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01 April 2011, Volume 32 Issue 2 Previous Issue    Next Issue

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Discussion on Several Factors Affecting the Amount of Hydrocarbon Resources ZHOU Zong-ying 2011, 32 (2):  105-108.  Abstract ( 109 )   PDF (324KB) ( 197 )   Save The knowledge and appraisal of hydrocarbon resources potential is a long process, and the amount of resources can be changed with development of theory, increase of knowledge, change of resources connotation, progress of technical methods, difference of assessment method and change of international market oil price. Resources and reserves are intrinsically linked. Reserves are proven resources and an integral part of resources. With the deepening of the exploration practice, the resources may be shifted into the reserves. Moreover, the rationality of the resources appraisal result can be verified according to the intrinsic relations between the resources and the reserves and the characteristics of oil-gas reserves discovery curves. References | Related Articles | Metrics

Discovery of Slump-Turbidity Fan System in Fukang Sag of Junggar Basin and Feature of Its Hydrocarbon Accumulation HUANG Yun, MA Zhi-liang, CHEN Yong, YUAN Bo, WANG Jun, WU Yu-ping 2011, 32 (2):  109-111.  Abstract ( 96 )   PDF (305KB) ( 420 )   Save The slump-turbidity fan systems discovered in Sangonghe formation of Jurassic in eastern Fukang sag of the Junggar basin occur below the slope break in deep-water lake shale environment, above which there exist delta deposits of shore-shallow lake facies. The slump-turbidity fan systems are resulted from re-migrating toward deep-water position and deposition of the delta frontal sand bodies in form of turbid flow under the process of trigger factor. The channel sands in the fan systems are as good oil-gas reservoirs. Because the slump-turbidity fan sands directly covered by deep-water lacustrine shale are close to the source rocks, they could form good lithologic reservoirs. It is concluded that the slump-turbidity fan systems should be a new domain for petroleum exploration of the Jurassic in eastern Junggar basin. References | Related Articles | Metrics

Heterogeneity and Influencing Factors of Carboniferous Volcanic Reservoirs in Beisantai Area, Junggar Basin LUO Ming-gao, OUYANG Ke-yue, MA Ya-xi, LI Pei-jun, LIU Hao-tian, XIANG Hui, LI Gang 2011, 32 (2):  112-114.  Abstract ( 89 )   PDF (375KB) ( 301 )   Save The characteristics of reservoir lithology and petrophysical property as well as serious heterogeneity of the target zones in studied area are introduced in this paper. The study suggests that the heterogeneity is mainly influenced by weathering interface, lithology, lithofacies and fractures. In vertical, the effect of unconformity depth on heterogeneity is a key factor, and for the same depth, it is influenced by the lithology and dissolution, while the fractures expand the connectivity and scale of reservoir dissolution. Accordingly, two models for forming the favorable volcanic reservoirs are discussed. References | Related Articles | Metrics

Exploration Potentials of Pingdiquan Formation of Permian in Kelameili Piedmont of Junggar Basin GUAN Jian, CAO Feng, CHEN Yong 2011, 32 (2):  115-117.  Abstract ( 77 )   PDF (314KB) ( 195 )   Save The Pingdiquan formation of Permian in the annular Kelameili piedmont area of Junggar basin is dominated by alluvial fan and fan-delta in sedimentary facies, siltstone and shale siltstone in reservoir lithology, belonging to poor-medium reservoir in overall evaluation. The study shows that fracture is the key factor for improving the Darcy flow conditions of the reservoir rocks and the dolomite mudstone strata enriched with fractures and vugs have the good petroleum exploration potentials. At present, the petroleum exploration objects are dominated by lithologic trap and stratigraphic-lithologic trap, and the reservoir types dominated by lithologic reservoir and lithologic-stratigraphic reservoir. The comprehensive analysis suggests that there are five favorable areas for petroleum exploration in Kelameili piedmont of Junggar basin, these are, C46 area, Shazhang area, north D5 area, D1-D5 Wellblock and east D5 Well. References | Related Articles | Metrics

