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2014 Vol. 36, No. s1

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2014, 36(s1): .
Abstract(422) PDF-CN(340)
Abstract:
Fracture development regularity and its effects on hydrocarbon accumulations in Paleozoic reservoirs in western Bachu Uplift
Ma Zhongyuan, Yang Hongcai, Huang Wei, Zhang Li, Lan Mingjie
2014, 36(s1): 1-7. doi: 10.11781/sysydz2014S1001
Abstract(677) PDF-CN(389)
Abstract:
Based on core, thin section, geophysical and testing data, the fracture development in the Paleozoic reservoirs in the western Bachu Uplift was studied. It was concluded that fractures were most developed in Carboniferous, and second in Ordovician, and least in Silurian and Devonian. The fractures were usually structural ones, among which the oblique fractures were most common, followed by the horizontal and vertical fractures. The fractures in Carboniferous were half-filled by calcite, dolomite, terrigenous clastic and anhydrite, etc, while those in Ordovician were filled or half-filled by calcite and shale. The development of the fractures was controlled by tectonic stress and position, fault, lithology, thickness and rock combination. Fractures could not only improve reservoir performance, but also help karstification and create favorable conditions for the formation of se-condary pores. Fractures were also an important medium in the process of oil and gas migration and accumulation, and controlled oil and gas accumulation.
Fault characteristics and its control on hydrocarbon accumulation in Xianbazha area of Markit Slope, Tarim Basin
Qiu Huabiao, Wu Liming, Yin Ting, Ma Hailong, Liu Zihao
2014, 36(s1): 8-11. doi: 10.11781/sysydz2014S1008
Abstract(899) PDF-CN(388)
Abstract:
Based on the interpretation of 3D seismic sections, strike-slip faults were widely developed in Xianbazha area besides thrust faults. The faults appeared in different layers and overlapped in the space. The evolution of the faults experienced three stages including the middle Caledonian, the late Hercynian and the Himalayan. The faults played an important controlling role in oil and gas accumulation. The small thrust faults in the middle Caledonian were conducive to karst reservoirs as passageways of meteoric fresh water, and the strike-slip faults in the late Hercynian were favorable to reservoir reconstruction for deep thermal fluid. The Xianbazha fault controlled the development of trap in the upper Paleozoic. The strike-slip faults were favorable to oil and gas aggregation in the upper Paleozoic and restricted oil and gas accumulation in the Ordovician as vertical migration pathways.
Accumulation conditions and favorable exploration zones of shale gas in Kongquehe Slope, Tarim Basin
Chen Xuyun, Zhu Xiuxiang, Zhang Genfa, Yang Zichuan
2014, 36(s1): 12-17. doi: 10.11781/sysydz2014S1012
Abstract(988) PDF-CN(400)
Abstract:
In the Lower Cambrian Xidashan Formation, the Middle Cambrian Moheershan Formation and the Middle-Lower Ordovician Heituwa Formation in the Kongquehe Slope, marine facies black shale rich in organic matter was developed. Outcrop observations and the integrated analyses of drilling and seismic data indicated that the shale was featured by big thickness, wide distribution, high organic matter abundance, favorable organic matter type, high thermal maturity, well-developed micro-pore and micro-fracture, brittleness mineral, favorable preservation condition, and moderate burial depth, which were favorable for shale development. Several favorable exploration zones in the Kongquehe Slope were predicted, such as the Yuli fault belt, the northern Qunke tectonic belt and the northern Central slope.
Characteristics and development model of hydrothermal alteration reservoir of Ordovician Yingshan Formation in northern slope of central Tarim Basin
Han Jun, Lü Haitao, Cao Zicheng, Qiu Huabiao, Wang Baocai, Sha Xuguang, Liu Jun
2014, 36(s1): 18-25. doi: 10.11781/sysydz2014S1018
Abstract(854) PDF-CN(407)
Abstract:
In the Middle-Lower Ordovician Yingshan Formation in the northern slope of the central Tarim Basin, typical epithermal hydrothermal mineral assemblages, such as hydrothermal quartz, lath gypsum and saddle dolomite, were found in carbonate rocks. For different types of quartz inclusions, measured temperature was significantly higher than maximum evolution temperature. The relation between the Yingshan reservoir distribution in typical wells and the potential unconformities in the study area was studied, indicating that the Yingshan reservoirs generated from hydrothermal alteration, rather than the karstification of meteoric water. The main space of the Yingshan reservoirs was secondary hole (cave) and expansion fracture, with low porosity and permeability. They were divided into 3 types: hole type, hole-fracture type and pore type. Analysis of the main controlling factors of hydrothermal alteration reservoir showed that fault-fracture system was a precondition for reservoir deve-lopment, and the NE and NEE main strike-slip faults of the late Caledonian-Hercynian and the secondary faults controlled the plane distribution of hydrothermal reservoir. Deep hydrothermal fluid altered reservoir, and fluid properties and reservoir lithologic structure controlled the vertical distribution of hydrothermal reservoir. The development model of hydrothermal alteration reservoir was established. Hydrothermal alteration reservoirs, which were featured by big thickness, little affected by depth, and widely developed along main and secondary faults, were new gas exploration fielda of carbonate rocks in the Tarim Basin.
