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Reservoir characteristics and evaluation of tight sandstone of He 8 member in southeastern Sulige Gas Field,Ordos Basin
GUO Yanqin, HE Ziqiong, GUO Bincheng, HUI Lei, CAI Zhicheng, WANG Meixia, LI Wenhou, LI Baiqiang
2019, Vol.31(5): 1–11
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372 )
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397
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Control of fault activity on sedimentation of Paleogene in Dongpu Sag
YU Haibo, CHENG Xiushen, QI Jiafu, TAN Yuming, XU Tianwu, ZHOU Yan
2019, Vol.31(5): 12–23
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250 )
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(5520 KB)
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337
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Characteristics of seismites and their geological significance of the upper fourth member of Shahejie Formation in Western Sag, Liaohe Depression
ZHAO Qingfeng, ZHANG Jianguo, KANG Wenjun, WANG Siqi, JIANG Zaixing, DU Kefeng, HUANG Changwu
2019, Vol.31(5): 24–33
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297 )
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(7628 KB)
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341
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Development model of secondary pores in coarse-grained deposits:a case study of Permian Xiazijie Formation in northwestern margin of Junggar Basin
MA Yongping, WANG Guodong, ZHANG Xianwen, PAN Shuxin, HUANG Linjun, CHEN Yongbo, GUO Juanjuan
2019, Vol.31(5): 34–43
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295 )
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(5777 KB)
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370
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Hydrocarbon accumulation characteristics of Cretaceous volcanic rocks in Wangguantun tectonic zone, Huanghua Depression
ZHENG Qinghua, YOU Jiyuan
2019, Vol.31(5): 44–51
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270 )
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(4588 KB)
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236
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Pore structure characteristics and adsorption capacity of Niutitang Formation shale in southern Shaanxi
CHEN Xianglin, GUO Tianxu, SHI Dishi, HOU Qidong, WANG Chao
2019, Vol.31(5): 52–60
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314 )
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(3838 KB)
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337
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Gas-water distribution characteristics in S48 block, western Sulige Gas Field
FENG Qianghan, YANG Shengguo, XIONG Zhe, GAO Hang, ZHANG Jiachao, YANG Yi, YANG Zhen
2019, Vol.31(5): 61–69
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318 )
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(3646 KB)
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374
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Analysis and logging identification of diagenetic facies of dolomite reservoir with low and ultra-low permeability:a case study from Ma 5 member in Yishan slope,Ordos Basin
LI Baiqiang, ZHANG Xiaoli, WANG Qicong, GUO Bincheng, GUO Yanqin, SHANG Xiaoqing, CHENG Hao, LU Junhui, ZHAO Xi
2019, Vol.31(5): 70–83
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280 )
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(9395 KB)
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262
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Lithology identification of complex carbonate based on SOM and fuzzy recognition
ZHONG Hongru, CHENG Yuhong, LIN Mengxiong, GAO Shichen, ZHONG Tingting
2019, Vol.31(5): 84–91
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240 )
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(3973 KB)
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335
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Random noise attenuation based on joint sparse representation in common offset gathers
SHI Zhanzhan, XIA Yanqing, ZHOU Huailai, WANG Yuanjun
2019, Vol.31(5): 92–100
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225 )
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(4827 KB)
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421
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New method for evaluating water flooding development effect and its oil field application
JIA Hongbing, ZHAO Hui, BAO Zhijing, ZHAO Guangjie, MAO Wei, LI Yaguang
2019, Vol.31(5): 101–107
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296 )
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(1573 KB)
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287
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Dynamic and static comprehensive evaluation method for reservoir connectivity of low-permeability oilfield
ZHANG Zhigang, LIU Chunyang, LIU Guozhi
2019, Vol.31(5): 108–113
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235 )
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(1476 KB)
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252
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Influencing factors of dynamic imbibition displacement effect in tight sandstone reservoir and application
LIU Xiuchan, CHEN Xipan, LIU Wei, WANG Xia
2019, Vol.31(5): 114–120
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299 )
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(1766 KB)
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407
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Main controlling factors of productivity and reasonable development methods of low-rank coalbed methane in block M of Australia
SU Penghui, XIA Zhaohui, LIU Lingli, DUAN Lijiang, WANG Jianjun, XIAO Wenjie
2019, Vol.31(5): 121–128
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222 )
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283
