, Volume 28 Issue 5
    

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    石油地质研究
  • Characteristics and pool-forming regularity of immature oil in western Baiyinchagan depression, Erlian basin.
    ZHAO Guangzhen; ZHANG Jiazheng; ZHANG Yuanzhi; YAN Dongyu; SONG Zhixia and NIU Xiaofang
    , 2001, 28(5): 131-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Cretaceous immature oil in west part of Baiyinchagan depression appears mainly in the first Member of Douhongmu Formation with abundant soluble and good organic matter at a depth less than 1000m. Compared to the mature oil discovered in the same area, its aromatic and asphaltic contents are similar to that of the latter, while its non-hydrocarbon content ishigher and saturated hydrocarbon content is lower. It has a significant odd-even predominance in normal alkane series. Its Pr/Ph value is low (<0.6), and Pr/nC18 value is high (>2.37). C29 20S/ (20S+20R) is less than 0.30, C29ββ/(ββ+αα) is less than 0.35, C3122S/(22S+22R) is less than 0.5. The value of ααα-20RC27/C29,ααα-20RC28/C29and the characters of carbon isotope show that mature and immature oil came from the same oil-kitchen. Immature oil is characterized by early generation, early expelling, late formation of oil pool and short distance migration. The accumulation and pooling of oil were controlled by the fracture. It is found that oil pools are mainly distributed in the sand bodies of delta-front and slump turbidity in the front of the delta.
  • Geological feature and sealing property evaluation of caprock in the northern margin of the Qaidam basin.
    HONG Feng; YU Huilong; SONG Yan and XIA Xinyu
    , 2001, 28(5): 132-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Caprock in the northern margin of the Qaidam basin is mainly composed of mudstone. Regional cap rock includes Tertiary Lulehe Formation and the upper part of the Lower Ganchaigou Formation; local cap rock includes Jurassic and Upper Ganchaigou Formation and Youshashan Formation (Tertiary). Breakthrough pressure of Jurassic caprock can be as high as 16-23MPa, while that of Tertiary caprock can reach up to 12.7MPa with enough burial depth. Threshold depth for efficient sealing of caprock in the Lenghu and Maxian areas is 1613.7m and 1094.46m respectively. The time for Jurassic to get sealing ability is earlier than it reached oil-window, while that for Tertiary is later than hydrocarbon climax of Jurassic source rock. According to their geological feature and sealing ability, the Jurassic and Lower Ganchaigou Formation（Tertiary） caprock belong to type Ⅱ caprock and the Tertiary Lulehe Formation belongs to type Ⅲ caprock.
  • Thermodynamic behavior of E′centers in quartz from deep sediments, Tarim basin
    YE Yuguang; DIAO shaobo; WU Xianglong and HAN Zhenhua
    , 2001, 28(5): 133-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The intensity of E′centers may be used instead of the relative amount of oxygen vacancies usually by thermal activation technique, and the life estimation of E′centers is also carried out by the thermal activation technique. In the ESR research of deep sediments (4895-5102m, Permian System) from Well TK301, Tarim basin, the authors found that the intensity of E′centers in quartz did not increase after heating at 300℃ for 30min and decreased greatly up to 500℃. This observation is consistent with the experimental result of Toyoda (1994). Although the formation efficiency of oxygen vacancies is very low, but the external β and γ rays of environmental matter may create oxygen vacancies in natural quartz during the long time. The intensity of E′ centers in quartz from deep sediments can be directly used instead of the relative amount of oxygen vacancies, the experimental process of ESR dating can be simplified.
  • Analysis on material sources and palaeogeographic landscapes of Weixinan sag
    ZHAO Jun; HONG Qingyu and DONG Weiliang
    , 2001, 28(5): 134-0.
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    Weixinan sag is an episodic tension subgraben basin which developed in Mesozoic and Cenozoic. The basin, which stands the south ledge of Eurasian plate, was interacted by Pacific-oceanic plate, Eurasian plate and India plate, forming the so called “South China Sea type” passive continental margin with extremely complicated features in tectonics, and an unique source. On the basis of heavy minerals data the combination arrays of heavy minerals are researched carefully according to the weathering degree and the variations of its content through transport. The result is that the main material source of paleogene strata comes from the west and the secondary material sources come from the northwest in the Weixinan sag. On these bases the palaeogeographic landscapes are analyzed with the specific characteristics of sedimentology and construction. The expanding direction of the sedimentary system is from west to east and is unsymmetrical. This system is thick in the west and thin in the east under the control of the three periods of episodic tension.