Carbon isotope characteristics of Ordovician in Yubei area, Tarim Basin: A case study of well Pishanbei2
Cheng Junfeng, Tan Guanghui, Ma Dongchen, Yue Yong, Wu Tao
2014, 36(s1): 26-29. doi: 10.11781/sysydz2014S1026
Abstract(810) PDF-CN(601)
Abstract:
According to the analyses of 71 carbon isotope samples from Ordovician in the well Pishanbei2 in the Yubei area, GICE event was discovered for the first time under well in the Tarim Basin. The carbon isotope features of Ordovician were classified into three periods as followed. In the first period, it gradually increased in the lower and middle Yingshan Formation. In the second period, it varied nearby zero value from the upper Yingshan Formation to the lower and middle Lianglitag Formation. In the third period, the GICE event took place in the upper Lianglitag Formation. The carbon isotope values slowly raise from negative to positive in Ordovician, and broke into positive in the upper Lianglitag Formation in the study area.
Reservoir development regulations of Ordovician carbonate formation in Yubei area
Xiao Honglin, Zhou Wei, Cheng Lan
2014, 36(s1): 30-33. doi: 10.11781/sysydz2014S1030
Abstract(568) PDF-CN(390)
Abstract:
After multiple stages of tectonic movement, the Yubei area is featured by complicated tectonic pattern and strong reservoir heterogeneity. Based on the formation evolution in depression area, it was analyzed in this article the relations between well location and reservoir development, by comparing resistivity value and seismic coherence characteristics among depression, slope and broken ridge belt in limestone of the Yijianfang and Yingshan Formations. By means of logging data, imagine data and formation test data, we studied the relationship between dolomite degree and reservoir in dolomitic limestone of the Yingshan Formation and dolomite of the Penglaiba Formation. For the limestone formations, reservoirs were well-developed in broken ridge belt and poorly-developed in depression and slope. For the dolomitic limestones and dolomite formations, reservoir developments were related to dolomitization degree.
Further evaluation of source rocks in eastern Tarim Basin
Chang Qi, Yang Shiguo, Zhang Genfa, Chen Xuyun, Wang Bin
2014, 36(s1): 34-39. doi: 10.11781/sysydz2014S1034
Abstract(806) PDF-CN(644)
Abstract:
The studies of organic abundance, type and maturity of source rocks from wells in the eastern Tarim Basin showed that the Middle-Lower Cambrian source rocks were the most favorable source rocks in the study area. The organic abundance was high, with the average TOC content higher than 1.0%. The organic type was good, generally type Ⅰ-Ⅱ1. The organic maturity was high, with Ro ranging from 0.88% to 2.75%, indicating for high-mature and over-mature stages.
Logging evaluation of ultra-low porosity and super-low permeability reservoirs in Silurian, middle Tarim Basin
Qin Weiqiang, Sun Zhaohui
2014, 36(s1): 40-43. doi: 10.11781/sysydz2014S1040
Abstract(1097) PDF-CN(444)
Abstract:
The Silurian reservoirs in Shuntuoguole area of the middle Tarim Basin are featured by ultra-low porosity and super-low permeability. Based on conventional logging, NMR logging and core data, the logging responses and micro features of reservoirs were analyzed. The features of oil and water beds as well as the properties of fluids were identified. The oil/water interfaces were evaluated. The studies provided technical supports for the fine description and exploration of reservoirs with ultra-low porosity and super-low permeability.