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Influence of ion composition and salinity on recovery of water flooding with low salinity
HUANG Guangqing
2019, Vol.31(5): 129–133
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202 )
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(1742 KB)
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241
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Transformation of development model of horizontal wells in ultra-low permeability and low-pressure reservoirs
AN Jie, TANG Meirong, CAO Zongxiong, WANG Wenxiong, CHEN Wenbin, WU Shunlin
2019, Vol.31(5): 134–140
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216 )
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(2337 KB)
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276
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Anisotropy and energy evolution characteristics of Zhangjiatan continental shale of Yanchang Formation in Ordos Basin
WANG Yuepeng, LIU Xiangjun, LIANG Lixi
2019, Vol.31(5): 149–160
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246 )
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323
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Pressure transient of fractured horizontal well with complex fracture distribution in composite reservoir
XU Youjie, LIU Qiguo, WANG Rui, LIU Yicheng
2019, Vol.31(5): 161–168
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Reservoir characteristics and evaluation of tight sandstone of He 8 member in southeastern Sulige Gas Field,Ordos Basin
GUO Yanqin, HE Ziqiong, GUO Bincheng, HUI Lei, CAI Zhicheng, WANG Meixia, LI Wenhou, LI Baiqiang
2019, Vol.31(5): 1–11
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372 )
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doi: https://doi.org/10.12108/yxyqc.20190501
Zhao 41 well area is the main gas producing area of tight sandstone of He 8 member in southeast Sulige Gas Field. However,the single well production is low and the productivity varies greatly. The petrological characteristics,diagenesis,physical properties,pore structure and seepage characteristics of reservoir were studied and evaluated by using data of cast thin sections,scanning electron microscope,cathodoluminescence,highpressure mercury injection,petrophysical analysis,nuclear magnetic resonance,gas-water relative permeability experiment and gas test,and the relationship between reservoirs type and natural gas productivity was discussed. The results show that the reservoir rocks of He 8 member in the study area are mainly lithic quartz sandstone,followed by lithic sandstone and a small amount of quartz sandstone,and the fillings is basically cements which are mainly illite,chlorite,kaolinite,siliceous and ferron calcite. Diagenesis is mainly compaction-pressure solution,cementation and dissolution,which has generally entered the stage B of middle diagenesis. The pore types are mainly secondary pores such as debris dissolved pores and intercrystalline pores,followed by residual intergranular pores,and the pore structure mainly consists of coarse pore-middle throat and fine pore-small throat. The saturation of movable fluid varies greatly,which is closely related to physical properties and increases with the improvement of physical properties. Based on the characteristics of reservoir physical properties,pore structure,sedimentary facies zone and sand body distribution,the reservoir of He 8 member in the study area was divided into four types. The productivity of natural gas is obviously controlled by reservoir types,and with the decline of reservoir type,the productivity of natural gas gradually decreases.
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Control of fault activity on sedimentation of Paleogene in Dongpu Sag
YU Haibo, CHENG Xiushen, QI Jiafu, TAN Yuming, XU Tianwu, ZHOU Yan
2019, Vol.31(5): 12–23
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doi: https://doi.org/10.12108/yxyqc.20190502
In order to study the basin structure,fault activity and its control on sedimentation in Dongpu Sag, seismic data interpretation,non-seismic geophysical data analysis,drilling core and logging curve analysis were carried out. The results show that:(1)The Paleogene basin in Dongpu Sag had the structural characteristics of multi-fault,multi-convex and multi-subsag. The fourth member of Shahejie Formation of Eocene was a single fault lake basin with broad lake surface,forming a set of high-quality source rocks,which were mainly composed of deltaic facies and shallow and semi-deep lake subfacies,and locally deep lake subfacies.(2)The lower submember of the third member of Shahejie Formation was dominated by the structural style of"multi-convex and multi-subsag". The center of the lake basin moved westward,and the hydrocarbon generation interval was somewhat different from that of Sha-4 member. The deposits were delta,shallow lake,semi-deep and deep lake. (3)During the sedimentary period of the upper sub-member of the second member of Shahejie Formation,multisubsag developed successively,the lake basin shrank,and the hydrocarbon generation potential became worse. The Weidong-Wendong fault system began to develop,resulting in a larger sedimentation range in the subsag area in the east and rapid maturity of hydrocarbon source rocks.(4)During the period of frequent fault activity,highquality hydrocarbon source rocks were developed in the region with large fault spacing,and delta front sand bodies, beach bar sand and turbidite sand developed in the nearby subsags adjacent to hydrocarbon source rocks were all good reservoirs. The early formed and long-term active secondary and tertiary faults were the main channels for hydrocarbon migration. Therefore,the turbidite sandstone reservoirs in Liutun and Puwei subsags,the updip pinch-out reservoirs of Sha-3 member in Mazhai subsag can be judged as the tapping potential of future exploration. The research results have guiding significance for the exploration of Dongpu Sag.
