, Volume 27 Issue 1
    

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    地质勘探
  • Study and application of 3D paleo-hydrodynamic numerical simulation method.
    Deng Lin; Tang Lie; Kang Zihong; Wang Yingming and Huang Dilong
    , 2000, 27(1): 3-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The paleo-hydrodynamic evolution in a basin is very important to the processes of petroleum accumulation in the basin, but so far the literature about the study of 3D paleo-hydrodynamic numerical simulation method has not been found out. Beginning with geologic model description of hydrodynamic evolution, and considering synthetically paleo-landform, the flow of compact-driven water and that from basin surface, the character of strata in fluent and the character of the basin structural evolution, the authors created a 3D numerical simulator of paleo-hydrodynamic evolution which could reflect the flow rule of unstable groundwater in the anisotropic medium. This simulator can be used to simulate the basin hydrodynamic processes in each geological period and stratum, and then acquire some parameters including 3D flow potential field, flow speed field, flow direction field and alternating times of stratum water, and finally model the active circumstance of groundwater in each geological period. This simulator has been applied to Tarim basin, the results have shown the primary evolution characters of petroleum accumulation in Tarim basin. This indicates that the method and software system is innovative and useful in basin modeling.
  • Orogeny timing and fault-slip rate and their significance to the rejuvenated foreland thrusts belt of Kuche.
    Liu ZhiHong; Lu Huafu; Jia Chengzao; Lie Ganglin; Chen Chuming; Wang Gouqiang and Fan Xiangtao
    , 2000, 27(1): 4-0.
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    Growth fault-related folds are discovered in the rejuvenated foreland thrusts of Kuche which is located along the northern flank of the Tarim basin. According to the Show J H and Suppe J's model of growth fault-related folds, the orogeny time of the rejuvenated foreland thrusts is discussed. Typical growth triangle and growth strata are identified in seismic profiles. The continuity of the growth strata shows that the orogeny of rejuvenated foreland thrusts belt has been in active stage with the orogenic rate and strength progressive increased since the beginning of Jidike stage in Miocene, and which was in the stable structure background in Jurassic-Palaeogene. Growth strata show the faulting time (Neogene-Quaternary), which reflects that the flat-ramp stepped thrusting expended and the main thrusts migrated from north to south in sequence. In light of the growth triangle, the fault-slip rates are calculated as 0.10-0.71 mm/a during Jidike stage (25 Ma), 0.13-0.40 mm/a in Kangcun stage (16.9 Ma), 0.76-2.11 mm/a in Kuche stage, 1.33mm/a in Xiyu stage (2.5 Ma). The forming of structural traps and the migration of oil and gas occurred during the fault-related folding. The oil and gas of the rejuvenated foreland thrusts of Kuche accumulated in Neogene-Quaternary, earlier in the north and later in the south (for the Dongfeng anticlinal belt front mountain closely oil and gas accumulated in Jidike phase, for northern anticlinal belt oil and gas accumulated in Kangcun time, and for southern anticlinal belt oil and gas accumulated in Xiyu period).
  • Origin and geochemical significance of Hg in natural gas from Liaohe basin
    Chen JianFa; Tuo Jincai; Li Chunyuang; Cheng Zhengyan; Zhang Zhanweng and Pu Mingzhi
    , 2000, 27(1): 5-0.
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    The concentration of mercury (Hg), which is a comment of non-hydrocarbon components of natural gases, ranges from less than 1 to 103μg/m3. The previous researchers considered the main factor which affects the concentration of Hg, is the type of the parent matter. The content of Hg in coal-type gas generated from type Ⅲ organic matter is relatively high. On the contrary, that of oil-type gas generated from type Ⅰ to Ⅱ organic matter is relatively low. So the concentration of Hg in natural gas is regarded as a geochemical index to determine the source rock of the gas. But in Liaohe depression, the Hg concentration of oil-type gas in western and local eastern sag (14.4-1930μg/m3) is higher than that of coal-type gas in eastern sag (25.2-52.5μg/m3) obviously, and the Hg concentration of natural gas is especially larger than that from stable cratonic basin in our country. The studied result from Liaohe basin shows the concentration of Hg in natural gas is mainly affected by tectonic properties of basin and deep geological process. The Hg concentration of natural gas has a positive relationship withthe3He/4He ratio, which indicates the Hg of natural gas may, partly, origin from the deep earth volatile matter or be affected by deep geological action.
  • Applying the theory of hydrocarbon expulsion threshold to evaluating the carbon source rock in Tangyuan fault depression
    Zhou HaiYan and pang xiongqi
    , 2000, 27(1): 6-0.
