Xinjiang Petroleum Geology

Tectonic Coupling and Segmentation of Marginal Structural Belt in Junggar Basin

MA Zong-jin, QU Guo-sheng, LI Tao, ZHAO Rui-bin, XU Jian-dong

2008, 29 (3): 271-277.

Abstract ( 169 )

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Researches indicate that the marginal structural belt of Junggar basin undergone the phases of strong coupling of Hercynian, weak coupling and adjustment from Mesozoic to early Cenozoic as well as strong coupling of southern margin of Junggar basin since Neogene. The degree of activity of marginal structural belt of Junggar basin assumes obvious decline since Hercynian, weak adjustment in Mesozoic and reascending in Cenozoic with less level than in Hercynian. Such orogenic events allowed the hexagon marginal belt with distinct structural configurations of Junggar basin to be divided into 6 marginal structural segments such as west segment (free restricted thrust nappe)and east segment (strong restricted thrust nappe)of southern margin of the basin, western margin segment (EW compressiondeformation belt)of Zhundong (east Junggar)uplift, northeast segment or Ulungu segment (kink fault terrace and basement sags), northwestern margin segment or Zhayir segment (thrust-nappe superimposed system)and west Junggar marginal segment (kink belt structure).

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Deep-Shallow Structures in Tianshan Mountain and Basin-Mountain Coupling Relationship

ZHAO Rui-bin, LU Jing-fang, YANG Zhu-en, QU Guo-sheng, MA Zong-jin

2008, 29 (3): 278-282.

Abstract ( 223 )

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Tianshan mountain tectonic belt is of a complicated relationship between the deep and shallow structures indicated by the synthetic researches in geology and geophysics. The structures on the south and north sides of Tianshan display obvious symmetry with the axis of Nalun-Nalati-Hongliuhe tectonic suture belt, and it vertically appears in particular spherical structure like a "sandwich" with rigidity in the top and bottom and the weak in the middle. On the south side of it, it appears that Tarim plate subducts northward intracontinentally, being interbedded to and detached with the lithosphere in Tianshan; in the piedmont Tianshan, the basement is entangled into cap rocks or covers and then deformed. On the north side, Junggar plate enters into Tianshan and has fluxion structures followed by shaping deep piedmont depressions. Therefore, the basin-mountain coupling feature is quite different in the south and north sides of Tianshan mountain.

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Analysis of Tectonic Framework in Junggar Basin

LU Bing, ZHANG Jin, LI Tao, LU Miao-an

2008, 29 (3): 283-289.

Abstract ( 195 )

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The crust in Junggar basin can be divided into the upper, middle and lower ones from the bottom of sediments to the Moho. The middle crust is thinner than the upper and the lower. The basement of the basin is formed by two parts: the folded basement and the crystalline one. The upper basement is composed of the Upper Paleozoic. In the southern basin, the folded basement is thinner or absent, with four structural lines of NW, NE, SN and EW trends. The NW and NE lines control the SN zonation in Class-II tectonic elements; the SN and EW lines are blind ones. The basement of hinterland in Junggar basin is composed of a series of blocks with the EW and SN lines crossing each other, and the secondary swells are formed at the apical corners. Two groups of faults with NE and NW trends exist in the northwestern margin, generating some small blocks like "H" shape. In the Indo-Chinese epoch, the NWW and NE faults crossing each other in eastern Junggar basin shaped the structure of "# Type" because of the clockwise distorting of the basement. In the southern margin of it there exists one SN structural line or belt for about per half degree from 84°E to 91°E. These longitudinal belts have the properties of low density, medium-low resistivity and low velocity, and can be as the buffer zones, which take important controlling parts in sedimentary facies change, tectonic migration and hydrocarbon accumulation here.

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Fault Structures in and Around Junggar Basin

QU Guo-sheng, MA Zong-jin, ZHANG Ning, LI Tao, TIAN Ye

2008, 29 (3): 290-295.