Identification of Lithologic Traps in Xiayan Nose Structural Belt of Luxi Area LI Xia, ZHANG Rong, XIE An, MENG Qing-yang 2011, 32 (2):  119-121.  Abstract ( 84 )   PDF (399KB) ( 246 )   Save Luxi area of Junggar basin is rich in hydrocarbon resources, and in recent years, a series of lithologic hydrocarbon reservoirs have been found during hydrocarbon exploration of Sangonghe formation of Jurassic in Xiayan nose structural belt, which reveals great prospects in shallow layers. In this paper, technologies including sedimentary reservoir geological modeling, seismic attribute prediction, wave impedance inversion and data object visualization analysis are adopted to synthetically identify five lithologic traps, such as northern Well Madong-2 trap, Wellblock Madong-3 trap, eastern Well Madong-3 trap, southern Well Xiayan-6 trap and southern Well Xiayan-3 trap. The total area of these traps is 361.7 km2, the deepness of highs ranges from 2 150 m to 2 270 m, and the largest closure in eastern Well Madong-3 trap reaches 460 m. The synthetical analysis indicates that the lithologic traps are developed in Xiayan nose structural belt, and the geological conditions are favorable for forming lithologic hydrocarbon reservoirs. References | Related Articles | Metrics

Identification and Distribution of Low-Resistivity Reservoir in Wutonggou Formation of Upper Permian in Xiquan Area, Junggar Basin XIONG Ting, ZHAO Zhe, WANG Yan, HU Yang, XIONG Xiao-hua 2011, 32 (2):  122-125.  Abstract ( 90 )   PDF (451KB) ( 197 )   Save Low-resistivity reservoir of Wutonggou formation of the Upper Permian in Xiquan area in eastern Junggar basin is found rather than other areas with middle-high resistivity beyond Xiquan. The reservoir in Xiquan area is characterized by "three lows", namely, low resistivity, low density and low gamma ray. And the lithology of low-resistivity reservoir is medium-fine lithic greywacke with lots of plastic pelolithic texture and calcareous interbeds, belonging to medium porosity and low permeability reservoir, according to the rock samples analysis. The direct reasons for forming low resistivity are high shale content and high water saturation. Through log interpretation for identification of the lithology of reservoir, integrated with seismic interpretation result, the target reservoir's oil is accumulated in the lithologic trap formed during low and lake transgressive system tracts deposition. The scale and distribution of the lithologic reservoir are controlled by the development of lithologic traps. Meanwhile, the formation of lithologic traps is controlled by the depositional setting. These are essential factors for forming the "three lows" in Xiquan area. Exploration survey shows that similar traps in this area are developed widely, which is favorable for shaping lithologic hydrocarbon reservoirs. References | Related Articles | Metrics

Hydrocarbon Distribution of Ordovician in Carbonate Vuggy Reservoirs in Halahatang Area, Tarim Basin CUI Wen-juan, LI Ming, ZHANG Li-juan, GAO Li, TANG Jun-wei, XIA Wei-jie, MA De-bo 2011, 32 (2):  126-128.  Abstract ( 108 )   PDF (825KB) ( 237 )   Save The carbonate vuggy reservoirs in this study area show obvious "string beads" reflection in seismic profile and star or massive feature in plane map of seismic attributes. The hydrocarbon-bearing vugs are characterized by low gamma ray and low velocity from geophysical analysis. The hydrocarbon-bearing property is identified by pseudo-acoustic impedance inversion using the method for reconstruction of acoustic velocity curve from gamma ray curve. Combination of this method with seismic attribute technique can more precisely predict the distribution of oil-gas reservoirs. References | Related Articles | Metrics