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    By using the actual data of Tertiary muddy source rocks from Wells Tangcan-1 and Tangcan-2 of Tangyuan fault depression in the northern end of Yilan-Yitong graben and applying the theory of hydrocarbon expulsion threshold (HET), the authors investigated the characteristics of hydrocarbon expulsion, and then built up the chart for identification criterion of hydrocarbon expulsion threshold of muddy source rocks in this area and the chart for quantitative evaluation of their hydrocarbon amount. The study shows that source rocks with a high level of organic matter abundance (C) but a bad kerogen type index (KTI) and those with a low level of C but a good KTI can both cross threshold of hydrocarbon expulsion. The burial depth at which source rocks reach the threshold point of hydrocarbon expulsion decreases with the increasing of C, KTI and Ro, which are complementary to each other; the amount of hydrocarbon expulsion from source rocks become larger with increases of C, KTI and Ro. Generally, source rocks cross heavy gas expulsion threshold later than methane expulsion threshold but earlier than liquid hydrocarbon expulsion threshold. The evaluation result is that the Tertiary muddy source rocks of Wells Tangcan-1 and Tangcan-2 belong to non- and bad hydrocarbon types, which mostly cross methane and heavy gas expulsion stage, and little cross oil expulsion stage.
  • The recovery of Mesozoic formation erosion thickness in the north margin of Qaidam basin.
    Mu ZhongHai; Cheng Zhiyong; Lu Tingqing; You Fubao and LI Deqi
    , 2000, 27(1): 7-0.
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    The critical factor affecting the recovery of formation erosion thickness is that whether the pressure, which is exerted by the formations above the unconformity to the formations below it, is greater than that exerted by the erosive formation, not that the thickness of formations above the unconformity is thicker than the erosive formation thickness. This is a new point of view in this paper. It is suggested that when the pressure exerted by the above new formations is greater than that exerted by the erosive formation, the compaction regularity in the formations below the unconformity was altered, that made it impossible to use acoustic (interval) transit time to recover the erosive thickness. Otherwise, it is possible to do so. According to the point of view, with the combination of the unerosive formation thickness trend method and the basin tectonic evolution analytical method, the Mesozoic erosive thickness in the north margin of Qaidam basin has been recovered, and which increases from west to east. The erosive thickness (about 500m) of Kunteyi depression and Lenghu structural belt is large than that (about 100m) of Nanbaxian and Yuka area, and which of Qianxi-Lenghu No.4 area is the largest (may be over 1400m).
  • On the differentiation of geochemical effects and its genesis in various parts over a reservoir
    Tang YuPing; Cheng Yinhua; WEI Wei; WU Xianghua; LI Shanggang and WANG Guojian
    , 2000, 27(1): 8-0.
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    The C2+/C1 of acidolysis hydrocarbon is the index of alkane migration, and fluorescent F360nm/F320nm indicates the migration information of aromatic hydrocarbon. This article has provided the comparative analysis on the geochemical effects, and the research of well-tie profile in oil, marginal and dry wells over an oil field. Based on the extreme analysis on C2+/C1, F360nm/F320nm, C2+, C1, F360nm and the organic correlation in the geochemical information, it is found that there are various characteristics of indicators and various migration effects in wells over various parts of a pool. The positive gradient variation and the upward light-taxis constructional gradient reflect that the vertical micromigration objectively exists, and reflect the tomography and constructional differentiation during hydrocarbon's migration. Synchronous fluorescence, δ13C1 and adsorbate wire method also indicate significant migration effect. Horizontally, indicator concentrations (or intensions) and their gradients also show the characteristic of marginal wells >> oil wells > dry wells. This indicates that it is in the margin of a pool where seepage is the largest. There is significant difference among various parts over a pool, either by the variable assemblage or by the sample one. This represents the differentiation of data structure in various parts over a pool. It also reflects various geochemical effects caused by hydrocarbon's vertical micromigration. It quite well explains the genesis of annular anomalies which often exist in the surface. And it is able to take an important role in the research of the genetic mechanism of petroleum anomalies.
    • 油田开发
  • Applying the numerical reservoir simulation technique to study cyclic waterflooding
    Wen GuoFeng; REN Baosheng; NI Tianlu; SHI Mingyi; SHEN Haihua and XIAO Yinquan
    , 2000, 27(1): 9-0.
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    In the condition of a bigger inner layer and inter-layer, non-stabilized permeability contrast pressure field is formed by utilizing cyclic waterflooding, which may improve development effect of waterflooding reservoir. By applying the numerical reservoir simulation technique and combining laboratory research product, the mechanisms of cyclic waterflooding has been analyzed. It is manifested that permeability and capillary force are main factors influencing cyclic waterflooding effect. In addition, different working system, rational waterflood cycle and water injection rate varying range are also having certain influence. On the basis of this a pilot test of cyclic waterflooding in Guan 80 fault block of Wangguantun oil field in Huanghua depression is made, with results showing that cyclic waterflooding can enhance recovery factor and increase the swept volume of multiple zone heterogeneous reservoir under the circumstance that the formation energy is maintained and injection and production rates keep equilibrium. It should maximize the water injection variation. When the inter zone contrast is more serious, a zonal cyclic waterflooding should be applied. With regarding to water supplement and formation pressure maintenance, dissymmetrical cyclic waterflooding is better than symmetrical one.