    • 综合勘探开发技术
  • The fault-sealing prediction software system—FSPS
    WANG Xiaohong; GUO Qiulin; MI Shiyun; YANG Qiulin and ZHANG Qingchun
    , 2001, 28(5): 135-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    It is very important to predict the sealing capability of a fault in reducing the risks of hydrocarbon exploration. The parameters of estimating sealing capability from each point on the fault surface need to be calculated rapidly by using computer methods, because the fault sealing varies over the fault surface along strike of the fault and on depth points of layers at same part of the fault surface. The fault sealing prediction system, FSPS, has been developed to assess the fault sealing or nonsealing by quantitative analysis of lithology juxtaposition and the shale smear factor, and by qualitative analysis of cataclasis and diagenesis. FSPS can estimate a hydrocarbon spill point on a fault block and calculate likely the range of a trap and essential elements of the trap (e.g., trap height, trap area, etc), it is convenient and rapid to input source data, calculate parameters, and display results. An example of applying FSPS to predict fault sealing of 7 sand layers on small fault blocks area in the east of China is given. The maximum hydrocarbon heights estimated on two small fault blocks of the area is equal to the result estimated by capillary pressures, and this effect shows that the results provided by FSPS are reasonable and FSPS is abroad worthy to application.
  • Reflectance signature and occurring position of turbidite in the third Member of Shahejie Formation, Lengdong region, Liaohe depression.
    TAN Rong; ZHAO Zhichao and ZHAO Xiafei
    , 2001, 28(5): 136-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    By statistically analyzing and explaining lithology, AC curve, drilling and logging data of some key wells and combined with seismic phase displacement wave equation forward modelling, seismic reflectance signature of turbidite is established, which provides a diagnostic criterion for turbidite. Interval velocity was inverted by G-log technology, so that interval velocity was separated from wave impedance by using the correlation curves of interval velocity vs. lithology, porosity and permeability, and then transformed into lithological plane views. Combining with lithology, petrophysical property of turbidite, the occurring position of turbidite was successfully predicted. From the above study, it can be concluded that:(1) Interval velocity change in seismic inversion, generally reflects the change of lithology. (2) Forward modelling result indicates that seismic characteristic explained in time-section has velocity structure of fan delta-turbidite.
    • 油田开发与油藏工程
  • The mathematical model of unstable flow of fluids through porous media with non-uniform thickness lateral heterogeneity of fractal reservoir
    XIANG Kaili; LI Yun and LI Tiejun
    , 2001, 28(5): 137-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The theories and mathematical model of well testing analysis of fractal reservoir with non-uniform thickness lateral heterogeneity are discussed. In order to completely describe the situation of real reservoirs, the fractal reservoir with variable thickness is defined as fractal reservoir that consists of many zones with non-uniform thickness, different fluid, different format properties and variable fractal parameters. A new effective well radius mathematical model of this fractal reservoir is suggested in which the wellbore storage and skin effects are considered. The analytical solutions in Laplace-space for the mathematical model are obtained by Laplace transformation. The dimensionless flowing wellbore pressure for the modern well test analysis is given by numerically inverting method. The well test analysis theories and the pressure behavior of this reservoir are discussed. The model and solution can be used in the fractal reservoir with variable formation properties or containing water injection wells, gas injection wells, polymer injection wells or finite damaged zone.
  • Some considerations on the application of water drive characteristics curve in recoverable reserves calculation.
    WANG Shuhua; YANG Fengbo; SUN Jiwei and TANG Lei
    , 2001, 28(5): 138-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Water drive characteristic curve is one of the main methods to estimate recoverable reserves of oilfield at mid/late development stage. From both the theoretical and practical view points, this article points out that some attention should be paid to once applying water drive characteristic curve. Only when the reservoir types, recovery methods and water cut are matched, the water drive characteristic curve will possess the characteristics of reduplication and the development units can be merged and the recoverable reserves can be calculated approximately, otherwise the development units can be calculated separately and then sum them up. At present, among the six water drive characteristic curves that are recommended by the industrial standards (SY/T?5367-1998) in recoverable reserves calibration, Sipachef curve and ZHANG Jin-qing curve are regarded as most appropriate to calculate the recoverable reserves. The results of Nazalorf curve and YU Qi-tai curve have small error while that of Marksimof-TONG Xian-zhang curve and Shazonov curve have bigger error. Gradient method should be adopted in the judgment of regression straight line. Inheritance and continuity must be included in the method of year/phase recoverable reserves calibration. Those calculation results, which match relatively with production performance, should be selected as standards but not the average value of total results of all the methods. According to the relation curve of recovery percentage of recoverable reserves and accumulative water cut or the matching relationship of development index and remaining recoverable reserves, we can judge the rationality of the results in recoverable reserves calibration.
