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01 April 2010, Volume 31 Issue 2 Previous Issue    Next Issue

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The Deep Structural Features and Hydrocarbon Prospect in Hinterland of Junggar Basin QI Xue-feng, WU Xiao-zhi, LIU De-guang, TANG Yong 2010, 31 (2):  111-114.  Abstract ( 138 )   PDF (316KB) ( 640 )   Save Thrust-fault system and palaeohighs are developed in deep structures in hinterland of Junggar basin. In the north the burial depth of them is shallower and characterized by concave-convex structural framework; in the south that is deeper and features relatively independent palaeohighs. The oil sources of the deep strata (C-P) are adequate, and the petrophysical properties of reservoirs can be conserved effectively. In the Lower Carboniferous occur dark argillaceous source rocks of transitional facies, which are favorable for selfgeneration and self-preservation due to rich resources; while the special volcanic reservoirs of Carboniferous are not restricted by burial depth, thus relatively premium reservoirs are developed in deep strata which undergo such four-stage reservoir formations, destructions and adjustments as Late Hercynian, Late Indosinian, Middle Yanshan and Late Yanshan orogenic movements. The deeper the deep target strata, the more adjacent they from the source rocks, and the easier the self-generation and self-preservation becomes, even they could form deep-basin natural gas reservoir combination patterns with high temperature and high pressure around inherited palaeohighs. It is concluded that the volcanic rocks of Carboniferous will be a most realistic domain for petroleum exploration for their big thickness, wide distribution and a series of giant forward structures. The Moshen-1 Well in Mosuowan swell drilled 7 500 m in depth and penetrated 700 m of Carboniferous indicates that in hinterland of Junggar basin, deep volcanic reservoirs of Carboniferous are developed, revealing bright prospects for exploration. References | Related Articles | Metrics

The Effects of Secondary Outgrowth and Replacement on Reservoir Property GAN Gui-yuan, YAO Xi-hai, WANG Wen-di, YU Hai, ZHU Ye-qian, GUO Li-jun 2010, 31 (2):  115-117.  Abstract ( 108 )   PDF (208KB) ( 566 )   Save The sandstone reservoirs are broadly found in south area in western Qaidam basin, in which existing diagenetic phenomena such as the secondary outgrowth of quartz and the replacement of calcite, dolomite and anhydrite are of great effects on the reservoir petrophysical property. This paper presents the effects of the secondary outgrowth pattern and the replacement intensity on the reservoir petrophysical property. The study shows that the deep strata in Wunan-Lvcaotan area are of developed quartz secondary outgrowth, where the reservoir property is poor; while the replacement of calcite, dolomite and anhydrite reaches strong or extremely strong, the property becomes poor obviously. References | Related Articles | Metrics

Strike-Slip Fault System in Kuqa Foreland Basin and Its Control on Hydrocarbon WU Xiao-zhi, LI Bai-hua, LV Xiu-xiang, XIE Hui-wen, LIU Zhi-gang 2010, 31 (2):  118-120.  Abstract ( 146 )   PDF (386KB) ( 590 )   Save In Tianshan orogen formed by collision between Tarim plate and Junggar plate shaped strike-slip fault system vertical and parallel to Tianshan orogen. The strike-slip fault system parallel to it is of an important effect on the formation and reformation of different structural zones in Kuqa foreland basin, while that of vertical to it gives rise to the structural segmentation in it. Strike-slip faults can form a series of related traps which provide sites for hydrocarbon accumulation. The arterial strike-slip faults have good sealing ability to stop hydrocarbon migration from one side to the others, while the derived strike-slip ones have good connectivity. Hence, the hydrocarbons in this basin could mainly accumulate in area with derived strike-slip faults; the arterial strike-slip faults allow the hydrocarbons to distribute by east-west segmentation and south-north zoning. References | Related Articles | Metrics

The Difference of Maturity History of Carboniferous Source Rocks and the Oil-Gas Distribution in Ludong-Wucaiwan Area XIANG Bao-li, WANG Xu-long, YANG Di-sheng, ZHAO Zeng-yi, LI Lin, WANG Jian-xin 2010, 31 (2):  122-124.  Abstract ( 132 )   PDF (244KB) ( 345 )   Save The difference of maturity of the Carboniferous source rocks in Ludong-Wucaiwan area is analyzed. Such a difference is mainly related to the source rock depth and the subsiding and upstanding of strata in the tectonic movements. The maturity history indicates that there exist three peak stages of hydrocarbon generation for the source rocks in this area, namely, the end of Permian, the end of Middle Jurassic and the end of Early Cretaceous. In different areas the hydrocarbon generation stages are different. The end of Early Cretaceous (the Middle Yanshan movement) is the key period of these source rocks finally reaching mature and the oil-gas accumulation. The distribution of the source rocks controls the distribution of oil and gas in this area, while the maturity of the source rocks controls the component of hydrocarbons. References | Related Articles | Metrics