  • A current formula of generalized increase and decline curves for predicting oilfield development indexes
    Yu QiTai
    , 2000, 27(1): 10-0.
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    A current formula of generalized increase and decline curves is proposed. The formula is a increase curve which can be used to carry out description and prediction of production indexes in the whole course of oilfield development, and also a decline curve which can be used to undertake description and prediction of production indexes at the decline stage of oilfield development. As an increase curve, it can reflect concave upward and downward these two curves of production Qt vs. cumulative production Np in later phase of oilfield development, thus, it can be used to describe conditions under which production peak appears at any time in the whole course of oilfield development as well, so it is better than the common increase curves. As a decline curve, it can reflect concave upward and downward these two curves of Qt vs. Np, and maximum recoverable reserves can be calculated in any condition, so it is better than Arps' declines. The formula is a increase but also a decline curve whose suitability is very wide, so it is named “the current formula of generalized increase and decline curve”. The examples by Mafang, Renqiu and Shuangtaizi oilfields that represent different types of reservoir and oil displacement show that calculating curve accord with actual data very well, its prediction's function is very good. Comparing with water drive curves and common decline curves it can greatly move up time that begin prediction of development indexes by using performance methods. The example also shows that the longer the matching time, the more accurate the calculated results.
  • Characteristic solution and finite difference solution of two-phase percolation in the direction of normal of ellipse and calculation of development indexes.
    Deng YingEr; LIU Ciqun and WANG Yuncheng
    , 2000, 27(1): 11-0.
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    Hydraulic fracturing, which can form a symmetrical and vertical fracture in the formation around the wellbore, is an effective measure of production stimulation. A vertical fractured well can bring out two-dimensional flow in the direction of normals of developing ellipse—conjugate ellipse isobar and hyperbola streamline bunches with the two ends of the fracture as their focuses. A mathematical model of oil and water two-phase non-Darcy fluid flow in the direction of normal of the ellipses with initial pressure gradient (IPG) is taken into account, which is a nonlinear equation with moving boundary and is established according to concepts of perturbable ellipses and equivalent developing regulations. Characteristic solution and finite difference solution are derived respectively and water saturation distribution curves are presented and the law of the moving boundary is found. Results show good agreement between the characteristic solution and finite difference solution. Moreover, formulas of waterflooding indices of oil with IPG included for vertical fractured wells are derived. Laws of change of production and pressure difference with time are recognized. Influence of IPG and injection rate on the flow and the development indexes is discussed. The paper provides numerical simulation and dynamic analysis and prediction of waterflooding development of low permeability oil fields in the case of vertical fractured wells with theoretical basis. The mathematical model is also fit for waterflooding development of Bingham viscous oil fields in the case of vertical fractured wells. The study on waterflooding development of higher permeability oil fields under the condition of vertical fractured wells is a special case of the paper.
  • Using artificial neural network to realize type curve match analysis of well test data
    Deng YuanZhong and CHEN Qinlei
    , 2000, 27(1): 12-0.
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    Type curve match analysis is the main method of modern well test interpretation, but the error of this method is unavoidable because of the limitation of the type curves in a sample plot. Besides this, it usually needs a few of type curve sample plots to deal with the complex well test problem, so the using of this method is actually limited. In this study, by means of the property of artificial neural network (ANN) that any function can be approached by a three layer ANN, a ANN type curve sample plot has been established and the analysis method is also delivered. This ANN type curve sample plot includes all curves message, and the error of the traditional method is eliminated. Any well test data can get an accurate match in this ANN type curve sample plot. The analysis process is also simplified. The establishment of ANN type curve sample plot makes the intelligence realization of type curve match analysis possible. On the other hand, we can make the ANN type curves including more message, so as to obtain more parameters through once analysis.
  • Reasonable well pattern study for ultra-low permeability reservoirs in Ansai oil field, Changqing oil complex.
    Hou JianFeng
    , 2000, 27(1): 13-0.
