, Volume 29 Issue 1
    

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    北京石油学会青年科技论坛论文专
  • Hydrocarbon occurrences and exploration suggestionsin the foreland basins of central western China
    ZHANG Guangya and XUE Liangqing
    , 2002, 29(1): 163-0.
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    The foreland basins in NW China have multi-cycle composite features: (1)the Mesozoic (including the late period of late Paleozoic in local areas) sediments of the foreland basins are main bodies of basin fillings, which are completely composed of nonmarine sequences; (2)the sedimentary sequences underlying the Mesozoic foreland basins lack passive-continental-margin sediments of typical foreland basins and mainly consist of the late Paleozoic or even earlier folded “basement” or foreland basins; (3)the Mesozoic foreland basins are generally overlain by the Cenozoic rejuvenated foreland basins. The Triassic and Jurassic source rocks (including the Carboniferous-Permian source rocks in some regions) are major source rocks in the foreland basins of central western China, whose formations are controlled by depressions or faulted sags developed in the early stage of the foreland basins and warm-humid climate. These source rocks have big thickness, high organic richness, and predominant typeⅢ kerogen. Hydrocarbon-generating peak appeared late and oil/gas pools formed late as well, which were controlled by the stacked Neogene sediments deposited in rejuvenated foreland basins. Natural gas accumulation is dominated in the region of the thick sediments of the stacked rejuvenated foreland basins because buried depth is very deep and hydrocarbon generation is at the high-matured to over-matured stage, while oil accumulation is dominated in the region of the thin, stacked sediments. Hydrocarbon occurrences are obviously controlled by basin architecture of foreland basins. There are different play types within different structural units. The thrust belt: the formation of oil and gas pools is related to thrust faulting, and hydrocarbon migration is vertically dominated, showing the feature of short distance close to source rocks. The foreland slope belt: the formation of oil and gas pools is of stratigraphic-facies pool type and fault-block pool type, displaying features of long distances and lateral directions of hydrocarbon migration. Richness of hydrocarbon accumulation in northwestern Chinese foreland basins is controlled by basin prototype development, stacking and reformation. The early formed, long evolutionary history, continuous developed or stacked foreland basins have good hydrocarbon potential, while relict foreland basins have poor hydrocarbon potential. On the basis of analyzing hydrocarbon geological conditions of foreland basins and their folded-thrust belts, further exploration fields are proposed. These favorable fields contain the Kuqa depression of the Tarim basin, the southern margin of the Jiuquan basin, the southwestern margin of the Tarim basin, the nouthern margin of the Jiuquan basin, the southwestern margin of the Qaidam basin, the western Sichuan depression and the northern margin of the Qaidam basin.
  • Thermal evaluation and hydrocarbon generation history of the sedimentary basins in western China
    QIU Nansheng
    , 2002, 29(1): 164-0.
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    Thermal regime is of significant important to reveal the geodynamic processes of continental lithosphere and the generation of hydrocarbon from source rocks in sedimentary basins. There have some lower thermal background in the area of western China. However, the thermal history, modeled from apatite fission track and vitrinite reflectance data, evolved differently because of the different tectonic history in the Tarim basin, Junggar basin and Qaidam basin. The thermal gradient in the Qaidam basin decreased since the Tertiary time, but changed only a little during the Quaternary. The Tarim basin underwent a relative complicated thermal history. The thermal gradient at Permian had a relative high value because of the volcanic activity. It decreased rapidly at the Neocene to Quaternary. The present-day's thermal gradient is only 20℃/km. The thermal gradient in the Junggar basin decreased with the geological evolution. The above differential thermal histories resulted in the different hydrocarbon generation in the three basins.
  • The relationship between overpressure and reservoir forming mechanism
    ZHA Ming; QU Jiangxiu and ZHANG Weihai
    , 2002, 29(1): 165-0.
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    Compared with the normal pressure system, under the same condition, the maturation and gas production rate of organic matter in overpressure system are obviously lower， whereas the oil production rate is relatively higher. It can be argued that the microfractures resulting from overpressurenot only act the vertical pathway for hydrocarbon migration but also prominently improve the porosity and permeability of the reservoir. One of the key factors that determine the accumulation and pooling of natural gas is the sealing for the fault and hydrocarbon in various forms by the high-pressured mudstone. the authors of this paper analyzed the relation between the temperature and pressure in overpressure system, illustrated the role of overpressure in the formation, migration, accumulation, sealing, pooling and distribution of the hydrocarbon with case study and discussed the controlling mechanisms of overpressure on the reser voir forming.
  • A method for calculating the quantity of hydrocarbon generation and expulsion
    ZHOU Jie and PANG Xiong-qi
    , 2002, 29(1): 166-0.