Classification of Characteristic of Igneous Rocks in Hinterland of Junggar Basin HE Gang, WANG Zhi-zhang, TAN Fu-lin, LONG Shan, DONG Yan-xi, WANG Hong-liang 2010, 31 (2):  125-127.  Abstract ( 204 )   PDF (165KB) ( 817 )   Save The igneous rocks in Junggar basin are in wide distribution. The igneous reservoirs are characterized by developed fractures and high yield. They play an important role in incremental reserves and production in Karamy field. This paper presents the classification and characteristic analysis of the igneous rocks in hinterland of Junggar basin in term of the chemical component, occurrence, texture and mineral composition of the rocks. It is recognized that there are relative complete types of igneous rocks composed of extrusive rock, intrusive rock and pyroclastic rock from basic to acidic ones in hinterland of Junggar basin, and part of them belongs to alteration ones. These recognitions could be helpful to proper knowledge of the potentials and to guidance of exploration and development of such reservoirs. References | Related Articles | Metrics

The Favorable Gas-Bearing Zones of 2nd Member of Xujiahe Formation of Upper Triassic in Baojie Area, Sichuan Basin HE Yan, PENG Jun, LIU Jian-feng 2010, 31 (2):  128-130.  Abstract ( 109 )   PDF (284KB) ( 273 )   Save This paper presents the classification and correlation of the Xujiahe formation of Upper Triassic in Baojie by means of highresolution stratigraphy using overwhelming drilled cores, well logs and other analytical data, integrated with the observation and description in surrounding field outcrops, and develops the sequence stratigraphic framework of 2nd member of Xujiahe formation, including in-depth studies of characteristics of its sedimentary facies, structure, reservoir, diagenesis, source rock and cap rock. The parameters such as the sedimentary facies, reservoir porosity, permeability, net pay thickness and reservoir type can be used for prediction of the zones through effective overlay technique. It is concluded that there exist five gas-bearing zones in this area, of which high capacity zones are distributed in the sedimentary microfacies of underwater distributary channel with large structural deformation, rough sediment grain-size and good porosity and permeability, and the reservoir types are dominated by Type I and Type II. References | Related Articles | Metrics

Origin of Heavy Oil in Huoyanshan Central Uplift Belt in Tuha Basin LI Hua-ming 2010, 31 (2):  131-133.  Abstract ( 200 )   PDF (250KB) ( 505 )   Save The heavy oil genetic mechanism is studied by analysis of the petroleum geologic and geochemical characteristics in Huoyanshan central uplift belt in Tuha basin. The result shows that the existence of 25-norhopane and 25, 30-bisnorhopane in the Triassic crude oil reveals the hydrocarbons in this area generally undergo biodegradation with different degrees in different areas. In Tuyuke area in low position of the structure, it is relatively weak; in Yingye'er area it is higher for it is in high position of it. Also, the fluid inclusion study indicates that in Shengjinkou area, normal crude oil occurs when oil charging followed by tectonic rising, biodegradation and forming heavy oil. The fluid inclusion from Yudong-1 Well appears in twice crude charges including normal oil and heavy oil. The fluid inclusions from Lu-8, Lu-9, Lu-11, Lu-2, Lu-10 wells reveal that from west to east the oil charges gradually change by migration from normal oil into complete heavy oil with the burial depth becoming shallower. Lu-10 Well could be the key point for crude oil to be thickened or oil composition to be dispersed at that time. References | Related Articles | Metrics