Identification and characterization of fracture-connecting components in carbonate fractured-vuggy reservoirs
Li Xiaobo, Li Xinhua, Rong Yuanshuai, He Xinming, Wu Bo
2014, 36(s1): 44-47. doi: 10.11781/sysydz2014S1044
Abstract(750) PDF-CN(673)
Abstract:
The spatial structure of fractures in the carbonate fractured-vuggy reservoirs in the Tahe Oilfield was very complicated; hence the identification and characterization of fracture-connecting components were difficult. Based on modern karst mode, we selected isolated caves, karst rivers and micro-fractures to identify seismic properties. Seismic facies analysis was used to study caves and fractures. 3D geologic network was applied to establish a geometric geologic model quantitatively, which could describe the fracture-connecting components. Amplitude gradient properties could effectively determine the boundaries between "beaded" strong reflectance and formation reflectance, which could detect and image the spatial distribution of caves with beaded reflectance. Maximum curvature attributes could effectively describe the plane linear features and geometric boundary characteristics of faults and fractures, which showed the distribution of fractures. The fracture-connecting components described by karst seismic facies described the geometric states and spatial extensions of fractured-vuggy reservoirs; hence realized the precise description of internal structure and communicating channel, and provided important technical supports or the development of fractured reservoirs.
Reservoir prediction of Carboniferous Kalashayi Formation in Sangtamu block, Tahe Oilfield
Liu Liqun, Yang Zichuan
2014, 36(s1): 48-51. doi: 10.11781/sysydz2014S1048
Abstract(1065) PDF-CN(487)
Abstract:
The Carboniferous Kalashayi Formation in the Tahe Oilfield is one of the most important oil-bearing formations in the area. Sandbodies are characterized by small thickness and great lateral variation. A thorough understanding of its spatial distribution is crucial to exploration and production. To tackle the problem, the researchers studied the banded seismic anomalies developed in the sand groups Ⅰ, Ⅱ, Ⅲ with low sand/formation ratio in the Kalashayi Formation based on the high-resolution data from the Sangtamu block. Combined with well data, using strata slice, spectrum color mixing, coherence cube and seismic attribute techniques, a reservoir prediction method was proposed to identify Carboniferous reservoirs, and was proved effective.
Application of BP neural network to sedimentary micro-facies identification
Liu Junling, Wu Xuedong, Wang Dongzhai, He Zhenggang
2014, 36(s1): 52-55. doi: 10.11781/sysydz2014S1052
Abstract(1002) PDF-CN(706)
Abstract:
A method of sedimentary micro-facies identification based on logging data and BP neural network was proposed in this paper. Through deeply exploring limited logging data, sedimentological sample indexes were gained and the utilization rate of logging data was improved. A series of experiments were conducted in order to find the optimization criterion of the BP artificial neural network and a growing network training method was put forward. Finally, a actual case of net training and micro-facies identification by using sample set and natural samples was analyzed, which showed an accuracy ratio for 83% and realized both high efficiency and precision of micro-facies identification.
Residual oil distribution prediction and potential tapping in fractured-vuggy reservoirs
Li Chenggang, Zhang Wei, Cheng Hong, Jiang Lin, Chen Bintao, Ma Guojian, Wang You, Zhang Zhunxing
2014, 36(s1): 56-60. doi: 10.11781/sysydz2014S1056
Abstract(879) PDF-CN(675)
Abstract:
In the fractured-vuggy reservoirs in the Tahe Oilfield, oil production declined rapidly due to strong heterogeneity, and the recovery rate was low. Based on the geologic and developing features of fractured-vuggy reservoirs, we proposed a new concept, which divided flow unit in single well, to predict residual oil. Residual oil usually enriched in the partially-filled sealing formations with poor physical property and weak energy, the wings of water-flooded area, the regional higher position, low-efficiency oil-replacing area in reservoir after water-flooding, corner area in water-flooding, and the poorly-connected area among different flow units in single well. In the wells with decreasing fluid-supplying ability and energy, water-flooding and controllable massive cracking were still effective ways in residual oil exploration. For those wells failed in water-flooding, drainage recovery and hydraulic dilatancy were recommended. N2 and CO2 injections were economic and effective ways for EOR. Side-tracking and infill well could be deployed to extract residual oil accurately.