Key Control Factors of Tight Sandstone Gas Reservoir of Piedmont in Northern Tuha Basin CHEN Zhi-jun, SUN Yu-feng, MOU Lan-sheng, ZHENG Yu-ping, LIU Yu-xiang, JIA Guo-qiang, WU Wen-xi 2011, 32 (2):  130-132.  Abstract ( 95 )   PDF (287KB) ( 289 )   Save Based on the studies of favorable geological conditions and key control factors of tight sandstone gas reservoirs in the piedmont in northern Tuha basin, it is suggested that these reservoirs are characterized by the same source rocks, self generation and self reservoir. The coal measure strata of Shuixigou group of Middle-Lower Jurassic are a set of quality source rocks and the dominant contributors to natural gas enrichment in the studied area. In the sedimentary period of Shuixigou group, the source materials supplied from the piedmont zone was abundant in the north, so underwater channel sand bodies developed at front of braided river delta, becoming the main site of the tight sandstone gas accumulation. In structural highs, fractures and fissures commonly occurred under the strong folded process, raising the percolation capability of the sand bodies; while in the flat slope area, the following tectonic movement was faint and favorable to large-scale original tight sandstone gas accumulation. And the source rocks of Shuixigou group entered into great amount of gas-generating stages in Neogene and Quaternary period, characterized by late gas accumulation, being favorable to preservation of the tight sandstone gas reservoirs. References | Related Articles | Metrics

Structural Characteristics and Deformation Mechanism of Kedong Thrust Belt in Piedmont of Kunlun Mountain ZENG Chang-min, DU Zhi-li, ZHOU Xue-hui, FENG Xiao-jun, GUO Qun-ying, WEI Wei 2011, 32 (2):  133-135.  Abstract ( 108 )   PDF (421KB) ( 546 )   Save The newest seismic profile of "wide line and large array" in Kedong area is used to interpret Kedong structural belt, taking the KD-1 trap as an example, combining with the study on outcrop and drilling data. The new structural model is an imbricate structure made up of thrust fault blocks with different dips. The root of the fault blocks is extending toward the south and convergent on the reverse fault with steep basement. The frontal of the imbricate structure may be convergent on the contact interface between the Mesozoic and the Cenozoic, which causes slipping and forms thin-skinned thrust fault structure, in which the multiple fault blocks combining with related folds have shaped several traps in Kedong structural belt. References | Related Articles | Metrics

Mechanics of Normal Fault Formation and Its Control on Fault Gouge YANG Lei, QI Yao-guang, REN Xu-hu, LIU Xin-fu, SUN Zhi-xin 2011, 32 (2):  137-140.  Abstract ( 175 )   PDF (269KB) ( 624 )   Save Fault gouge is one of the main influence factors to the fault sealing. Dynamics and kinematics analyses are conducted on the mechanism of normal fault formation. From the time domain and space domain, the stress distribution of upthrow and downthrow blocks and the fault gouge distribution of normal fault are discussed. The study shows that the fault gauge is controlled by the fault and associated with the fault. The upthrow block is an active block and the downthrow block is a passive block. With the growth of normal fault, the fault gouge in the normal fault occurs in forms of thinning, elongate, smear and dragging as dynamic evolution process, and shapes to a certain width of the upthrow block of the normal fault. References | Related Articles | Metrics

Identification of Non-Structural Traps Using Reflection Phase Contrast and Seismic Multi-Attributes WU Cai-xi, LIU Ping, ZHAO Chang-yong, PAN Li-jun, MA Hui-shu, ZHOU Zuo-ming 2011, 32 (2):  141-142.  Abstract ( 81 )   PDF (250KB) ( 237 )   Save It is unreliable that using strong phase contrast method to identify the sequence stratigraphic interface and the subtle trap during seismic interpretation. This paper proposes the seismic reflection phase contrast and interpretation method, amplitude synchronism contrast principle and rationality examination. It suggests that these methods are effective for description of stratigraphic-lithologic traps and should be used to identify them with more accuracy. References | Related Articles | Metrics

Denudation Thickness Estimation of Sedimentary Formation in Ordos Basin by Acoustic Logging Information WENG Wang-fei, WANG Jian-qiang, ZHANG Rong-rong, CHEN Hong, GUI Xiao-jun 2011, 32 (2):  143-146.  Abstract ( 108 )   PDF (301KB) ( 310 )   Save By analyzing the principle of the method for estimating the denudation thickness according to interval transit time information and its applicable condition, it is recognized that the method can be used to estimate the denuded thickness after the Early Cretaceous in Ordos basin. The estimation result shows that the gradual denudation decreases from east to west: in eastern areas such as Shenmu, Yulin and Jiaxian whose strata had been denuded over 1 400 m; while in western areas such as Huanxian and Zhenyuan whose strata had been denuded about 400 m. It reflects that the late reconstruction of this basin is characterized by the strong in the eastern and boundary areas and the weak in the western and inner areas. References | Related Articles | Metrics