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    Hydrocarbon generating quantity of source rock is the sum of hydrocarbon remaining quantity in the source rock and hydrocarbon expelling quantity from the source rock. Hydrocarbon retention rate in the source rock can be obtained by analyzing the ratio of the extracts “A” over TOC. The decrease of (S1+S2)/TOC, which is the hydrocarbon generation potentials, during the evolution of source rock indicates that parts of the hydrocarbons generated by the source rock have been expelled from the source rock. No matter what the hydrocarbon generation mechanism of the source rock is, the difference between the current hydrocarbon generation potential index of source rock and the original hydrocarbon generation potential index before the hydrocarbon expelling from source rock always stands for current hydrocarbon expelling quantity of a unit weight of organic carbon (i.e. hydrocarbon expelling rate), based on this, it is able to calculate the hydrocarbon expelling quantity from source rocks in which unmatured-low matured oil were generated. The hydrocarbon generation quantity of the source rock can be calculated through extracting hydrocarbon-generating rate of source rocks and combining with the data about the source rock, such as thickness, area, TOC, vitrinite reflectance, kerogen type and density obtained. Application results of the method in Bamianhe oil field in Dongying depression indicate that the hydrocarbon generation and expulsion evolutionary patterns of mudstones and shales of Members S3 and S4 in Lower Tertiary of this area are different, the hydrocarbon generating quantity of mudstones is much larger, but its hydrocarbon expulsion efficiency is lower than that of shale.
  • Characteristics and evolution of composite petroleum systems and the exploration strategy in Junggar basin, northwest China
    ZHANG Yijie and LIU Guangdi
    , 2002, 29(1): 167-0.
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    he composite petroleum system is the aggregate of several petroleum systems in a certain area. In a composite petroleum system, the petroleum systems share the same reservoirs and caprocks and the petroleum accumulations are usually multi-sourced. There are 4 composite petroleum systems in Junggar basin including 16 petroleum systems, in which Muhu-West well Pen 1, Changji and Dongdaohaizi-Dajing composite petroleum systems have the most importance in the basin. The active source rocks in Muhu-West well Pen 1 composite petroleum system are Jiamuhe Formation and Fengcheng of Lower Permian and Xiawuerhe Formation of Middle Permian, they formed three petroleum systems. The active source rocks in Changji composite petroleum system are mainly Middle Permian and Lower Jurassic. The active source rocks in Dongdaohaizi-Dajing composite petroleum system are Carboniferous and Middle Permian. The multi-sourced and multi-phase hydrocarbon accumulation makes the most important characteristics of composite petroleum system in Junggar basin. The continuous and successive development of several petroleum systems is the main factor controlling the richness of hydrocarbon in a composite petroleum system. The emphasis of hydrocarbon exploration in Junggar basin should be focused on the uplifts and the related slopes in the three rich composite petroleum systems.
  • Fault characteristic analysis for the hinterland of Junggar basin
    LI Zhenhong; TANG Liangjie; DING Wenlong; YAO Suping; WANG Yingmin; LIU Hao and WANG Yuan
    , 2002, 29(1): 168-0.
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    Faults in the hinterland of Junggar basin may be divided into deep-fault system and shallow-fault system. Deep-fault system deve-loped mainly from late Hercynian movement, incising Triassic system and below strata, formed the reversed fault and thrust structure; Shallow-fault system developed mainly from early Yanshan movement, forming normal fault and graben and horst. On the planes faults have all kinds of style, N-E and N-W faults controlled main structural framework. On the cross section faults formed the overlaid composite structures which are dominated by the positive inverted structure. Faults in the hinterland are well campatable with the migration and accumulation of oil and gas. The pre-exited deep-faults link to act as the oil source faults, and the regional unconformity of Triassic system, acting as transition, connected the deep-faults with the shallow faults, making the deep faults， and unconformity as the pathways through which oil and gas migrated to and accumulated in the structural traps controlled by the shallow fault system.
  • Quaternary sequence stratigraphy and hydrocarbon evaluation in Qaidam basin
    ZHU Xiaomin; KANG An; HU Zongquan and XU Ziyuan
    , 2002, 29(1): 169-0.
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    Qaidam basin; Quaternary; sequence stratigraphic character; source rock-reservoir-cap combination; oil and gas evaluation
  • Petroleum geology conditions and exploration perspective in central south Qaidam basin
    MEN Xiangyong; WANG Zhiyi; WU Fengcheng and PENG Hongyu
    , 2002, 29(1): 170-0.
