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01 January 2019, Volume 35 Issue 3 Previous Issue    Next Issue

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Tectonic Deformation Characteristics of Jiuxi Basin and Its Formation Mechanism of FaultRelated Folds HU Wenrui1, HE Xin2, MU Langfeng3,4, XIAO Yuxiang2, HOU Xiulin2, ZHANG Yang2 2014, 35 (3):  1-1.  Abstract ( 133 )   PDF (300KB) ( 320 )   Save This paper analyzes the deformation features and the genetic mechanism of the main oil?bearing structures in Jiuxi basin. The heterogeneous episodic activity of Himalayan movement caused northward thrusting and parallel arrangement of the three rows of thrust faults in North Qilian, Laojunmiao and Xinminbao areas. The main reason for forming three segmental deformations in EW direction of North Qilian mountain is its elastic defference of the rocks. The elastic defferences between new and old strata, the tectonic stress direction, and size heterogeneity result in the fault bend folds in Qingxi oilfield, the fault detachment folds in Yaerxia Cretaceous reservoir and the fault propagation folds in Tertiary reservoirs. According to the oil reservoir profile with connected wells created by fine isochronous stratigraphic division and correlation, some new oil and gas resources are found in Yaerxia Cretaceous reservoir and in the northern margin thrust belt of Laojunmiao anticline. This materially supports the sustainable development of Yumen oilfield. Related Articles | Metrics

Petroleum Exploration Prospects of Carboniferous-Permian in Peripheral Mahu Sag, Junggar Basin CHEN Gangqiang1, AN Zhiyuan1, Abulimiti1, LI Xiao1, XU Qiulai1, ZHANG Luanfeng2 2014, 35 (3):  1-1.  Abstract ( 92 )   PDF (300KB) ( 269 )   Save The hydrocarbon accumulation conditions and exploration potential of the Carboniferous?Permian in Mahu sag and its periphery in northwestern Junggar basin have received little research attention due to deep burial depth and associated low exploration degree. This paper analyzes the basic hydrocarbon accumulation conditions and indicates there exist three source sequences in this area, including the Carboniferous, the Jiamuhe formation and the Fengcheng formation of the Lower Permian, which are all in highly matured evolution stage, with sufficient oil?gas source, and dominated by highly matured hydrocarbons. In this study area, large structural and stratigraphic traps are developed widely, including inherited foreland uplift anticlines, piedmont anticlines, fault block traps, stratigraphic and fault?stratigraphic traps. It is found in deep Mahu sag that special types of reservoirs are developed, such as volcanic reservoirs of the Carboniferous and the Jiamuhe formation and the dolomitic reservoir of the Lower Permian Fengcheng formation. In addition, wide development of fault, fracture and weathering crust has resulted in improvement of the reservoirs quality. It is suggested that the deep?buried lower hydrocarbon accumulation assemblage has the basic geological conditions for forming oil and gas pools with relatively large scale and high production, and could be as a new domain for petroleum exploration in Junggar basin. Also, the anticline surrounding Well DA?1 has been selected as preferred exploration target to look forward to get breakthrough Related Articles | Metrics

Fracture Prediction of Low Permeability Reservoirs of the Mesozoic in North Yellow Sea Basin WANG Houjin1, WANG Liaoliang1, WAN Xiaoming1, LEI Kehui2 2014, 35 (3):  1-1.  Abstract ( 57 )   PDF (300KB) ( 224 )   Save The North Yellow Sea basin on the Sino-Korean plateau is a Mesozoic-Cenozoic fault basin. The Mesozoic sandstone reservoirs featuring low permeability nature are proved to be the main exploration targets by drilling, and fractures inside are found to be the main reservoir space of the discovered oil pools. Based on the 3D seismic, core observation and imaging well logging data, this paper, by means of the latest FracPM curvature analysis with the characteristic of global optimization algorithm, combined with the ant?tracking method， achieves the high precision imaging of fractures. At the levels of big and small scale, the fracture growth level and distribution of the exploration targets are predicted, and good practical effects are obtained. The predicted fractured layers are proved by drilling with great hydrocarbon potentials Related Articles | Metrics

