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01 February 2006, Volume 27 Issue 1 Previous Issue    Next Issue

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Attempt to Explain the Enigma of“Chinese Geological Bermuda” LUO Zhi-li, YAO Jun-hui, SUN Wei, ZHAO Xi-kui, LIU Shu-gen 2006, 27 (1):  1-4.  Abstract ( 123 )   PDF (456KB) ( 287 )   Save The triangular Songpan-Ganzi folded area in eastern Qinghai-Tibetan plateau is almost covered with very thick Triassic turbidite deposit and lots of geologic information may be enveloped, so it becomes a mysterious land in China. Its particularity of geologic structure, multi-explanation of most geologic problems and uncertainty of domestic experts’recognitions allowed this area to be even called“Chinese Geological Bermuda”(after Xu Zhi-qin, 1991). This paper discussed this problem in detail in aspects of old plate tectonic evolution, “Emei mantle plume”, “Emei taphrogeny”and sedimentary basin evolution, etc., trying to uncover the mysterious geological veil. In addition, this paper puts forward several fundamental issues to be discussed that are most interested in nowadays in domestic geosciences field. References | Related Articles | Metrics

The Structur al Char acter istics and Oil-Gas Explor ative Dir ection in Junggar For eland Basin KUANG Jun, QI Xue-feng 2006, 27 (1):  5-9.  Abstract ( 144 )   PDF (423KB) ( 300 )   Save Junggar basin is regarded as a large-scale composite basin superimposed by intracontinental and foreland basins. Since Carboniferous era, it underwent the processes of three-period expanding and thermal subsiding, developing three series of source rocks. In its three-period foreland basins shaped a series of structural belts, developing three vital stages for hydrocarbon accumulation. It was the multi- superimposition that formed such three foreland thrust belts as the northwestern margin, the southern margin and the northeastern margin of Junggar basin, of which the overthrust fault belt in the northwestern margin was already by the proof a large-scale oil-gas accumulation belt; the large- and middle-scale oil-gas fields in thrust fold belt of the southern margin are being found one after another, and the foreland thrust belt in the northeastern margin has appeared better and better exploration prospects. The prospecting practices indicate that this foreland thrust belt in northeastern margin of Junggar basin has a great deal of explorative potentials with obvious realms and clear targets, being an important domain for the incremental reserves and productions in Junggar basin. References | Related Articles | Metrics

Sedimentary Setting of Mesozoic and Its Petroleum Geologic Featur es in Western Tar im Basin LIU Sheng, QIU Bin, CHEN Xin-an, LI Yong, ZHAO Wei-dong, ZHANG Xian-jun, ZHEN Ya-fang 2006, 27 (1):  10-14.  Abstract ( 82 )   PDF (757KB) ( 227 )   Save The geophysical information and surface geologic data from Kashi sag in Tarim basin are comprehensively analyzed. The study shows that several sedimentary centers appear in Mesozoic of this area, characterized by that the thickness in the west is bigger than that in the east and pinch-out toward the east. There exist two sedimentary systems in Jurassic: one is the fault basin within Talas-Ferghana fracture belt; the other is the piedmont depressions in South Tianshan and West Kunlun mountains, with distinct differences between them in lithology. Accordingly, the source rocks in the two systems produce two petroleum systems, and the petroleum geologic feature of Mesozoic in Kashi sag is obviously different with Kuqa depression in the east and Afghanistan-Tajikistan basin in the west. It is believed that the reason for such differences is that the sedimentary settings in Mesozoic era are different among them. References | Related Articles | Metrics

The Oil-Gas Migr ation Events in Kela-1 Structur e in Kuqa Depr ession, Tar im Basin GAO Gang, HUANG Zhi-long 2006, 27 (1):  15-18.  Abstract ( 94 )   PDF (529KB) ( 226 )   Save The logging and formation test data as well as soluble organic matter feature of Cretaceous and Tertiary reservoirs in Kela-1 structure of Kuqa depression in Tarim basin are analyzed and the multi-period petroleum migration events are discussed. The study shows that Kela-1 structure was not a gas pool, but in the course of its geological history, the multi-period petroleum migration events even occurred here. And the prevalent occurrences of its multi-period/stage petroleum migrations become one of advantageous conditions for hydrocarbon accumulation in Kuqa depression. The key factor that the hydrocarbon accumulation really occurred by the multi-period/stage petroleum migrations depended on whether there existed complete trap( s) and deep fault linked to the reservoirs and the source rocks or not, because the existing gas pools are mostly resulted from an effective match between the complete trap(s) and such a deep fault. References | Related Articles | Metrics