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    Ansai oil field in Ordos basin is a ultra-low permeability reservoir with natural and induced fractures, which caused serious lateral heterogeneity of permeability in the reservoir. For the conventional square well pattern used in oilfield development, production wells along fracture direction respond rapidly and water cut rise quickly too, but the production wells on both sides of fractures are less effected. Pingqiao reservoir having the general character of ultra-low permeability reservoir is used as a case study. Through reservoir simulation, the authors analyzed and correlated production results of reverse square 9-spot well pattern, reverse rhombus 9-spot well pattern and rectangular 5-spot well pattern and optimized well row spacing and well spacing of rectangular 5-spot well pattern. The study results show that reverse rhombus 9-spot pattern is more efficient than reverse square 9-spot pattern in the early period and rectangular 5-spot pattern, since we can fracture its production wells and injection wells on a large scale, thus its production rate and water-injection efficiency can be enhanced, and production wells can be prevented from rapid water breakthrough, by enlarging the well spacing in fracture direction (the most optimal well spacing is 450-500m) and shortening well row spacing in perpendicular direction (the most optimal spacing is 150m), we can make production wells taking uniform injection effect and enhancing developing efficiency.
  • Mathematical simulation of coupled fluid flow and geomechanical behavior for full low permeability gas reservoir fracturing
    Fan XuePing; LI Xiusheng; ZHANG Shicheng and XU Xiangrong
    , 2000, 27(1): 14-0.
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    Full reservoir fracturing will change the stress in the low permeability gas reservoir and induce the strain of rock, so it will influence the gas percolation. We suppose the temperature is constant in production, and there is one phase of gas, and that the porous reservoir will deform elastically, and also suppose the following other factors, such as rock deformation, changes of stress, induced fracture, coupled fluid flow and geomechanical behavior, coupled flow in fracture and that in matrix, and non-Darcy flow exist, the coupled fluid flow and geomechanics mathematical model is set up for full low permeability reservoir fracturing. In this paper, firstly, the gas percolation governing equation comprised the strain-stress of reservoir rock is deduced. Then, based on the linear elastic theory and effective stress concept, the governing equation on stress-strain of the rock containing gas is derived. Because both of the two nonlinear partial equations comprise pressure and stress-strain, the equations are discretized and arranged as seven-point stencils form by using the methods of finite difference and block centered grid. Its numerical solution is developed with implicit iterative sequence for better numerical stability. Analyzing the example, parameters of stress, strain, porosity and permeability change with time and space are revealed. It is shown that this model is more close to the practical results by comparing with other models.
    • 综合
  • The integrated reservoir description of volcanic rock in Zaobei area of Huanghua depression
    Shi YanMin and XIAO Dunqing
    , 2000, 27(1): 15-0.
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    Integrated reservoir description has been generally applied in many oil fields around the country, and become the continental sandstone reservoir description technology with Chinese characteristic. But the application to the volcanic rock has not succeeded yet. With big lateral and vertical variation and strong heterogeneity, the volcanic rock has very little to be known and great difficulty to be studied. During the exploration in Zaobei area, the process of volcanic rock reservoir description has been made according to its complexity and characteristics. Then the research in igneous rock segment sequence, the volcanogenic system, and the establishment of reservoir geology model have been done. Meanwhile, litho-density, dipmeter, long-spacing sonic, circum-ferential borehole imaging, etc., combining with conventional log analysis, have been applied to single-well logging interpretation. Based on that, the application of interactive workstation to calibration of net stereo horizon, interpretation and tracing by stages, reservoir prediction and neural network petroliferous diagnosis have had a good effect in the arrangement of hydrocarbon exploration and development on volcanic rock.
  • Log data application in reservoir characterization for Wenmi oil field, Turpan-Hami basin.
    Feng Fang; MO Zehui; ZHANG Keyin; WANG Hongjian; CHEN Yangai; YUAN Lianxi and LI Jiang
    , 2000, 27(1): 17-0.
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    Well log dependent reservoir characterization is a important part of reservoir description. According to correspondant analyses of rock core, natural gamma ray, and sonic interval transit time, we can establish a log facies model and reservoir parameters model, and then analyze porosity, permeability, oil saturation and oil productivity of main layers of interest in Wenmi reservoir. Researches indicate: the main depositional sub-facies sedimentary system of Sanjianfang Formation in Wenmi reservoir of Turpan-Hami basin are braided stream delta front, prodelta of braided stream and infralittoral turbidite fan. The major factor which affects reservoir parameters and productivity is the type of microfacies.
    • 应力场研究
  • Study of in-situ stress state evolution in geologic fault structure.
    Sun ZongQi; ZHANG Guobao and ZHANG Jinghe
    , 2000, 27(1): 18-0.