The Cenozoic Tectonic Stress Field Characteristics and Relationship of Hydrocarbon Migration/Accumulation in Qingdong Sag in Southeastern Bohai Bay Basin WEI Hongtao1LI Wei2, YANG Zhifeng2, HAN Shuai2, JIA Haibo2 2014, 35 (3):  1-1.  Abstract ( 72 )   PDF (300KB) ( 241 )   Save This paper presents numerical simulation of the Cenozoic paleo?tectonic stress field in Qingdong sag of southeastern Bohai Bay basin using 2?D finite element method, analyzes the differences and space distribution regularity of the Cenozoic tectonic stress fields in different stages and discusses the relationship between the tectonic stress field characteristics and the hydrocarbon migration and accumulation. The results show that the sedimentary period of the Kongdian group and the lower part of the fourthmember of the Shahejie formation is the structural transformation period, in which Qingdong sag is located in NNE-SSW tension stress field, dominated by NW fault system, Tanlu fault left?lateral strike?slip process is weaker than the tension; during the sedimentary period of its second member to the upper part of the fourth member of the Shahejie formation, Qingdong sag is in NNW-SSE tension stress field, Tanlu fault becomes right?lateral strikeslip process, the strike?slip and tension processes are all stronger; during the sedimentary period of the frist member to Dongying formation, Qingdong sag is in right?lateral shear stress field, the basin regional tension stress field becomes weaker; by the end of sedimentary period of Dongying formation, Qingdong sag is in right?lateral compressive tectonic stress field, Tanlu fault is transformed from dextral tenso?shear period into dextral compresso?shear movement; during the sedimentary period of Guantao formation to Minghuazhen formation,Tanlu fault has weak dextral shear process and tension stress. In key period of hydrocarbon accumulation of Qingdong sag, the hydrocarbons in its favorable hydrocarbon?generating zone migrate along NW-SE direction under the process of NS and NNW-SSE maximum principal stress into the slope zone and transition zone in the west and the strike?slip belt in the east, respectively. So the low?value area of minimum principal stress and the high?value area of shear stress in this basin now could be the favorable zones for hydrocarbon migration and accumulation Related Articles | Metrics

The Influence of Neotectonic Movement on Hydrocarbon Accumulation Patterns in Tarim Basin LIU Mingyi1 , CAO Yuanting2HU Li3, WEI Hongxing4 2014, 35 (3):  1-1.  Abstract ( 65 )   PDF (300KB) ( 239 )   Save The remote tectonic effect resulted from collision between the Indian subcontinent and the Eurasian continent broke the structural equilibrium state at the end of the Paleogene in Tarim basin. With the method of paleo?structural restoration, this paper estimated the regional changing characteristics of Tarim basin since Paleogene as follows: The Maigaiti slope in southwestern Tarim basin migrated northward, increasing the width of the north and south; the south part of Bachu uplift became slope area and width narrowed; Tabei uplift migrated southward on the whole; the Manjiaer sag in eastern Tarim basin shrank northward, while the south and southeast boundaries extended outward; the range of Tazhong uplift became obviously narrowed; Tadongnan uplift’s structural size became gradually smaller but its amplitude increased. Having influenced by the neotectonic movement, the hydrocarbons in different regions showed different oil and gas accumulation patterns. The Bashituopu oilfield in southwestern Tarim basin tilted with a fulcrum of Qun?5 well area. Different traps in the same tectonic unit were shifted, forming the hydrocarbon accumulation pattern of“the ebb and flow type of convergence”; the Carboniferous strata in Hudson oilfield in northern Tarim were reversed on the whole, with structural highs migrating southward, which made oil?water interface tilt under normal temperature and pressure, forming“post conveyor type”oil?gas accumulation pattern; the old faults in Tazhong?4 oilfieldrevived episodically, with multiple oil?gas?water interfaces, forming“residual leakage type”accumulation pattern. The oil and gas accumulation kept in unsteady state characteristics of episodic balance and adjustment. Research on hydrocarbon’s adjustment characteristics in the neotectonic period has a guiding significance on the petroleum exploration and development in Tarim basin in the future Related Articles | Metrics