Abstract ( 205 )

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The periphery fault structures and spatial distributions in Junggar basin are analyzed. Based on the 3D structural analysis of folded basement, crystal basement and Moho, the EW and SN trending lithospheric fracture in this basin are identified, in which the Kelameili-Eastern Sangequan-Sangequan fault belt controls the tectonic evolution of Luliang uplift. The SN trend faults in basement of the basin are firstly discussed. The analysis of superposed fault system in different sedimentary cap rocks shows that the dense fault belts are closely associated with long-term activities of deep faults, which form the shallow-deep fault configuration. The present landform is mainly controlled by the deep fault structures.

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Oil-Gas Origin and Accumulation Model of Nanyishan Structural Reservoir in Qaidam Basin

LU Jun-gang, CHEN Shi-jia, WANG Xing-zhi, LI Yuan-kui, ZHOU Zhi-ling, DAI Zhen-gang

2008, 29 (3): 296-298.

Abstract ( 210 )

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Nanyishan structural reservoir is the biggest reservoir in northwestern Qaidam basin at present. The deep E23 is a condensate gas reservoir and the shallow N2 2 is a conventional oil reservoir. Study and anatomy of such reservoirs with a unique distribution in this area is of significance to its petroleum exploration. It is suggested from comprehensive recognition of oil source in terms of the light hydrocarbon, gas carbon isotopes and biomarkers that the crude oil in the shallow N22 is different from that in the deep E23 . The former comes from the N1 source rocks, while the latter from the E23 source rocks, and pointed out that the oil and gas of Nanyishan structural reservoir are captured from the source rocks in the vicinity, not migrated from the south of Qaidam basin. The shape of deep condensate gas reservoir is controlled by the kerogen type and the maturity.

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The Effects of Source Rock, Depositional Environment and Maturity on Distr ibution of Neutral Nitrogen Compounds

WANG Chuan-yuan, DUAN Yi, DU Jian-guo

2008, 29 (3): 299-302.

Abstract ( 138 )

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The distribution of neutral nitrogen compounds in oils from Erdos basin and Qaidam basin is investigated. The control effects of source rock, depositional environment and maturity on such compounds are further discussed. The results indicate that there are some distinct differences of relative abundance of pyrrolic nitrogen compounds in various crude oils; the source rock affects little on the distribution of pyrrolic nitrogen compounds; the depositional environment and maturity have important effects on the abundance of pyrrolic nitrogen compounds; m(1-MC)/m(4-MC), m(1,8-DMC)/m(2,7-DMC)and m(benzo[a]carbazole)/m(benzo[c]carbazole)can be used as maturity parameters. It is suggested that pyrrolic nitrogen compounds have potential significance both in oil-gas migration and in paleoenvironment and thermal maturity evaluation.

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Sedimentary Characteristics and Developing Conditions of Gravity Flow-Genetic Reservoirs in Ramp Margins of Depression-Lacustrine Basin—An example from Wellblock Shinan-31 in hinterland of Junggar basin

REN Xiao-jun, YU Xing-he, LI Sheng-li, SHI Xin-pu

2008, 29 (3): 303-305.

Abstract ( 125 )

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Shinan-31 Wellblock is a large lithologic oil-gas reservoir discovered in Shinan area in hinterland of Junggar basin in recent years. Its petroliferous strata around the ramp margins of depression-lacustrine basin belong to the K1q 11 sand layer of Qingshuihe formation of Cretaceous. But there has been controversial on the sedimentary facies type of the reservoir. The core observation and seismic information analysis suggest that in Shinan-31 Wellblock possesses the necessary conditions for forming gravity flow sediments. It is concluded that in the conditions of valley, terrace and plentiful mass supplementation, gravity flow sediments can develop in the depression-lacustrine basin.

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Effect of Dissolution on Forming High-Quality Reservoir in Alkaline Volcanic Rocks—An example from Carboniferous volcanicrocks in Luxiarea in Junggar basin

LEI Tian-zhu, SHI Xin-pu, KONG Yu-hua, ZHANG Shun-cun, FANG Lin-hao, SHI Ji-an

2008, 29 (3): 306-308.