Study on Hydrocarbon Accumulation of Litho-Str atigr aphic Tr aps in Southern Songliao Basin WU Ya-dong, ZHAO Wen-zhi, ZOU Cai-neng, LI Ming, WU Xian-shun 2006, 27 (1):  19-22.  Abstract ( 76 )   PDF (1162KB) ( 214 )   Save With further exploration of major structural traps in southern Songliao basin, the prospecting target has gradually focused on the non-structural reservoirs dominated by litho-stratigraphic traps. However, the complex and hidden nature of this type of reservoirs in geologic condition and distribution pattern cause them to be difficult to understand or recognize, adding the difficulty for their explorations. The great potentials for exploration of litho-stratigraphic reservoirs do not appear until new methods and technologies have been applied and in-depth understandings have been gained. In recent two or three years, big discoveries have been made in Jilin oilfield, in which 80 percent of reserves are found in some areas of thin sand-shale interbedding of its delta front There still exist petroleum potentials amounting to 6×108 t for exploration in this area, especially in southern Songliao basin where the litho-stratigraphic traps will be more important domains and deserve extra attention. Hence, geologically speaking, this study on the hydrocarbon accumulation of lithostratigraphic reservoirs in Songliao basin is of vital significance to exploration of the southern Songliao basin. References | Related Articles | Metrics

Hydrocarbon Fluid Inclusions and Petroleum Accumulation in Subei Basin CHANG Xiang-chun, WANG Ming-zhen, LIU Yu-rui 2006, 27 (1):  23-26.  Abstract ( 89 )   PDF (622KB) ( 179 )   Save By means of fluid inclusions testing technique, the reservoir fluid samples from different strata in two sags of Subei basin are analyzed. The homogenization temperature distribution of hydrocarbon inclusions shows positive correlation with the diagenesis of host minerals. Geochemical study of these inclusions indicates that source input and maturity variations occur in different areas and horizons. The multiple biomarkers reveal the reducing sedimentary environment with high salinity. The diversity of hydrocarbon-generating conditions cause that the oil charging period in Gaoyou sag is earlier than Jinhu sag at the same horizon and Fu-1 member is earlier than other horizons or members at the same area. References | Related Articles | Metrics

Evolution of Faulted Lacustr ine Basin and Hydrocarbon Accumulation in Huimin Sag ZHU Guang-you, JIN Qiang, ZHANG Shui-chang, ZHANG Lin-ye, LI Jian 2006, 27 (1):  27-30.  Abstract ( 78 )   PDF (564KB) ( 344 )   Save Shahejie formation of Paleogene is the most important source rock in Huimin sag which is divided into sub-sags of Linnan, Zizheng, Yangxin, Lizezheng. The differences of these sags' depositions lead to their different environments and potentials for hydrocarbon generation. Linnan sub-sag is in big thickness of deposition, which is favorable for source rock evolution such as Sha-3 and Sha-4 sections, belonging to stable subsiding or deep buried type, around which there exist large scale hydrocarbon accumulations; while Xinyang, Zizheng and Lizezheng are in relatively shallow buried depth due to late slowing subsiding of pelitic rock deposits in certain depth of Sha-3 and Sha-4 sections, belonging to gradually rising and mid-shallow buried type, and their slower hydrocarbon-generation evolutions allow scattered low mature or immature hydrocarbons to be found around them. It is the episodic and multi-cycle features of sedimentation and evolution in Linnan sub-sag that form multi-set source rocks with rich organic matters. The correlation among the oil sources shows that producing crude oil just comes from Sha-3 source rock. The upper section of Sha-4 source rock is in deep buried depth and high maturity, but related oil-gas reservoirs are not found up to now. Hence, the upper section of Sha-4 source rock should be as an important target for petroleum exploration in future here. References | Related Articles | Metrics

Biomarker Char acter istic of Crude Oil and Sour ce Cor r elation in Ying' er Sag, J iudong Basin MA Li-yuan, CHENG Ke-ming, XIONG Ying, YANG Zhi-ming 2006, 27 (1):  32-34.  Abstract ( 92 )   PDF (427KB) ( 168 )   Save Through analyses of the biomarker characteristic and its effect on sedimentary setting, water salinity, maturity and parent material, the crude oil from Ying'er sag in Jiudong basin can be classified into the crude from Zhonggou formation in Yingcan-1 Well and the crude from Jiucan-1 Well, Chang-101 Well and Chang-2 Well. These two types of crude oils are distinct in maturity and biomarker characteristic. The source correlation result shows that the former crude mainly originates in the source rock of Zhonggou formation, being a product of immature to low-mature phases, hence regarded as immature-low mature crude; the latter primarily originates in those of Chijinbu formation and Lower Xiagou formation in mid-south part of Ying'er sag, and high maturity, partial acid sediments and bacterium depositional organic matters with clay minerals are its major sources. References | Related Articles | Metrics