Application of Convolution Model for Prediction of Volcanic Rocks Distribution in Dixi14 Well Area in Kelameili Gas Field, Junggar Basin DU Qingxiang1, SHEN Xiaoli2, LI Daoqing3, WANG Bin3 2014, 35 (3):  1-1.  Abstract ( 48 )   PDF (300KB) ( 178 )   Save When the seismic wavelet has little temporal and spatial changes, single reservoir time thickeness is much more than 1/4λ, and the wave impedance′s change of caprock is not large, we can get a positive correlation formula between seismic amplitude and P?wave impedance through the convolution model′s derivation. This paper makes a more detailed subdivision to composite volcanic rocks and the lithology distribution prediction in Dixi?14 well area in Kelameili gas field by combining with the seismic attributes such as amplitute, frequency, waveform, as well as the reflection time to the top of the Carboniferous in longitudinal. Dixi?14 well area′s reservoir belongs to Carboniferous volcanic rocks dominated by volcanic breccia and tuff, which is mainly effusive basalt and rhyolite in the rim and tuffaceous sandy conglomerate in the middle. With the wave impedance becoming larger, from tuffaceous sandy conglomerate to volcanic breccia, tuff, and then rhyolite, dacite or basalt, the seismic amplitudes enhance successively. The study suggests that there may exist many craters in the area, which include positive structure and negative structure like caldera. In the same way, this paper develops the volcanic spatial eruption modle for Kelameili gas field Related Articles | Metrics

Shale Gas Reservoir Characteristics of Middle Jurassic in Northeastern Kuqa Depression, Tarim Basin XIAO Fei, LIU Luofu, GAO Xiaoyue, REN Zeying, WU Kangjun, XIAO Zhengyang 2014, 35 (3):  1-1.  Abstract ( 51 )   PDF (300KB) ( 193 )   Save The Middle Jurassic is one of major source rocks in the northeastern Kuqa depression for it has a typical continental shale, and it is of good potential of shale gas generation. The study of characteristics of the shale gas reservoir from X?ray diffraction, scanning electron microscope and argon?ion polishing techniques that its organic matter?rich shale mineral components are mainly composed of quartz (18%~55%) and clay minerals (9%~76%), the latter are dominated by illite/smectite mixed layer and illite, with the shale porosity of 0.5%~7.3% and permeability of less than 0.1mD, belonging to a supper?low porosity and ultra?low permeability reservoir; The shale reservoir spaces mainly include nano?micron mineral matrix pores, organic micro?pores, structural micro?fractures and diagenesis micro?fractures. Comparing with the typical gas?bearing shales in North America, the Middle Jurassic shale is of similar reservoir characteristics and could be faverable shale gas reservoir. Also, the research shows that the mineral composition，diagenesis and structural process mainly influence the characteristics of the reservoir in this area. It is suggested that the gas?bearing nature and the modifiable property of the Middle Jurassic shale are paid more attention to in next?step researches and further exploration and exploitation Related Articles | Metrics

Derivation, Comparison and Application of Forecasting Water Drive Volume Sweep Efficiency Methods with Comments on Hu GangsNew Method CHEN Yuanqian1, ZOU Cunyou1, ZHANG Feng2, HAO Mingqiang1 2014, 35 (3):  1-1.  Abstract ( 81 )   PDF (300KB) ( 196 )   Save The definition of water drive volume sweep factor is the ratio of natural water drive or artificial waterflooding occupied volume and oil pore volume. Water drive volume sweep factor is the important base for judging waterflooding development effect and EOR. The method for forecasting water drive volume sweep factor methods by Type?C and Type?D water drive curves has received attention and application in practice, while there still no related method by Type?A and Type?B water drive curves recommended by the petroleum industry standard and applied universally in China. This paper proposes the forecasting water drive volume sweep factor methods through Type?A and Type?B water drive curves based on the study of related literatures. The applied examples show that the water drive volume sweep factors predicted by Type?A, Type?B, Type?C and Type?D water drive curves have the very good consistency. The derivation from the "new method" given by Hu Gang is wrong, so, it is necessary to be corrected Related Articles | Metrics

