combining mechanical and hydraulic methods was well developed, which presents the formation and development regulations of rock cracks under bi-stresses of drilling pressure and shearing stress induced by swirling jet, to develop the bit design theory concerning both mechanic and hydraulic effects. The development of radial horizontal well drilling technology was under the studies on swirling jet theory and rock failure mechanism. To further develop the abrasive water jet perforation technology, experiments were conducted to study jet features and optimize jet parameters. The studies on the feasibility of water jet deep penetrating assisting hydraulic formation fracturing operation, on dual jet theory and features, and on ultra high pressure water jet assisting drilling illustrated well of the large scope application of water jet technology in the petroleum engineering industry.
  • New technology to drill horizontal wells with under-balance pressure by air injection
    LIU Huixin and MENG Yingfeng
    , 2005, 32(1): 1056-0.
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    As a result of the research on the new technology to drill horizontal wells with under-balance pressure by air injection, a whole set of practical and effective techniques have been developed in China to solve the special difficulties in under-balance pressure horizontal well drilling by air injection. The key technologies are reviewed: a new type of dual injection casing head, that may hang, fix and recover the temporary casing and also connect the air injection pipeline, is developed; two types of proper wellbore structure (three plans) have been put forward based on the successful drilling experience abroad and actual situation of casing, drill bit and drilling equipment in China; some bottom fixing assemblies of the temporary casing string have been designed such as air-liquid helical flow mixed nipple joint, groove casing shoe, anti-abrasive casing nipple joint and anti-backoff rotation device. Drilling technologies have also been studied to meet the requirements of horizontal well drilling with under-balance pressure by air injection.
  • Application of compound-penetration in Changqing Oilfield
    LI Baomin and ZHAO Dahua
    , 2005, 32(1): 1057-0.
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    Compound perforation technique is a pore-fracture and super-depth perforation technique and also can conquer the shortcoming of conventional perforation technique since a conventional perforation technique has shallow penetration, can not break through the damage zone near the bore and compacted formation damage exists. Compound perforation technique explodes compacted sandstone which is made by conventional perforation technique. In order to evaluate the 6 year application of compound perforation technique in Changqing Oilfield, 24 wells used compound perforation technique and 28 wells used conventional perforation technique in 5 blocks, which have similar physical properties of reservoir, have been selected for the comparison. The compound perforation technique can reduce 3-5MPa of formation break-pressure and increase formation permeability around the perforation channel and can reduce effectively perforation cost of oil-gas wells.
    • 油田开发与油藏工程
  • Development of low permeability reservoir with closely-spaced wells
    YAN Cunzhang; LI Xiusheng; CHANG Yuwen; YU Lijun and SHI Jianzi
    , 2005, 32(1): 1058-0.
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    The fractured thick-bed clumpy conglomerate reservoir of Wuerhe Formation in Block 8 of Keramay Oilfield is characterized by low porosity and super-low permeability. The research on development layer division and combination, and on the reasonable relationship between the well pattern and fractures, is carried out by numerical simulation for closely-spaced well pattern development of the reservoir. The optimum layer combination is determined with the best opportunity for the upward movement of producing layer set to be at the watercut point of 75%. The linear waterflooding pattern, with the injector array parallel to the fractures, is most desirable for the reservoir development and the fracture penetration coefficient should be controlled by around 40%. The best conversion opportunity is at the watercut point of 80%. The closely-spaced well development scenario demonstrates production expectations after implement, the recovery will be enhanced by 11.78%, and thus provides a successful example for similar reservoirs.
  • Water extraction and cone control of horizontal well in exploitation of bottom water reservoir
    WANG Qing; WU Xiaodong and LIU Genxin
    , 2005, 32(1): 1059-0.
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    The effects of well type, water extraction time and water extraction quantity on the control of bottom water coning are studied by numerical simulation. The results suggest that a reservoir with low vertical permeability and interlayer above the water oil contact would have good effect of water extraction and cone control. The effect of water extraction with horizontal well is better than vertical well; the earlier the water extraction is applied, the better the effect of water control is obtained; the larger the quantity of water extraction is, the more obvious is the water control effect, and water extraction time and water extraction quantity has optimal value. In addition, water extraction and cone control is not effective to all bottom water reservoirs that are developed with horizontal well. If the vertical permeability of reservoir is high and have not effective block off of interlining or interlayer above the water oil contact or the water body is giant, the water cut of horizontal well will go up rapidly and the effect of water extraction will be difficult to achieve.
  • Casing damage mechanism in sand producing formations
    ZHANG Guangqing; CHEN Mian; GENG Yudi and WANG Huaiying
    , 2005, 32(1): 1060-0.
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    Mechanical model for casing damage in sand producing formations is established with the finite element method. The factors influencing casing strength,including height of sand production, internal pressure of casing, and the vertical earth stress, are investigated, indicating that sand production interval increases the risk of casing damage greatly. The damage degree is in parabolic relation to sand production height, and the maximum equivalent stress is in bi-linear relation to the internal pressure. The vertical earth stress has significant impact on casing strength. Then in order to avoid or decrease casing damage, except for the conventional methods such as using appropriate sand prevention tools and high strength casing, the critical height for sand production should be avoided as far as possible, with the internal casing pressure approaching critical value as close as possible.
  • New technology for casing damage prevention and cure of thermal production wells in Liaohe Oilfield
    YU Lei and BO Min
    , 2005, 32(1): 1061-0.