Abstract ( 127 )

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The study on volcanic rocks from Luxi area in Junggar basin shows that the dissolution of the alkaline volcanic rocks of overflow facies is a key factor to form high-quality reservoir. The discussion of the origin of acidic fluids and mechanism of dissolution suggests that there are different dissolution mechanisms between inorganic acids and organic acids. The inorganic acids mainly take K+, Na+ and other ions away to have a dissolution, however, the organic acids largely depend on increasing the activity of Al3+ for it. The acidic fluids for dissolution were derived from volcanic degasification, fluids overflowed upwards along the deep faults and organic matter. It is concluded that the adjacent to craters, lateral of deep faults and hydrocarbon-generation sags would be the favorable zone for petroleum prospecting. In Luxi area, the most potential zones could be found in line from Well Xiayan-2 to Well Da-1 and Shixi area. In addition, the more potential zones place in line from Well Xiayan-1 to Well Shinan-4 and from Well Madong-2 to Well Lu-2.

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256 Strike-Slip Fault Zone Characteristic and Its Geological Significance in Northwestern Margin of Junggar Basin

XU Zhao-hui, XU Huai-min, LIN Jun, PENG Jian-cheng, ZHANG Bing, ZHANG Guang-qun

2008, 29 (3): 309-310.

Abstract ( 203 )

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This paper, using 3D seismic information and well log data, combined with regional geological features, presents the distribution characteristic of this fault zone and suggests that such a fault is characterized by strike-slip nature flower structure, riband effect, crushed zone and volcanic rock body leap, etc. It has an important effect on Lower Wuerhe reservoir, and the extension area of this fault zone could be an oil-gas enriched area.

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Dissolved Pores and Evolution of Carbonate Reservoir in Majiagou-514 Sub-Member in Jingbian Area

CHEN Xiao-wei, CHEN Hong-de, ZHAO Jun-xing, HOU Ming-cai

2008, 29 (3): 311-313.

Abstract ( 124 )

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In this paper, the samples are collected from Majiagou-514 sub-member in Jingbian area and analyzed by scanning electronic microscopy (SEM), casting thin section and mercury penetration. The category and feature of pores in carbonate reservoir dominated by dissolved and intercrystal pores are presented. The reservoir property has been obviously improved by the paleokarst process. Its genetic process of secondary pores can be divided into the meteoric water controlled karst phase and the buried condition controlled solution phase.

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Multi-Scale Frequency and Absorption Attributes of Seismic Signals

CHENG Bing-Jie, XU Tian-Ji

2008, 29 (3): 314-317.

Abstract ( 132 )

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Based on wavelet theory, this paper obtained the multi-scale dominant frequency (MSF)by using wavelet analysis, and derived a new relationship algorithm between travel-time, frequency and absorption coefficients from transforming the seismic amplitude equation proposed by Aki & Richards (1980), then calculating the multi-scale absorption attributes (MSA)of seismic signals in time-frequency domain, which effectively show the oil and gas response characters, such as low main frequency, serious high frequency absence, dimming reflection, reflection blank, reflection disorder and fat wave shape. Hydrocarbon reservoir has special response to high frequency sects, and goes with intensive amplitude, energy and frequency absorption of seismic waves. Calculating MSF and MSA of seismic data at different scale can reveal frequency shift and absorption attenuation characters of seismic waves, which is favorable to lithology identification, petroleum reservoir prediction and synthetic interpretation. A case study of MSF and MSA techniques applied to seismic data from dense clastic rocks of Xujiahe formation in depression of western Sichuan basin provides robust indications for reservoir prediction and gas detection.

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Modeling and Application of Fractured-Vuggy Carbonate Reservoirs

ZHAO Min, KANG Zhi-hong, LIU Jie

2008, 29 (3): 318-320.