Production Well Control Mechanism of Pair of Horizontal Wells by SAGD Process with Application QIAN Gen-bao, MA De-sheng, REN Xiang, SUN Xin-ge, XI Chang-feng 2011, 32 (2):  147-149.  Abstract ( 98 )   PDF (380KB) ( 341 )   Save Production mechanism of pair of horizontal wells by steam-assisted gravity drainage (SAGD) process is studied from the monitoring data and analytical method. Analysis shows that the fluid in steam chamber flows mainly by gravity drainage with low pressure gradient. The fluid flow below the steam-liquid interface between the steam injection well and production well is dominated by pressure drive, different from the gravity drainage in the steam chamber, with relatively high pressure gradient. Sub-cool control is optimized using discretization wellbore model based on the understanding of pressure gradient distribution of production well. The result indicates that sub-cool control ranging from 10℃ to 15℃ is consistent with the field analysis results. References | Related Articles | Metrics

Gas Hydrate in Shengshen 2-1 Block: Forming Experiment and Prediction YANG Shu-ren, PENG Peng, PENG Yuan 2011, 32 (2):  150-152.  Abstract ( 70 )   PDF (267KB) ( 262 )   Save The accurate prediction of the critical condition of gas hydrate formation for effective prevention is difficult. This paper compares and modifies the existing prediction models, mainly considers the equilibrium among the hydrate, gas and rich water phases while forming the gas hydrate, thus the prediction model for the gas hydrate is more reasonable based on the predicted critical condition. The results show that for a certain component of natural gas and pressure, there is a critical point of hydrate formation temperature. Moreover, if gas temperature is lower or the pressure is higher or the relative density is larger, it is much easier to form hydrate. The maximum error between the calculated results and the experiment data is 0.385%, indicating this prediction model is so high in precision that it can provide important theoretical basis for the technical design of gas hydrate prevention used in fields. References | Related Articles | Metrics

Feasibility of Water Injection Close to Fracture Pressure for Low Permeability Hydrocarbon Reservoir—An example from Bei-16 reservoir in Beisantai oilfield LIANG Cheng-gang, LIU Wei-dong, SHI Yan, WANG Guo-xian, XIE Jian-yong, CAI Jun, WANG Hui-qing 2011, 32 (2):  153-155.  Abstract ( 87 )   PDF (229KB) ( 254 )   Save Low-permeability hydrocarbon reservoir is normally characterized by high starting pressure differential, high injection pressure and serious under injection, etc. Augmented injection measures of injection wells, such as fracturing, acidizing and ultrasonic vibration, mostly have the problems of less incremental water injection rate and short response time. When injection pressure is up to the formation fracture pressure, micro-fractures will produce around injection wells, which can improve the permeability of immediate vicinity of wellbore. Injection water filtrating rapidly along fracture wall and fracture extension pressure decreasing will cause limited length and height of fracture extension and little effect on casing and barriers. By water injection close to fracture pressure at Bei-16 low-permeability reservoir, its water injection rate, formation pressure and waterflood swept area are all enlarged, with obvious response from production wells. The predicted recovery rate can be increased. References | Related Articles | Metrics

Domain Material Balance Method for Low Permeability Gas-Oil Reservoir by Depletion Drive Process CHEN Guang-mei, CHE Xiong-wei 2011, 32 (2):  157-159.  Abstract ( 86 )   PDF (200KB) ( 292 )   Save Researches show that the fluid flow in low permeability media needs a start-up pressure gradient. That is, the drive pressure must be greater than a certain threshold pressure if the fluid is to flow. Such a flow feature cause that the pressure drops at the locations with different distances from the well are obviously different from each other. Therefore, the pressure drops for different locations can not be approximately thought as the same. However, these pressure drops are treated as the same one by using the conventional material balance method. The domain material balance method is presented for this case, and used to determine the elastic drive recovery of low permeability reservoir. The principle, usage and case study of this method are introduced in this paper. The calculated result by the method is more accordant with real conditions of low permeability reservoirs. References | Related Articles | Metrics