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    The central south Qaidam basin lies between the western Tertiary petroleum systerm and the eastern Quaternary petroleum system, and accepted very thick lake facies deposits in the Tertiary. There are good structural trap condition and mudstone cap condition. And the E23—N1 formations are the main source rocks with an accumulated thickness more than 2000m, so there have good resources potential. Contrast with western oil field area, there have some changes that the source rock thickness becomes thin, the organic matter abundance reduces, the buried depth is deeper and the heat evolution of the organic matter arrives high maturity stage. The unfavourable conditions for oil and gas pooling are the undeveloped sandstone reservoirs, and their poor petrophysical properties. Based on the above analysis, the authors think that the exploration should try to find gas reservoir firstly, and then oil reservoir, and to find reservoirs with structural fractures is the key step. Tugeda structure which lies the margin of Gansenhu sag is the object which needs serious evaluation.
  • Fluid geochemistry, dynamics and hydrocarbon migration and accumulation in Lukeqin structure, Turpan-Hami basin
    ZENG Jianhui and ZUO Sheng-jie
    , 2002, 29(1): 171-0.
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    The geochemical analysis of underground water and fluid inclusion and the research on conditions for hydrocarbon migration and accumulation in Lukeqin structure, Turpan-Hami basin have shown that: (1)the plaeo-fluid in Tuyuke experienced stronger evaporation and rock-fluid interaction while the plaeo-fluid in Yudong and Lukeqin mostly experienced rain precipitation. Nowadays fluid has better conditions of occlude and experienced much stronger rock-fluid interaction. The geochemical evolvement of fluid in Lukeqin structure shows that occlusion condition became better, rock-fluid interaction became stronger, the content of geochemical component and the total dissolved solution increased. (2)The underground water dynamical evolvement in Lukeqin structure could be divided into two phases: The first phase is late Indosinian epoch to middle Yanshan epoch. During this period there existed two types of underground water, one was the sedimentary water from northwest to southeast, the other was atmosphere water from southeast to northwest with stronger hydraulic power. The second phase is from late Yanshan epoch to now, during this period the main movement is sedimentary water migration from deep to upper formation laterally and vertically with smaller hydraulic power. (3)The research on geochemistry and hydraulics of geofluid verify that the hydrocarbon migrated from northwest to southeast in Lukeqin structure. During late Triassic to middle Jurassic, hydrocarbon had been degraded along with migration. During middle Jurassic to now, the degradation became weak, the reservoirs formed previously were only modulated.
  • A numerical simulation on amount of remained gas in Jurassic coal-measure strata in Taibei sag
    ZUO Shengjie
    , 2002, 29(1): 172-0.
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    On the basis of studying the influence factors on amount of remained gas in all phases and establishing the corresponding quantitative relations respectively, a numerical simulation on amount of remained gas in Jurassic coal-measures strata in Taibei sag, Turpan-Hami basin was carried out by using the theory of hydrocarbon expulsion threshold and the material balance method. The results show that main mechanisms of gas retained in coal-measure strata include dissolution in formation water, free phase, dissolution in oil and diffusion, with the last two being the most important. Comparing Carbonaceous shale with mudstone, the amount of remained gas in coal is the largest. In the studied region, the amount of methane and heavier hydrocarbon gases remained in 1m3 coal source rocks is 10.64m3 and 2.384m3, respectively. With the burial depth increasing,remained gas in coal measure strata increases firstly, but decreases later. The total amount of remained gas in the middle and the lower Jurassic coal-measure strata is 5.63×1012m3 and 13.12×1012m3, respectively. It is suitable to explore coal-bed gas in Taibei sag.
  • Evaluating low-permeability reservoirs of Hongliuquan lithological trap
    DOU Qifeng; HUANG Shuwang and WANG Shaohua
    , 2002, 29(1): 173-0.
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    In order to evaluate the E13 ultra-low-permeability lithologic reservoir in Hongliuquan oil field, Qaidam basin, a research on reservoir distribution is carried out with the method of grey cluster analysis on the basis of investigating microfacies and reservoir parameters quantitatively. The influence factors of each type of reservoir and their control effects on oil-gas distribution are analyzed. The results show that the distribution of the sedimentary facies controls the overall tendency of the distribution of various kinds of reservoirs, namely, the favorable sedimentary facies belts may develop high-quality reservoir. However, the post-sedimentary diagenesis has stronger influence on the development of the reservoir quality. The favorable reservoir facies belts are generally in the areas where is low carbonate-content and weak cementation, and vice versa. Moreover, the heterogeneity characteristics of post-sedimentary diagenesis caused the isolated and discontinuous planar distribution of all types of reservoir. So, the grey cluster analysis method is worth spreading for reservoir comprehensive evaluation.
  • A new integrated pore pressure evaluation method for shale-sand formations
    FAN Honghai
    , 2002, 29(1): 174-0.