Fracture closure of carbonate reservoir in Tuofutai area of Tahe Oilfield
Ma Guojian, Jiang Lin, Cheng Hong
2014, 36(s1): 61-63. doi: 10.11781/sysydz2014S1061
Abstract(862) PDF-CN(617)
Abstract:
In the Tahe Oilfield, the Ordovician carbonate reservoirs are deep-buried with high overburden pressure, which might cause fracture closure. The critical fluid pressure of fracture closure was 37-42 MPa in the Tuofutai area. The comparisons between production statistics and production phenomenon proved the existence of fracture closure. The main factors influencing closure included reservoir burial depth, fracture dip and the angle between fracture trend and maximum principal stress. During production process, some pressure-maintaining measures such as reducing pressure drop and injecting a amount of water could slow crack closing speed. Acidification measures could benefit oil wells to regain some diversion capacity by etching fractures.
Design of hydrocarbon metering system for single well
Kong Xiangmin, Shi Qiang, Li Peng, Hu Yougang
2014, 36(s1): 64-66. doi: 10.11781/sysydz2014S1064
Abstract(746) PDF-CN(433)
Abstract:
The hydrocarbon metering system for a single well was mainly composed of parallel large and small range flowmeters and PLC controller. In the actual measurement process, PLC controller controlled program according to design requirement and flow size. Hydrocarbon metering system could automatically switch to small range, wide range or the combination of both, which effectively expanded the scope of flow measurement (range ratio) and met the need in the accurately calculation of oil and gas. This system provided accurate and reliable production data about reservoir change, well production condition and hydrocarbon exploration scheme. The method was mainly used in oil and gas field development in the process of multi well concentrated metering system, and other wide range flow measurement engineering.
Development and application of acid fluid system for acid fracturing of high-temperature carbonate reservoirs
Tian Jiang, Yang Yingda
2014, 36(s1): 67-69. doi: 10.11781/sysydz2014S1067
Abstract(1045) PDF-CN(721)
Abstract:
In the reformations of fractured and vuggy reservoirs in the Tahe Oilfield, acid fluids and rocks reacted rapidly under high temperatures, and the filtration amount was large. Conventional acid fluid systems failed to realize deep reformations and to improve the conductivity of acid-etched fractures. Thanks to years of laboratory experiments and field tests, multiple sets of acid fluid systems including gelled acid, variable viscosity acid, steering acid and surface cross-linked acid were proposed. Through the analyses and comparisons of high-temperature rheological curves, different acid fluid systems were chosen according to different reservoir types. They were used to guide acid liquid selection and to improve technique in single well, and had obtained good application effects.
Exploration and practice of gas driving in well groups with high water content in carbonate fractured-vuggy reservoirs
Lu Haitao, Wang You, Zhang Zhunxing, Cheng Hong, Wu Hui, Ma Guojian, Wang Huiyong
2014, 36(s1): 70-73. doi: 10.11781/sysydz2014S1070
Abstract(925) PDF-CN(551)
Abstract:
The carbonate fractured-vuggy reservoirs in the Tahe Oilfield are featured by high burial depth, super heterogeneity, various reservoir spaces and so on, with little previous experience resources to draw on and also rather restricted in effective measures available to combat high water cut issues for major well units. In order to keep oil production at a quite high and stable level, we need to do a feasibility study relating to injecting gas between well groups to enhance oil recovery. In this article, relevant theoretical models and mechanism for gas driving in well groups are deduced and the optimizing principles are also introduced through physical simulation experiments, by deeply studying gas injection development situations in China and abroad. Finally, by analyzing some practical cases, it is well-confirmed that gas driving in well groups shows a better performance for large carbonate fractured-vuggy reservoirs and provides new ideas and methods to enhance oil recovery and control the natural declination of such kind of reservoirs.
Mechanisms of in-advance failures in water injection wells
Wen Bo, Wang Dong, Su Hongtong
2014, 36(s1): 74-76. doi: 10.11781/sysydz2014S1074
Abstract(638) PDF-CN(713)
Abstract:
Thanks to the application of water injection in carbonate reservoirs in the Tahe Oilfield, oil productions were improved obviously. The water injection wells in different regions displayed unique dynamic characteristics when more wells were injected with water and more water was injected in wells. After water injection failure, the cumulative injection production ratio was much lower than that of the other wells in the area. Productions decreased sharply when water injections failed in advance.