Geologic Attr ibute of Large-Scale Build-Up in Cambr ian Platform Margin, Tahe Oilfield DING Yong, YUN Lu, WANG Yun-cheng 2006, 27 (1):  35-37.  Abstract ( 130 )   PDF (828KB) ( 182 )   Save Tahe oilfield, located in Akekule swell of south flank of Shaya uplift in northern Tarim basin, is an important base for incremental reserves and production of Sinopec. In 2004, the clue of Cambrian large-scale build-up was found by Northwest Branch during nine-block seismic interpretation. The determination of the geologic attribute of this build-up is of great significance for the nextstep exploration and its long-term deployment. This paper excludes the possibility that the build-up could be salt and volcanic rocks by the analysis of Cambrian reef-building organisms, the case study and the evaluation of sedimentary environment of the build-up, especially by the correlation of geophysical characteristics between the build-up and the volcano and salt body. The analogue from these geophysical characteristics and proved organic reef suggests that this build-up may likely be a bioherm. References | Related Articles | Metrics

Analysis of Oil Source in Well Z-1 in Junggar Basin LI Zhi-ming, QIN Jian-zhong, LIAO Zong-ting, LIU Wen-bin, FAN Ming, WANG Chuan-sheng 2006, 27 (1):  38-41.  Abstract ( 86 )   PDF (539KB) ( 163 )   Save Well Z-1 is located at joint among Changji sag, Maqiao swell and Zhongguai swell that are regarded as Grade-2 structural units in Junggar basin, in which two oil-bearing zones are found at 4 788—4 797 m (K1tg) and 4 808.5—4 812.5 m (J1$s^{1}_{2}$). The GC-MS analyses indicate that both of them have generally consistent geochemical properties in crude family component, carbon isotope and biomarkers, and the same oil source from reducing, salt-bearing and algae-enriched lake facies sediments with high maturity. Oil-source correlation shows that the crude oils in two zones mainly originate in the source rocks of Permian, mixed with certain crude oils from Jurassic or Jurassic-Triassic source rocks. Such a result is consistent with the geological background of existing multi-set source rocks in the studied area. References | Related Articles | Metrics

Integrative Fracture Detection for Carbonate Reservoir by Confidence Limit Analysis WEN Xiao-tao, HE Zhen-hua, HUANG De-ji 2006, 27 (1):  42-44.  Abstract ( 69 )   PDF (389KB) ( 135 )   Save Complexity of carbonate reservoir pore space allows single parameter or method to give non-uniqueness of solutions and be likely limited by regional geologic conditions. For this reason, this paper presents a method for confidence analysis-based integrate fracture detection. The method makes use of correlation between well log fracture interpretation and other fracture detection results to weight all results from different detecting methods in order to improve the detection reliabilities. The method can be used in different areas like Tahe oilfield without any restriction from complicated geologic conditions. The case study shows better effectiveness than before. References | Related Articles | Metrics

The Effect of Faulted Structure on Petroleum Accumulation—An example of Dongpu sag LEI Li-an, DUAN Ai-li 2006, 27 (1):  45-48.  Abstract ( 84 )   PDF (482KB) ( 326 )   Save The development and origin of faults in Dongpu sag are studied. The effects of the faulted structures on the petroleum accumulation in this area are discussed. It is pointed out that these faults with different classes and different phases are characterized by long-term inherited development, which not only control the formation and development of Dongpu sag basin, but also control the source sub-sag's formation and distribution as well as the sedimentations of source rocks and reservoir rocks, followed by controlling the shape, distribution and enrichment of every oil-gas trap in this basin. References | Related Articles | Metrics

Heavy Minerals Char acter s and Geologic Significance of Yanchang Formation in Fuxian Exploration Area, Ordos Basin ZHANG Xin-jian, ZHANG Jian-jun 2006, 27 (1):  49-52.  Abstract ( 85 )   PDF (315KB) ( 196 )   Save Proper understanding of paleocurrent and source direction in study area at stage of hydrocarbon prospecting is of great significance for the reservoir prediction and the trap evaluation. Fuxian exploration area is located in the southeastern Ordos basin, adjacent to lacustrine sedimentary area of the basin. In recent years, there are some debates about the directions of paleocurrent and sources. There are many kinds of methods for source analysis such as heavy minerals method, sedimentology method and geochemistry method. The heavy mineral analysis method is applied to analyze the characteristics of Yanchang heavy minerals in study area. Combined with the paleocurrent survey data of the outcrops and the regional lithofacies paleogeography feature, it is pointed out that the sediments in this exploration originate from the northeastern Ordos basin and the paleocurrent directions point to the southwest on the whole. References | Related Articles | Metrics