Measures for Overall Development of Loose Sand Reservoir with Bottom Water CHEN Wei-hua, NING Yu-ping, LIU Wei-xin 2011, 32 (2):  160-162.  Abstract ( 90 )   PDF (217KB) ( 377 )   Save In consideration of overall development difficulties of Xijiang 23-1 oilfield that is a typical loose sand reservoir with bottom water, many new technologies have been applied, such as pipe base completion, reasonable sand production, reservoir damage prevention and drilling for improving quality of horizontal well interval, etc. These technologies to overcome horizontal drilling buildup difficulty, formation damage and bottom water coning allow the overall development of Xijiang 23-1 oilfield to be finally successful. Accordingly, a series of development technologies and experiences suitable for such a reservoir are accumulated. References | Related Articles | Metrics

Optimization Principles for Horizontal Wellbore Length WANG Da-wei, LI Xiao-ping 2011, 32 (2):  163-166.  Abstract ( 121 )   PDF (306KB) ( 325 )   Save At present, the optimization of horizontal wellbore length is based on Dikken's principle in most cases, that is, the optimal horizontal wellbore length is the length that the production decreases by 20% due to the friction loss. A formula is derived from the mathematic model of optimal horizontal wellbore length to calculate the ultimate output for horizontal well in definite reservoir and fluid condition. Integrated with case analysis, the rationality of Dikken's principle is analyzed. It is suggested that the horizontal wellbore length calculated by Dikken's principle cannot reach its full potential in reservoir development, and with the contrast to the ultimate output, the recovery percent is relatively low. This paper proposes the calculation method for optimal horizontal wellbore length on the basis of the ultimate output principle and analyzes the relationship between such two optimization principles. The study is of significance for guiding horizontal well development and optimization design. References | Related Articles | Metrics

Water Breakthrough Characteristic of Horizontal Well in Bottom Water Reservoir in Tahe Oilfield, Tarim Basin XU Yan-dong, LI Dong-mei, LI Jiang 2011, 32 (2):  167-169.  Abstract ( 74 )   PDF (265KB) ( 207 )   Save The horizontal well following water breakthrough in bottom water reservoir is characterized by the rapid water-cut raise, the production decline, the difficult later water blockoff and the high operation cost. This paper studies the watered-out horizontal well feature in bottom water reservoir, according to water breakthrough characteristic of horizontal well, by means of physical modeling, theoretical derivation and numerical simulation, and proposes the watered-out model for horizontal wells in homogeneous and inhomogeneous reservoirs. References | Related Articles | Metrics

Determination of Reasonable Producing Pressure Differential of Lvda 5-2 Oilfield KANG Kai, FENG Min, LI Yan-lai, LI Qi-zheng, SU Yan-chun, ZHANG Cai-qi 2011, 32 (2):  170-172.  Abstract ( 128 )   PDF (197KB) ( 304 )   Save Lvda 5-2 oilfield belongs to an unconsolidated sandstone reservoir, with the characteristics of poor cementation, strong sand carrying capacity of fluid, and easy sand production during exploitation. It is significant to determine producing pressure differential scientifically, implement refined management of oil well for ensuring stable production and achieve maximum oil productivity. The rock mechanics method is used to determine the critical sand production pressure differential in Lvda 5-2 oilfield. By combination with the research results of formation-saturation pressure differential and real production conditions, the limit of reasonable producing pressure differential of Lvda 5-2 oilfield is proposed. References | Related Articles | Metrics

Experiment on Saturated flow in Ultra-Low Permeability Reservoirs without Threshold Pressure Gradient XIE Quan, HE Shun-li, JIAO Chun-yan, ZHU Hua-yin, LV Zhi-kai 2011, 32 (2):  173-175.  Abstract ( 93 )   PDF (217KB) ( 347 )   Save According to the fundamental differences about the threshold pressure gradient existing in ultra-low permeability reservoirs given by domestic and foreign researchers, this paper proposes unsteady approach to test the threshold pressure gradient of saturated and unsaturated flow in the lab using the outcrop full-hole core with ultralow permeability of the Triassic in Ordos basin by means of fullyautomatic flooding system of AFS300TM provided by the Core Lab in U.S.A. The threshold pressure gradient in the saturated flow has been analyzed with the investigation of pressure variation from downstream and upstream of the core holder. The experimental results indicate that the threshold pressure gradient is not existent in terms of flowing of brine, kerosene and crude oil, and the interaction between the molecular of the fluid and the porous surface of the core plugs will not cause the threshold pressure gradient. References | Related Articles | Metrics