Application of water injection indicative curves in deep pumping of carbonate reservoirs in Tahe Oilfield
Ding Lei, Zhang Shiliang, Hai Tao, Yao Junbo
2014, 36(s1): 77-80. doi: 10.11781/sysydz2014S1077
Abstract(586) PDF-CN(528)
Abstract:
The technique which injects water to replace oil in single well is an effective and economic way to slowdown production decline in the carbonate fractured-vuggy reservoirs in the Tahe Oilfield. The physical meanings of the different characteristics of water injection indicative curves were analyzed. According to the seepage formula of low-permeability reservoirs, the fluid-supplying condition of the 2nd set of reservoir was calculated. Combined with present pumping techniques, we used deep pumping to drawdown dynamic liquid level to the height which had smaller pressure than the inflecting point of water injection. In this way, production pressure difference was enlarged, which caused the liquid supplying of the 2nd set of reservoir in far wells. The technique was applied in field works and had achieved good effects.
Research of paraffin removal & controlling techniques of gas condensate wells in 9th district of Tahe Oilfield
Ouyang Dong, Li Shujie, Xing Yu, Diao Xianwei
2014, 36(s1): 81-84. doi: 10.11781/sysydz2014S1081
Abstract(775) PDF-CN(949)
Abstract:
In view of the difficulties of paraffin removing in acidic condensate gas wells in the 9th district of the Tahe Oilfield, we analyzed the composition and physical/chemical property of sedimentary clogs by means of X-ray diffraction, energy spectrum, infrared spectrum and DSC tests. Different from paraffin deposited in conventional condensate gas wells, the clogs in the 9th district were mainly microcrystalline wax, with melting temperature above 82 ℃. According to wax features and field work situations, a paraffin removal technique with oil soluble chemical paraffin removal agent and paraffin inhibitor through slim tube was recommended for the study area.
Optimization of cyclic gas injection parameters in Dalaoba Condensate Gas Reservoir
Zhang Ai, Huang Jie, He Lei
2014, 36(s1): 85-88. doi: 10.11781/sysydz2014S1085
Abstract(836) PDF-CN(533)
Abstract:
Due to retrograde condensate and water invasion effect in the failure type development of the Dalaoba Condensate Gas Reservoir, there was a rapid decline in gas well productivity. In order to enhance recovery, a cyclic gas injection strategy was adopted. During the cyclic gas injection production period, the injection-production parameters were the key index to influence gas recovery and economic benefits. For the water-drive gas condensate reservoirs which were in the middle and late stages of development in the Dalaoba area, numerical simulation was conducted in this paper to optimize the parameters including injection-production mode, injection-production ratio, etc. The purpose of this research was to improve the effect of cyclic gas injection production by optimizing parameters and scheme.
Origin and identification of low-resistivity oil and gas reservoirs in no.1 structure, north of Luntai condensate gas reservoir
Yao Tianwan, Lü Ping, Ma Haihu, Xu Shisheng, Wu Jian
2014, 36(s1): 89-91. doi: 10.11781/sysydz2014S1089
Abstract(917) PDF-CN(535)
Abstract:
Influenced by structures, reservoirs and accumulation conditions, the resistivity of the Paleogene condensate gas reservoir in the no.1 structure of the northern Luntai condensate gas reservoir was 1.3 Ω·m, which was lower than that of aquifers in gas reservoir of the Bashijiqike Formation in Cretaceous by 2.0 Ω·m. It led to the neglect of low-resistivity reservoirs in early exploration. The origin of low-resistivity oil and gas reservoirs in Paleogene in the Luntai area was studied. A new identification standard to distinguish low-resistivity reservoirs and aquifers was established, which led to a great discovery of condensate gas reservoir in Paleogene of well YL2.
Plugging mechanism and prediction of asphaltene in Bashituo Oilfield
Yang Xiaoteng, Yu Jian, Zhang Kun, Liu Yingtao, Wang Ligang
2014, 36(s1): 92-94. doi: 10.11781/sysydz2014S1092
Abstract(634) PDF-CN(600)
Abstract:
"Wellbore plugging" phenomenon, which always accompanies the whole production cycle, has seriously affected oil and gas production and reservoir exploitation in the Bashituo Oilfield. Colloid instability of internal oil, formation, and pressure drop are the main reasons for asphaltene precipitation and wellbore plugging. By pressure derivation, the predicted depth of asphaltene precipitation ranges from 500 to 2 400 m. Mechanical descaling focused on these sections during production process can successfully help to achieve the purpose of wellbore plugging prevention.