Effect of the Composition of Formation Crude Oil on PVT Data LI Aifen, WANG Shoulong, L? Jiao, JIANG Kailiang, LI Xuguang 2014, 35 (3):  1-1.  Abstract ( 84 )   PDF (300KB) ( 418 )   Save The PVT data of reservoir fluids are mainly influenced by the reservoir temperature, pressure and the composition of formation crude. The PVT data of three different crude oil samples obtained from Tahe oilfield in Tarim basin and Chunliang field in Shengli oilfield are measured in detail in this paper. The results show that under the same conditions, the higher the wax content and the solution gas?oil ratio of the formation crude, the higher bubble point pressure and the formation volume factor; when the reservoir pressure is greater than bubble point pressure, the lower the wax content and the higher the gas?oil ratio, the more significant the effect of the reservoir pressure on the formation volume factor and oil density, while the higher the wax content, the less the effect of the reservoir pressure on them. For the formation crude with high wax content, the viscosity reduction of crude oil dissolved with natural gas is obviously better than that of light oil Related Articles | Metrics

Study on the Performance of Flue Gas Improving Steam Huff and Puff for SuperHeavy Oil Reservoir LI Zhaomin1, SUN Xiaona1,2LU Teng1, XUE Xingchang3a, YAO Yuping3a, YI Huaifeng3b 2014, 35 (3):  1-1.  Abstract ( 71 )   PDF (300KB) ( 274 )   Save Based on the foundation of typical steam huff and puff well model, the performance of flue gas assisted steam huff and puff for super?heavy oil reservoir was studied by numerical stimulation. The results show that flue gas assisted steam huff and puff for super?heavy oilcan improve energy utilization efficiency, reduce the volume of steam injection and improve cumulative oil steam ratio, meanwhile, reduce the environment pollution. The optimized injection parameters are then obtained, such as that the cyclic injection volume of flue gas is 60 000 m3, the injection rate of flue gas is 800 m3/h, the cyclic injection volume of steam is 1 000 t, the soak time is not less than 3 d, the cyclic time is 6 mon, besides, the CO2 content in flue gas is more than 20% and the flue gas injection temperature is higher than 100℃ are also beneficial to improve the oil production Related Articles | Metrics

A Study of WaterDrive Type Curves Corresponding to the Classical Theories for Water Displacing Oil GAO Wenjun, SONG Chengyuan, FU Chunmiao, XU Chuanyan 2014, 35 (3):  1-1.  Abstract ( 76 )   PDF (300KB) ( 383 )   Save Based on Buckley?Leverett theory of water displacing oil in non?piston, Welge’s average water saturation equation and Efros’ experimental results, the water cut vs recovery efficiency curve, the water drive characteristic curve and the water cut rising curve corresponding to the classical water displacing oil theories are derived in this paper. Although the oil?water two?phase relative permeability function is not introduced in the process of derivation, the cumulative oil production vs cumulative liquid production can also be given from the theoretical and experimental research results, which has a big difference with previous derivation methods for water drive type curves. Through field application, the effect is very good and worthy of popularization and application Related Articles | Metrics

Characteristics of Remaining Oil MicroDistribution in Laojunmiao Oilfield after Waterflooding SUN Yingying1, SONG Xinmin1, MA Desheng1, XUAN Yinglong1, LI Haibo2, ZHANG Xiaodong3 2014, 35 (3):  1-1.  Abstract ( 63 )   PDF (300KB) ( 269 )   Save Using the fresh oil?bearing core samples, this paper studied the remaining oil micro?distribution or occurrence and the influence of long?term waterflooding on the reservoir pore structures in major reservoir of Laojunmiao oilfleld in Yumen. The study indicates that the remaining oil occurrence in the reservoir is dominated by film or interstitial form, and the pore stucture is the key factor influencing the remaining oil distribution and oil displacement efficiency. After long?term water flooding, the interstitial material and flowing resistance are decreased in the pores with better physical property. For L layer, its remaining oil is still distributed in big pores，while for M layer, its one third of remaining oil is in the small pores or disseminated on rock surface, and hard to flow. The content of movable water in the big pores is directly related to the total water cut in the reservoir Related Articles | Metrics

The Influence of Drying Temperature on Methane Adsorption Capacity of Shales CAO Taotao1,2, WANG Sibo1, SONG Xu1, SONG Zhiguang1 2014, 35 (3):  1-1.  Abstract ( 60 )   PDF (300KB) ( 216 )   Save The contrast experiment for the same shale sample after different drying temperature processing shows that the water loss rate of shale sample at 110 ℃ drying temperature is higher than that at 60 ℃, and the methane adsorption capacity at 110 ℃ is also much higher than that at 60 ℃. As a result, the drying temperature is obviously a very important factor influencing the shale methane adsorption capacity. Even so, the study indicates that the drying temperature mainly affects the shale adsorption capacity, but does not influence the mechanism of shale adsorption for the same shale sample, which suggests that higher drying temperature can remove the moisture in shale away and increase the porosity adsorpted in shale Related Articles | Metrics