  • The development mode of complicatedly fractured, low-permeability and thinly interbed reservoir in Chunhua oil field.
    RONG Qihong; PU Yuguo; LI Daoxuan; SONG Jianyong; ZHOU Chuanhong and JIANG Qingsong
    , 2001, 28(5): 139-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Chunhua oil field is characterized by the features of complicated fracture, low-permeability and interbed thin layers. The complexity of fracture is typical in Jiyang depression. On the basis of early structural style and delicate structural style and for the purpose of reducing interlayer and lateral conflicts and increasing the reserves and oil production, a system engineering was used successively in Chunhua oil field through more than 30 years of development, which includes producing oil by elastic drive, waterflooding development, infill drilling, zonal production, progressive delineation, sporadic development, improvement, modification of injection-production pattern and so on. And has got a good result in the development of reservoirs with complicated fractures, low permeability and interbed thin layers. The oil production was more than 4×106t in 1980, and then from 1981 to 2000 this production was stably increased. Studies on the distribution rule of remaining oil in Chunhua oil field indicate that remaining oil enrichment region is virtually a lower potential close region formed by static shelter and dynamic potential of water. In practice, wells newly drilled in the lower structural region with high water cut did not produce water in early days. This maybe provides a new type and region of potential tapping that is different from the so-called “potential region”, which is the positive microstructures, and also have theoretic and practical significance in guiding the direction of tapping potential old fields like Chunhua from 2001 to 2005.
  • A new quantitative method to study flow unit of non-marine reservoir
    PENG Shimi; YEN Zhijun; CHANG Xuejun and HAO Jianming
    , 2001, 28(5): 140-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Most of oil fields in our country have now entered into middle-high water-cut phase. In order to stablize and increase production, it is critical for oil fields to predict correctly the distribution rules of remaining oil, make rationally development plan and as a result, increase recovery factor. Subsurface condition should be correctly recognized to gain this target. Flow unit is a continuous reservoir region, within which reservoir's physical characteristic is similar horizontally and vertically. As the basic seepage unit of subsurface fluid, flow unit is the comprehensive reflection of reservoir's lithology, physical feature and micro pore throat characteristic. This paper brings forward a new quantitative method to build flow unit model. Firstly, the original flow unit is made through selected parameters from core wells, then discriminant function of flow unit is arrived by cluster and classifies analysis, and with which flow units of wells that haven't obtained cores are able to be determined. Consequently, sequential indicator simulation, one of geo-statistic methods, is introduced to predict flow units between wells. Three types of flow unit (that is A, B and C) are plotted out in Fault Block Gao 3102, Gaoshangpu oil field with this method, which is testified by the dynamic data of oil field production. According to flow units, we can evaluate reservoir, find favorable regions, predict remaining oils, adjust development well patterns, and as a result increase recovery factor.
    • 油田非注水开发
  • Research on mixed flooding of flue gas with steam in cores for Block Gao-3 oil field
    LIU Huiqing; HOU Zhijie; GAO Bencheng; ZHOU Yunheng and GUO Yunrao
    , 2001, 28(5): 141-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Steam-flooding experiment with flue gas as additives has been performed for Block Gao-3 oil field, and theoretical study and simulated distillation test have been made also. It has been shown that steam partial pressure will decrease and steam quality increase in the gas mixture, so the sweeping volume will increase for same cold water equivalent. Steam distillation effect has been enhanced, initial distillation temperature decreases 22℃, and available distillation volume increases from 5% to 10%. It has been shown that recovery factor will increase with the gas-steam ratio, and the tendency become mild after steam temperature increasing. Favorable gas-steam ratio is 0.5∶1, if flue gas is mixed with steam in the experiment, and additional 3% recovery can be reached for Block Gao-3 oil field.
    • 油藏物理
  • Petrophysical facies study of conglomerate rock reservoir in Block 8 of Kelamayi oil field
    TAN Chengqian; SONG Ziqi and WU Shaobo
    , 2001, 28(5): 142-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The reservoir petrophysical facies is considered as the combination reflection of sedimentation, diagenesis, late construction and fluid reworking. The same rock facies can be correspondent to different petrophysical facies. However, the hydraulic and physical properties are similar in one petrophysical facies unit. Based on the parameters of flow zone indicator, porosity, permeability, shale content and mean value of the grain size, the Block 8 sandstone reservoir petrophysical facies was divided into 4 types in Kelamayi oil field, by means of gray system theory. Finally, through discussing in detail the main characteristics of each of them and combined with the actual of geology and production situation in the area, some analytical results on the relation between the petrophysical facies and the remaining oil have been obtained, which shows that the petrophysical facies Ⅱand Ⅲ are the enrichment distribution zones of the remaining oil in the field.