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    The traditional pore pressure estimation methods based on sonic logs use a shale disequilibrium compaction model and a normal compaction trend for their calculations. In this paper, a new method called Integrated Evaluation Model is proposed, which uses sonic and other related well log data to evaluate pore pressure, that is, with giving consideration to the effect of clay content, porosity, vertical effective stress of shale-sand formation on sonic velocity. Firstly the clay content and porosity are calculated from related well logging data; then vertical effective stress is calculated from sonic velocity and finally the pore pressure is calculated from obtained effective stress. Practical application shows that excellent results can be obtained with this model for the shale-sand formation.
  • Analyzing near-surface problem in Eboliang mountainous region with mathematical and physical models
    WANG Shangxu; DI Bangrang and WEI Jianxin
    , 2002, 29(1): 175-0.
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    Mountains in Eboliang region of Qaidam basin are characterized by monoclines of high-velocity, which are coexisted with the Quaternary loosen deposits and by near-surface velocity varying violently in cross. In order to study the seismic prospecting problems of this mountainous region, the traveling laws of seismic wave in complicated condition and the influence of the complicated near-surface geological structure must be studied and analyzed. Either in mathematical modeling or physical modeling, it is necessary to simplify the realistic problem and to highlight principal contradiction. The purpose of this thesis is to study the influences of the complicated near-surface, monoclinic, high, precipitous zone to seismic wave traveling and imaging, therefore the undulate of the mountainous region and the complicated geological structure of the middle and deep layers were simplified in mathematical and physical models. Same model parameters are used both in mathematical modeling and in physical modeling, in order to compare and analyze the results. In this experiment, multifold coverage geometry is adapted. The results of the modeling implies as follows:(1)The near-surface structure of mountainous regions can violently reform the reflecting of the deep and middle layers, and influence the imaging of these layers. It is important for us to realize the influence and to improve the gathering mothod of mountainous seismic data, processing sequences and the modeling interpretation; (2)The near-surface high and precipitous structure can produce noise similar to refracting wave; it is easy to take the noise as valid wave in singular shot record or stacked profile; and (3)When near-surface geological structure is high and precipitous, and there is no shallower refracting surface (it is often in mountainous region). The first arrival is not refracted wave. Then it is suggested that the refracting static method should be applied carefully when processing seismic data from mountainous region.
  • A study on the restoration of the original fracture information
    CAO Siyuan; LIU Hongwei and SA Liming
    , 2002, 29(1): 176-0.
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    This paper discusses the phenomenon of fault with integrated elastic wave field, which is usually appeared in seismic sections, was discussed in this paper. In-depth research has been conducted with the application of multi-scale analysis developed from wavelet theory. As a result, we can restore original fracture information and expand the application of seismic data. The method of distinguishing fracture from above mentioned fault has been created by exploration practice in MB area,which includes: (1)Checking lateral energy change of seismic wave around target stratum,which will indicate that the fracture will be most likely exist where the energy change is detected,and then inspecting continuity of this phenomenon on the adiacent seismic sections. (2)In the case that spacial continuity can be proved, but not clearly enough to provide fracture information, post-stack processing based on the wavelet theory will be necessary. It is suggested that the modules to improve S/N ratio based on statistic principle of signal should be used as less as possible. In case of applying those modules, fewest seismic traces should be used to prevent obviously damage to diffracted wave and other useful information.
  • The study and practice of technology for maintaining production during
    XU Anna; JIANG Tongwen; WU Yiming and GAN Gongzhou
    , 2002, 29(1): 177-0.
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    On the basis of categorying the distribution pattern of oil production potential at Lunnan field, the development strategy has been established by the way of reservoir characterization and horizontal well technology. Through studying and practicing, it is concluded that horizontal well technology, progressive exploration and development, comprehensive adjustment of injection and production system, optimization of well pattern are the key technologies to maintain oil production currently. These technologies have been applied to production practice and the encouraging result has been achieved. Over the last three years, the increase of proven reserve has reached 125×104t and the production capacity of about 90×104t has been achieved.
  • Experimental study on water/oil displacement mechanisms in fractured reservoir by real sandstone micro-models
    ZHAO Yang; QU Zhihao and LIU Zhen
    , 2002, 29(1): 178-0.
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    The structural fractures in fractured low-permeability sandstone reservoirs have great effect on displacement efficiency. An ideal tool to study micro water displacing oil mechanisms is the micro-model of water/oil displacement experiment for real sandstones. Water displacing oil experiments (including single model and combined model experiments) were done to study fractured low-permeability sandstone reservoirs by this technique. Experiments show the different kinds of fracture to have different percolation phenomenon and have different effect on displacement efficiency. In the course of the water displacing oil, the injected water was moved evenly along many pathways to outlet in the model with no fractures; the water and oil were moved quickly in the model with fractures (30μm wide and long extended); wide but short extended fractures do not play any special role in the water displaying oil; pore-sized fractures (whether short or long) do have no unfavourable effect on water displacing oil, on the contrary, they make the permeability improved; fully filled fractures will block percolating oil and water; the fractures whose directions are perpendicular to the streamlines have some effect on percolation. When using commingled injection or production method, the better a layer's permeable property is, the higher the layer's water-oil displacement efficiency is; conversely, the poorer a layer's permeable property is, the lower the layer's water-oil displacement efficiency is.