Research and application of composite wellbore viscosity-reduction technology about heavy oil in Tahe Oilfield
Ding Baodong, Li Shujie, Yang Zuguo, He Long, Xing Yu
2014, 36(s1): 95-98. doi: 10.11781/sysydz2014S1095
Abstract(868) PDF-CN(279)
Abstract:
Since the effects of individual viscosity reduction were limited in the Tahe Oilfield, composite viscosity reduction technologies were discussed. Laboratory experiments showed that water-oil soluble viscosity-reducing agents could emulsify heavy oils with viscosity higher than 100×104 mPa·s. The compound of heated and oil-soluble viscosity-reducing agents had better effects. Field works indicated that the chemical compound viscosity reduction could save light oils by 69.8%, and the heated and oil-soluble viscosity reduction could save light oils by 51.27%.
Dispersion and removal of asphaltene in heavy oil, Tahe Oilfield
Yang Zuguo, Wang Lei, Cheng Zhongfu, He Long, Li Shujie
2014, 36(s1): 99-103. doi: 10.11781/sysydz2014S1099
Abstract(988) PDF-CN(397)
Abstract:
Due to the high content of asphaltene in crude oil in the Tahe Oilfield, wellbore plugging was very common as reservoir/wellbore pressure and temperature field changed in oil production process. With X-ray fluorescence spectrometry, component analysis and solvent extraction method, the plugging composition was analyzed, among which over 90% was organic matter. Asphaltene accounted for over 38% in the organic matter. A new asphalt plugging removal agent was innovated and evaluated. The highest dissolution rate at 60 ℃ could reach 2.956 mg/(mL·min). For the crude oil with colloid unstable index bigger than 0.9, asphaltene deposition could be inhibited by adding the new asphalt plugging removal agent with mass concentration of 1%.
Comprehensive control of condensate gas reservoirs in T2a3, block AT1, Tahe Oilfield
Jiang Siyong, Zhang Wei, He Jinxiu, He Xueqin, Tang Jing
2014, 36(s1): 104-106. doi: 10.11781/sysydz2014S1104
Abstract(793) PDF-CN(339)
Abstract:
In sandstone condensate gas reservoirs, production declined rapidly after water breakthrough and countermeasures were expensive and difficult. In the condensate gas reservoirs in T2a3 in the block AT1 of the Tahe Oilfield, wells were deployed unevenly, resulting in excessively high recovery speed regionally, strong re-servoir heterogeneity, strong gas recovery intensity in initial stage, and restricted potential prediction. The abnormal signals in production indicated bottom oil in gas reservoirs. Oil-based water-plugging agent was applied to improve recovery rate. Interlayers and plane heterogeneity were applied to tap residual oil.
A new water-detection technology for condensate oil in Tahe Oilfield
He Shu, Chen Qiang, Ren Bing
2014, 36(s1): 107-109. doi: 10.11781/sysydz2014S1107
Abstract(721) PDF-CN(298)
Abstract:
The present conditions of water detection in condensate oil in the Tahe Oilfield were discussed. A new device for water detection in uniform liquid was innovated. It was a vertical storage tank with 2-points structure, and realized on-line detection. The new method solved safety problems, saved time and improved the accuracy of water detection.
Causes for wellbore instability in igneous formations in MTT region, Tahe Oilfield
Liu Biao, Pan Lijuan
2014, 36(s1): 110-112. doi: 10.11781/sysydz2014S1110
Abstract(613) PDF-CN(661)
Abstract:
The causes for well instability in igneous formations in MTT region of the Tahe Oilfield were discussed to ensure production safety. Based on the analyses of formation lithology, geostress status, pressure profile, logging data and caliper data, combined with the collapsing features of igneous formations, it was evaluated in this paper the matching of drilling fluid property and formation lithology as well as the sealing ability of plugging materials. The causes for wellbore instability were concluded as followed. (1) Mudstones which interbedded with igneous formations changed to slurries when they met drilling fluids. (2) Micro-fractures were widespread in igneous formations, and drilling fluids could easily expand into igneous formations when their sealing ability was poor. (3) Strike-slip geostress field existed in the study area, showing strong tectonic forces, which desired for drilling fluids with high density.