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    The casing damage was serious during the thermal production in Liaohe Oilfield. Through investigations and researches, reasons for the initial casing damage were determined as follows: higher thermal stress, sand production in oil wells, unfit sub with API round thread and bias buttress thread, low cementing quality, easily appearing casing deformation in cementing annular section, and improper heat insulation tubing and heat insulation measures. The measures adopted are: prestress pulling up, substituting N80 casing with bias buttress thread for the common casing, using special cement for thermal production wells and returning to the surface, and utilizing fine heat insulation tubing. After the management, the casing damage in thermal wells was decreased, but the initial casing damage was still heavy. Thus new techniques were adopted: reducing the casing stress during steam injection using heat stress compensate tool, increasing the deformation resistance using TP100H casing, and solving hoop stress problems of production casings caused by sand production and perforation using TP120TH external upset casing. Through the long-term researches and practices, the initial casing damage rate of thermal wells was reduced.
  • Optimization of the staggered well pattern of mixed horizontal and vertical wells
    ZHAO Chunsen; XIAO Danfeng; SONG Wenling; FENG Fengping and SHAN Chunlong
    , 2005, 32(1): 1062-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Using pseudo three-dimensional method and conformal transformation, the potential function of a row of horizontal wells is deduced, with the function and superposition principle method, an analytical solution of production for the rectangular mixed well pattern is given. Well pattern optimization analysis is carried out by introducing 2 dimensionless parameters, dimensionless shape factor and dimensionless horizontal length, and the relationship between the dimensionless horizontal length and optimum shape factor is derived. The results show that the optimum shape factor is dependent on the dimensionless horizontal length, and the pattern area and formation thickness have little effect on it, based on which the optimization designing methods for horizontal well pattern are provided.
    • 油田非注水开发
  • Development technology for low-permeability sandstone reservoirs in Shengli Oilfield
    LI Yang and CAO Gang
    , 2005, 32(1): 1063-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The low-permeability sandstone reservoirs in the Shengli Oilfield consist of turbidite fan deposits in deep to moderately deep lakes. Deep burial, poor petrophysical properties, strong heterogeneity, and fracture development make them difficult to be developed. The necessary technologies for developing the low-permeability reservoirs have been improved greatly and mojor progress has been made. The modes of formation for the low-permeability sandstone reservoirs have been established, including two modes, one in the box and the other at the edge of the box. Both fracture and matrix models have been constructed based mainly on the study of fractures and structural stress. The capillary equilibrium method is developed to measure the minimum starting water injection pressure. The empirical formula for low-rate non-Darcy percolation is proposed and used to plot an application chart. The numerical simulator with options describing self-adaptive percolation and general percolation is developed. There has been progress on the study of low-permeability formation protection, formation stimulation and water-flooding.
  • Pilots of ultra-low interfacial tension foam flooding
    ZHAO Changjiu; MA Cuijie; YANG Zhenyu and YAO Shichun
    , 2005, 32(1): 1064-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The ultra-low interfacial tension foam flooding (LIFTF) is a new tertiary recovery method. The displacement efficiency is better than ASP flooding, and the recovery is improved by around 25% than water flooding. By laboratory studies the testing program was determined and the pilots of LIFTF were carried out in Daqing Oilfield. Large amounts of foam generated in the reservoir, the sweep volume increased and the oil displacement efficiency improved. The injection pressure rised and the pressure difference between injector and producer enlarged obviously. The fluid injectivity and productivity index increased greatly, oil production increased and water production decreased greatly, and gas breakthrough is controlled effectively. The dual string injection should be used in the LIFTF to avoid the generation of hydrate. Because of the higher injection pressure, the compressor of better performance should be adopted to meet the request of the designed gas/liquid ratio.
  • Remaining oil distribution in shallow, thin and super-heavy oil reservoir of Henan Oilfield after steam stimulation
    SHAO Xianjie; SUN Chong; WANG Guopeng; GAO Xiaotian and WANG Pei
    , 2005, 32(1): 1065-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The steam stimulation recovery is only 15%-18% in shallow, thin and super-heavy oil reservoir of Henan Oilfield. In order to further enhance the recovery, it is very important to find out the law of remaining oil distribution in shallow, thin and super-heavy oil reservoir after steam stimulation. The characteristics of core and electrical properties of water-flooded zones have changed obviously. Based on the relationship between the cores and logging curves, a set of fast and intuitive techniques have been set up to interpret water-flooded zone by using plot of the sonic differential time and the deep lateral logging data. Combined with the field testing, performance analysis, numerical simulation and geologic analysis, the remaining oil distribution law is disclosed. Vertically, there are 3 types of waterflooding: waterflooding in top layer of homogeneous rhythmic reservoir; waterflooding in middle layer of compound rhythmic reservoir; and waterflooding in bottom layer of positive rhythmic reservoir. Areally, the remaining oil normally enriches in areas of low well control level, low oil recovery, multi-facies control, and the areas affected by stratigraphic dip.
    • 国际交流与合作
  • Sequence stratigraphy and tectonics in Middle Indus Basin, Pakistan
    HUANG Zuxi; WANG Yuman and WANG Yucheng
    , 2005, 32(1): 1066-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The Middle Indus Basin (MIB) constitutes a major gas province in the Southern Pakistan. The main current exploration activities is concentrated on the gas accumulations in Lower Goru sandstone in structural, stratigraphic and mixed stratigraphic/structural traps at the average depth of 3500 m. To better understand the petroleum system of the MIB and the residual exploration potential in this region, according to the Exxon method of identifying unconformities and their correlative conformities, a sequence stratigraphic interpretation was carried out on the Jurassic to recent sediments of the MIB. The plate tectonic setting of depositional environment for source, reservoir and seal play elements has been evaluated. Additionally, two proven play fairways in the MIB were described by using the framework of the new sequences stratigraphy.
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