Reformation Effect of Hydrocarbon Alkali Fluid on Volcanic Reservoir in First Member of Yingcheng Formation in Xingcheng Region LIU Cheng-zhi, YU Hai-shan 2010, 31 (2):  135-138.  Abstract ( 96 )   PDF (434KB) ( 601 )   Save The volcanic gas reservoir of Yingcheng formation in Xushen gas field in Xingcheng region is dominated by acidic volcanic rocks with reservoir spaces like primary pore, secondary pore and fissure. The reformation effect of hydrocarbon alkali fluid on the volcanic rocks appears in the formation and development of secondary pore zone, which lies on the scale of material inflow and outflow in the reservoir caused by this fluid. The volcanic reservoir reformation by the fluid under open system includes primary mineral metasomatic alteration and dissolution, which leads to damage of inner structure of the rocks, such as mechanical strength reducing, porosity increasing. The structure is very favorable for structural fragmentation, attracting hydrothermal liquids and mineral enrichment. The hydrocarbon alkali fluid can not only cause porosity and permeability increasing by the alteration and dissolution of primary minerals, but also make porosity and permeability decreasing by packing or filling pores. The study shows that the particular lithology and lithofacies as well as structural factors in this region lead to that the outflow rate is larger than the inflow rate by hydrocarbon alkali fluid, the developed secondary pores could be connected into secondary pore zones, which can be as good migration channels and reservoir spaces. References | Related Articles | Metrics

Prediction of Fractures of Carbonate Rocks in Tabei Area in Tarim Basin Based on Fractural Orientation Attribute LIU Jun-ying, YANG Wu-yang, GAO Jian-hu, LIU Wei-fang, YONG Xue-shan, ZHANG Xi-mei 2010, 31 (2):  139-140.  Abstract ( 118 )   PDF (464KB) ( 211 )   Save The well developed fractures in carbonate rocks allow the strata to be of strong anisotropy which causes obvious orientation in seismic wave propagation such as amplitude, travel-time, interval velocity, frequency and absorption, etc. Their variations are closely related to the fractural orientation and density, hence the fractural prediction can be conducted using P-wave orientation characteristics. This paper studies the method for fractural prediction by using orientation and interval travel-time, by which the fracture development situation of carbonate rocks in Tabei-Eastern Lungu area in Tarim basin is predicted and good effectiveness or results are obtained. References | Related Articles | Metrics

Simulation of Fracture Parameters of Permian Volcanic Reservoir in Tahe Oil Field, Tarim Basin JI Zong-zhen, Dai Jun-sheng, WANG Jun, LI Ming, PAN Yao-li 2010, 31 (2):  142-145.  Abstract ( 112 )   PDF (478KB) ( 288 )   Save Based on the rules of rock fracture, the relationship between the paleo- and present stresses and the fracture parameters is established, and the feature and direction of paleo-stress during the fracture initiation period are determined by structural analysis. The present stress' direction and size are calculated using sonic velocity, hydraulic fracturing and acoustic emission methods. By substituting the fracture parameter calculation model into the numerical simulation result of the paleo- and present stress fields, the fracture aperture, porosity and density of the Permian volcanic reservoir in Tahe oilfield are simulated and calculated. The fracture parameters from the core observation and log interpretation are used to plot the contour map of fractural line and volume density in the whole area for verification. The result shows that the simulated results are reliable. References | Related Articles | Metrics

Sedimentary Facies of Nantun Formation in Beixi Area of Beier Sag YANG Ting, WANG Jian-xin, WANG Pu, ZHANG Lei, ZHAO Kun, WANG Zhe 2010, 31 (2):  146-149.  Abstract ( 121 )   PDF (474KB) ( 535 )   Save Based on lots of logging and core data, the Nantun formation in Beixi area of Beier sag (western Beier sag) is divided into four three-order sequences (SQ1-SQ4), among which five types of sedimentary facies are identified, i.e. fan delta, braided channel delta, neritic subsea apron, slump turbidite fan and lake ones. In this studied area, the sedimentary characteristics in different periods are mainly controlled by the tectonic evolution. In SQ1 period, Beixi area is divided into south and north parts, dominated by fan delta, braided channel delta and lake facies; in SQ2 period, continuous raise of the lake base level forms a unified lake basin with sedimentary characteristics like SQ1, except for forming new fan delta in the southwestern margin of this sag for existence of provenance; in SQ3 period, the lake base level reaches the highest with obvious shrinkage of sizes of the fan (braided channel) delta, dominated by slump turbidite fan; in SQ4 period, the tectonic activities are active, causing shrinkage of the lake area and not big change of deposit sizes in northwester and northern margin of the sag except its southeaster part for insufficient provenance, which leads to the disappearance of the central and southeastern braided channel delta. References | Related Articles | Metrics