  • The S-N tectonic system in the west of Qaidam basin and its control on petroleum
    LI Yuxi; PANG Xiongqi; TANG Liangjie; JIANG Zhenxue; ZHOU Ruinian and JIANG Wuming
    , 2002, 29(1): 442-0.
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    The changing regulation of the residual thickness of Mesozoic strata and distribution pattern of sedimentary facies of Cenozoic strata shows that the S-N tectonic system formed before Cenozoic. When the Cenozoic tectonic system forming, the S-N tectonic system joined in it, and the S-N faults were re-activated by forming S-N dextral convergent strike-slip faults zones and transformation zones. The S-N tectonic system also controlled the deformation of Tertiary strata as deep boundary constraints. The S-N tectonic system has a critical influence on reservoir forming. The oil and gas fields discovered in the west of Qaidam basin have a close relation to it. And the S-N dextral convergent strikeslip fault zones and the transform zones are also the main target area for exploring good Tertiary fractured oil and gas reservoirs.
  • Study on the period and time of oil and gas accumulation in Yanqi basin, Northwest China
    LIU Guangdi; ZHANG Zhongpei; CHEN Wenxue; CHEN Wenli and LIN Sheqing
    , 2002, 29(1): 443-0.
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    The time of petroleum accumulation in Yanqi basin, Northwest China is determined according to the studies of hydrocarbon generation history of source rock, oil and gas maturity, homogenization temperature of fluid inclusion and K/Ar dating of illite in reservoir. The source rock of Badaowan Formation of Lower Jurassic has two main generation periods in geologic time, with one in the late Jurassic and the other in late Tertiary. The fluid inclusions mainly occurred in the dissolution or pressure solution pores of sandstone reservoir, the homogenization temperature of which is 101-130℃, suggesting that the fluid inclusions were mostly formed in late diagenesis stage in late Jurassic. K/Ar dating shows that the ages of the very fine-grained illite fall in two time intervals, 170-140Ma and 120-100Ma, indicating the time of petroleum entrapment in late Jurassic and the time of destruction of petroleum accumulation in the tectonic event in Cretaceous respectively. The maturity indices of biomakers from oil also show that the maturity of source rock when the oil was generated is equivalent to the vitrinite reflectance value of 0.70%-1.0%, the maturity of Badaowan source rock in the end of Jurrassic. In summury, there are two peroids of oil and gas entrapment in Yanqi basin, with the main peroid in late Jurassic and the other in late Tertiary.
  • The fissure type and characteristics of Liugouzhuang-Kulongshan reservoir in Qingxi depression
    PANG Xiongqi; YAN Weipeng; ZHU Xiaomin; ZHANG Qin; GU Li; ZHANG Qunwei; ZHANG Zhensheng and WANG Xiaoshan
    , 2002, 29(1): 446-0.
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    According to the data of core description, thin-section observation, X-CT scanning and analysis of drilling and logging data, the authors of this article studied the fissure type and character of Liugouzhuang-Kulongshan reservoir, and analyzed the geological factors controlling the development of fissures and the controlling effect of fissures on gas and oil. The authors hold that the fissures are divided into three basic types—structural fissure, structural-solution fissure and pie-shaped fissure. They are mainly controlled by factors such as tectonic stress field and tectonic position. According to the shape and filling character of fissures and the relationship of the two factors, the formation of fissures can be divided into three stages. The fissures formed in the third stage during the late Himalayan movement are the most effective fissure for petroleum migration and accumulation. It is concluded that fissure is the main controlling factor of reservoir space and petroleum accumulation of Liugouzhuang-Kulongshan reservoir.
  • Reservoir space feature and evolution of the volcanic rocks in the Santanghu basin
    XIE Qingbin; HAN Dexin; ZHU Xiaomin and ZHU Yixiu
    , 2002, 29(1): 447-0.
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    Three typical igneous rock series are located in Upper and Lower Permian as well as Carboniferous in Santanghu basin. The main kinds of the rock are basalt, andesite and diabase etc. Reservoir space consists of primary space (involving fracture) and secondary space (involving dissolved pore and fracture). They are subdivided into primary gas bubbles, residual gas bubbles, primary interparticle pore, cooling crack, shrinkage joint, grain explosion crack, phenocryst solution pore, moldic pore, interparticle solution pore, groundmass solution pore, alteration mineral solution pore, filling material solution pore, amygdaloid solution, structural fracture, weathering fracture and solution fissure. Diagenetic events have happened which included replacement, alteration, filling and dissolution. Primary space shows present features after it passes through a complex process of filling and solution. Igneous rock lithofacies, diagenesis and regional tectonic movement mainly control reservoir features.