Study of the methods for Seismic Data Processing in Henan Prospecting Area in Tarim Basin DU Yao-bin, ZENG Qing-cai 2006, 27 (1):  53-55.  Abstract ( 81 )   PDF (599KB) ( 220 )   Save The 2-D initial seismic data show that Abei, Shunbei and Caohu areas in Tarim basin are characterized by deep buried target zones, complex surface and subsurface geologic structures, problems in static correction, developed interference wave and low signal-tonoise ratio. This paper uses the techniques such as composite static correction of partial offset distance and dominant frequency, multi-domain noise elimination, accurate velocity analysis and deep superimposed imaging to better deal with the problem appeared in past static correction and low signal-to-noise ratio, improving the accuracy of the deep superimposed imaging. Preliminary seismic interpretation and geologic analysis indicate that the processed profile is in good continuity of events, high signal-to-noise ratio, proper return, clear structural attitude and larger scale, generally revealing the subsurface structures in the profile-studied area, including some structures or structural shows that never recognized before. This study enriches knowledge about the structural characteristics and structural evolution in this area. References | Related Articles | Metrics

Novel Progress of Upper Carboniferous Study in West Section of Mageti Slope, Tarim Basin ZHANG Xian-jun, WANG Yue-hua, MA Li-ke, ZENG Chang-min, FENG Xiao-jun, HAN Li-jun, QU Dong-feng 2006, 27 (1):  56-58.  Abstract ( 80 )   PDF (580KB) ( 194 )   Save The correlation and study of Upper Carboniferous in west section of Megati slope show that two unconformities occur within the Carboniferous: one lies in major limestone between Nanzha formation of Permian and Xiaohaizi formation of Carboniferous, which is of distinct litho-electric feature and oil/gas-controlled process; the other lies at the top of Kalashayi formation of Carboniferous in west section of Mageti slope, being a large and regional unconformity. It is concluded that the latter is shaped by regression and tectonic movement in Late Carboniferous in Tarim basin. References | Related Articles | Metrics

Project Design for Gas Dr ive of Lower Kar amay Reservoir in West Distr ict No. 5-(2), Kar amay Oilfield MEI Hai-yan, GU Hong-jun, XU Guo-yong, DONG Han-ping 2006, 27 (1):  59-61.  Abstract ( 72 )   PDF (372KB) ( 214 )   Save Twenty two gas-drive projects for Lower Karamay reservoir in west District No.5-(2) are designed with individual production performance index prediction for each project. Sensitivity analyses of each gas injection duration, gas injection rate and gas-water alternation cycle are made with numerical simulation method. The results show that by gas-water alternation displacement process, the sum of cycles is not sensitive factor to the production performance, but the gas-water alternation duration and gas injection rate have great effects on gas-injection incremental oil production and gas injection oil production reduction ratio. And the gas drive process is an effective way to improve the reservoir behavior with high water cut and can be applied for great increase of oil recovery compared with waterflooding process. References | Related Articles | Metrics

Application of Generalized S-Shape Growth Curve to Forecast Water -Cut of Oilfield LI Zu-you, ZHU Yi-dong, TANG Jian, YANG Bai-shu, RONG Ning 2006, 27 (1):  62-63.  Abstract ( 97 )   PDF (133KB) ( 241 )   Save The graph of growth curve in its growth process is normally characterized by an oblate shape like "S". A lot of field data got from oil exploration, exploitation and production also appear such a S-shape varied tendency. This paper presents the available six types of S-shape, analyzes their growth rate-varied patterns and deduces the generalized S-shape growth models and curves, followed by developing the oilfield water-cut forecast model the represents these six S-shape growth curves and making solutions with trial and error method. Case study indicates that the generalized S-shape growth model proposed in this paper can be applied to forecasting oilfield water-cut, being as a guide for development of water flood oilfields. References | Related Articles | Metrics

Dynamic Analysis for Bottom-Hole Pr essur e in Composite Gas Condensate Reservoir by Using 3-Realm Flowing Model ZHAN Jing, LI Yun, ZHANG Lie-hui, HU Shu-yong 2006, 27 (1):  64-67.  Abstract ( 86 )   PDF (421KB) ( 242 )   Save The oil-gas distribution model for conventional gas condensate reservoir is not used to properly deal with the bottom-hole pressure in gas condensate reservoir. A new 3-realm composite well testing model of such a reservoir is developed in this paper. The external boundaries with infinite, enclosed and constant pressures are taken into consideration for educing expressions of bottom-hole pressures under different external boundaries and plotting corresponding type curves. The dynamic changes and affected factors to the bottom-hole pressure in this reservoir are analyzed and discussed. The study shows that this new model is more closed to the real conditions in the process of gas condensate production, and it can be as a guide for performance analysis of such reservoirs. References | Related Articles | Metrics