Quantitative Characterization of Diagenesis and Pore Evolution of Super-Low Permeability Reservoirs—An example from Jiyuan area in Ordos basin LIANG Xiao-wei, GAO Wei, WANG Fang 2010, 31 (2):  150-153.  Abstract ( 106 )   PDF (304KB) ( 691 )   Save This quantitative study is conducted by means of cast thin-section observation and petrophysical property analysis of the reservoir. It is shown that the Chang 4+5 and Chang 6 of Yanchang formation in Jiyuan area is dominated by relatively tense and low permeable reservoirs with high feldspar, deep buried and complicated pore structure, which are important factors causing the reservoir quality to become poor. By reformations of compaction, cementation, dissolution and metasomatism, these reservoirs are now in diagenesis periods of late A and early B, of which the compaction could be result in overwhelming loss of reservoir porosity as the most important reason of the reservoirs becoming poor. References | Related Articles | Metrics

Geological Genesis of Low Resistivity Formation with Thin Sand-Shale Interlayer—An example from M1 oil measure of A reservoir in Pearl River Mouth basin LIAO Ming-guang, SU Chong-hua, TANG Hong, TAN De-hui, JIANG Wei, CHEN Xiao-qiang 2010, 31 (2):  154-157.  Abstract ( 143 )   PDF (254KB) ( 583 )   Save M1 oil measure of A reservoir in Pearl River Mouth basin is characterized by high porosity, low permeability and low resistivity. In order to examine its main control factor of low resistivity, this paper conducts the analyses of the grain size distribution, shale content, clay mineral type and distributive form, pore structural feature, conductive mineral content, thin sand-shale interlayer development status, with comparison with M2 oil measure of high resistivity. It is concluded that there are three factors for it: the reservoir is of high fine-particle content, high shale content, high percentage of fine pore throat volume, which result in its high irreducible water saturation and enhance its conductive property; its clay mineral is dominated by illite-montmorillonite mixed layer and kaolinite, showing film-like, flocculation-like and dispersion-like distribution, enhancing its additional conductivity; the development of thin sand-shale interlayer allows the low-resistivity formation of its own to become much lower by the effect of surrounding rocks with low resistivity. Also, the conductive minerals and the salinity of formation water have some effects on reducing resistivity of the reservoir, but they are not main factors for it. References | Related Articles | Metrics

Approach and Application of Determining Economic Limit Water-Cut Using Water Drive Curve Methods CHEN Yuan-qian 2010, 31 (2):  158-162.  Abstract ( 146 )   PDF (381KB) ( 393 )   Save Water drive curve methods are the important approaches for prediction of oilfield recoverable reserves by waterflooding process in China. The effective application of such methods depends on the reliability of linear stage selection and the rationality of limit watercut determination. However, for waterflooding oilfields with variable mobility, it is regulated to only take water-cut of 98% as basis for prediction of recoverable reserves in accordance with existing industry standard. This measure is not only improper, but also short of theoretical basis. Based on the previous study achievements by the author and the varied technical and economic conditions, this paper proposes the method for determination of economic limit water-cut to predict economic recoverable reserves of oil fields that have entered into middle-high water-cut stage characterized by production decline. The case study indicates that this method is practical and effective. References | Related Articles | Metrics

Primary Study on EOR for High Temperature and Salinity Reservoirs in Tarim Basin ZHOU Ming, FENG Ji-lei, JIANG Tong-wen, LIU Jian-xun, ZHOU Li-zhi 2010, 31 (2):  163-165.  Abstract ( 160 )   PDF (350KB) ( 760 )   Save The exploitation status and existing issues are reviewed of Lunnan field and Tazhong-4 field in high water cut stage as major oil fields in Tarim basin. The primary research on EOR for reservoirs with high temperature, high salinity and high Ca and Mg ions are proposed. It is recognized that the key point should be focused on the remained oil distribution and new materials such as aqueous polymer gel, polymer resin, organic/inorganic composite material and inorganic material, which are suitable for profile control. And the nonionic-anionic surfactants, multi-polarization surfactants and special surfactants as oil displacement agents are technically and preliminarily studied in this paper. References | Related Articles | Metrics