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    The hydrofracturing tests have been conducted in near thousand oil wells drilling at 86 oil-gas fields of 13 big oil areas in China. Test results show that minimum principle stress, δ3 is always horizontal and parallel to the strike of normal and reversed faults. This is discrepant with traditional point of view, which states that minimum principle stress is horizontal and perpendicular to the strike of normal fault or is vertical for reversed fault. This paper points out that traditional point of view explains the stress state on fault occurrence and the relationship of three principle stresses with different fault structure. The measured stresses based on hydrofracturing tests in oil fields are stresses after completion of fault movement. Obviously, the stress state before fault occurrence continuously changes during fault formation. In the system of normal fault the horizontal stress, perpendicular to the strike of fault increases continuously up to the level which is enough to stop normal fault movement. Thus after formation of normal fault the horizontal stress becomes larger than the horizontal stress, parallel to the strike of normal fault. The last one becomes minimum principle stress. During reversed fault formation the horizontal stress, perpendicular to the strike of the fault decreases continuously up to the level which becomes incapable of moving the block forward. The horizontal stress, parallel to the strike of the fault decreases continuously too and always is less than the horizontal stress, perpendicular to the strike of the fault, being minimum principle stress after fault completion.
    • 油田开发
  • The F-model for predicting production rate and reserves of oil and gas fields.
    Zhu YaDong; GAO Min and XIONG Tie
    , 2000, 27(1): 602-0.
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    Predicting production rate and reserves is one of the most important parts of reservoir management research. The variation of the production rates of oil and gas fields can be described by means of mathematical model or accreting curve. The papers published on this subject were more than 25 by the end of 1998. Based on the F-distribution in mathematics statistics, this paper introduces the time conversion constant during the derivation of the model conversion for the first time, and establishes the F-model—a new mathematical model for predicting the production rates and reserves of oil and gas fields. This paper presents the calculation formulas of F-model's production rate, cumulative production, maximum production rate and its time of generation, and introduces the derivation of this formulas. Among them production rate and cumulative production are expressed by means of β function and incomplete β function, respectively. Because there are 4 parameters in the F-model, the model curve can be adjusted in a wider range, it is not only suitable for predicting the situation of single-peak production curve, but also for the pure decline curve. The 4 parameters are solves by means of multiple repeated linear regression. The application of the F-model in the fields like Wumishan and Chaheji of Renqiu oil complex indicates that the model is very useful.
  • Analysis of pressure and production in deformable porous media
    Song FuQuan and LIU Ciqun
    , 2000, 27(1): 603-0.
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    Many experiments show that: when a well produces oil from a reservoir, the porosity and permeability will decrease as fluid pressure drops, especially for low permeability reservoir with abnormal high pressure, and the law characterized by exponent of pressure drop. This paper analyzes how the deformation of porous media influences oil development and well testing curves in a low-permeability reservoir. The basic non-linear differential equations of percolation are derived on the base that permeability is proportional to exponent of the pressure-drop at any location in a reservoir. By using numerical computation method, a numerical model regarding well-bore storage and skin effect is built up and some typical well testing curves are calculated and analyzed. Finally the influences of deformability coefficient to well production in a reservoir with non-flow boundary are discussed. The result shows that the deformation of porous media must be taken into account in a reservoir with deformation.
  • Extreme value study on well testing in homogeneous reservoir
    Ran; XinQuan and LIAO Xinwei
    , 2000, 27(1): 606-0.
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    The pressure derivate extreme value indicates abundant reservoir information. This paper deduced corresponding relation of pressure derivate extreme value and CDe2S (CD is dimensionless wellbore storage factor, S is skin factor) by twi-derivating pressure of well test in homogeneous reservoir and presented the relation formula of pressure extreme value with CDe2S and time extreme value with CDe2S. By the equations, wellbore CD and skin S may be obtained. With the solution type curve can be matched efficiently.
  • Experiment study on oil displacement by in-situ combustion.
    Wang YanHui; CHEN Yaping and LI Shaochi
    , 2000, 27(1): 607-0.
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    The burning propagation and displacement characteristics of in-situ combustion are very complex. This experimental research focuses on the effects of temperature on combustion mode (dry combustion or wet combustion) and water air ratio for wet type by oil oxidation cell and combustion tube. The results show that there is a critical temperature between LTO and HTO, which is about 380-450℃, which can be identified by the contents of CO2 and O2 of produced gas. The CO2 can be less than 6% and O2 availability can be less than 75%-80% at LTO, but the CO2 can be more than 12% and O2 availability can be near 100% at HTO. The wet combustion is superior to dry combustion because of the important contributions of steam zone during wet combustion with the decrease of burning zone width and peak temperature. Wet combustion shortens the start duration of oil production, decreases the air consumption and air oil ratio, and increases the average oil production rate and displacement efficiency. The suggested ratio of water to air is 1.65kg/m3.
  • Damage mechanism of and protection measures for low permeability sandstone formations in Gubei oil field
    Zhang SouPeng; LI Huaiyuan; WAN Xuxin; XIA Yun and TIAN Fang
    , 2000, 27(1): 610-0.