Evaluation of Reservoir Quality of Lower Karamay Formation in West District No.1 with Type Logs XIN Yu-xia, WANG Zhi-zhang, PANG Xiong-qi, ZHANG Yan, LIN Jun, GULIZADAN, LI Wen-feng 2011, 32 (2):  176-178.  Abstract ( 78 )   PDF (506KB) ( 182 )   Save The type logs from west District No.1 in Karamay oilfield are classified as the normal logs and composite logs. The normal logs from most wells are poor in quality, so the porosity and permeability models developed by them are lower in interpretation accuracy. For this reason, this paper proposes that for wells without the composite logs, the normal logs can be inverted to composite logs by means of neural network method, by which the porosity and permeability models are developed on litholgy, thus satisfying the requirement of logging interpretation. On the basis of these, the reservoir quality evaluation the Lower Karamay formation in west District No.1 in Karamay oilfield is conducted. References | Related Articles | Metrics

Application of Cyclic Water Flood Technology to Liaohe Tanhai Oilfield ZHANG Zuo-yang 2011, 32 (2):  179-180.  Abstract ( 91 )   PDF (121KB) ( 210 )   Save Hainan-3 fault block in Liaohe Tanhai oilfield is a layered lithologic-structural reservoir with edge water. Following 10-year waterflood development, the inconsistency of development is more and more emerging. In despite of conducting a series of producer water plugging and injector adjustment and obtaining some responses, the year-by-year water cut increasing has caused it to become poor in water drive effectiveness. Searching for new water flood mode to improve the water drive response becomes a necessary task. This paper selects favorable test area based on the geologic feature of Tanhai oilfield for first feasibility evaluation of its cyclic water flood, parameter estimation and field test. The good results for increasing production and improving displacement response provide foundation for implementation of next large-scale cyclic water flooding in this field. References | Related Articles | Metrics

Response Evaluation Technique for Neural Network-Based Reservoir Modification and Its Application GUO Da-li, LING Li-su, XU Jiang-wen, LI Xue-bin, ZHANG Tian-xiang 2011, 32 (2):  181-182.  Abstract ( 109 )   PDF (119KB) ( 238 )   Save Artificial neural network is a technique that can analyze and control the inherent regularity of corresponding input and output data pre-available, and obtain the estimating output results from the new input data. On the basis of this technique, this paper presents the prediction model and method for deliverability of reservoirs following hydraulic fracturing, mainly studies the relative five parameters to fracturing modification of reservoirs in normal conditions, such as fracture length, fracture conductivity, fracture height, extent of fracture communicating with aquifer, degree of damage of fracturing fluid on formation. Also, based on the comparison of more accurate prediction result of reservoir productivity with current program and fracturing effect, the reservoir modification prospect evaluation technique and corresponding software package are developed and widely used in explorative blocks in the northwestern margin of Junggar basin. The overall coincidence rate has reached 83.33%. References | Related Articles | Metrics

Sublacustrine Fan Identification by Seismic Interpretation Technology—An example from Karamay oilfield DONG Wen-bo, WU Yu-han, WU Cai-xi, MAO Dan-feng 2011, 32 (2):  183-184.  Abstract ( 118 )   PDF (364KB) ( 258 )   Save Sublacustrine fan is a kind of deposit of gravity flow developed on slope of deep lake-bathyal subfacies area, which occurs widely in most of the continental sedimentary basins. In view of its distribution in group, it has become a major domain for petroleum exploration of lithologic reservoirs. Taking the sublacustrine fan of Lower Wuerhe formation of Permian in K-81 Well east area of Karamay oilfield as an example, this paper presents the seismic identification model for the sublacustrine in deep lake-bathyal subfacies area from the outside reflection feature and inner reflected structure of the seismic reflection event, integrated with seismic multi-attribute analysis, spectrum decomposition and layer flattening techniques for verification, and finally confirms its range in plane distribution. References | Related Articles | Metrics