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Characteristics of seismites and their geological significance of the upper fourth member of Shahejie Formation in Western Sag, Liaohe Depression
ZHAO Qingfeng, ZHANG Jianguo, KANG Wenjun, WANG Siqi, JIANG Zaixing, DU Kefeng, HUANG Changwu
2019, Vol.31(5): 24–33
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297 )
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doi: https://doi.org/10.12108/yxyqc.20190503
In order to study the development characteristics and geological significance of the seismites of the upper fourth member of Shahejie Formation in Western Sag of Liaohe Depression,core observation and description,thin section identification and restoration of paleo-magnitude were carried out. The results show that:(1) Nine kinds of brittle plastic deformation structures such as liquefied veins,liquefied breccia,liquefied crinkled deformation,annular bedding,mounds and troughs,vein structure and syn-sedimentary fault formed in the finegrained sedimentary rocks of the upper fourth member of Shahejie Formation in Western Sag.(2)vertical vibration sequence of the seismites in the study area from bottom to top is as follows:shattered rock bed,liquefied crinkled deformation interval,interval of syn-sedimentary fault,interval of ball-and-pillow structure and vein structure,liquefied crinkled deformation interval and normal homogenized overlying bed.(3)The paleo-magnitude restoration based on sedimentary structures shows that the set of seismites was formed in earthquake events on the Richter scale at magnitude 5-8. Micro-fissures and faults caused by seismic events provided effective seepage channels for hydrocarbon migration,and a large number of dissolved pores developed around the channel. It has a certain improvement effect on the dense fine-grained carbonate reservoir in the study area. The research results show new fields and directions for the next oil and gas exploration in the Western Sag.
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Development model of secondary pores in coarse-grained deposits:a case study of Permian Xiazijie Formation in northwestern margin of Junggar Basin
MA Yongping, WANG Guodong, ZHANG Xianwen, PAN Shuxin, HUANG Linjun, CHEN Yongbo, GUO Juanjuan
2019, Vol.31(5): 34–43
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295 )
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370
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doi: https://doi.org/10.12108/yxyqc.20190504
Coarse-grained glutenite bodies in near-source fan delta,generally with complex sedimentary regularities,are characterized by massive structure,different gravel sizes,large variations in grain size,high argillaceous matrix content,poor reservoir physical properties and rapid lateral changes,leading to difficulties in assessment and exploration of oil and gas enrichment regularities of tight glutenite. Based on well-seismic integrated research method,the data of three-dimensional seismic,casting thin sections,rock physical properties,geochemistry were used to analyze the sedimentary facies division,petrologic features,physical properties,pore types and diagenesis of Xiazijie Formation in the northwestern margin of Junggar Basin. The tight glutenite reservoir was dominated by lithic sandstone with low compositional and structural maturity and the pore type was mainly secondary dissolved pore,with a small amount of residual intergranular pores and poor physical properties. The evolution model of reservoir pores of Xiazijie Formation was established by quantitative analysis of porosity evolution. The results show that the pore evolution of Xiazijie Formation in northwestern margin of Junggar Basin has undergone four diagenetic stages:rapid compaction,early cementation,organic acid dissolution and late carbonate cementation. In the rapid compaction stage,strong mechanical compaction resulted in a sharp decrease in the original porosity from 29.8% to 15.1%. The clay,matrix and zeolite cements formed in the early diagenetic stage destroyed the reservoir space and the porosity decreased by 6.5% on average. Organic acid dissolution was the diagenesis that plays a key role in improving reservoir physical properties and was mainly for zeolite cements. Porosity increased from 8.6% to 12.1% after early cementation and reservoir properties were greatly improved. Additionally,the dissolution coincided with the main hydrocarbon expulsion period of source rocks,which was conducive to effective filling of oil and gas. In the late diagenetic stage,with the increase of burial depth and pressure dissolution and precipitation of siliceous and carbonate cements,grain-support mode changed from point-line contact to line contact, the reservoir physical properties deteriorated again and the porosity loss was about 3.4%. In the context of a series of complex diagenesis,the current tight glutenite reservoir was developed,with a porosity of about 8.7%. The results of this study can provide a reference for the reservoir prediction of Xiazijie Formation in the study area.