  • The 3D simulation and recognition method of oil/water well casing defects
    DOU Jihong; ZHANG Yikuan and CUI Zhiming
    , 2001, 28(5): 143-0.
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    Pattern recognition of casing defect and its forecasting is an important issue in the process of real-time monitoring and forecasting of casing damages. Combined with specific examples (the photos of casing defects from a region of Zhongyuan oil field), the 2D mathematical model that can restore the photos of casing defects is constructed firstly by using coordinate transformation and image processing methods, which by using Visual C++ programming technology and the 2D simulation of casing defects is presented and analyzed. Then, the 3D simulation of casing defects of oil/water well is presented in the light of Photoshop software and grayscale function, and the photos of casing defects of oil/water well are restored effectively. Finally, the casing defects are classified by using the properties of grayscale function, and the lifetime of casing is forecasted. A new way is given to recognize casing defects of oil/water wells and to forecast the lifetime of casing.
    • 应力场研究
  • Using logging data to quantitatively study terrestrial-stress of Kuqa field
    LI Jun; WANG Guiwen and OUYANG Jian
    , 2001, 28(5): 144-0.
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    It is very important for petroleum exploration and development to determine the terrestrial-stress distribution of compressional region of western China. The basic steps in quantitative studies of terrestrial-stress by using resistivity logging and acoustic logging are as following: (1)determine by statistic method the relation of the maximum stress with resistivity and acoustic time in the stable field；(2)optimize the statistic model through analysis of logging data distribution characteristics in the compressional field；(3)apply the model to calculate terrestrial-stress in Kuqa compressional field and (4)compare the calculated results with the results derived from acoustic log to improve the quantitative model. In this research the calculations of stress from logging data are close to those from Kaiser Effect experiment. The fact proves that the statistic model proposed here is reliable. It is possible to obtain the quantitative stress and determine its distribution regulation along wells by applying the models to logging data calculations, and this will be much helpful to petroleum exploration and development.
    • 讨论
  • Analysis of low velocity non-Darcy flow mechanism.
    XUE Yun; SHI Jingping and HE Chengzu
    , 2001, 28(5): 145-0.
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    The low velocity non-Darcy flow mechanism is always a controversial subject. Over the past ten years, the Chinese researchers have made many extensive simulations and experimental studies of this flow in oil and gas reservoirs, most of them believe that this phenomenon is related to the anomalous boundary layers of the fluids. The boundary water was considered to be a crystalline substance formed by the action of the remaining force field at the solid surface. But early in 1970s this viewpoint was refused by the researchers including the advocator. The surface force measurement shows that the viscosity of water adjacent to the silica surface is not different from the bulk water and at most 1-2 layers of water molecule are immobilized at this solid surface. On the basis of recent surface and colloid chemistry theory, it is held that the low velocity non-Darcy flow of the liquid in the reservoir rock could be attributed, not to the anomalous boundary layers, as generally been assumed, but to the plastic flow caused by the colloid substances in the reservoir rock entering into the fluid and also held that the low velocity non-Dary flow of the gas in watered rock could be attributed,not to the water membrane,but to the redistribution of water in the rock resulted from the delay of the gas phase permeability.
  • New look on removing liquids from gas wells
    LI Min; GUO Ping and TAN Guangtian
    , 2001, 28(5): 146-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    In 1969, Turner put forward the formulae of minimum gas velocity and producing rate for continuous removal liquids from gas wells by supposing that the liquid is in spherical shape. However, when these formulae are put into practical use, it has been found that gas well production is not load-up even the producing rate of gas wells is much below the producing rate calculated by Turner's formulae. In fact, as a liquid drop is entrained in high velocity gas stream, there exists a pressure difference between the fore and aft portions of the drop. The liquid drop is deformed under the applied force and their shape changes from the spherical shape to the shape of a convex bean. The paper takes the deformation of liquid droplet entrained in high velocity gas stream into account and deduced new formulae for calculating minimum gas velocity and producing rate for continuous removal liquids. Minimum gas velocity and producing rate calculated by the formulae is only about 38% of that predicted by Turner's, but the results accord with practical situation of load-up and unload gas wells in China.