Abstract ( 130 )

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Geological spatial structure has been considered in 3D reservoir modeling technique, but it is not good enough. This paperpresents 3D geofacies model through the seismic re-sampling to 3D seismic waveform and the restraining to oil-water distribution in vuggyreservoir available for modeling, and aim at space distribution about oil and water, finally finish the 3D-reservoir modeling. This modelreproduces the geometry of uncharged vugs in District No.8 in Tahe oil field, which provides strong support for exploration and devefpirea of this kind of reservoir.

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Quantities of Hydrocarbon-Biting Bacteria in Near -Sur face Soil and In-Situ Oil-Gas Distribution

HE He-nan, LU Ting-qing, ZHANG Ting-shan

2008, 29 (3): 321-322.

Abstract ( 169 )

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The significances of methane-oxidizing bacteria, anaerobic cellulose-decomposing bacteria and sulfate-reducing bacteria in the soil from the Xindu gas field for its petroleum exploration are discussed. The results show that the quantities of these microbes as a function of hydrocarbon biting are obviously different: the methane-oxidizing bacteria and sulfate-reducing bacteria were found in high quantity, and anaerobic cellulose-decomposing bacteria in low quantity. However, the methane-oxidizing bacteria and sulfate-reducing bacteria were found in low quantity, while in outer edge of Xindu gas field, all these bacteria above mentioned are in low quantity, which is just accordant with the oil-gas distribution in this field. The study indicates that the microbial prospecting technology could be effectively used for oil and gas prediction.

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Hydrocarbon Accumulation Mechanism of Large-Sized Reef-Shoal Complex Condensate Gas Field in Tazhong No.1 Slope-Break Zone, Tar im Basin

HAN Jian-fa, MEI Lian-fu, YANG Hai-jun, WU Guang-hui, YU Hong-feng, GUO Dong-sheng, DENG Li-ping

2008, 29 (3): 323-326.

Abstract ( 161 )

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Using carbon isotope, biological marker compound and other geochemical analysis methods, it is conformed that the Cambrian-Lower Ordovician source rocks and the paleo-oil reservoir cracking gas are the key factors for forming the large-sized condensate gas field in Tazhong No.1 slope-break zone; using inclusion and reservoir geochemical analysis technologies, combined with the source rock evolution history, structural history and deposition-reservoir evolution history to study the period of time and the migration of the hydrocarbon accumulation, this paper presents that Tazhong No.1 fault, the late deep strike-slip faults and multi-stage unconformities in process of shape of Tazhong paleo-uplift are the main transporting systems, thus clarifying the dynamic process of hydrocarbon accumulation in late Caledonian episode, paleo-oil reservoir adjustment, oil-gas transfer and generation from source rocks in late Hercynian episode, as well as multi-stage oil-gas charging processes of cracking gas in Himalayan paleo-reservoir into early oil reservoirs. In particular, this paper points out that the heterogeneity of reef-shoal complex and the diversity of transporting system are the key factors resulting in complex fluid distribution, hence develops the multi-stage charging and multi-stage adjusting hydrocarbon accumulation models. This study shows the characteristics of gas rich in outer zone and oil rich in inner zone of Tazhong No.1 slope-break zone, which enriches the theory of hydrocarbon accumulation in marine carbonate rocks in Tarim basin.

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Characteristics of the Ordovician Reef-Shoal Reservoir in Tazhong No.1 Slope-Br eak Zone,Tarim Basin

CHEN Li-xin, YANG Hai-jun, WU Guang-hui, HAN Jian-fa, CAI Chun-fang, ZHAI Shu-ling

2008, 29 (3): 327-330.

Abstract ( 171 )

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The Ordovician oil-gas field in Tazhong No.1 slope-break zone in Tarim basin is the first large-sized field where the reservoir is dominated by reef and shoal complex facies. This field is characterized by big differences of testing production and gas/oil ratio in different wells, complex oil and gas properties, having both normal oil and gas condensate, generally containing H2S in natural gas, and varied contents of non-hydrocarbon gas in different well blocks. The study shows that the gas is rich in the northern part and the oil is rich in the southern part; such distinctive oil and gas in sectional distribution mainly originated in the Cambrian. It is concluded that Himalayan movement is the main reason for forming this large-sized field of Ordovician due to cosmically gas invasion and better preserved conditions in this area.