Comparative Analysis of Isothermal Adsorption Models for Shales and Coals ZHAO Tianyi, NING Zhengfu, ZENG Yan 2014, 35 (3):  1-1.  Abstract ( 84 )   PDF (300KB) ( 407 )   Save The experimental data of CH4 adsorption on coals and shales are fitted by using Freundlich empirical formula, Langmuir model, extended Langmuir model, Toth adsorption model and Langmuir-Freundlich adsorption model. The fitting degrees is also examined. The results show that both the coal and the shale, the fitting precision of three?parameter model is higher than that of two?parameter model. For the two?parameter models, the fitting degrees of Langmuir model on coal and shale is much higher than the Freundlich empirical formula model by more than 8 times. For the three?parameter models, their fitting degrees are all higher, of which Toth model is the highest in fitting degree than E?F and L?F models at an averge temperature for shales, but for coals, it is lower than the other two. On the whole, Toth model and L?F model are better for fitting of coals and shales rather than Freundlich empirical formula. The study results are of guiding significance in proper selection of isothermal adsorption model for coals and shales Related Articles | Metrics

Analysis of Influencing Factors about MultiStage Fractured Horizontal Well Productivity in Shale Gas Reservoir ZENG Huia, YAO Juna, FAN Dongyana,b, WANG Weia 2014, 35 (3):  1-1.  Abstract ( 60 )   PDF (300KB) ( 285 )   Save Considering coexistence of the adsorbed gas and free gas in shale gas reservoir, a model for productivity calculation of shale gas reservoir by horizontal drilling in view of the desorption process of adsorbed gas was developed in this paper. The analysis of factors affecting the horizontal well productivity indicates that the productivity without the effect of natural micro?fractures is almost zero, so only those shale gas reservoirs with developed natural micro?fractures have commercial exploitation value. In the development process, the proportion of the desorption gas becomes larger and larger, the production will be higher and the stable production time of duration will be longer. So, the gas adsorption and desorption must be taken into consideration for development of shale gas reservoir. The result of orthogonal test indicates that natural fracture permeability has the most significant effect on productivity, and the occurrence of micro?fractures should be paid more attention to for it could directly determines the productivity of fractured horizontal wells Related Articles | Metrics

Establishment and Application of New Water Drive Characteristic Curve at High WaterCut Stage ZHOU Peng1, CHEN Ming1, XU Feng2,3, CHEN Fenjun4 2014, 35 (3):  1-1.  Abstract ( 64 )   PDF (300KB) ( 203 )   Save The traditional water drive characteristic curves have a better adaptability to waterflood process of medium water?cut stage rather than high water?cut stage for its trend of upwarping characteristic curves, which results in large errors of the development of performance analysis and dynamic index prediction at high water?cut stage. In this paper, a new type of water drive characteristic curves is established to be suitable for the high water?cut stage, and the relationship graphics of water cut and the degree of recovery of recoverable reserves are plotted. Since the derivation constraint, the new water drive characteristic curve is not applicable in the presence of water?free production period of oil and gas reservoirs. The cases studies show that the new water drive characteristic curve for prediction of the upwarping trend of water cut at high water?cut stage may match well with the real history and allows the error between the predicted recoverable reserves value and the actual value to be small Related Articles | Metrics

Analysis on Adaptability of Production by InSitu Combustion Process in Heavy Oil Reservoir in Well Block Hongqian1, Karamay Oilfield LI Qingyuan 2014, 35 (3):  1-1.  Abstract ( 73 )   PDF (300KB) ( 261 )   Save In?situ combustion, a kind of thermal production technology for generating heat within an oil zone, is also called fire flooding process. It is not only a method used to improve oil recovery factor, but also an effective approach to convert production methods in middle to late stages of oil field development. Laboratory experiments have proved that, the residual oil saturation in the combusted zones is almost zero, while the recovery factor can be as high as 85%~90%. In the implemented in?situ combustion projects on the field, the recovery factor can also be as high as 50%~80%. Based on the geologic characteristics and current development status of the heavy oil reservoirs in Karamay oilfield, this paper makes probe into the test effect of the technology applied in the heavy oil reservoir in Wellblock Hongqian?1 in Hongshanzui oilfield. On the basis of comprehensive evaluation, this technology is believed to be adaptable to development of heavy oils for EOR during late stage of cyclic steam stimulation Related Articles | Metrics