Fractal Mathematic Model for 3D Acid Corrosion of Rough Carbonate Rock Particles LI Xiao-gang, YANG Zhao-zhong, SU Jian-zheng, LIU Chang-yin, ZHANG Ru-sheng 2010, 31 (2):  167-170.  Abstract ( 130 )   PDF (248KB) ( 323 )   Save Acid fracturing as an important stimulation technology for carbonate reservoir is closely related with reaction process of acidrock reaction process in effectiveness. The previous acid-rock reaction models have failed to describe fractal feature of rock particle surface and 3D corrosion of acidic liquid on the grain, so there are obvious differences compared with such a real reaction process. This paper conducts regular characterization of the area and volume of rough rock particles by method of fractal geometry, develops the fractal mathematic model of 3D acid corrosion of rough carbonate rock particles on the basis of chemical reaction kinetics and mass transfer theory, and analyzes the variation trends of total corrosion time and corrosion rate of carbonate rocks. The study shows that the effect of fractal dimension of carbonate rock particle on the total corrosion time is remarkable, and the larger the fractal dimension, the longer the total corrosion time; moreover, such a time is not increasing or decreasing monotonously with the increases of rock equivalent radius and main concentration of hydrogen ion content. For a certain relative reaction time, the larger the fractal dimension, the higher the particle corrosion rate. References | Related Articles | Metrics

Physical Modeling of Water-Oil Displacement in Hydraulic Fractured Horizontal Wells LIU Hua-lin, XIONG Wei, GAO Shu-sheng, XUE Hui, HU Zhi-ming 2010, 31 (2):  171-173.  Abstract ( 100 )   PDF (211KB) ( 318 )   Save The water-oil displacement process in hydraulic fractured horizontal wells (five-spot well pattern) is simulated by three models of dumbbell, nun and equal-length crack shapes, with their pictures of sweep regularity and records of oil and water production. The process can be divided into four stages, and each stage corresponds to different sweet area. Two dead oil areas are found in the end of the process. The experiment indicates that for water-free recovery, the nun model gives the highest, the dumbbell model gives the lowest; in water-bearing recovery stage, the nun model gives the lowest water cut and the highest oil recovery rate, while dumbbell model is in contrary for these values; however, the dumbbell model and equal-length model have relatively easy or stable stages in water cut and oil recovery rate, the nun mode has not; such three models are generally similar in the recovery, larger in injection pore volume, of which nun model is the biggest, dumbbell model is the smallest. According to the correlations of these models in water-free recovery, oil recovery rate and injection pore volume, water cut, the nun model has the best effect of water injection, the dumbbell model has the worst of it, while the equal-length crack model has the intermediate. References | Related Articles | Metrics

Application of Reservoir Natural Drive Index to Waterflood Performance Analysis NIE Ren-shi, JIA Yong-lu, SHEN Nan, QIN Xu-sheng, ZHANG Wu, LIU Shun 2010, 31 (2):  174-177.  Abstract ( 138 )   PDF (320KB) ( 495 )   Save The traditional analysis method of the reservoir natural drive index can only be used in the judgment of reservoir natural energy scale prior to waterflooding. The theoretical study shows that the correlation curve of Δp and Npr assumes some kind of power relations, the bi-logarithmic curve assumes linear pattern; on the bi-logarithmic plot, the more dense the iso-time interval spots are, the more timely the energy feeding of bottom and edge water to the formation is, and the quicker the water influx rate is. The natural drive index can also be suitable for the analysis and evaluation of reservoir after waterflooding, and the variation of the curves is unchangeable, namely, the more tight the iso-time interval points are, the better the water flooding effectiveness. Also, the correlation of Δp and Npr is properly applied to prediction of oil recovery factor and hence to determination of rational accumulative and stage injection to production ratios integrated with waterflood characteristic curves of the reservoir. Finally, the case study shows good prediction of them. References | Related Articles | Metrics

Mass Production Optimization Based on Analysis of Waterflood Response WU Shu-cheng, LIU Ming, WANG Yun-xian, WANG Li-rong 2010, 31 (2):  178-180.  Abstract ( 153 )   PDF (231KB) ( 605 )   Save The lateral heterogeneity of an oil reservoir is one of important factors affecting its waterflood response. Based on the time and characteristic of response and water breakthrough in an oil well following waterflood, the heterogeneous coefficients between two wells can be calculated, by which the mass production is optimized, allowing oil wells with different well spacing and core intersection in a well group to realize the minimum affect from such a lateral heterogeneity to the reservoir. This method has been applied to BZ25-1S field in performance management and the obvious effectiveness has been achieved. References | Related Articles | Metrics