Long-Cor e Test Study of Carbonate Reservoir in Lunnan Bur ied Hill WANG Zi-ming, SONG Wen-jie, LIU Jian-yi, LIU Yong, DU Juan, HUANG Chuan, LIN Shu-wen 2006, 27 (1):  68-70.  Abstract ( 101 )   PDF (402KB) ( 160 )   Save The physical simulation test for depletion drive in carbonate reservoir in Lunnan buried hill is conducted according to the real reservoir conditions of modeling. The domestic artificial map cracking (cavity) core is first presented, which is accordant with prerequisites similar to the real permeability and the percolation spatial configuration of the reservoir, and successfully applied to the long-core test under the conditions of high pressure, high temperature, high salinity and high viscosity available. The test results as basic experimental data have effectively supported the investigations for determination of effects of the petrophysical property, the fluid property and the displacement rate on the oil displacement efficiency in this carbonate reservoir. References | Related Articles | Metrics

Development of Huangshatuo Volcanic Reservoir in Liaohe Basin CHEN Yuan-chun, WU Chang-zhi, WU Yi 2006, 27 (1):  71-75.  Abstract ( 117 )   PDF (427KB) ( 206 )   Save Based on the study of volcanic reservoir in Huangshatuo oilfield of Liaohe basin, the production performance study and field test of it are made, and the development scheme for volcanic reservoir is discussed. It is suggested that because the volcanic reservoir has very high heterogeneity, waterflooding process should not be adopted rashly in the early production period until obtaining experiences from clustered- well test; infill drilling and adjustment during the period of early production may enhance producing extent, prolong waterfree oil production period and improve performance response; a number of horizontal wells drilled during the mid-period of production may further increase the single well productivity and keep relatively long-term production stable and high. These experiences are worthy of use for reference for development of other volcanic reservoirs. References | Related Articles | Metrics

The Equivalent Numer ical Simulation of Fr actur e-Vuggy Carbonate Reservoir in Tahe Oilfield LIU Xue-li, ZHAI Xiao-xian, YANG Jian, ZHANG Lin-yan, REN Cai-qin 2006, 27 (1):  76-78.  Abstract ( 86 )   PDF (172KB) ( 215 )   Save The Ordovician carbonate reservoir in Tahe oilfield is characterized by deep buried depth, multiple storage spaces, complex reservoir type, which lead to difficult reservoir simulation and performance prediction for the existing simulators are hard to simulate the dual porosity reservoirs. This paper develops the mathematical model for fracture-vuggy reservoir and proposes the expression or formula that fracture-vuggy media system is equivalent with fracture-matrix media system by using percolation dynamics theory, in order to better use existing simulators of such kinds of reservoirs. This method is effectively applied to simulate an oil well penetrating the Ordovician carbonate reservoir in Tahe oilfield. References | Related Articles | Metrics

Thermodynamic Model for Pr ediction of Wax Pr ecipitation in Gas Condensate Mixtur es LI Dao-xuan 2006, 27 (1):  79-81.  Abstract ( 108 )   PDF (169KB) ( 150 )   Save Based on the experimental results, this paper puts forward a thermodynamic model for prediction of was precipitation in gas condensate mixtures. The model regards the process of wax precipitation as that of multi-solid phase precipitations. The precipitated wax composed of a number of solid phases, and each phase is made up of a pseudo-component, without any mixture among the solid phases. Accordingly, this paper proposes a vapor-liquid-multi-solid material balance equation. Integrated with the empirical equation for calculation of solution heat in condensate system and the multi-solid flash numerical algorithm, this model can be applied to quantitative simulation and estimation of the wax precipitation amount, obtaining vapor-liquid parameters by using equation of state. The estimation results show that the wax precipitation amount and related temperature given by the model are in good agreement with the experimental data for the condensate hydrocarbon mixtures. References | Related Articles | Metrics

The Simulation Test for Effects of Changes in Sandstone Thickness and Quality on Hydrocarbon Accumulation JIANG Su-hua, LI Tao, JIANG Yu 2006, 27 (1):  82-85.  Abstract ( 80 )   PDF (513KB) ( 184 )   Save On the basis of comprehensive geological study of hydrocarbon migration and accumulation of Neogene in eastern beach area of China, the simulation test for effects of changes in sandstone thickness and quality on hydrocarbon accumulation in two sides of conducting fault is conducted by means of 2-D model. The result shows that in one hand, in two sides of fault, the thick sand layers is the most favorable to become a reservoir; the intermediate sand layers are regarded as oil layers where quality is good and as water layers where quality is poor, appearing the oil layer, the oil-water layer and the water layer in turn in terms of distances from the conducting fault; the thin sand layers could not become oil layer until the quality is the best, otherwise, become water layer. Hence, the sand layer thickness plays a decisive role, while the quality has an important effect on becoming a reservoir, both of which there have been some complementary relations. In the other hand, the sand layers indirectly connected with the conducting sand beds and the conducting faults, the reservoirs are not only related to their thickness and quality, but also depend on the conducting sand beds' thickness and quality. Only connecting such sand beds with big thickness and fine quality, could the petroleum accumulation or oil layer be favorably formed; otherwise, oil-water layer or just water layer be formed instead of become oil layer. The changes of conducting sand beds' thickness and quality are the key for affecting petroleum accumulation within sand layers. References | Related Articles | Metrics