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Hydrocarbon accumulation characteristics of Cretaceous volcanic rocks in Wangguantun tectonic zone, Huanghua Depression
ZHENG Qinghua, YOU Jiyuan
2019, Vol.31(5): 44–51
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doi: https://doi.org/10.12108/yxyqc.20190505
Many high-yield wells have been found in Cretaceous volcanic rocks in Wangguantun tectonic zone, and oil and gas are enriched. In order to explore the main controlling factors of hydrocarbon accumulation,combined with inclusions and burial history,the petroleum geologic characteristics of Cretaceous volcanic rocks were analyzed,and hydrocarbon accumulation stages and model were defined. The results show that the Cretaceous oil and gas in Wangguantun tectonic zone originated from dark mudstone and shale of the second member of Kongdian Formation. The volcanic reservoir was dominated by lava,pyroclastic rocks and pyroclastic sedimentary rocks. The lithofacies can be divided into four lithofacies and seven subfacies. Primary reservoir space mainly included pore,intercrystal pore,intergranular pore and shrinkage fracture,and secondary reservoir space mainly consists of high-porosity structural fracture and dissolution pore. There are two sets of reservoir-cap assemblages in the Cretaceous volcanic rocks,which have two types of traps:horst structure trap and fault nose structure trap. Its hydrocarbon filling period began in the Late Oligocene and lasted till now. It was a typical lateral hydrocarbon supply and accumulation model of Cenozoic-Mesozoic reservoir. The main controlling factors of hydrocarbon accumulation are that:hydrocarbon supply window controls lateral hydrocarbon supply of source rocks;structural fracture and dissolution improve reservoir performance;structural style and evolution control hydrocarbon preservation and accumulation.
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Pore structure characteristics and adsorption capacity of Niutitang Formation shale in southern Shaanxi
CHEN Xianglin, GUO Tianxu, SHI Dishi, HOU Qidong, WANG Chao
2019, Vol.31(5): 52–60
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314 )
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doi: https://doi.org/10.12108/yxyqc.20190506
In order to reveal the pore structure characteristics and adsorption capacity of rich organic shale of Cambrian Niutitang Formation in southern Shaanxi,a series of experimental testing techniques and methods such as field emission scanning electron microscopy,organic geochemistry,X-ray diffraction(XRD),nitrogen adsorption and isothermal adsorption experiment,were used to study the pore structure types by combining qualitative observation and quantitative characterization,and the main controlling factors of pore structure and adsorption capacity of shale were discussed. The results show that the main shale pore types of Niutitang Formation are organic pores,intragranular pores,intergranular pore and microfractures. The pore diameter is 1.8-316.7 nm, the BET specific surface area is 1.34-13.20 m2/g with an average value of 6.83 m2/g,the BJH adsorbed total pore volume is 0.003-0.011 mL/g with an average value of 0.006 mL/g. The direct factors affecting shale pore development are total organic carbon content and thermal maturity,which are positively correlated with pore volume and specific surface area. The indirect factors affecting shale pore development are tectonic movement and sedimentary environment around Hannan paleo-uplift and,which have great influences on thermal maturity,burial depth, thickness and lithologic changes of Niutitang Formation shale,thus indirectly control the development of shale pore structure. The adsorption capacity of shale is mainly affected by total organic carbon content,pore volume and specific surface area,which are positively correlated with methane adsorption volume. The research results are of great significance to the potential evaluation of Cambrian shale gas resources and the evaluation of selected areas in southern Shaanxi.