  • The application of spectral analysis of logs in depositional cycle studies
    WANG Guiwen; DENG Qingping and TANG Weiqing
    , 2002, 29(1): 450-0.
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    The characters of strata are shown continually and sensitively by well logs, which include a great amount of geological information. The purpose of well log interpretation is using various tools and technologies comprehensively to tap the strata information which is involved in logging data, to set up the relations between logging data and geological objective and to describe the geological characters of the targets. The subject of studing sedimentary cycles of the reservoir is small-scale cycles of strata. Well logging data became the main sources of small-scale cycle study duo to their many good characters such as good continuity and large quantity. The periodic occurrence of any sedimentary event may be expressed by the frequency in the time series. During the course of deposition, the periodicity of sedimentary cycle may be embodied in the logging data. Some data processing systems can be designed for extracting the information from the logging data and the deposition characters can be analyzed, described and identified with the information extracted from the logging data. The authors of this paper put forward a method called the maximum entropy spectra analysis, which can extract the major composition from logging data, do the the maximum entropy spectra analysis and spectra character analysis, and then identify and study sedimentary cycles according to the width of spectra and its rhythm. Compared with other spectra analysis, such as Fourier entropy and periodic picture, this method has many advantages such as no limit to sampling length and higher resolution to the spectra. The results of processing actual data from the Tarim basin show the feasibility and validity of this method.
  • A study on the multi-well interpretation of production well logging data
    ZHAO Liang; WU Xiling and WANG Zhonghao
    , 2002, 29(1): 451-0.
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    A multi-well interpretation method for production well logging data is presented. With this method, the production logging data acquired from different wells in different time can be analyzed and the regularity of the performance change in the reservoir exploitation can be studied comprehensively. The interpretation method consists of three processing parts: (1)Multi-well data standardization—Standardizing the production logging data acquired under different condition and in different time to make multi-well production logging data analogical; (2)Correlation of multi-well production logging data-Based on the similarity and correlativity of reservoir physical properties, the factor composition can be picked up and the factor order can be correlated, and lateral reservoir continuity can be defined with connection analysis; and (3)The evaluation of oil layers' performance-Firstly, based on the law of fluid percolation, single-well remaining oil saturation and productivity can be predicted, then the evaluation to reservoir performance can be done with multi-well data and areal prediction and finally, multi-well data from a certain block in a certain field can be processed and interpreted. The comparesion between the calculation results of single-well remaining oil saturation and core test results show good predicted results, which indicate that the prediction results of main action factor analysis are more reasonable than that of trend surface analysis and that of fractal Kriging technique.
  • The disturbing wave analyses and seismic data processing for mountain topography in Yingxiongling area, Qaidam basin
    SHAO Wenbin; CHEN Xiaohong; LIU Yang and WANG Shoudong
    , 2002, 29(1): 454-0.
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    The topography of seismic prospecting area in Yingxiongling Mountain of Qaidam basin is very complicated. In the mountain area, hard strata outcropped and the dip angle of formation is large. There are many channels in this area, which formed special surface geological condition. Based on mountain surface geological condition, the analysis model for dip formation and gully was studied with forward modeling. The analysis of disturbing wave for this special case was done. These show that the main reason of bad processing profiles of seismic data is related with complicated earth's surface, especially in area of gully. The strata reflection and offside reflection cross in the profile, which may result in false appearance. Thus the seismic data processing should be done under constrains of surface geological model to analyze seismic wave propagation and disturbing wave. The real seismic data processing shows no difference with the theoretical analyses. There is a very strong crossing evens, which are from mountain surface, in seismic profile. The conventional seismic data processing is difficult to identify correct evens from strata. While the better and reasonable profile can be obtained by using constrains of surface geological model. The final profile reflects the underground geological structure.
  • Geological model of carbonate reservoirs in Tahe oil field
    WANG Genjiu; WANG Guihong; YU Guoyi; YANG Rongjing and SUN Ai
    , 2002, 29(1): 455-0.
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    Tahe oil field is a fracture and cave-dominated carbonate reservoir. The difficult problem in describing the fractured and caved zones, especially the calculation of hydrocarbon in place, has not been solved so far. The main objective of this study is to attempt to solve this problem. From the results of the study, it is concluded that density log may be used to model fractured and caved zones as well as poro-sity. Lateral extent of each zone appears to be near horizontal. Lateral continuity appears to be low, especially in northwest-southeast direction. Seismic inversion is based on horizontal of fractured and caved zones. Net thickness of the fractured and caved zones is estimated roughly 5% of the gross thickness.