Well-controlling techniques for completion of leaking wells in Tahe Oilfield
Liu Lian, Zhao Gang, Hu Yong, Fan Lingyun, Li Jing, Hou Xiaojiao
2014, 36(s1): 113-116. doi: 10.11781/sysydz2014S1113
Abstract(983) PDF-CN(454)
Abstract:
According to the features of carbonate fractured-vuggy reservoirs in Ordovician in the Tahe Oilfield and the well-controlling problems such as killing methods, completion testing string designs and wellhead-dressing methods, new techniques were innovated for wellhead-dressing and new tools for well-controlling were introduced. In view of the reservoir size and fluid properties of Ordovician, a new method suitable for killing the Ordovician complex reservoirs in the Tahe Oilfield was proposed, and a conventional completion testing string system was designed, which could deal with the Ordovician reservoirs with different oil properties and different gas/oil ratios.
Optimized and fast drilling technology for unconventional gas reservoirs in block K in Tarim Basin
Li Shuanggui, Gao Changbin, Yi Hao, Shen Qingyun, Wang Yonghong
2014, 36(s1): 117-119. doi: 10.11781/sysydz2014S1117
Abstract(844) PDF-CN(296)
Abstract:
In the block K of the Tarim Basin, shale gas evaluation parameters such as shale sedimentary environment, organic matter abundance, maturity, continuous producing layer thickness, and brittle mineral content are favorable, hence show a good potential for exploration. Through the studies of mature blocks for shale gas explorations, effective drilling techniques for unconventional gas reservoirs in the study area were discussed. 51/2″ casing pipes were recommended for perforation and completion. Due to the wide distribution and big thickness of shale gas reservoirs, borehole trajectory control was not strictly restricted. The conventional MWD+ drilling resis-tance instruments worked well in the borehole trajectory control of horizontal wells.
Tapping of remaining oil in compound perforating interlayers in Tahe Oilfield
Chen Dongbo, Xu Gang, Zheng Xiaojie
2014, 36(s1): 120-122. doi: 10.11781/sysydz2014S1120
Abstract(938) PDF-CN(322)
Abstract:
In conventional perforations, drilling path often deviates from reservoirs, and drilling depth is not enough to penetrate interlayers. In view of the difficulties of remaining oil tapping, a new perforating technique with gunpowder was innovated. To seal water, mechanical water plugging experiments were made under perforating hole environments. The technique was applied in one well with the fine interpretation of interlayers and the optimization of gunpowder. The interlayers were perforated through and the remaining oils were exploited, providing a new idea for tertiary oil recovery in the Tahe Oilfield.
Fishing technology of logging cable and example analysis in Tahe Oilfield
Luo Rong, Luo Fengming
2014, 36(s1): 123-126. doi: 10.11781/sysydz2014S1123
Abstract(852) PDF-CN(456)
Abstract:
Logging cable is an important matching tool in the process of obtaining strata information while logging. Once dropping well, fishing is very difficult and the processing cycle will be quite long. In recent years, according to the processing methods of lost cable in the Tahe Oilfield, the reasons for logging cable dropping and different states of logging cable in wells are analyzed. Combining with the techniques of drilling tool fishing and logging cable fishing in the current work areas, it states three dimensions: application and improvement of fishing tools, fishing method, abnormal condition.
Pressure sealing on salt layer and technology of drilling fluid through salt layer in well AT40 area
Yang Junyi, Wang Jian
2014, 36(s1): 127-130. doi: 10.11781/sysydz2014S1127
Abstract(872) PDF-CN(275)
Abstract:
In the third opening of the well AT40 area, "salt gypsum layer" was encountered. For the balance of "salt gypsum layer" formation creep, the density of drilling fluid was up to 1.65-1.70 g/cm3. In order to avoid pressure leakage and differential pressure sticking risk in the low-pressure formations such as Cretaceous, Jurassic, Triassic and Carboniferous during the same opening, pressure plugging was demanded. Due to long opening hole and complex formation lithology, problems existed for pressure sealing. Besides, while drilling in the "salt gypsum layer", controlling the creep rate of "salt gypsum layer" to satisfy the requirement of casing, and the good rheological properties and anti-collapse performances of high-density and under-saturated saltwater polysulfonate system were the difficult points of drilling fluid technology. Aiming at the complicated situation in this area, taking the measures of plugging while drilling, sectional bearing, reasonable selection of drilling fluid density, optimizing drilling fluid rheology, we solved the difficulties of pressure sealing on the salt layer and the technology of drilling fluid through salt layer in the well AT40 area.