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Gas-water distribution characteristics in S48 block, western Sulige Gas Field
FENG Qianghan, YANG Shengguo, XIONG Zhe, GAO Hang, ZHANG Jiachao, YANG Yi, YANG Zhen
2019, Vol.31(5): 61–69
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doi: https://doi.org/10.12108/yxyqc.20190507
He 8 member and Shan 1 member are the main production layers in western Sulige Gas Field. The gaswater relationship is complex,and most of the gas wells produce water,which seriously affects the normal production of gas wells and deployment plan design of blocks. Based on gas test and dynamic monitoring data,the differences of production curve characteristics between water-producing gas wells and non-water-producing gas wells in block S48 of western Sulige Gas Field were analyzed. The production wells were divided into three types:non-water-producing in gas test and production process,non-water-producing in gas test but producing water in production process,producing water in gas test and production process. Then the characteristics of logging curve of water-producing well were analyzed by the constraint of dynamic production date and gas test data. The results show that:For the wells with non-water-producing in gas test but water-producing in production process, if logging data reflects good,gas test conclusion is gas layer,then the water source is mostly from the upper and lower adjacent layers;if the logging response is poor and the gas test conclusion is gas layer,the water source is mostly from the capillary water in the production layer. For the wells that with water-producing in gas test and production process,the logging interpretation and gas test conclusions are mostly gas-water layers,the water source is mostly from free water and capillary water in the production layer. Comprehensive analysis of logging data combined with gas test and production data is useful to identify gas and water layers. Gas-bearing layer and gas-water layer have similar logging response characteristics,and they are all distributed in the transitional zone between gas layer,dry layer and water layer in the resistivity-acoustic moveout crossplot. Five types of gas-water distribution were divided:pure gas,gas above the water,dry(water) above the gas,gas-water coexi-stence,gas layer inter-distributed between dry/water layer. Engineering reform measures were proposed for different types of gas-water distribution.
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Analysis and logging identification of diagenetic facies of dolomite reservoir with low and ultra-low permeability:a case study from Ma 5 member in Yishan slope,Ordos Basin
LI Baiqiang, ZHANG Xiaoli, WANG Qicong, GUO Bincheng, GUO Yanqin, SHANG Xiaoqing, CHENG Hao, LU Junhui, ZHAO Xi
2019, Vol.31(5): 70–83
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doi: https://doi.org/10.12108/yxyqc.20190508
In order to study the logging identification method and quantitative classification of diagenetic facies of dolostone reservoir with low and ultra-low permeability and clarify the spatial distribution characteristics of diagenetic facies and the favorable exploration area of dolostone reservoir". Based on core observation,identification of ordinary and casting thin section,and cathodoluminescence analysis,combined with X-ray diffraction and physical property data,the diagenetic environment and diagenesis of dolomite reservoir with low and ultralow permeability of Ma 5 member in Yishan slope were analyzed. Then the quantitative identification standard for diagenetic facies of dolomite reservoir with low and ultra-low permeability was established through the crossplot analysis of conventional logging curves and application of software program. The results show that the diagenetic facies of the dolomite reservoirs with low and ultra-low permeability can be divided into six types:early atmospheric freshwater dissolution,supergene atmospheric freshwater dissolution,shallow buried active reflux seepage dolomitization,shallow buried latent reflux seepage dolomitization,calcareous cementation and clay minerals filling. The crossplot method of logging parameters represented by Pe and DEN,RLLD and DEN,and RLLD and AC,and the comprehensive application of software program are effective approach for vertical quantitative identification and continuous division of different diagenetic facies of dolostone reservoir with low and ultralow permeability in single well. The spatial distribution of diagenetic facies of dolostone reservoir shows a typical characteristic of longitudinal zonation and planar partition. The favorable reservoirs are mainly developed in diagenetic facies of early atmospheric freshwater dissolution and shallow buried active reflux seepage dolomitization,followed by supergene atmospheric freshwater dissolution,and there is less reservoir deve-loped in shallow buried latent reflux seepage dolomitization diagenetic subfacies.