  • A study on the method for measuring and analyzing the fluid entry profile of pumping wells
    WU Xiling; XIONG Junjun; WANG Jieyi and TAN Zhiwu
    , 2002, 29(1): 460-0.
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    At present, many oil fields in China have come into the middle or late period of exploitation, and over 80% of oil wells are producing on artificial lift. Once producing by socker rod pump, the velocity and pressure of liquid are changing with the time in unsteady flow. But for a long time at home and abroad, the analysis of production log is used with steady model, and this may lead to wrong results. Considering this problem, the authors of this paper make an analysis of the mechanics of the unsteady flow, and found the following characters: on the upper stroke of piston, the flow rate increases with time, the trend is close to the π/2 period of the sinusoid; on the down stroke of the piston, the flow rate decreases with time, the trend is close to the exponent decline curve. Considering the wavelength of the fluid flowing is larger than the diameter of the fluid path, the authors of this paper cites and put forward the one-dimensional sequential wave equation which can be used as the model of analysis and measurement. The key of this analysis lies in the calculation of the velocity of disturb, the related parameters can be determined according to the condition of practice production and the response of logging, then correctly calculate the total even velocity and volume flow of liquid.
  • Evaluation of hydrocarbon resources of superimposed basinand its significance
    PANG Xiongqi; JIN Zhijun; JIANG Zhenxie and ZUO Shengjie
    , 2002, 29(1): 484-0.
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    Superimposed basin is characterized by multi-sets of source rock, multi-types of reservoir-seal assemblage, multi-times of hydrocarbon generation and expulsion, multi-stages of accumulation. Target bed, usually deeply buried, has long evolutionary history, and complex hydrocarbon accumulation history whose distribution pattern is controlled by multiple factors. Concerning resource evaluation of superimposed basin, there are four aspects of matters must be paid attention to: The first is evaluation of source rock quality can't reply on “A” and C%, because those source rocks of high “A” and C% value have not always large amount of hydrocarbon generation and expulsion. The second, the evaluation of prospect of explorative area should not count completely on hydrocarbon generation and expulsion quantity, because intensive tectonic movements can destroy the hydrocarbon expulsed from source rock entirely. The third, the method of migration-accumulation index is not suitable for superimposed basin because its hydrocarbon accumulative efficiency is far smaller than that in simple basin. The forth is explorative prospect of an area should not be denied based only on the failure of some wildcat wells, because complex basin has complicated and particular hydrocarbon accumulation mechanism and distribution pattern. The research about the above four problems is important for correctly evaluating and predicting hydrocarbon resource of superimposed basin.
  • Key factors controlling migration and accumulation efficiency of oil and gas and their quantitative evaluation
    ZHOU Haiyan; PANG Xiongqi; JIANG Zhenxie and ZHOU Jie
    , 2002, 29(1): 485-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Since a large amount of oil and natural gas would be lost during the progress of migration and accumulation, the migration and accumulation efficiency of oil and natural gas are determined by the hydrocarbon quantity wasted during migration and accumulation, which includes four parts, i.e., hydrocarbon retention quantity in source rock, hydrocarbon retention quantity in reservoir, hydrocarbon dissipation quantity during migration and hydrocarbon quantity destroyed by tectonic movements. That the migration and accumulation efficiency of natural gas is far less than that of oil results from their differences in physical properties such as solubility, diffusion and absorptivity. It is shown by simulation results of source rocks of Cambrian-Lower Ordovician and Middle-Upper Ordovician in Tarim basin that the key factors determining the migration and accumulation efficiency of oil are tectonic movements and retention in reservoir and those of natural gas are dissipation during migration and tectonic movements. Tectonic movements is most important for proper evaluation of oil and natural resources since it determines both migration and accumulation efficiencies of oil and gas.
  • Generation and evolution of Tazhong low uplift
    ZHANG Zhensheng; LI Ming-jie and LIU Sheping
    , 2002, 29(1): 496-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Based on analysis on structural sedimentary characters (including structural stress field, structural framework, sedimentary environments and sources, vocanic activities, thrusts and seismic reflection characters) of Tazhong region and the whole Tarim basin, it is considered that the Tazhong low uplift was generated by collision of southern Tarim Plate with southern Kunlun Plate at the end of early Ordovician which caused co-existence of the passive margin basin in the northern part of Tarim Plate with the back-arc foreland basin in the sorthern part. Tangguzibasi depression is a back-arc foreland basin, and Tazhong low uplift is a foreland uplift, Tazhong No.1 fault is a thrust of Tazhong foreland uplift, faults to the south are accommodation faults or compensation faults. The thrust belts formed during this stage are pre-existed fault belts for late Aerjing strike-slip fault system. The authors of this paper also discussed structural sedimentary evolution characters of Tazhong foreland uplift. Tazhong No.1 fault was generated at early stage with large throw, and its northern part connected with the source depression. It is an important fault connecting with the source depression, and can also improve the quality of reservoir rocks. Buried hills along this fault should be important exploration areas. Its eastern part was more intensively deformed than the western part, therefore should be a better exploration area than western part. Intensive vocanic activities during early-middle Ordovician might cause poor source rock development in the Tangguzibasi depression. Compensition faults were mainly developed during Silurian-Devonian. Generally, Tangguzibasi depression was steadily uplifted after Carboniferous, therefore the special attention should be paid to in the exploration of this depression.