Well Testing Model for Finite Multi-Well System and Type Curve Analysis ZENG Tao, JIA Yong-lu, WANG Hai-tao, TANG Dong, ZHANG Wu 2006, 27 (1):  86-89.  Abstract ( 153 )   PDF (889KB) ( 217 )   Save Study of finite multi-well system is made by taking two wells an example. A new method for pressure superposition of Laplace transformation is applied to deduce the Laplace's solution of well testing model for finite multi-well system. The convenient and practical method can be easily extended to the conditions of many adjacent wells. This paper draws the type curves and analyzes influences of various factors such as distance and production from adjacent wells on the two testing wells. The results show that most wells would be influenced by adjacent wells in the subordinate phase of production characterized by the dropping of differential of pressure curve similar to that of boundary reflection. Using this well testing model for interpretation could exclude these interferences to a large extent and improve the utilization and effect of well testing data. References | Related Articles | Metrics

Application of Gener alized Regr ession Neur al Network and Genetic Algor ithm to Production Decline Analaysis WANG Guo-chang, LV Xue-ju 2006, 27 (1):  90-93.  Abstract ( 84 )   PDF (129KB) ( 193 )   Save Most oilfields developed in China up to now have already entered into the stage of production decline, so the theories about this stage are in urgent demand. But the shortages of conventional theory about it cause its application to be greatly restricted for the key problem of solution for decline index. The generalized regression neural network (GRNN) and the genetic algorithm (GA) are regarded as the artificial intelligence techniques. GRNN has little demand on data sampling, easily approaching to any type of functions; GA can be used to look for the best results in full and partial ranges. The combined application of these two techniques will overcome the shortages of conventional theory. This paper established the GRNN and uses an improved GA to search for the optimum smoothing factor in full range, hence proposes a model. By application of this model to Gudao oilfield in the stage of production decline, good effects are gained. References | Related Articles | Metrics

Optimum Per for ated Interval for Well Producing from Bottom Water Reservoir with Gas Cap LI Chuan-liang, JIN Hai-hu 2006, 27 (1):  94-95.  Abstract ( 166 )   PDF (174KB) ( 240 )   Save For a well producing from reservoir with bottom water and gas cap, the water and gas avoidances must be taken into consideration for its position of optimum perforation. The critical flow rate of well decreases with the increase of perforated degree, while the flow rate of well increase with the increase of perforated degree. Base on theoretical analysis, the method for determination of optimum perforated degree of reservoir with bottom water and gas cap is presented. Technically, the optimum perforated degree of well is defined as its critical flow rate is equal to its flow rate. However, the case study shows that under barrier-free condition the perforated degree is used to being lower and resulting in lower flow rate of well. Therefore, the barrier distribution should be taken into consideration for the perforation of reservoir with bottom water and gas cap. References | Related Articles | Metrics

Composite Application of Well Log Data to Evaluation of Oil-Gas Zones—An example of Shinan field, Kar amay oilfield SONG Yu-xin, ZHANG Jun-jie, YANG Hong, JI Jia-qi, DONG Yan-xi 2006, 27 (1):  96-98.  Abstract ( 110 )   PDF (381KB) ( 250 )   Save Well logging methods and applied conditions are presented. Combined with the geologic feature of Toutunhe reservoir in Shinan-21 Well Block, the method for identifying and quantitatively evaluating oil-gas zone by using well log data is approached. The analysis of applied response from array induction log and the analysis of filtrate-invaded zone are conducted to study the log response features of oil and water layers, by which a quick and visual distinguishing method for distinguishing pay zone by means of well log data is proposed. The core-calibrated log approach and the statistical analysis technique are adopted to realize the application of developed quantitative reservoir evaluation model to detailed reservoir evaluation and well log interpretation and offer more proper parameters. For the study of oil-water distribution, the multi-well MDT data are used to build up the reservoir pressure profile and determine the fluid density of the reservoir. By the composite analysis of available conventional well log and production test data, the oil-water contact of this reservoir is exactly determined. References | Related Articles | Metrics