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    The Gubei oil field is one of the difficult develop reservoirs in Shengli oil complex. The mostly reason is that low-permeability sandstone formations stand intricate diagenesis in different reservoir evolution stage, and reduce a large number of pore volume in reservoir's original framework, resulting in drilling fluid seriously polluted reservoirs in the course of drilling. In order to understand the course that formation permeability was damaged, the different rock and disproportion of its composition and structure of Gubei low-permeability sandstone formations have been analyzed by using identification means to the rock and the mineral and electrical scanning microscope to the sample area. Mechanisms of formation permeability damage by micro-solid particle migration, invasion of filtering fluid and clay mineral action have been studied as well. The plan of protecting low-permeability sandstone formation is offered in the course of drilling. During drilling, the positive colloidal solution is adopted to adjust the drilling fluid density dynamically, to ensure drilling at near balance pressure. Temporarily shielded plugging technique is used to keep drilling fluid (especially, the solid particle) out from reservoir. After that, the newly drilled wells in the old area of the lower production can obtain commercial oil and gas, and bring obviously economic benefit.
  • A thermodynamic model for the prediction of paraffin deposition
    Mei HaiYan; KONG Xiangyan; ZHANG Maolin; LI Shilun; SUN Lei and SUN Liangtian
    , 2000, 27(1): 611-0.
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    Crude oil with dissolved paraffin is a true solution. When thermodynamic conditions changes, paraffin may deposit on the surfaces of porous media or on pipe walls in the form of crystals resulting in a plugging giving serious troubles in oil production. A thermodynamic model is suggested in this paper to predict the deposition of paraffin from the crude oil. Corrections are made to the non-ideal condition caused by solid mixture according to the normal solution theory. This model uses the equation of state to describe gas phase and liquid phase simultaneously, giving the effects of the compositions of the system, pressure as well as the mutual effects of various components; and thus the multiple phase equilibrium regularities can be reflected more accurately. The effects of thermodynamic capacity difference of liquid phase and solid phase on the deposition of paraffin are considered and this model can be used to determine the temperature (or pressure) at which paraffin may begin to settle out from the crude and the amount of paraffin deposited out as temperature (or pressure) is lowered more and more. The temperature at which the paraffin begin to deposit predicted with this model conforms fairly well with that given by actual experimental data.
    • 地质勘探
  • Megascopic pyrolysis characteristics of organic matter samples related to the occurrence of immature and low mature oils
    Lu ShuangFang; Feng Yali; Liu Xiaoyan; FU Xiaotai and Xue Haitao
    , 2000, 27(1): 612-0.
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    Two types of sample (taken from the resins and peribles of the immature mudstones in 6 wells of 5 districts, which are considered as predecessor of resins and suberins of modern high plant) and a part of reference samples (containing normal organic matters) are pyrolysed at a constant rate of temperature increase under similar conditions. Rate of hydrocarbon generation vs. temperature curves are obtained. With these and the chemical dynamic behavior of all types of organic matter closely related to the immature and low mature oils (including original organic materials, soluble organic materials, sulphura2rich organic materials, and organic materials modified by microbes) are dealt with quantitatively. Results of megascopic pyrolytic characteristics and the quantitative chemical dynamic analyses of these samples show that: although the occurrence and accumulation enrichment of immature and low mature oils are related to a number of different geological factors and conditions, under relatively low thermodynamic stresses organic matters related to immature and low mature oils do be matured to generate hydrocarbons. This not only shows the reasonability of the close relationship of these samples with the occurrence and accumulation of immature and low mature oils, but shows that the generation of immature and low mature oil may be a process of chemical reaction under certain thermodynamic conditions and low mature and only, the process of hydrocarbon generation requires a thermodynamic stress condition lower than that under which normal organic matter may generate mature oil.
  • Mixing characteristics of oil and gas in YA13-1 gas field.
    Fu Ning and YU Xiaoguo
    , 2000, 27(1): 613-0.
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    YA13-1 gas field is located at the juncture of Yinggehai and Qiongdongnan basins, and its gas source has been argued for a long time. Using the new technique of GS/MS analysis and based on the biomarkers of natural gas and organic inclusion, fluid inclusion temperature of reservoir, carbon isotopic and composition of light hydrocarbon etc., the authors investigate the source and mixing of gas in YA13-1 gas field. The results show that the gas from YA13-1 gas field is a typical mixed gas composed of organics and gas with different types of source rocks and maturity (including coal-formed gas and high mature and over mature marine gas, the marine gas is predominant). The northern block is filled with mixed gas from type Ⅲ and Ⅱ kerogens, and the southern block is filled with gas from type Ⅱ kerogens. The major gas-source rock is probably the Paleogene marine YC and LS Formations (with type Ⅱ kerogens) in the depocenter center of Yanan seg. The secondary source rock is the coal mudstone of YC and LS Formations underlying YC13-1 gas field. Condensate of YA13-1 gas field is coal-formed gas and results from the evaporative fractionation process. The deep fractures in Qiongdongnan basin cut down layers of carbon source rocks to form local low-pressure belt, and to provide the main geological background for the evaporative fractionation process.