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Query, Derivation and Comparison About Joshi's Production Rate Formula for Horizontal Well in Anisotropic Reservoir

CHEN Yuan-qian, GUO Er-peng

2008, 29 (3): 331-334.

Abstract ( 156 )

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In the past 20 years, major development has been made in horizontal drilling and production technologies applied to domestic onshore and offshore areas. How to reliably calculate the production rate by horizontal drilling process is becoming an important task to reservoir engineers. There are four methods widely applied at home and abroad at present: Joshi's method, Borisov's method, Giger's method and Renard-Dupuy's method. This paper presents a new method for it proposed by Prof. Yuanqian Chen. Under homogeneous conditions, satisfactory results can be all given by these methods. In anisotropic conditions, Joshi had given two modified methods which were widely used, but this study indicates that such modified methods have no basis from theoretic derivation, so the results are not correct. Adding theoretic analysis and derivation, this paper presents Joshi's production rate formula for horizontal well in anisotropic reservoir. Meanwhile, anisotropic corrections for other methods are made correspondingly, including calculations of different factors influencing individual productivity. Case study shows that the method proposed in this paper is proper and effective.

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Inflow Performance Prediction Method for Condensate Gas Well

HE Zhi-xiong, SUN Lei, LI Shi-lun

2008, 29 (3): 335-337.

Abstract ( 162 )

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Based on phase-state theory and flash calculation method for condensate oil/gas system, this paper presents the deliverability equations of oil and gas obeying Darcy's law, gas obeying non-Darcy's law, oil obeying Darcy's law, oil and gas obeying non-Darcy's law in condensate gas well according to flow characteristics of gas and retrograde condensed liquid in strata. In these equations, the phase state and composition changes are considered well and two-phase pseudo pressure function of steady state theory calculation is introduced. The case study shows that there exists a breakpoint in inflow performance curves when bottom pressure is at dew-point pressure, which is coincident with the characteristics of condensate gas well; in inflow performance prediction of gas condensate well, the deliverability equation of gas obeying non-Darcy's law while oil obeying Darcy's law should be adopted.

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Theoretic Basic of Bilogarithmic Water-Drive Characteristic Curves

GAO Wen-jun

2008, 29 (3): 338-340.

Abstract ( 167 )

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Both of Wan Jiye's extra-protruding curve and Bridge's curve belong to bilogarithmic water-drive characteristic curves with similar function, which are major methods for waterflood oilfield development evaluation. Because of lacking theoretical deducing, these curves have been ignored by reservoir engineers for a long time. Following the research thoughts of the literature [1], combining Welge's equation with material balance equation, this paper presents two types of average water saturation functions and exit-end water saturation function, and then gives the theoretic deducing process of above two curves and individual corresponding percolation expressions to oil and water. This study provides both in-depth recognition of above two curves and credible theoretic basis for their popularization.

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Study on Dynamic Sanding Prediction in Donghe Oilfield, Tarim Basin

QI Da-sheng, XIANG Lin-na, PEI Bai-lin

2008, 29 (3): 341-343.

Abstract ( 163 )

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Donghe oilfield in Tarim basin is an ultradeep sandstone reservoir with well compacted rocks. The prediction in the early phase of production was that it would not produce sand. So, no sand control measure was made after putting it into production. However, with reservoir pressure drawdown and water-cut increase during the production, the sand production became more and more serious. Following analysis of the main affecting factors, this paper proposes two modification factors (λ1 and λ2)for conventional sanding prediction formula. Using the modified formula, the calculation results and prediction conclusions match the reservoir conditions very well. This method could be as a guide for other sandstone reservoirs in dynamic sanding predictions or sand controls.

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Application of Catastrophe Theory to Integrative Evaluation of Reservoirsby CO2 Miscible Flooding Process

CHEN Ren-bao, SHI Jun-feng, WU Han

2008, 29 (3): 344-346.