Application of Water Drive Type Curves and Production Decline Law in District No.8 of Karamay Oilfield JIANG RuizhongWANG YangHE WeiXING Yongchao 2014, 35 (3):  1-1.  Abstract ( 64 )   PDF (300KB) ( 224 )   Save The water drive type curves and production decline law are the two important methods for dynamic prediction of reservoir engineering.Previous studies of these laws often take them as an independent approach，but they both have their own limitations in practical application:the water drive law describes the relationship among cumulative oil production，cumulative water production and water oil ratio， which lacks the concept of time；production decline law describes the change of annual oil production and cumulative oil production with time，which lacks the concept of water cut. Through the combination of the two methods，we can get water cut and cumulative water production in different time，oil production in different water cut，cumulative water production in different oil production, etc. Also, the methods above are used to predict the dynamic indices in Wuerhe oilfield and get good result Related Articles | Metrics

The Application of MultiWave and MultiComponent Joint Inversion of Seismic Data to S Oilfield in Tabei Uplift, Tarim Basin YANG Jing1, WANG Jiushuan1, PENG Gengxin2, MA Ning1, XIE Nan1 2014, 35 (3):  1-1.  Abstract ( 52 )   PDF (300KB) ( 292 )   Save The Triassic is the major exploration area of S oilfield in Tarim basin, with good physical property of sandstone reservoir in the delta front sedimentary facies. However, its P?wave velocity of gas?bearing sandstone appears to that of mudstone velocity. Based on the multi?wave and multi?component data, the effective reservoir parameters are determined by the crossplot of logging data. According to the fine calibration and P?wave and PS?wave match, the joint inversion is carried out to get those parameters, including P?impedance, S?impedance, vp /vs . The S?impedance is used to accurately identify the sandstone distribution, and the hydrocarbon property of reservoirs is predicted by vp /vs . The study result shows that the reservoir prediction by using multi?wave data is more accurate than that of P?wave data. It provides important information for the well deployment of the oilfield Related Articles | Metrics

Application of Water Control and Steering Hydraulic Fracturing Technology in High WaterCut Fractured Reservoir A case study of H1238 Well in Huoshaoshan oilfield, eastern Junggar basi YIN Huia, LIU Jinjuna, GUO Jiaojiaoa, YE Junhuaa, TANG Xiaochuana, JIANG Hongb 2014, 35 (3):  1-1.  Abstract ( 62 )   PDF (300KB) ( 266 )   Save Zhundong fractured oilfield has entered into middle?high water cut stage, by conventional single expansion of refracturing process, water channeling in it was easy to create, causing the rapid increase of the water cut in post?frac wells and the decrease of response effects year by year. In order to improve the stimulation effect of the fractured oilfield with high water by hydraulic fracturing, this paper proposes the technology for combining water control with steering fracturing process. The test application to H1238 Well shows that the fracturing effect is remarkable, realizing the purpose of incremental oil and water control by hydraulic fracturing in high water?cut stage Related Articles | Metrics

Drilling Technology of Large Displaced Cluster Horizontal Well for Tight Oil in Changji Oilfield, Junggar Basin WEN Qianbin, YANG Hu, SHI Jiangang, YAN Peng 2014, 35 (3):  1-1.  Abstract ( 68 )   PDF (300KB) ( 264 )   Save The low?cost strategy is the core of development of tight oil. The experience from successfully developing tight oil in USA shows that the combination of suitable engineering technique and factory operation mode is the effective ways to reduce the cost. In order to further reduce the development cost, Changji oilfield tight oil test area in Xinjiang has employed the large cluster platform horizontal wells to meet the need of the factory operation mode. According to the geologic characteristics of tight oil of Permian in Changji oilfield, this paper introduces the key technologies such as optimizing the structure of the hole, PDC bit type selection, selection of horizontal well azimuth, optimal design and fine control of 3D trajectory, anti?collision of cluster horizontal wells and optimization of drilling fluid systems. The well structures turn four into three by field experiment. Compared with the previous, the average rate of penetration is increased by 2.43 times, drilling duration is reduced by 82.75 d. The conventional deflecting tools meet the demands of well trajectory control of 1 300~1 800 m horizontal section, and the drilling costs are greatly cut. All of these create favorable conditions for effective development of Changji oilfield tight oil Related Articles | Metrics