Calculation of Wellbore Temperature and Pressure in Deepwater Oil-Gas Wells LIU Tong, LI Ying-chuan, ZHONG Hai-quan 2010, 31 (2):  181-183.  Abstract ( 162 )   PDF (303KB) ( 1242 )   Save The wellbore temperature profile is the necessary parameter for exploitation and performance analyses of deepwater wells. However, the hole interval submerged in deepwater is too long, its heat transfer law in seawater is different from that in stratigraphic section, and the seawater temperature assumes the nonlinear distribution with well depth and the periodic change with the season, hence its temperature calculation in deepwater is much more complicated than in onshore and shallow sea oil fields. Based on the basic theory of heat transfer and wellbore heat transfer characteristics in seawater and strata, the mathmatic model of wellbore temperature-pressure coupling in deepwater is developed and calculated by Runge-Kutta iteration method. In this model the varied environmental temperature gradient, hole structure, casing oblique angle and heat transfer medium, etc. The case study shows that the model result is in accordance with the field data, and meets the demand for the development engineering or project. References | Related Articles | Metrics

Applied Condition of Type-Y1 Water Drive Characteristic Curve in Bottom Water Reservoir ZHOU Yu-hui, HU Shu-yong, DONG Hai-jing, HU Xiao-yun 2010, 31 (2):  184-185.  Abstract ( 111 )   PDF (197KB) ( 413 )   Save Type-Y1 water drive characteristic curve is of wider applicability, less parameter required, simpler and quicker calculation than general water drive characteristic curve. This paper studies the rising regularity of water cut in horizontal well in a bottom water reservoir, and presents that the single horizontal well prediction of water cut is on the large deviation using this curve for calculation of the low water-cut stage. By means of limiting the initial water cut of this curve, the performance prediction of the horizontal well in bottom water reservoir is then more satisfactory in effectiveness. References | Related Articles | Metrics

Determination of Blocking Agent Position in Bottom Water Reservoir Without Partition Board LIU Yan-cheng, WANG Jian, JI Lei, MENG Jian-xun, LIU Pei-pei, FAN Wei, LU Guang-liang 2010, 31 (2):  186-186.  Abstract ( 113 )   PDF (141KB) ( 304 )   Save Based on "partition board theory" proposed by Dr. LI Chuan-liang for development of bottom water reservoir, this paper discussed the partition board of oil well in such a reservoir, and deduces the reasonable position of blocking agent injection. This is helpful to further stable oil production measures making and scientific development of bottom water reservoirs. References | Related Articles | Metrics

The Fluid Diversion Technology by Water Shutoff and Well Shutdown Suitable for Low Permeability and Fractured Reservoirs—An example from Huoshaoshan field WANG Guo-xian, LIU Wei-dong, DANG Jian-xin, LI Wen-bo, ZHANG Jian-he, SHI Yan, QIAN Li-jun, MA Bao-jun 2010, 31 (2):  188-189.  Abstract ( 160 )   PDF (165KB) ( 320 )   Save For reservoirs with super-low permeability and high-angle fractures, the gross water cut increases quickly and some wells are suddenly water-flooded in the early phase of development. A series of water shutoff measures carried out in this phase do obtain obvious effectiveness, but with the increasing of water shutoff rounds, the effect is getting worse gradually. Field test shows that to prolong well shutdown time after water shutoff, the effect may be improved clearly for the reason of changing the flow direction allows to redistribute oil-water flowing system by full infiltration and exchange between matrix and fractures. This paper presents fine description of the reservoir in Huoshaoshan field and analysis of previous stimulations and effects, and proposes the fluid diversion technology for such a fractured reservoir by water shutoff and well shutdown. A great deal of field tests indicates its remarkably oil-incremental effects, providing precious experiences for post phase of development and stable production for such a reservoir. References | Related Articles | Metrics

Theoretical Model and Application of Secondary Sand Fracturing LI Yong-ming, LI Lian-ming, GUO Jian-chun, ZHAO Jin-zhou 2010, 31 (2):  190-193.  Abstract ( 164 )   PDF (282KB) ( 606 )   Save As a kind of applied technology for special reservoir development, the secondary sand fracturing is of obvious advantage in shaping short and wide fracture and avoiding fracture penetrating interlayer, which has been successfully applied in fields. However, for the lack of relevant theoretical research, the field design of it is still in great blindness. This paper presents the fracture-extending model for secondary sand fracturing considering the impact of sand bank height change with time on fluid pressure drop; the proppant sedimentation and migration model considering the proppant convection impact, by which the proppant migration and distribution is gained by interface tracing; and proposes related program for correlation and analysis of fracture parameters from both secondary sand fracturing and conventional fracturing. The calculated results indicate that the secondary san fracturing is characterized by decreases of the length and height, and obvious increases of the width and conductivity of proppant fractures. According to the real reservoir petrophysical properties, the optimized secondary sand fracturing technology has satisfactory effect for stimulation, being worthy of popularization and application. References | Related Articles | Metrics