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Lithology identification of complex carbonate based on SOM and fuzzy recognition
ZHONG Hongru, CHENG Yuhong, LIN Mengxiong, GAO Shichen, ZHONG Tingting
2019, Vol.31(5): 84–91
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335
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doi: https://doi.org/10.12108/yxyqc.20190509
Carbonate reservoir is influenced by structure,sedimentation,ancient landform and other factors, which make it become complex and diverse. Therefore,it is significant to identify lithology based on logging data in the process of reservoir assessment. Aim to the problems of the current methods of lithology identification, such as poor generalization ability and the obstacle in combining with geological experience,taking the lower carbonate reservoir in block Sudong 41-33 of Sulige Gas Field as an example,a lithology identification method based on self-organizing map(SOM) and fuzzy recognition was proposed. The SOM was used in unsupervised form to unearth the relationship information and topological structure of six well logging parameters,such as acoustic travel time,compensated neuron and density,which are sensitive to the lithology,and then the SOM model was locally corrected by using fuzzy recognition method. The practical application results show that the lithology identification accuracy of this method was 7.3% higher than that of traditional fuzzy recognition method. It provides a new idea for lithologic identification.
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Random noise attenuation based on joint sparse representation in common offset gathers
SHI Zhanzhan, XIA Yanqing, ZHOU Huailai, WANG Yuanjun
2019, Vol.31(5): 92–100
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225 )
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421
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doi: https://doi.org/10.12108/yxyqc.20190510
Under the restriction of multiplicity and single-channel signal processing methods,the traditional onedimensional random noise attenuation method based on sparse representation faces two problems:Firstly,the single-channel signal processing method does not consider the spatial correlation of the effective signals,thus the de-noise performance degrades significantly and may damage effective waves. Secondly,the sparse representation algorithm suffers from multiplicity,and the processing results of adjacent seismic traces are quite different, which makes it difficult to adapt to the spatial variation. The waveforms in the pre-stack common offset gathers are characterized by horizontally events,and have the same two-way travel time. Therefore,each trace signal in a gather shares the universal support. In this gather,joint sparse representation was used to suppress random noise,which can balance the correlation between channels and spatial variations of signals so as to reduce the multi-solution of the algorithm. The optimal sparse representation was obtained under the same conditions for each channel participated in the calculation,so the processing result had good consistency. The results of numerical simulation and practical data trial show that the proposed method can suppress random noise and maintain the effective signal,and has a good application effect.
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New method for evaluating water flooding development effect and its oil field application
JIA Hongbing, ZHAO Hui, BAO Zhijing, ZHAO Guangjie, MAO Wei, LI Yaguang
2019, Vol.31(5): 101–107
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296 )
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287
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doi: https://doi.org/10.12108/yxyqc.20190511
In order to clarify the influencing factors of waterflooding development effect and effectively guide the comprehensive adjustment of oilfield,a new approach of using chart to evaluate development effect was put forward. Based on Sherkachev formula and Arps production decline equation,considering reservoir properties, fluid properties,relative permeability characteristics,well spacing density and recovery degree,a water flooding development effect evaluation chart was established. The application in block A shows that the evaluation results of this chart is consistent with the actual oilfield development characteristics. The development law and water injection contradiction of different blocks can be distinguished obviously. Based on the evaluation of water flooding development effect,the comprehensive adjustment measures of block A were put forward,and it had a good implementation effect. This method is simple and practical,and has certain popularization value.
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Dynamic and static comprehensive evaluation method for reservoir connectivity of low-permeability oilfield
ZHANG Zhigang, LIU Chunyang, LIU Guozhi
2019, Vol.31(5): 108–113
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252
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doi: https://doi.org/10.12108/yxyqc.20190512
The water drive control degree of block Gu137 in Puxi Oilfield is 79%,while more than 50% of the oil wells in the oilfield are not affected by water injection,indicating that the adaptability evaluation of injectionproduction system by water drive control degree cannot meet the demands of oilfield production. Therefore,the connectivity relationship in the research of injection-production system was subdivided into static connectivity and dynamic connectivity,and the concept of effective connectivity coefficient was proposed,which is the ratio of the thickness of the water injection effect to the static thickness of the sand body. The commonly used(true) water drive control degree was defined as the product of apparent water drive control degree and effective connectivity coefficient. The method implements a phased evaluation of static connectivity and dynamic connectivity. This method was used to analyze the essential difference of poor water injection efficiency between the test area and G137 block in Puxi Oilfield. The former is due to the small size of the sand body and static disconnection, while the latter is due to poor physical properties of the reservoir and dynamic disconnection. Therefore,for lowpermeability oilfields,it is more reasonable to decompose the water drive control degree assessment index of oilfield development into visual water drive control degree and effective connectivity coefficien.