  • The Triassic sequence stratigraphy and the prediction of thefavourable exploration targets in Tarim basin
    LU Xueyan; ZHU Xiaomin; SHEN Yinmin and GAO Lei
    , 2002, 29(1): 497-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Based on the cores, mud logs, well logs and seismic data, five sequences bounded by unconformities have been identified in the Triassic of Taipen area in Tarim basin by sequence stratigraphy study. These sequences from bottom are named sequence Ⅰ, sequence Ⅱ, sequence Ⅲ, sequence Ⅳ and sequence Ⅴ, respectively. Sequence Ⅰ is distributed mainly in Tazhong prominence and is composed of lowstand system tract, transgressive system tract and highstand system tract. In the lowstand system tract deposited braided delta sediments and lacustrine sediments in other places. Sequence Ⅱ is limited in the Tazhong prominence and consists of the lowstand system tract and transgressive system tract, which developed lacustrine sediments. Sequence Ⅲ is dominated by braided river deposits, which located in the Tazhong prominence and the Majier sag. The sequence Ⅳ is equal to the middle Triassic and composed of lowstand system tract and transgressive system tract, which developed meandering river in the Tazhong proninence and deposited braided river and lacustrine sediments in the Tabei uplift. The sequence Ⅴ, equal to the upper Triassic, was preserved only in the Tabei uplift and the northern slope of the Majier sag which contains lowstand system tract, transgressive system tract and highstand systems tract. In this sequence developed fan delta and lacustrine systems. The formation of these sequences is a combination result of tectonics, lake level change, sediment supply and climates, among which tectonics, lake level change, and sediment supply are the controlling factor. According to the known principle of the oil and gas distribution in the Triassic, the authors of this paper point out that the Lower Triassic in Tazhong prominence and the MiddleUpper Triassic in Caohu sag near the Luntai faults are the favourable exploring targets.
  • Sequence stratigraphy of the Jurassic in Junggar basin
    BAO Zhidong; GUAN Shouri; LI Rufeng; WANG Yingmin; LIU Ling; ZHAO Xiuqi and QI Xuefeng
    , 2002, 29(1): 520-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The Jurassic in Junggar basin is characterized by coal-bearing or noncoal-bearing strata which mainly consist of conglomerates, sandstones and mudstones, and can be divided into two supersequences, seven sequences and fifteen system tracts among which the first supersequence is composed of sequence Ⅰ, Ⅱ, Ⅲ and Ⅳ, respectively equivalent to Badaowan Formation, Sangonghe Formation and Xishanyao Formation of Group Shuixigou, the Lower and Middle Jurassic, and the second supersequence consist of sequence Ⅴ, Ⅵ and Ⅶ, respectively equivalent to Toutunhe Formation, Qigu Formation and Kalazha Formation of Group Shishugou, the Middle and Upper Jurassic. The sequence duration of the Jurassic in Junggar basin is 7-13Ma, and the basal boundaries of the sequences Ⅰ, Ⅳ and Ⅵ are consistent with those of the global sequences UAB1, LZA1 and LZA3.
  • Basic characteristics and main controlling factors of Jurassicreservoirs in Junggar basin
    KUANG Jun; TANG Yong; ZHU Guohua and CUI Bingfu
    , 2002, 29(1): 521-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The analysis of Jurassic reservoirs in Junggar basin is based on four sequences, which include the basic feature description, the ana-lysis on key factors controlling the reservoir properties, establishing genetic model and evaluating and forecasting the reservoir properties. On the basis of summing up the reservoir lithology systematically to points out the stage of diagenesis and compaction are the key issues. In the paper, it is also pointed out the comparatively good reservoir is the reservoir with residual primary intergranular pores, and solution contributes a little to permeability. The presenation conditions of pores in non-coal measures are much better than that in coal measures. This is the reason why the sandstone properties of Sangonghe Formation, Toutunhe Formation and Tugulu Group are much better than that of Badaowan Formation and Xishanyao Formation. Based on the above studies, the genetic-evolution models on the two type reservoirs were built up. By these models reservoir evaluation and forecasting were done by area and layer, and the depth limit of different reservoirs with different permeability as well as the planar spreading of the comparatively good reservoirs were pointed out.
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