Management method of risk assessment of ultra-deep heavy oil ESP in Tahe Oilfield
Du Linhui, Liu Yuguo, Chen Huaqiang, Zhao Yuan, Tu Dong
2014, 36(s1): 131-134. doi: 10.11781/sysydz2014S1131
Abstract(1562) PDF-CN(594)
Abstract:
In order to improve the management level and life of electric submersible pump (ESP) and to reduce lying rate, technicians selected nine "quantifiable and controllable" indicators from the eleven stages of ESP system life cycle. According to the relevance of index value and ESP life, the indicators were given different weights and scores to evaluate the running state of ESP. The ESP state was classified into excellent, good, normal, risk and high risk. Two aspects of works should be done in ESP system management. 1) Analyzing the factors influencing ESP running state, and taking the corresponding measures of production management and control; 2) Optimizing index parameters when selecting well, matching and designing ESP system management. Field applications in the past two years show that this method can objectively reflect the operation state of ESP, help to improve ESP operating life, and reduce lie well rate.
Research of fractured sucker rod in heavy oil of Tahe Oilfield and countermeasures
Yuan Bo, Tu Dong, Du Linhui, Jiang Lei, Wang Leilei
2014, 36(s1): 135-138. doi: 10.11781/sysydz2014S1135
Abstract(685) PDF-CN(543)
Abstract:
Through the comprehensive analyses of the rod fracture situation, the diagram of load monitoring, the rod stress evaluation, the fractured sucker rod corrosion and the abnormal situation before broken, combined with the failure analysis report of fractured rod, the main influencing factors of sucker rod fracture mainly include high load, high alternating load and corrosion of hydrogen sulfide and injection gas. The reasonable choice of pump and pump depth, the optimization of rod string design, the strict production control and the reasonable optimization of pumping rod can effectively reduce the probability of sucker rod fracture.
Plug sweeping in coiled tubing in Tahe Oilfield
Zhao Xinghua, Xia Fuliang, Wang Meng
2014, 36(s1): 139-142. doi: 10.11781/sysydz2014S1139
Abstract(1200) PDF-CN(525)
Abstract:
In recent years, due to its unique advantages, coiled tubing was introduced by many oilfields. It was widely used in oil and gas drilling, completion, workover, well logging and other construction operations, and played an increasingly important role in oil and gas exploration and development. It was introduced in this paper the principles, advantages and disadvantages, ground equipments and downhole tools of plug sweeping in coiled tubing. A case study was made in the well TK7219CH in the Tahe Oilfield in order to evaluate double pumping pressure, sweeping depth and working efficiency. The prospect and developing direction of this technique were also discussed.
Application of pressure testing technology with capillary in deep wells of Tahe Oilfield
Yang Kun, Fan Lingyun, Zhang Jia, Zhao Zhonghui, Zou Wei
2014, 36(s1): 143-145. doi: 10.11781/sysydz2014S1143
Abstract(845) PDF-CN(612)
Abstract:
Due to the features of super deep, super thick, high temperature, high pressure, high viscosity, high salinity and high content of hydrogen sulfide in the districts ten and twelve of the Ordovician reservoirs in the Tahe Oilfield, it has brought great challenges to dynamic monitoring. In order to solve the problems of pressure monitoring of super deep and thick wells in the Tahe Oilfield, pressure testing technology with capillary is utilized, which transfers all the test components to the ground. Compared to regular pressure testing methods, this technology improves the ability to resist temperature, pressure and adapt inclination greatly, which meets the real-time display and storage of pressure data, and satisfies various kinds of production testing requirement. This technology has been applied successfully in the well TH10315X in the Tahe Oilfield, and has achieved good results.
Countermeasures for collapse in super-deep wells in Tahe Oilfield
Fan Weidong, Liu Lei, Zhang Xiao, Sun Heng
2014, 36(s1): 146-148. doi: 10.11781/sysydz2014S1146
Abstract(748) PDF-CN(563)
Abstract:
Due to the special geological structure in the Tahe Oilfield, most of the Ordovician wells are in open-hole completion, and parts of the mudstone and limestone production layers are exposed. Well collapses are common in the recent years, in view of which, many studies and field practices have been carried out. This paper mainly aimed at the countermeasures for collapse, and classified them into mild, severe, repeat ones and compound comprehensive accident. Corresponding countermeasures were given, especially assembly tools, drill grinding, grinding parameters in operation.

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