Study on Estimation Methods for Hydrocarbon Economic Recover able Reserves ZHANG Yu, BAI He-xian, QIU Yang, LI Jie 2006, 27 (1):  99-103.  Abstract ( 78 )   PDF (176KB) ( 404 )   Save According to the new criterion for Classification of Oil and Gas Resources/Reserves (GB/T19492-2004) issued in 2004, this paper reviews the studied methods at home and abroad for the purpose of establishment of new series of recoverable reserves such as technically recoverable reserves, economic recoverable reserves, sub-economic recoverable reserves and remaining economic recoverable reserves of oil-gas fields. Combined with the oilfield geology and development feature, this paper further researches and proposes the estimation methods for economic recoverable reserves such as economic limit, well pattern density, marginal cost and analogy ones, based on domestic current financial and taxation system and cash flow method followed by making category and analysis according to the basic principles and applied conditions of each method. Finally, this paper develops a model for estimation of the reserves value, which allows the estimations of the economic recoverable reserves and the remaining economic recoverable reserves to be more scientific by elaborating given parameters hypotheses and by converting the estimation of physical quantity into that of combination of both physical quantity and value quantity, thus brings the work in line with the international practice for reserves estimation. References | Related Articles | Metrics

Application of Capillary Pr essur e to Determination of Cut-off Pore-Throat Radius in Reservoirs WAN Wen-sheng, DU Jun-she, TONG Guo-zhang, ZOU Min, QIN Xu-sheng, TAN Wen-dong, NAN Hui 2006, 27 (1):  104-106.  Abstract ( 108 )   PDF (300KB) ( 335 )   Save The logarithmic graph and the cumulative probability diagram for pore-throat radius vs mercury injection saturation are presented, in which the straight-line portion similar with the suspending line portion on cumulative grain-size probability curve means the difficult-to-flow and stagnation pore domains in reservoirs, from which the typical cut-off pore-throat radius is read directly and verified by the conventional pore-throat radius method and the modern nuclear magnetic resonance technique. In addition, the combination of capillary pressure curve and spectrum t2 of nuclear magnetic resonance can help to directly determine the cut-off oil-bearing pore-throat radius. References | Related Articles | Metrics

Productivity Calculation for Near -Wellbor e Scale of Hor izontal Well with Par tial Degasification LI Chun-lan, CHENG Lin-song, ZHU Guo-jin, FENG Guo-zhi 2006, 27 (1):  107-108.  Abstract ( 103 )   PDF (206KB) ( 266 )   Save The reservoir pressure is generally higher than the bubble point pressure, but the flowing bottom-hole pressure is often lower than it. The near-wellbore tends to appearing partial oil degasification. This phenomenon is usually neglected. However, the single-phase flowing formula used for calculation of horizontal well productivity in this case may cause a bigger error. This paper simplifies the flowing model and conducts an infinitesimal processing of the two-phase flowing zone, thus establishing a more reasonable method for calculating horizontal well productivity with partial oil degasification. This method can also be used to calculate the limit oil productivity and the limit producing pressure differential of horizontal well. References | Related Articles | Metrics

A Novel Method for Calculation of Heating Radius in Heavy Oil Reservoir by Steam Stimulation Process FAN Hai-jun, YAO Jun, CHENG Zhi-jun 2006, 27 (1):  109-111.  Abstract ( 124 )   PDF (194KB) ( 233 )   Save The flowing material balance method, a new method for reservoir engineering dynamic analysis, is presented and applied to the well test analysis of heavy oil steam stimulation, calculating the heating radius and formation contaminant factor in this paper. The case study shows that production and monitoring/testing data are comprehensively used to conduct dynamic analysis of heavy oil reservoir engineering by this method, with simple procedure and reliable results of calculation. References | Related Articles | Metrics

A Review of Deep Origin of Crude Oil ZHANG Zhi-yi 2006, 27 (1):  112-117.  Abstract ( 95 )   PDF (553KB) ( 184 )   Save Microelements of crude oil and isotope compositions (Pb, Sr and Nd) show petroleum is a product from deep mantle source. The facts that there is coexisting relationship among petroleum, metal and diamond deposits, and hydrocarbon and bitumen occur in the inclusion and kimberlite indicate that petroleum even took part in the hydrothermalism. That crude oil and natural gas lie in petroliferous basins is related to the basinal basement crust's insulation which allows the preservation of volatile compositions in asthenosphere of upper mantle bulge and the full geochemical actions. The basinal basement crust is the more stable hard block, its rotation occurred under the global strike-slip process may lead to forming variety of deep faults and traps under the compresso-shear and tenso-shear stresses besides uplifting of mantle. The deep faulting in late periods of tectonic movements becomes the channels for oil-gas migration, when the oil-gas reservoirs will be formed as long as there is any trap. The theory of deep source origin is based on strict experiments. The petroleum thermodynamic equilibrium calculation demonstrates that oils can be originated in mantle's asthenosphere. The different depths of hydrocarbon composition occurrences provide rational explanations for zonations of oil and gas. References | Related Articles | Metrics