Abstract ( 141 )

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A new assessment method combined catastrophe theory and fuzzy mathematics is established and applied for the first time to evaluate and select the candidate of CO2 miscible flooding reservoirs. Based on the subordinate functions in it, the comprehensive values of all candidate reservoirs are calculated. Case study shows that the results evaluated by such a method is accordant with other evaluation methods, ensuring the veracity and creditability of the results and avoiding the randomicity and troubling of hierarchy process, factor analysis, fuzzy comprehensive appraisal and other assessment methods.

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Influence of Property and Structure of Crude Oil on Its Viscosity

LIU Hai-bo, GUO Xu-qiang

2008, 29 (3): 347-349.

Abstract ( 369 )

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Viscosity is one of the important physical properties of fluid. Accurate calculating the value of viscosity is of important significance in making policy of field development and selecting proper chemical separation technologies. This article inspects computation precision of the existing viscosity models to the viscosity of the crude oil, and showed that the prediction errors are bigger. On the basis of this, this article presents a method for using four-component lab data to separate plus fraction of crude oil into saturated hydrocarbon, aromatic, resin and asphaltene for crude characterization. This method can be used to more precisely describe the influences of different properties of crude components and structures on crude viscosity.

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Flow Model and Well Test Type Curves for Triple-Medium Reservoirs

CHEN Fang-fang, JIA Yong-lu, QIAO Zhong-ming, YAN Yu-peng, WANG Feng

2008, 29 (3): 350-353.

Abstract ( 130 )

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Aimed at the polluted zone produced around a well in the course of drilling, completing and producing and the heterogeneous conditions of triple-medium carbonate reservoirs, a well test interpretation model for triple-medium composite reservoir with consideration of skin effect and wellbore storage effect is developed. Through Laplace transformation, the Laplace space analytic solution has been obtained, and converted into real space solution by means of the numerical inversion of Stehfest. The pressure and the pressure derivative bilogarithmic type curves have been drawn up. From the physical percolation mechanism, the curve shape characteristics and the flow phase are analyzed and divided, obtaining the effects of inner-and outer-zone permeability ratio, inner-zone radius, interporosity flow coefficient and storativity ratio on the pressure behavior of such a reservoir. The results indicate that when the value of the permeability of inner zone is less than that of outer zone, the pressure derivative curves of these two zones will go down. On the contrary, when the value of the permeability of inner zone is bigger than that of outer zone, the pressure derivative curves of them will go up. It is concluded that the radius of inner zone determines the time of pressure transmitting to the boundary of the outer zone; the interporosity flow coefficient determines the coming time of crossflow; the storativity ratio affects the degree and the lasting time of crossflow. These results can be used for study of percolation of tripe-medium composite reservoirs and for analyses of pressure behavior and well test.

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Fracture Identification Method for Lower Wuerhe Reservoir of Distr ict No.8 in Karamay Oil Field

LEI Cong-zhong, LIN Jun, PENG Jian-cheng, ZHANG Bing, GU Yuan-xi

2008, 29 (3): 354-357.

Abstract ( 131 )

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Fracture identification and evaluation are difficult to run in the research of reservoir quality in oilfield development. Based on the core data and EMI fracture analysis of Lower Wuerhe reservoir in District No.8 in Karamay oil field, the basic characteristics of various fractures in this area are described, numerous conventional well log data are analyzed and calibrated in terms of natural fractures, thus developing model for identification of the fractures by means of conventional well log data. By processing and interpretation of wells in this area, the types and developed extent of the fractures in single well are confirmed, the space distribution of the fractures in Lower Wuerhe reservoir is revealed.

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Optimum Programming and Decision-Making for Production Allocation in Clustered Gas Fields in Western Sichuan Province

LI Xiao-ming, ZHANG Jian, ZENG Xian-bing, LIU Bo

2008, 29 (3): 358-360.