    • 综合
  • Predicting the sandstone reservoir thickness and oil saturation by using seismic attributes
    Zhang E; GAO Shuqin; HOU Chengfu; LIU Aixiang; LUO Yongsheng; WANG Qi and ZHANG Jing
    , 2000, 27(1): 616-0.
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    During progressive exploring and developing Menggulin oil field of Erlian basin, some difficulties arisen: the sand from Tengger Group of Lower Cretaceous is extremely heterogeneous and the distribution of oil and water is very complex. To solve this problem, by using re-processed 3D data of the entire area, we created synthetic seismograms of two deeper wells, which were then verified by more than 80 wells. Then these seismograms were used to accurately define the strata, and detailed structure interpretation of top reservoir was performed. On the basis of the interpretation, we use Landmark interactive system to extract 20 seismic attributes, which can be grouped 4 classes: amplitude spectrum, duplicated seismic trace, spectrum and stratigraphy sequence. Through correlation analysis, three attributes (maximum amplitude of trough, mean instant frequency, ratio of positive sample to minus sample) can be selected to be used in polymerization analysis. Then a white seismic attribute distribution plane map reflecting low frequency and high amplitude can be gained. After that, combining the reservoir parameters of needed wells with the three attributes described above to perform polynomial regression analysis, then to get the depth of the reservoir and oil-bearing saturation distribution. Comparing the predicted result to drilled result, the sand depth error is between 1-2 m, and the saturation error is between 1%-5%. From that, the authers think the predicted result reliable and visualized. This research result provides basis for further progressive exploration and development project of Menggulin oil field.
  • Methods for sandstone reservoir lateral correlation and prediction in the development phase of the oil field
    Chen Bo and LI Xiaojun
    , 2000, 27(1): 617-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    In the development phase of sandstone oil fields, lateral correlation of sand bodies and then their prediction of shape and distribution are very important geological research works whose veracity has much effect on improving the production efficiency of oil fields, and also on predicting the distribution of remaining oil. By using the method of high resolution sequence stratigraphy to establish high resolution chrono-stratigraphic framework and to determine the reservoir size and shape, and based on core, logging and high resolution seismic data to undertake detail reservoir depositional micro-facies analysis so as to determine the combination type spreading law, shape and distribution of depositional micro-facies of sand bodies are presented in the paper. With the constraint of above conditions correlation and prediction principles of single sand layer are established. This method has been applied to fluvial reservoirs of lower Minghuazhen Formation of Gangdong oil field, including setting high resolution isochronal stratigraphic framework on the base of intermediate term stratal cycle and predicting the location and type of sand bodies based on their size derived.
    • 地质勘探
  • Significance of the Tertiary plaster salt rock in Taibei depression to migration and accumulation of hydrocarbon
    Luo QuanSheng; Jing Wengbo and Nie zhaoqiang
    , 2000, 27(1): 632-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    During the deposition period of Taoshuyuan Formation from Eocene to Oligocene-Miocene developed almost one-thousand-meter-thick plaster salt rock, whose most component is anhydrite, in the Yanmuxi-Shenquan region of the west of Taibei depression. Synthetical analysis on the sediment characteristics of plaster salt rock combined with the condition for forming pools shows that plaster salt rock is vital to the migration, accumulation and conservation of hydrocarbon in the shallow formations. The circumference of Shengnan and Yanmuxi oil fields where plaster salt rock is greatly developed is of advantage for continuously progressive exploration in the shallow formation, which should be much thought of.
  • Fractal and grey system evaluation of Ordovician paleocrust of weathered reservoir in central-eastern Ordos basin.
    Ma ZhenFang; YU Zhongping; Zhou Shuxun; Pan Linghong; Xa Riyuang and Tang Jiansheng
    , 2000, 27(1): 633-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    By using fractal dimension—the characteristic quantitative parameter of reservoir pore and fracture, the reservoir fracture of M51-M54 in weathered Ordovician paleocrust can be divided into 7 types, and the cave 8 types. The fractal dimension for each type could be calculated out. It pointed out that there have been a low value zone of fractal dimension, extended from north to south, existed between the control and the cast part of Ordos basin, it has been proved that this zone is a regional lithology tight zone. Taken the fractal dimension as a main parameter of reservoir evaluation, combining permeability and the saturation index of dolomite and calcite, using the decision making method of grey theory, the prediction and evaluation had been done to the major pay M531 of the paleocrust gas reservoir in Ordos basin. The result indicated that SH9-SH117, SH100-SH109 are the favorable reservoir zones, and SH188-SH50, the area of Dabaodang and etc. are the relatively favorable zones for exploration in future.
  • The concept of “petroleum migration and dynamic accumulation” and its application in petroleum exploration in cratonic area, Tarim basin.