Application of Combination Model to Prediction of Oil Production by Polymer Flooding Process QIU Hai-yan, DING Xian-feng, HU Xiao-yun, LIU Ping 2010, 31 (2):  194-196.  Abstract ( 128 )   PDF (191KB) ( 235 )   Save Predictive Results of oil production by polymer flooding process are directly related to annual planning and mid-long term planning deployment in the process of oil field development, so the selection of forecast model is particularly important. This paper briefly introduces the combination forecast model and develops an optimal combination model for oil production forecast based on Weibull, HCZ and generalized Weng's prediction models, in which the weighting coefficient is determined by the criterion of minimum square sum of predictive error. The precision of such a model is compared with those given by the three models by means of real production data, proving this model is effective and practicable. References | Related Articles | Metrics

Application of Seismic Multi-Attributes to Identification of Non-Structural Traps—An example from 201 Well Area in Karamay field ZENG Bo, WU Yu-han, QU Jian-hua, WU Cai-xi, WEN De-jin, HU Song 2010, 31 (2):  197-198.  Abstract ( 100 )   PDF (457KB) ( 532 )   Save With the progress of oil-gas exploration in Junggar basin, the structural traps to be explored become less and less. The explorative targets have been converted from structural traps into lithologic and stratigraphic non-structural traps. This paper presents the composite interpretation and analysis of seismic multi-attributes of the lithologic (oil-bearing) sands in 201 Well Area in Karamay field, in terms of waveform and mutative area, well restrictive inverse and root-mean-square amplitude, etc., and good geologic results are gained. References | Related Articles | Metrics

Application of Forward Modeling to the Seismic Data Acquisition in Dapingfang Volcanic Area in Liaohe Depression WANG Hai-bo, LIU Bing, YU Jian-hua, WANG Chang-jiang 2010, 31 (2):  200-202.  Abstract ( 92 )   PDF (593KB) ( 303 )   Save The geology of Dapingfang volcanic area in Liaohe depression is introduced briefly. Based on the analysis of the theory of low frequency signal which is beneficial to the image of underlying strata of volcanic rock, integrated with the present geologic knowledge, the forward model is developed for shot record and migration section obtained from different seismic wavelet. The modeling results indicate that low frequency signal is beneficial to the image of middle and deep strata, which should be protected in the further exploration in this area. References | Related Articles | Metrics

The Methods for Determination of Cutoff Values of Reservoir Porosity and Permeability WANG Juan, LIU Xue-gang, CUI Zhi-lin 2010, 31 (2):  203-204.  Abstract ( 689 )   PDF (270KB) ( 1177 )   Save This paper presents four methods of empirical statistical analysis, throat radius cut off, relative permeability curve and gas test for effective determination of reservoir porosity and permeability cutoff values for the purpose of oil-gas reservoir identification and reserves estimation. These methods are applied to determination of cutoffs of porosity and permeability of the He-8 member, Shihezi formation in Wellblock-8 in a gas field in Ordos basin, showing that the porosity cutoff value is 6.25%, the permeability cutoff value is 0.1×10-3 μm2. References | Related Articles | Metrics

Origin of Tuffaceous Clastic Rocks of Lower Wuerhe Formation in Wuerhe Oil Field ZHANG You-ping, GONG Qing-shun, LIU Jing, LU Shu-ping, DING Liang-bo 2010, 31 (2):  205-207.  Abstract ( 112 )   PDF (355KB) ( 258 )   Save A set of special tuffaceous rocks compose of ash tuff, bedded tuff and tuffaceous glutenite is partly developed in the Lower Wuerhe formation of Middle Permian in Wuerhe oil field and characterized by high resistivity and low interval transit time on the electriclog curves. Based on the analysis of core, cast thin section, logging and seismic data, it is considered that the tuffaceous clastic rocks are in closed to semi-closed arm of lake environment that is saline and alkaline and shaped by ash-clastic mixed accumulation. Such a reservoir is of feature of dual porosity media. References | Related Articles | Metrics