    • 油田开发与油藏工程
  • Improving generalized model for forecasting oil/gas field production capacity
    GAO Wenjun; XU Jun; WANG Zuojin and LIU Ying
    , 2001, 28(5): 474-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Based on the study and analysis of three generalized gas/oil field models built up previously, and combined with the Beta-cyclical, the Log-Normal-Distribution and some other prediction models, a new generalized prediction model was developed which has simple format and complete function. By selecting parameters, this model can be transferred into previous generalized prediction models (including respective basic prediction models) and the Beta-cyclical, the Log-Normal-Distribution and the other prediction models, which really indicates the theoretic and general adaptability of the generalized prediction model. In this way, the whole process the field production will be matched and predicted by using selecting parameters representing different drive types and combining the study results of literature［8, 9］. It has been proved effective in the example application.
  • Analysis of factors influencing production characteristics of Kela 2 overpressured gas field
    ZHU Yuxin; XIE Xingli; LUO Kai and LIU Yuhui
    , 2001, 28(5): 475-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The production characteristics of overpressured gas reservoirs are obviously different from that of normal-pressure gas reservoirs. Water influx from associated aquifer, formation rock expansion and connate water expansion are important influence factors. In studying the drive energy of formation expansion, there are two different views of using constant or variable rock compressibility. The result of rock load experiment of Kela 2 gas field shows that the original rock compressibility is 5-10 times higher than that of the late period of pressure decline. Therefore, using variable rock compressibility is more close to the real production performance. The material balance method offered by Adel M. Elsharkawy may underestimate the drive energy of water influx from associated aquifer, formation expansion and connate water expansion of overpressured reservoirs. This paper presents a modified gas material balance that can more accurately express the drive energy of every drive mechanism at the different pressure stages. The study shows that incorrect extrapolation of early data may result in serious overestimation of original gas in place and remaining recoverable reserves.
    • 油田非注水开发
  • The effects of polyacrylamide structure on the properties of microgel system
    KONG Bailing and HAN Jie
    , 2001, 28(5): 478-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Compared with the polymer flooding, microgel flooding technology can reduce significantly the amount of HPAM used in oil field and increase the toleration at the high temperature and salinity. The effects of HPAM structure on the properties of microgel system have been investigated in this paper. The higher the molecular weight of HPAM, the shorter the gelation time and the higher the gel viscosity of microgel system. As the molecular weight of HPAM is increased from 5×106 daltons to 20×106 daltons, the gelation time is reduced from 38 days to 4 days, viscosity of microgel system is increased from 23.7 mPa·s to 168 mPa·s .Reducing the hydrolysis degree of HPAM from 25% to 13%, the gelation time is reduced from 8 days to 4 days, and the viscosity of microgel system is increased from 21.1mPa·s to 52.6 mPa·s . The mechanism of reaction is mainly intermolecular crosslinking reaction between HPAM chains. The reactive group on the HPAM chain is amide group. The more coiling and shrinkage the HPAM chains, the more easily intermolecular crosslinking reaction takes place.
  • The migration ability and rule of microbial in reservoir
    LEI Guanglun; LI Ximing; CHEN Yueming and WANG Weidong
    , 2001, 28(5): 479-0.
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    Microbial can migrate in reservoirs; this is an important reason why it is used to improve oil recovery. This paper firstly introduces the experiment results and the research of mathematical model on this in China. The experiment results show that the microbial has high movement ability in porous media, probably the reason behind is strain can change its shape and have the tendency at the throat, so MEOR can be used in reservoirs with permeability equal or over 0.03 Darcy (30×10-3μm2). Based on the dispersion and absorbsion of bacteria, a new migration mathematical model has been set up. This model can calculate the distribution of microbial concentration in formation. The results of calculation have also shown that during migration this concentration degrease quickly and the effective radius is shot, therefore the bacteria reproduce fast and to inject properly nutrition is necessary in MEOR.
    • 油藏物理
  • Stress sensitivity analysis of Changqing tight clastic reservoir
    SHI Yu-jiang and SUN XiaoPing
    , 2001, 28(5): 482-0.
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    Stress sensitivity of Changqing tight clastic gas reservoir is studied quantitatively by CMS-300, which is a auto core analysis instrument. The results indicate that:(1)The relationship between stress(independent variable,x) and permeability/porosity (dependent variable, y) is extremely accord with exponent function mode, which is y=a/xm and a is highly related to m with different core samples; (2)Commonly,the permeability in formation condition is 5%-80% of that in surface condition,for porosity, the value averagely decreases 0.4%; (3)The stress sensitivity is related to lithological and physical properties; generally, litharenite sandstone is more sensitive than quartzy sandstone, conglomerate than sand and the low permeability than the high permeability.