Abstract ( 148 )

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A series of problems occurred in major Chuanxi (west Sichuan)gas fields due to unreasonable production allocation that resulted in higher cost, short stable-production cycle and rapid production decline. This paper presents a set of new methods for clustered partition and integrated optimization of production allocation for these gas fields. On the basis of these methods or mathematical models, the optimum planning schemes are obtained, which provide quantitative basis of macro-control of all these gas fields for the decisionmaker (s). Comparing with existing development schemes, the studied results in this paper show that the unit cost for gas production can be obviously decreased. Integrated

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Application of Well-Log Information to Recognition of Reservoir Architectural Boundary Surfaces—An example from Donghe sandstone in Hade-4 oil field

JIAO Cui-hua, XU Huai-min, WANG Hai-geng, LIU Tai-xun, CHANG Lun-jie, NIU Yu-jie

2008, 29 (3): 361-363.

Abstract ( 147 )

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Diplog data are characterized by high vertical distinguishability and good consistency. Based on the core and outcrop analyses of Donghe sandstone in Hade-4 oil field, integrated with GR, SP and Rt log curves and dip-log interpretation result, log responses and modes of six-grade architectural boundary surfaces in the studied area are given in this paper, thus realizing the recognition of single well architectural boundary surface for the sake of detailed research of the architectural elements.

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Using 3D Visualization Technology to Interpret Complicated Fault Structures in Buried Hill

MIAO Qing, PAN Mao, GAO Hong-liang, ZHANG Bo

2008, 29 (3): 364-366.

Abstract ( 123 )

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This paper presents the application of 3D visualization technology to the buried hill area A with complicated structures in Tabei uplift of Tarim basin, including seismic horizon calibration, trace strata, structural interpretation, fault interpretation, etc. The preliminary approach to the fault structures in buried hill allows the problems about such a systematic interpretation and description of fault structures in studied area to be well solved, which is difficult to be done by conventional seismic interpretation methods.

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Application of Multi-Well Constrained Seismic Inversion to Reservoir Prediction

WANG Quan-feng, WANG Yuan-jun, GUO Ke, SU Jiang-yu

2008, 29 (3): 367-369.

Abstract ( 149 )

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Langa anticline belt located in southern Tahe oil field is of condition of non-anticline trap with low degree of exploration. The conventional inversion method depending on the initial model could inversion not be used to get exact inversion result, while the constrained sparse-pulse inversion does not depend on any model but on the characteristics of original data. This paper presents the principle of the constrained sparse-pulse inversion technology and its application to Langa area in reservoir prediction, including extraction of the wavelet of seismic traces near the borehole, synthetic seismogram, horizon calibration, wave impedance inversion, and conversion of obtained the absolute wave impedance profile into sand-shale seismic profile. The results are accordant with the drilling results.

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Application of Spectrum Decomposition Technique to Prediction of River Channel Sands

HU Shui-qing, HAN Da-kuang, LIU Wen-ling, WANG Yu-xue

2008, 29 (3): 370-372.

Abstract ( 119 )

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Based on the seismic reflection of fluvial reservoirs, using the spectrum decomposition technique by Discrete Fourier Transform in short window, this paper attains the object using the imaging feature of 4D time-frequency volume in frequency domain to predict the distribution of river channel sands, by which the spectrum decomposition data from 1st block of East-1 area in Dagang oilfield are applied to analysis of the distribution feature of fluvial channel in southern studied area with low well-control condition. The predicted results have been proved by drilling data.

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Application of Shear Wave Anisotropy to Fracture Evaluation in Anpeng Area

SHEN Hui-lin, YANG Jin-hua, GAO Song-yang

2008, 29 (3): 373-375.

Abstract ( 168 )

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According to the split phenomenon of shear wave transmitted in anisotropic strata, the natural or induced fractures parallel or oblique cross to a bore hole could create shear wave anisotropic characteristic. The size of anisotropy reflects the growth degree of fractures. The polarization direction of fast shear wave indicates the trend of fractures. Hence, the fast and slow shear wave information could be picked-up using dipole acoustic imaging log data, obtaining the size of anisotropy, from which the validity and trend of fractures in Anpeng area are evaluated qualitatively.