A Production Rate Equation for Long Horizontal Wells LI Chuanliang, LIN Xing, ZHU Suyang 2014, 35 (3):  1-1.  Abstract ( 77 )   PDF (300KB) ( 305 )   Save Short horizontal wells are those which lengths are much shorter than the size of drainage area. The conventional production rate equations are all established for short horizontal wells, which can not be used to calculate the production rates of long horizontal wells. So called long horizontal wells are those which lengths are almost the same with the size of drainage area. Based on the equivalent flow resistance theory, a production rate equation was derived in this paper, which can be used for production rate calculation of long horizontal wells, but can not be used for that of short horizontal wells, otherwise, the production rate may be overestimated. The production rate calculated by the long horizontal well equation is the lower limit of production rate calculated by horizontal well equations Related Articles | Metrics

The Problems Existing in Relative Content Analysis of Sandstone Clay Minerals ZHANG Lixia, SHI Yan, LIANG Chenggang, ZHU Xiping, XIANG Hui, XU Xuelong, WANG Jing 2014, 35 (3):  1-1.  Abstract ( 77 )   PDF (300KB) ( 262 )   Save The current domestic analysis method for relative content of sedimentary clay minerals is based on the PRC Oil and Gas Industry Standards SY/T5163-1995 "The X?ray Diffraction (XRD) Analysis Method for Relative Content of Sedimentary Clay Minerals".The disadvantage of this analysis method is that when the separation of clay in sandstone, by crushing the samples, soaking to less than 2 μm in diameter, the plastic debris composed of illite and illite/montmorillonite mixing layer, chlorite and chlorite/smectite mixed layer will inevitably be dispersed into the clay composition which may mixed with clay minerals in sand interstitial materials and directly influence the composition analysis of the clay minerals in sand interstitial materials in the reservoir, resulting in lacking fidelity of relative content of various clay minerals and affecting precise evaluation of the reservoir sensitivity. This paper proposes a new method for such a relative content analysis of interstitial clay minerals, by which the plastic debris can be separated from the interstitial materials, thus avoiding the lacking fidelity phenomenon Related Articles | Metrics

Geological Characteristics and Hydrocarbon Accumulation Model of the Upper Paleozoic Khuff-Lower Mesozoic Sudair Play in the Central Arab Basin JIA Xiaole1, HE Dengfa1, TONG Xiaoguang2,WANG Yumei3a, JIA Aiting3b, TAO Qin’e3c 2014, 35 (3):  1-1.  Abstract ( 88 )   PDF (300KB) ( 474 )   Save The Khuff-Sudair play is an important play in Persian Gulf Basin. This paper studied the paleogeography evolution, hydrocarbon source rocks, reservoir rocks, cap rocks and hydrocarbon accumulation process and model of the Khuff-Sudair play. The Lower Silurian Qusaiba source rock was deposited in anoxic marine shelf in fast subsiding depo?center of Arabian platform. Its source rock went into oil window in the Callovian period of Late Middle Jurassic and into gas window in the Early Cretaceous-Turonian period. The oil and gas migrated vertically through faults and fractures and horizontally through overlying sandstone into the Khuff reservoir of the Upper Permian. The Sudair formation of Lower Triassic provided an effective regional seal. The time of oil generation and expulsion was earlier than the time of trap formation, so the oil was difficult to accumulate. The time of gas generation and expulsion was at the same time with the trap formation, so the gas accumulation occurred in the structural trap formed by the basal activity. The Upper Paleozoic Khuff-Lower Mesozoic Sudair play in the North-South Pars gas field could be a major target for petroleum exploration in the Mid-Arab ersian Gulf basin in the future Related Articles | Metrics