A Linear Type Chart for Production Decline Analysis and Its Application FAN Hai-jun 2011, 32 (2):  185-186.  Abstract ( 118 )   PDF (200KB) ( 283 )   Save A new linear type charting method for production decline analysis and the curve matching procedure and the parameter estimation are presented. It is easier to get history match, determine the decline exponent and judge the decline type compared with the traditional curve type chart. The case study shows its applicability. References | Related Articles | Metrics

Prediction of Pore Pressure, Fracture Pressure and Collapse Pressure with Well Logging Data GUO Gui-sheng, LIN Jing-qi, ZHANG Zhong-hua, WU Cong-wen, HOU Qing-yu 2011, 32 (2):  187-189.  Abstract ( 166 )   PDF (202KB) ( 689 )   Save The drilling mud leakage, formation fluid overflow, well wall collapse, formation breakdown, reservoir pollution and other anomalies are mainly controled by pore pressure, fracture pressure and collapse pressure ("three pressures"), which are common problems faced by drilling technicians. Establishing a "three-pressure" profile before drilling, a safe drilling mud density window can be designed to ensure drilling safety for oil field exploration and development.Using wireline formation testing for directly obtaining pore pressure and dipole acoustic logging method for predicting rupture and collapse pressures, the continuous profile of formation fracture and collapse pressures can be established, based which the "three pressures" results database and online query system in Junggar basin have been provided for designers of drilling, geology and downhole operations. The effect is proved to be good in two-year appliction by Xinjiang Oilfield Company. References | Related Articles | Metrics

Multi-Arm Caliper Imaging Logging (MCI) and Its Application in Karamay Oilfield LI Gang, ZHU Guang-liang, WANG Yong-kang, ZHAO Zhong-he 2011, 32 (2):  190-192.  Abstract ( 102 )   PDF (408KB) ( 584 )   Save MCI is one of main technologies for casing damage detection. This paper reviews the status of its application to production well casing damage detection in Karamay oilfield. According to real requirement, the effectiveness of the special technology is detected and verified. The case study indicates that MCI is in good application and of broad prospects in Karamay oilfield. References | Related Articles | Metrics

Research on In-Situ Stress and Wellbole Stability of Overthrust Structural Belt and Its Application SHEN Hai-chao, HU Xiao-qing 2011, 32 (2):  193-196.  Abstract ( 96 )   PDF (306KB) ( 231 )   Save Overthrust nappe structure usually has strong tectonic stress and abundant bedding and cracks, and borehole instability has plagued its drilling operation. It is necessary to determine the in-situ stresses distribution before research on wellbore stress state and wellbore stability. In this study, a new method for study on the in-situ stress distribution of overthrust nappe structure is proposed. Based on in-situ stress measurement, adopting the constrained optimization finite element method (COFEM), 3D in-situ stress of this structure is numerically simulated and verified by field formation leak-off test data. The feature of shale hydration and the relation between the rock mechanical properties and water content are analyzed from the experiment of the shale hydration. Based on the behavior of shale hydration and the failure criterion of rocks, the model for stress distribution of the water sensitive shale borehole surrounding beds was developed and the software for shale borehole stability is programmed. The software can be used to research on the collapsing pressure, fracture pressure, the safe drilling fluid density window and the shale collapse cycle. This study is useful for the mechanism analysis of shale wellbore instability in the overthrust nappe structure and the related countermeasures arrangement. References | Related Articles | Metrics

There Is No Oil-Wet Rock Underground LI Chuan-liang 2011, 32 (2):  197-198.  Abstract ( 180 )   PDF (157KB) ( 657 )   Save Wettability of rocks can be determined through experimental measurements indoors. However there is no oil-wet rock underground. By experiment, the degree of water-wettability of rocks can only be measured rather than the oil-wet property of rocks. The water-wet property of rocks makes them possible that oil and gas migrate to traps successfully, and the pressure of reservoirs distributes normally. If the rock underground is oil-wet, oil and gas will scatter along the migration way and no hydrocarbon will be accumulated finally. In oil-wet reservoirs, the distribution of formation pressure will appear as incredible phenomenon. It is concluded that there is no oil-wet rock underground, and the rocks underground can only be water-wet in nature. References | Related Articles | Metrics