  • Effect of reservoir stimulation by low frequency pulse wave
    ZHANG Renxiong; XIANG Yang and SONG Jianping
    , 2001, 28(5): 483-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Mechanism of low frequency pulse wave (LFPW) stimulating reservoir includes: forming fissure, removing the damage near the wellbore, enhancing permeability and changing physical and chemical peculiarities of fluid structure. The low frequency pulse equipment, developed by Henan oil field, is very advanced in structure and technology. That for shallow wells is suitable for oil/water wells shallower than 600m. Its main specifications include the highest voltage of 10kV, the highest energy of 220kJ, discharging time of 10-100μs, release frequence of 1-10 times/m and the well center biggest pressure of 2000MPa. The main specifications of low frequency pulse equipment for medium-deep wells include the highest voltage of 3kV, the biggest energy of 5000J, discharging time of 30μs, released frequence of 1-2 tmes/m, the highest temperature of 105℃ and the biggest pressure of 30MPa. The result of applying low frequency pulse wave to about 40 oil/water wells has confirmed that the blockage is eliminated easily and all relevant expenditure is low. The damage is no longer existed. The success ratio of operation is 100%, the effective ratio is above 85%, and the longest effective time is 9 months. During the effective time, output increment of oil wells is more than 40% averagely, and the increased water injected in water wells is also big.
    • 经济评价
  • A study on economic limit production from wells by bailing
    YU Shiquan; WANG Yongzhuo; WANG Jianzhu and LI Xinfeng
    , 2001, 28(5): 486-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Producing oil by bailing is more suitable for new wells with low oil production, sporadically distributed wells and the pumping wells with low productivity and low profit. The scale of producing oil by bailing of the peripheral oil fields in Daqing is gradually expanded. In order to increase the employment percentage of the OOIP in fields with low-permeability and low production, a simple and applicable formula, which is suitable for determining economic limit production from wells by bailing, is derived from profit and loss balance principle, based on oil reservoir engineering theory and the practices from on-the-spot producing oil by bailing. It can be considered as an economic evaluation tool for economically and effectively producing oil by bailing in the peripheral oil fields of Daqing in the coming years.
    • 讨论
  • An approach to the application of petroleum system method.
    SHANG Erjie
    , 2001, 28(5): 487-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    In recent years, some scholars use petroleum system as an oil geological unit of basin, so that they have put forward a suggestion of treating it as a target at some exploration stage. How to use the concept directly relates to the result of its application. Mechanically applying petroleum system would make you being at a loss as to what to do or restricted on continually extending the exploration area in practical exploration. Proceeding from practice, it is appropriate that petroleum system is defined as a comprehensive analysis method. The exploration of a basin is a progress step by step, and the geological knowledge of the basin is corrected and deepened again and again in the progress. In the light of the original meaning, petroleum exploration is not to prove some objective reality but to press on towards the objective facts for the purpose of profits in the course of working. A petroleum system drawn in an area is only a view of some geologists at some exploration stage. Along with the deepening of exploration, the view must be revised continually. From this point, petroleum system is a progress of cognition accompanying petroleum exploration all along. Petroleum system is a comprehensive analysis method of excellent logic. The main peculiarity of it is that it forms a integrated effective analysis procedure by synthesizing various analysis methods. Through comprehensive analysis method, petroleum system links sources with reservoirs (traps) in time and space, conjectures favorable areas and guides exploring activities. Along with the deepening of oil exploration of a basin and the accumulating of data continually,the corresponding relationships between sources and reservoirs(traps)become manifold more and more,and the depictions of petroleum systems become much more clear.
    • 石油地质研究
  • Pool forming characteristics and regularity of the Upper Tertiary reservoirs in Bohai Bay
    XUE Yongan; WANG Yingbin and ZHAO Jianchen
    , 2001, 28(5): 509-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    In recent years, a big breakthrough of oil exploration in the Upper Tertiary was made in Bohai Bay, resulting in the discovered OOIP reaching 109t. The successful and unsuccessful experiences of oil exploration in the Upper Tertiary are analyzed based on the practical data from Qinan terrace zone, Shadongnan structural zone, Shaleitian uplift and the other oil pools in the Upper Tertiary of Bohai Bay. The oil pool forming characteristics and regularity of the two major types of structures are summarized:(1) The trap formation conditions, the density of the secondorder faults and the combination of the strata and the fault of the faulted nose, faulted block and faulted anticline in the Upper Tertiary developed in the sag are the essential elements to oil pool formation. This kind of oil pool is characterized by thin oil layer, lower richness and light oil;(2) Oil and gas enrichment is high in the drape anticlines developed in the uplift. But the distruction of faults, which was active in the late stage, is the essential influencing factor to this oil enrichment. The structures have favorable pathways for oil migration. The oil pools formed here are characterized by thick oil layer, high richness and heavy oil.