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Application of 3D Converted Wave Processing to Xinchang Area

MA Zhao-jun, TANG Jian-ming, LV Qi-biao

2008, 29 (3): 376-379.

Abstract ( 122 )

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With the fast development of multi-component digital seismograph and the improvement of acquisition methods, 3D converted wave seismic exploration tends to be more and more applied to global oil-gas exploration. However, most of real effects are almost all less than those by theoretical expectations. One important reason is that the 3D converted wave processing is to be improved for it does not allow to be processed by conventional P-wave technique. This paper presents the research of this 3D converted wave processing technique by the wide-azimuth 3D and 3-component data from Xinchang area, including coordinate rotation from acquired coordinate to processing coordinate, vector filter for denoise based on non-correlation between the signals and the noises, structural time-controlling converted wave static correction, four-parameter anisotropic velocity analysis and converted wave pre-stack Kirchhoff time migration techniques. Following processing by these techniques, the pre-stack time migration-stack profiles are clearer in imaging, more accurate in location, better in geological configuration and more accordant with the P-wave profiles in structure.

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Application of Reflection Strength Slope to Identification of Sequence and Sedimentary Environment

FENG Ming-you, HAN Qiang, PU Ren-hai

2008, 29 (3): 380-381.

Abstract ( 140 )

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Base on core and well log comprehensive analysis and the sensitivity of the slope of reflection strength of seismic attributes to depositional sequence, the sedimentary facies in sand-shale member of Bachu formation of Lower Carboniferous in Tahe oilfield of Tarim basin is studied, identifying flood tidal delta, coastal shoreface sand, lagoon and barrier island etc. from lateral variation map of reflection strength slope and sedimentary cycle correlation. The identified results are closer to real situations than those from utilizing the seismic attributes.

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Application of Support Vector Regression Machine to Productivity Prediction in Gas Well

TONG Kai-jun, SHAN Yu-ming, LI Hai-peng, LI Xing-yun

2008, 29 (3): 382-384.

Abstract ( 177 )

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The gas well productivity prediction is one of the main tasks to guide the reasonable production of a gas field in gas pool engineering study. It has intensely forecastive and initiative in the whole evaluation of a gas field and in the process of high efficiency development. Based on the well log interpretation, this paper introduces the support vector regression machine (SVRM)which has preferable forecasting effect to set up the forecasting model for gas well productivity, being suitably applied to prediction of the gas well productivity without dynamic data. The case study shows that this method has more accuracy than traditional nerve network and is a successful evaluating method for gas well productivity prediction. Meantime, it offers a new way for fast quantitative assessment of oil-gas reservoirs.

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Distribution and Structures of Large and Medium Oil-Gas Fields in China

JIN Zhi-jun

2008, 29 (3): 385-388.

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Based on the results studied from 100 large and medium oil-gas fields in 15 petroliferous basins of China, it is suggested that the large and medium oil fields of China are mainly distributed in rift basins, while the large and medium gas fields distributed in cratonic basins and piedmont basins. Continental source rocks as the main ones in the oil and gas fields in China are found from the Early Paleozoic and the Cenozoic. The gas source rocks are mainly distributed in the Tertiary in the South China Sea and the East China Sea, Jurassic, Carboniferous and Permian in northern China, and the Tertiary, Cretaceous, Jurassic, Triassic and Permian are the main oil source beds. The reservoirs in the large and medium gas fields are characterized by terrestrial rocks such as medium sandstone, fine sandstone and glutenite, with genetic types of fan delta and delta system, of which carbonate reservoirs are dominated by fractured and weathering crust types and cap rocks by homogenous shale. The hydrocarbon accumulation periods are generally late, most of the fields are formed in the Cenozoic. Therefore, many oil-gas fields with a quite lot of reserves are still not found in Lower Paleozoic strata. It is concluded that China is rich in petroleum resources, most of basins are in the early-middle stages for petroleum development, and findingout large and medium oil-gas fields in China is big in probability in the future.

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