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Influencing factors of dynamic imbibition displacement effect in tight sandstone reservoir and application
LIU Xiuchan, CHEN Xipan, LIU Wei, WANG Xia
2019, Vol.31(5): 114–120
Abstract
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299 )
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407
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doi: https://doi.org/10.12108/yxyqc.20190513
As an important technical measure for efficient development of tight sandstone reservoirs,imbibition displacement has attracted more and more attention in recent years. There are many factors affecting the effect of imbibition displacement in tight sandstone reservoirs. Taking a tight sandstone reservoir in a block of Ordos Basin as the research object,the effects of the types,concentration and injection volume of imbibition fluid,displacement velocity,reaction time and core permeability on dynamic imbibition displacement were evaluated by rock core dynamic imbibition displacement experiment. The results show that adding non-ionic surfactant HYS-3 into the infiltration fluid can significantly improve the dynamic imbibition displacement efficiency. The higher the concentration of surfactant in the infiltration fluid,the larger the injection volume of the infiltration fluid,the longer the reaction time and the larger the core permeability,the higher the dynamic imbibition displacement efficiency. With the increase of displacement flow rate,the dynamic imbibition displacement efficiency of the core increased first and then decreased. The optimum parameters of dynamic imbibition displacement experiment are:displacement velocity is 0.2 mL/min,concentration of imbibition fluid is 0.5% HYS-3,injection volume of imbibition fluid is 1.0 PV,reaction time is more than 48 hours. The field application test results show that the daily oil production of 5 wells in S oilfield is more than twice that before the implementation of the dynamic imbibition displacement measures of water injection huff and puff,the water cut is obviously reduced,and the effect of oil increase is remarkable.
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Main controlling factors of productivity and reasonable development methods of low-rank coalbed methane in block M of Australia
SU Penghui, XIA Zhaohui, LIU Lingli, DUAN Lijiang, WANG Jianjun, XIAO Wenjie
2019, Vol.31(5): 121–128
Abstract
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222 )
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283
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doi: https://doi.org/10.12108/yxyqc.20190514
Low-rank CBM reservoir has rich resources and huge development value. Combined with the production characteristics of low-rank coalbed methane wells and geological model of gas field,a numerical model of lowrank coalbed methane wells was established,the sensitivity analysis of the factors affecting the productivity was carried out,and the main controlling factors affecting the productivity of coalbed methane wells were defined. Based on the division of reservoir physical properties,the optimization study of reasonable development methods of low-rank coalbed methane was conducted. The results show that the commingled producing well passing through JJ and TT two sets of coal seam groups longitudinally had high degree of vertical reservoir control and large drainage,which is helpful for pressure reduction and desorption. Therefore,the commingled wells greatly increased the average single well production. The main controlling factors affecting the productivity of low-rank coalbed methane wells are cumulative net thickness,permeability, gas content, well spacing and gas saturation. Through the optimization analysis of well spacing for six types of reservoir,for the reservoirs with buried depth less than 250 m,the optimal well spacing is 1 500 m;for the reservoirs with buried depth of 250-350 m,the optimal well spacing is 1 200 m;for the reservoirs with buried depth of 350-450 m,the optimal well spacing is 1 000 m;for the reservoirs with buried depth of 450-600 m,the optimal well spacing is 8 00 m; for the reservoirs with buried depth greater than 600 m,the optimal well spacing is 700 m. This study could provide theoretical basis and technical support for the selection and development optimization of favorable areas in gas fields.
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Influence of ion composition and salinity on recovery of water flooding with low salinity
HUANG Guangqing
2019, Vol.31(5): 129–133
Abstract
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202 )
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doi: https://doi.org/10.12108/yxyqc.20190515
The implementation of water flooding with low salinity for EOR has certain requirements for the ion composition of injected water and formation water. Based on the laboratory sandstone core displacement experiment,the effect of ion composition of injected water and formation water on enhanced oil recovery by water flooding with low salinity was studied by contrast method. The results show that the formation water containing divalent cations Ca2+ or Mg2+ can improve oil recovery,and the effect of Ca2+ is better than that of Mg2+. Only when the salinity of injected water is lower than the salinity threshold determined by the oil-water system can the recovery be improved. Final determination of formation water containing bivalent cations Ca2+ or Mg2+,and the salinity of injected water need to be lower than the salinity threshold determined by reservoir oil-water system,is the necessary condition to achieve EOR by water flooding with low salinity.