Discussion of the Meaning of Convolution Model-Based Seismic Amplitude LIU Zhen-dong, ZHANG Xi-ke, XU Jie, ZHANG Heng-zhi 2010, 31 (2):  208-209.  Abstract ( 121 )   PDF (360KB) ( 426 )   Save Based on convolution model, the reflected wave amplitude is the superposition of single reflection coefficient and wavelet convolution. The amplitude of primary seismic reflection seismogram can be regarded as the limited bandwidth reflection coefficient in nature, while the event of seismic profile stands for the interface of wave impedance contrast of layers, which is not consistent with deposition interface. This paper illustrates wave impedance can not completely reflect the lithology of strata by combining with stratigraphic correlation, so it is inaccurate to only use the wave impedance for prediction of lithology. Also, this paper indicates from the model and cases that the pinchout of event does not express the pinchout of reservoir. References | Related Articles | Metrics

Tectonic Evolution in Oriente Basin of Ecuador DING Zeng-yong, CHEN Wen-xue, XIONG Li-ping, LIN Wei-dong, XU Hua-ming, TIAN Na-xin 2010, 31 (2):  211-215.  Abstract ( 239 )   PDF (470KB) ( 714 )   Save Oriente basin is one of the important petroliferous basins of Latin American region with higher levels of exploration and development. For the purpose of in-depth understanding of the tectonic evolution and the oil accumulation controlment in Oriente basin, the study of the sedimentary strata distribution and tectonic subsidence has been carried out through the overall consideration of MOP (Mranon-Oriente-Putumayo) petroleum province consisting of Ecuador's Oriente basin, Colombia's Putumaro basin and Peru's Maranon basin. Based on subsidence mechanism and sedimentary strata, Oriente basin is roughly divided into three stages in tectonic evolution, i.e. Paleozoic passive continental margin, Mesozoic back-arc rift and Cenozoic back-arc foreland. According to the characteristics of faults, considering subsidence-sedimentation characteristics of the entire MOP petroleum province, Oriente basin could be spatially divided into three tectonic units, i.e. the western sub-Andean belt, the central belt and the eastern foreland slope belt. Tectonic evolution has an absolutely dominant role in controlling hydrocarbon accumulation. Lots of low-amplitude anticline traps were formed mostly during the west (early) Andes episode in the central tectonic belt. Principal traps belong to reverse-thrust anticline traps and composite traps of structure-lithology formed during the east (late) Andes episode respectively in the western and eastern tectonic belts. References | Related Articles | Metrics

Hydrocarbon Accumulation Conditions of the Sub-Salt Strata in North-Northwestern Pre-Caspian Basin ZHOU Sheng-you, MA Yan, TANG Yong-kun, LI Chang-zheng, GUI Ju 2010, 31 (2):  216-218.  Abstract ( 126 )   PDF (366KB) ( 352 )   Save The sub-salt series of strata in north-northwestern step-fault zone of Pre-Caspian basin is a major target area for petroleum exploration and 35 oil-gas fields have been discovered. In this area, there are 4 sets of premium hydrocarbon source rocks with high abundance of organic matter, which provide premium reservoir conditions for hydrocarbon accumulation. The regional salt rocks of the Early Permian play better sealing role to the sub-salt reservoirs mainly formed in Paleozoic and dominated by organic buildup reef and anticline as types of reservoir traps. It is thought that the most favorable structural units are the zone beaded barrier reef of Permian and adjacent areas to Karachaganak oil-gas condensate field characterized by Carboniferous-Devonian reef carbonate rocks. References | Related Articles | Metrics

Tectonic Evolution and Dynamic Mechanism of Atlas Orogen WAN Zhi-feng, XIA Bin, CAI Zhou-rong, ZHANG Yi, LIU Wei-liang 2010, 31 (2):  220-223.  Abstract ( 192 )   PDF (406KB) ( 735 )   Save Africa is rich in petroleum resources. It is one of the hotspots for oil-gas exploration in the world and major blocks of China's overseas investment for it. The Atlas orogen in northern Algeria is characterized by complex structures and unclear structural evolution regularity, which becomes the bottleneck for inside hydrocarbon prospecting in its intermountain basin. Based on the theories of modern structural geology and geodynamics, the structural evolution in this area can be divided into three stages such as Triassic-Early Jurassic rift stage, Middle Jurassic -Cretaceous subsidence stage and Cenozoic reverse-uplifting stage. It is pointed out that its dynamic mechanism is that the open of the Mesozoic Neo-Tethys and Atlantic oceans and the dismember of Gondwana land are the dynamic settings for rift and subsidence of Atlas orogen, while the close of the Cenozoic Tethys ocean and the convergence between Africa plate and Eurasian plate are the main reasons for the reverse-uplifting of Atlas orogen. References | Related Articles | Metrics