The Prospective Evaluation for Explor ation of Coal-Bed Gas in South China QIN Jun, ZHANG Jie-hui, XU Ke-ding, YANG Bin 2006, 27 (1):  118-120.  Abstract ( 73 )   PDF (250KB) ( 186 )   Save coal-bed gas as a clean energy resource is closely related to coal resources and regarded as an unconventional natural gas with both source and reservoir. In South China, nine sets of coal measure strata have been found, but the exploration and development of them mainly lie in the Longtan formation of Upper Permian and the Anyuan formation of Upper Triassic. This paper presents the prospective evaluation of 25 blocks with preferable coal-bed gas conditions, of which Class-1 consists of seven blocks, Class-2 of six blocks, Class-2 to-3 of three blocks and Class-3 of eight blocks. The areas of Huainan, Xuhuai, Liupanshui, Zhina, Qianbei, Fuyuanenhong and Guiyang are the seven large-scale and advantageous blocks with enriched coal-bed gas accumulations. References | Related Articles | Metrics

Hypotheses of Or igins of Oil, Natur al Gas and Diamond by Underground Discharge/Radiation LIU Xian-zhi 2006, 27 (1):  121-123.  Abstract ( 118 )   PDF (116KB) ( 180 )   Save A brief introduction of hypothesis of earthquake and volcano origins by underground avalanche and discharge is made. Based on the fact of existing strong underground discharge and earthquake lighting (such as ultraviolet light, etc.), and the basic fact of organic compounds (such as amino acid, hydrocarbon, oil oligomer, etc.) generated by the process of inorganic matter under the discharge and ultraviolet radiation, the hypothesis of origins of oil, natural gas and diamond by underground discharge or underground radiation is proposed. The positive correlation phenomenon or adjacent phenomena between distributions of earthquake or volcano and the distributions of continental oil and gas fields in China are revealed. It is pointed out that the explorations of oil, natural gas and diamond should pay more attention to the regions where earthquake or volcano has been active and the vicinities where more carbon compounds and groundwater exist underneath. References | Related Articles | Metrics

Approach to Identification Method for Chaos Fr actal Char acter istic of Water -Flooded Zone WANG Ren-yi, WANG Qian-rong, ZHANG Bin-cheng 2006, 27 (1):  124-126.  Abstract ( 83 )   PDF (314KB) ( 188 )   Save The complex differential waveforms between geophysical logging curves conceal petroliferous information of reservoirs, which can be described by chaos dynamics system. And the chaos attractor is of low fractional dimension. The study shows that the phase space attractor of pay zone is characterized by self-scaling structure and relatively high dimension and fast convergence of correlation dimension spectrum; the phase space attractor of water-flooded zone or water layer is of clearly weakening chaos characteristic and simple/in-order system with low dimension and slow convergence of correlation dimension spectrum. The signal chaos dynamics characteristic only depends on the signal complexity level and is independent of the signal absolute value. It is concluded that the method for well logs-based chaos fractal characteristic to identify water-flooded zone can be well applied to distinguish low-resistivity pay zone and high- resistivity water-flooded zone or water layer that are badly identified by using conventional well log interpretation theory. References | Related Articles | Metrics

Poroperm Char acter istics and Their Var iation with Changing of Bur ied Depth of Jurassic Reservoir s in Nor th Par t of West Siber ian Province G. G. Xiemin, A. U. Niehaev 2006, 27 (1):  127-133.  Abstract ( 75 )   PDF (1101KB) ( 163 )   Save The regional classification of Jurassic reservoirs and a great deal of data about porosity and permeability of 8 000 samples are analyzed. It is pointed out that the Jurassic reservoirs are generally characterized by moderate-low porosity and lower permeability, where the Oxfordian and Bathonian stages are of the maximum values, while the Alinbayios and Toar stages the relatively low, and the Plinsbahe and Hettangian-Xinemuer stages the minimum. The pay zones$Ю_{1}^{1}-Ю_{1}^{4}$,Ю2,Ю3 are moderate in porosity and moderate-lower in permeability. How well the poroperm characteristics of these reservoirs depend upon the buried depths of them. The Upper Jurassic sands are moderate in effective porosity ranging from 14.2% to 11.2% and intergranular permeability from 236×10-3μm2 to 19.62×10-3μm2; the Lower Jurassic sands (in depth of 2 750—3 750 m) range from 14.8% to 7% and from 7.90×10-3μm2 to 0.03×10-3μm2; below depth of 4 250 m the granular reservoirs of Jurassic are in limited distribution, their petroleum potentials are possibly related to secondary undercompaction and fractured reservoirs development. It is concluded that the values of poroperm characteristics of Jurassic reservoirs in northern West Siberian province are decreased with the buried depth due to different compactions of the overburden pressures. References | Related Articles | Metrics