A Discussion of Oil Layers Membership for Chunfeng Oilfield in Chepaizi Area of Junggar Basin SONG Chuan-chun 2011, 32 (2):  199-200.  Abstract ( 109 )   PDF (372KB) ( 240 )   Save The major oil layers developing in Chunfeng oilfield are located near the unconformity between Shawan formation and Lower Cretaceous (N1s-K1), which membership is still disputed nowadays, thus influencing related exploration deployments and development designs for available different horizons. The comprehensive analyses of them are conducted by means of fine stratigraphic correlation, seismic horizon calibration, velocity analysis, attribute extraction and stratigraphic isotopic dating, etc. and it is shown that the major oil layers are of more similarity with the Cretaceous, and they should be reasonably classified into Lianmuqin formation (K1l) of the Lower Cretaceous. References | Related Articles | Metrics

Forward Modeling of Callovian-Oxfordian Reefs of Upper Jurassic in AS Block of Amu Darya Right Bank in Turkmenistan ZENG Zhong-yu, CHEN Fa-jing, CHEN Zhao-nian, ZENG Dong-dong 2011, 32 (2):  201-203.  Abstract ( 74 )   PDF (416KB) ( 280 )   Save Based on the geologic characteristics and electric feature in different litholigic intervals of Callovian-Oxfordian formation of the Upper Jurassic in AS Block of the Amu Darya right bank in Turkmenistan, a reef geological model is developed, and the seismic response of this model is simulated by wave equation forward modeling method, showing that the seismic response of reef in the area characterized by mound-shaped and lenticular reflections, and the reef edges often appear on onlap and difffraction phenomena, with dome hoisting, weak reflection, weaker amplitude and discontinuous waveform. Such messy or weak internal reflections cause the great differences between the reflected wave amplitude, frequency, phase continuity and those of surrounding rocks, the thickness of the inside is obviously greater than that of both sides of reef. These characteristics are consistent with seismic profile characteristics of reef over wells, so the seismic-identified characteristics and patterns of the reefs can be recognized and developed using forward modeling method. References | Related Articles | Metrics

Approach to Hydrocarbon Accumulation in Piedmont of Zagros Foreland Basin, Iran WANG Qiang, CHENG Xu-bin, ZHANG Wei-bi, WANG Wei-bin, YANG De-yin, ZHENG Shu-fen 2011, 32 (2):  204-206.  Abstract ( 124 )   PDF (368KB) ( 647 )   Save This paper presents period of hydrocarbon generation and trap structure formation in piedmont of Zagros foreland basin of Iran in view of the evolution history of source rocks and tectonic development history in this basin, and discusses its overall process of hydrocarbon accumulation from hydrocarbon-bearing characteristics in drilled structures. It is suggested that traps in the trailing edge of thrust group in southern Block-3 of Iran are dominated by oil accumulation, those in the middle of thrust group dominated by gas accumulation, while those in the peak of it are unfavorable for conservation and unsatisfactory in terms of exploration result and prospect. These recognitions can help to delineate the favorable places for oil-gas prospecting, and provide the significant pattern of hydrocarbon distribution in foreland basins. References | Related Articles | Metrics

Geological Characteristics and Reef-forming Pattern of Antelope Reef Gas Field in Papua Basin YANG Lei, KANG An 2011, 32 (2):  207-209.  Abstract ( 116 )   PDF (274KB) ( 359 )   Save Papua basin is a Mesozoic and Cenozoic basin which developed on the granite basements of Paleozoic in the margin of Australian continental plate. This basin is very rich in oil and gas resources especially in Antelope gas field, it is an infrequent large reef gas field. Antelope reef is a pinnacle reef which developed on the carbonate platform, with great thickness of reef due to its growth upward and good hydrocarbon bearing spaces. So lithologic-structural reservoir like such a reef can be a growth point of oil-gas reserves in Papua basin. References | Related Articles | Metrics