  • The major controlling factors and pool-forming pattern of oil and gas reservoirs in Kuqa petroleum system, Tarim basin.
    TIAN Zuoji; ZHANG Guangya; ZOU Huayao; LI Qiming and PI Xuejun
    , 2001, 28(5): 516-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Cenozoic Kuqa foreland basin was developed in the Paleozoic continental margin and Mesozoic intercontinental depression, in which there are some E-W fault belts. The structural styles of the basin are mainly composed of anticlines and fault relative anticlines. The structures formed their rudiment in the end of the Cretaceous period and finalized their shapes in Kuqa-Xiyu stage. There are abundant oil and gas resources in Kuqa petroleum system, in which 8 oil and gas fields have been discovered, such as the huge Kela 2 gas field. The pool-forming mechanism and patterns are various in different tectonic belts of Kuqa petroleum system. So it needs different exploration strategy. It must enhance the exploration in deep structures and give synchronously attention to shallow structures in Kelasu structural belt. The keystone exploration is gas condensate and wet gas in Yinan region, but condensate and oil in Yiqikelike fold belt. In Tabei uplift the condensate-pools should be the main exploration target.
  • The characteristics of Lower Ordovician fissure-vug carbonate oil and gas pools in Tahe oil field, Xinjiang
    ZHANG Ximing
    , 2001, 28(5): 517-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The Ordovician oil-gas pool of Tahe oil field is located in the southwest slope of Akekule salience in Shaya uplift, Tarim basin. It's a super large-scale oil-gas pool with about 2×108t OOIP. Through the progressive exploration and development of more than 2 years since being found in 1997, a production capacity of 200×104t/y has been built up there. The reservoir of the oil-gas pool belongs to superimposed-reconstructed fissure-vug type of paleo-weathering crust carbonate rocks. It can be divided into weathering-sedimentary hypergene, vadose zone plus undercurrent and undercurrent karst belts etc, in vertical. The above three superimposed and reconstructed karst belts are formed by basement rocks, which have undergone many times of uplifting by tectonic movement and karst transformation. In vertical orientation, it has many stages of karst (hypergene, vadose and undercurrent) superimposed on the different locations of the plane, and has formed very complicated, superimposed and reconstructed fissure-vug types of reservoir with obviously changeable reservoir performance in vertical. On the plane, reservoir beds are spread by layer 250m below the top of weathering crust with strong heterogeneity. The storage space of the reservoir is dominated by fissure and vug, and controlled by ancient structure, ancient karst land features and water system growth etc. The fissure and vug growth of the reservoir varies obviously and can be formed into many reservoir combination types. The basement rocks are mudstone, and matrix limestone with no porosity and permeability. Controlled by reservoir, the hydrocarbon zone is also distributed by layer. The types of oil-gas pool include paleo-weathering crust fissure-vug type of stratified condensate gas reservoir, paleo-weathering crust fissure-vug type of stratified　oil reservoir with stratified condensate gas cap, paleo-weathering crust fissure-vug type of black oil pool with low saturability. Most single well has high output after being acid fractured. The oil-gas pool has normal temperature and pressure system, and possesses many stages of petroleum formation. The oil-gas pool is driven mainly by elastic drive and dissolved gas drive and it has no unified bottom water.
  • A gas source study for Kuqa depression of Tarim basin
    LI Jian; XIE Zengye; LI Zhisheng; LUO Xia; HU Guoyi and GONG Se
    , 2001, 28(5): 528-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    KaLa 2, Tuziluoke, Dabei 1 and Dina 2 gas fields were discovered in recent years in Kuqa Foreland basin. In addition, gas pools such as Yinan 2 and Yishen were also discovered over there. Discovery of these gas fields brings forth wide foreground of natural gas exploration in this area and provide a solid resources foundation for the strategy of transporting western gas to east. Kuqa depression develops two kinds of source rock, i.e. lacustrine shale as well as coal bearing shale and coal. In order to clarify the natural gas discovered originated from coal bearing source rock or lacustrine shale, new gas source correlation techniques, such as light hydrocarbon monomer carbon isotopes of benzene, toluene, xylene, methylcyclohexane, are applied and combined with geology condition for the formation of natural gas in this article to carry out gas-source tracing and correlation. Through correlating, it is concluded that natural gas in main gas pools of Kuqa depression belong to coal-formed gas, natural gas in E, K pay zone of the middle and west of Kelasu structural belt is high-post mature coal-formed gas; gas in Jurassic pay zone of the east of Yiqikeli structural belt is mature-high mature coal-formed gas, natural gas in the pay zone of Jidike Formation is high-post mature coal-formed gas; natural gas in the Upper Tertiary-Quaternary of Dawanqi oil field belongs to mature-high mature coal-formed gas; and the natural gas of the main gas pools in Kuqa depression mainly originated from Jurassic-Triassic coal-bearing source rocks.