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Transformation of development model of horizontal wells in ultra-low permeability and low-pressure reservoirs
AN Jie, TANG Meirong, CAO Zongxiong, WANG Wenxiong, CHEN Wenbin, WU Shunlin
2019, Vol.31(5): 134–140
Abstract
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216 )
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276
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doi: https://doi.org/10.12108/yxyqc.20190516
Chang X reservoir in Ordos Basin has low pressure coefficient and poor physical properties. Advanced water injection in seven-spot pattern and long horizontal well development can lead to sharp water cut increase and high single well production rate. what's more,fracturing in order to avoid the cross between artificial fracture and the waist-water-line will make about 200 m useless because of no stimulation. Meanwhile,long shut-in time needed for advanced water injection affects the contribution of production wells. To solve the problem, based on experience of tight oil reservoir development and opposite development theory,this paper proposed a new development concept of none advanced water injection,less injection wells, shorter horizontal length, combination of volume fracture technique and dense tube cut method. After field experiment as well as optimization and research of well pattern adaptability,energy supplement,horizontal length and fracturing parameters,it shows that the proposed theory in five-spot pattern can provide better development effect,taking advantage of quick energy supplement,efficient water cut control and longer oil wells production time by 30%.This development method can contribute 20% cost reduction and 88% increase of total oil production per hundred meter. The research can be further applied and provide technical guidance to the tight reservoir development.
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Anisotropy and energy evolution characteristics of Zhangjiatan continental shale of Yanchang Formation in Ordos Basin
WANG Yuepeng, LIU Xiangjun, LIANG Lixi
2019, Vol.31(5): 149–160
Abstract
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246 )
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doi: https://doi.org/10.12108/yxyqc.20190518
In order to reveal the anisotropy of Zhangjiatan continental shale of Yanchang Formation in Ordos Basin and its influence on wellbore instability,microscopic pore structure was analyzed by means of scanning electron microscopy(SEM),and then laboratory acoustic and mechanical experiments based on standard rock samples were conducted to study the anisotropy of acoustic and mechanical parameters as well as energy evolution characteristics of continental shale. The results show that the types and abundances of pores and fractures are obviously various in different bedding plane directions in Zhangjiatan continental shale of Yanchang Formation in Ordos Basin. Acoustics and mechanical parameters and energy evolution characteristics of shale are strongly anisotropic. The angle between drilling direction and normal of bedding planes has a certain influence on wellbore stability in shale formation. The research results can provide technical references for the optimization design of wellbore structure of shale gas horizontal well and engineering application.
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Pressure transient of fractured horizontal well with complex fracture distribution in composite reservoir
XU Youjie, LIU Qiguo, WANG Rui, LIU Yicheng
2019, Vol.31(5): 161–168
Abstract
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266 )
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doi: https://doi.org/10.12108/yxyqc.20190519
Hydraulic fracturing technology is a vital method to increase oil field production and improve reservoir properties near wellbore. In the actual process of multi-stage fracturing volume modification,complex fracture network volume formed near wellbore due to complex formation conditions. Therefore,it is necessary to strengthen the study of volume fracturing modification test model of horizontal well. Based on the seepage characteristics of complex fracture distribution for multi-stage fractured well,a well-test mathematic model of radial composite multi-stage fractured well was established. Wellbore pressure was obtained by coupling reservoir and hydraulic fracture in Laplace domain,and the impact of wellbore storage and skin factor were considered by employing Duhamel principle. Applying Stehfest numerical inversion algorithm,wellbore pressure in real time domain can be calculated and pressure response log-log curve were plotted,and flow regimes were identified by characteristics of pressure-derivative curve. The correctness of this method was proved by model verification. The effects of fracture asymmetry factor,angle between fracture and wellbore,fracture distribution,radius of inner region and mobility ratio on characteristic curves were analyzed. The results show that the fractures of asymmetric staggered distribution are helpful to increase the control area of fractures,thereby reducing the pressure drop loss of fluid flowing into the wellbore,and larger inner radius leads to smaller pressure in log-log plot. This model can provide theoretical basis for the well-test interpretation and fracturing design of complex fracture formed by multistage fractured horizontal well.