    Zhou DongYan and Li Honghui
    , 2000, 27(1): 636-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The concept of “petroleum migration and dynamic accumulation” is proposed. The dynamic charging condition is characterized by first and secondary accumulation, and the research is proceeded on four levels. The major features of the particular petroleum geology conditions in cratonic areas of Tarim basin include: ①The distribution of favourable sedimentary facies belt controls the quality of Paleozoic source and percentage of petroleum-generating organic matters. ②There were paleouplifting, deep-burial, heating events, which lead to the limited distribution of Cambrian and Ordovician effective source in particular areas. So the petroleum source must be determined according to the dynamic evolution of the source rock. ③The regular migration of multi-cycle tectonism and deposition results in the superposition of petroleum systems. Four migration and accumulation stages can be identified: ①Original pool with source and reservoir in the same formation and pool destroying and leaking exist at the same time in the lower tectonic section in middle Ordovician-early Silurian. The hydrocarbon dynamic accumulation apparently is controlled by paleo-uplifts. ②The tar sands resulted from secondary hydrocarbon migration in middle Silurian-Permian. The western plunging end of the uplift is of favorable migration and accumulation. ③Migratory concentration and pool generation dominated during Permian-Tertiary. Tazhong 10 and Tazhong 1 fault zones are of favorable migration and accumulation. South to the primary separator valley (the interlaced zone of north nose-like uplift and center host) is not of pool-forming due to the lack of hydrocarbon source. ④The modification of pools dominated since Neogene. The key contributors to evaluation for the lower structural section in Tazhong area are maintenance of paleo-pools and later charging of hydrocarbon, especially the lithological traps within favorable accumulation area. Some exploratory and planing suggestions about Tazhong are provided, and it is believed that a research system and exploratory mode based on “dynamic” idea from start to end should be established.
  • Logging prediction of organic reef in East Sichuan, China
    Ren XingGuo; LUO Li; YAO Shengxian and ZHANG Shudong
    , 2000, 27(1): 637-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Trough analysis of logging and geologic data, the close relation between the purity and the thickness of the shale at the bottom of Triassic Feixianguan Group and the development of reef in underlying Permian Changxing Group in Chuandong (East Sichuan) region is found, and what caused the close relation is analyzed that the place where the reef of Changxing Group developed is a local positive landform which was in the comparatively high energy sedimentary environment which resulted in very few deposition and unpurity of shale, therefore it can predict the vertical distribution of Changxing Group reef based on the rock type and thickness of the bottom sediment of Changxing Group. The reef interpreted from logs is compared with the abnormal section of CSI logs which are used as the basis for the prediction of the transverse development and distribution of the reef and the distribution of reef in Well Yun'an 14 is also predicted. The principal azimuth of reef is forecasted by using the red pattern of vector points from dipmeter logs; the shape of reef in Changxing Group of Wubaiti structure is restored using CSI logs and Kriging technique; the presence of reef in Changxing Group in Wells Tiandong 71, 72 and 76 is predicted and this has been proved by the penetration of reef in Changxing Group in Well Tiandong 72, which shows that it is possible to study the lateral distribution and scale of organic reef by integrating many logging methods, in which CSI logging technique has its predominance obviously.
    • 油田开发
  • A preliminary discussion on numerical simulation of microbial flooding process.
    Chen JunBin; ZHANG Rongjun and GAO Xiaopeng
    , 2000, 27(1): 638-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    In order to deal with various mechanisms in the process of microbial enhanced oil recovery (MEOR),a 1-dimensional,3-phase mathematical model of microbial flooding is established preliminarily to describe the transportation of microbes and their nutrition fluids and the procreation of microbes in an oil reservoir to give a base to the engineering design and evaluation for MEOR. This model takes both the amount of microbes in the fluid injected and the deposition rate of the microbes into consideration. The procreation and the transportation of microbes are described by the equation considering the volume of microbes, given by Gruesbeck and Collins. Density of volumetric rate of flow is related to absolute permeability of the porous media. The adsorption of nutrition material is described by Langmuir's Equation and dispersion as well as seepage in the saturated water in the nutrition fluids in the porous media are also considered. The rate of increase of microbes and its relation to the concentration of the nutrition fluids is described by Monod Equation. The set of partial differential equations is changed into a set of finite difference equations, then a set of linear algebraic equations is obtained by linearization of all non-linear coefficients, and thus the distribution and variation of all necessary unknowns are found out. Production data of 1 oil well in an actual oil field is taken to carry out numerical simulation. Results show that this mathematical model can reflect the basic mechanism in the process of MEOR. Results of simulation show when microbes are injected into the reservoir: ①Production of this well is changed very little in the early stage, but increased clearly in the later stage; ②The variation rate of oil saturation is maximum in the first 30 days, after the injection and it changes little as time goes on; ③Water saturation increases with the time.
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