    • 综合勘探开发技术
  • Dynamic numerical modeling of petroleum system (Ⅱ) — A case study on the Manjar petroleum system, Tarim basin
    ZHANG Qingchun; SHI Guangren; MI Shiyun; GUO Qiulin; YANG Qiulin and WANG Xiaohong
    , 2001, 28(5): 529-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The Manjar petroleum system, which is located in the central part of the Tarim basin and with Cambrian-Ordovician as its main source rock formation, is a Lower Paleozoic cratonic petroleum system. On the basis of the previous achievements of the “Ninth Five-Year Plan”, the software DYMAPS (Dynamic Modeling Analysis of Petroleum System) is used to carry out the modeling analysis for the Manjar petroleum system. The research results indicate that, the Lower Paleozoic source formations have two hydrocarbon generation and expulsion peaks, the end of late Ordovician and the end of Tertiary, representing the two critical moments of the petroleum system. Of all the hydrocarbons yielded up to the present, Cambrian source rock′s 89% of oil and 44% of gas and Lower Ordovician source rock′s 79.6% of oil and 26.3% of gas were generated at the first moment. The second critical moment is mainly the second gas generation peak, with a given amount of oil generated. Nowadays, at the western slope and the northern and southern uplifts the Lower Paleozoic source formations are still in the active oil generation threshold (Ro <1.3%). By means of the pseudo-3D and two-phase hydrocarbon migration and accumulation model, oil and gas accumulation amounts of the main reservoir formations (∈, O1, O2-3, C and T) of the petroleum system are simulated. Play numerical modeling result shows that there exist 9 most favorable plays and 10 favorable plays in the petroleum system.
  • Well logging interpretation for water flooded zone
    GAO Yinjun; LI Caixiong; WANG Daxing; MENG Wenjian; WEI Yumei; CHEN Jun and SUN Dehai
    , 2001, 28(5): 552-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    It's very important to improve the accuracy of the well log interpretation of the water flooded zone for the high-water-cut oil field in the east of China. So a set of fast and intuitionsitic techniques has been set up to interpret the water flooded zone qualitatively and quantitatively, which includes normalizing the log data to relative log parameter value; measuring the flooding degree according to the transformation rule of the resistivity curve and SP curve; identifing the water flooded zone by using the fuzzy and integrative estimating methods and fractal dimension estimating methods. Based on the establishment of the relationship plate among production test data, mercury intrusion data and the log relative value and taking the regional experience into account, the quantitative interpretation model and standard of water flooded zone are set up with parabola match methods. The water flooded zone are evaluated comprehensively by using the result of correlation of oil layers and analysis among neighbor wells. The application in 16 wells of Zao 1281 fault block in Dagang oil field confirms that the coincidence rate of the water flooded zone interpretation reaches 86.3%.
    • 油田开发与油藏工程
  • Analysis of effects of permeability on gas well productivity equation and open flow capacity.
    HE Zixin and HAO Yuhong
    , 2001, 28(5): 553-0.
    Abstract ( ) Knowledge map Save
    Based on the derivation of the coefficient expression of the binomial equation of gas well productivity, the authors believe that during gas well productivity testing, permeability and influenced radius have effects on only the coefficient A in the productivity equation, regardless of the coefficient B, after the well bore accumulation effect disappeared. That is, the open flow capacity derived from the productivity equation varies upon only the coefficient A. Taking analysis of results of modified isochronal testing (not reaching the pseudo-steady state) of Well Shaan-61 of Changqing gas field as an example, effects of permeability and influenced radius on gas well productivity equation and open flow capacity are studied in this paper. Conclusions are as follows: (1)For the reservoirs whose permeability becomes obviously better from well bore to the periphery, the permeability and influenced radius affect less on the coefficient A. As long as the pressure performance is basically stable, a reliable stable productivity equation and open flow capacity are obtained; (2)For the reservoirs whose permeability becomes worse from well bore to the periphery, permeability influences obviously the coefficient A. During the gas well test for productivity, strive to make the pressure performance approach or reach the pseudo-steady state, otherwise it could make bigger errors and (3)For the homogeneous gas reservoirs, the coefficient A varies with only the influenced radius. Striving to make the testing procedure of gas well test for productivity reach fully steady state is necessary.
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