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Assessment of glutenite reservoirs and optimization of prospects of Zhenzhuchong Formation in Jiulongshan gas field，Sichuan Basin
ZHANG Manlang, KONG Fanzhi, GU Jiangrui, GUO Zhenhua, FU Jing, ZHENG Guoqiang, QIAN Pinshu
2020, Vol.32(3): 1–13
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336 )
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316
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Multi-scale joint characterization of micro-pore structure of low-rank coal reservoir
YANG Fu, HE Dan, MA Dongmin, DUAN Zhonghui, TIAN Tao, FU Deliang
2020, Vol.32(3): 14–23
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325 )
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515
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Hydrocarbon generation kinetics of source rocks of the first member of Nantun Formation in peripheral sags of Hailar Basin
XIE Mingxian, CHEN Guangpo, LI Juan, MA Fengliang, SONG Xiaowei
2020, Vol.32(3): 24–33
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240 )
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(3504 KB)
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432
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Diagenetic characteristics and quantitative porosity restoration of Chang 61 tight sandstone reservoir in Hujianshan area，Ordos Basin
WANG Jiwei, ZHU Yushuang, RAO Xinjiu, ZHOU Shuxun, WU Yingqiang, YANG Hongmei
2020, Vol.32(3): 34–43
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323 )
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(9026 KB)
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291
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Restoration of paleokarst geomorphology of Lower Permian Maokou Formation and its petroleum exploration implication in Sichuan Basin
ZHANG Ya, CHEN Shuangling, ZHANG Xiaoli, ZHANG Xihua, XIE Chen, CHEN Cong, YANG Yuran, GAO Zhaolong
2020, Vol.32(3): 44–55
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390 )
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(9118 KB)
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355
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Natural gas accumulation patterns of Upper Paleozoic in eastern Hangjinqi area，Ordos Basin
LIU Yuzuo, SHI Wanzhong, LIU Kai, WANG Ren, WU Rui
2020, Vol.32(3): 56–67
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244 )
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(10928 KB)
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339
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Sedimentary characteristics and high-precision sequence division of lacustrine carbonate rocks of BV Formation in L oilfield of Santos Basin，Brazil
LUO Xiaotong, WEN Huaguo, PENG Cai, LI Yun, ZHAO Yan
2020, Vol.32(3): 68–81
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343 )
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(17734 KB)
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446
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Formation mechanism of high-quality sandy-conglomerate reservoir of Triassic Karamay Formation in Mahu area
XU Ziyu, WANG An, HAN Changcheng, TIAN Jijun, ZHANG Junsheng, LIU Lei, ZHANG Nan
2020, Vol.32(3): 82–92
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321 )
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(13517 KB)
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344
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Sequence architecture and structural response of the third member of Shahejie Formation in Liuzan area，Nanpu Sag
REN Mengyi, JIANG Qingchun, LIU Zhen, LU Chaojin
2020, Vol.32(3): 93–103
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291 )
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(10724 KB)
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361
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Distribution characteristics and oil-source analysis of Lower Cretaceous source rock in southern trough of Hurenbuqi sag，Erlian Basin
SHAN Xinjie, WANG Feiyu, LIU Nian, FENG Weiping, JIANG Tao, DU Xi, CHENG Zhiqiang, LI Sijia, LI Yue
2020, Vol.32(3): 104–114
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348 )
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(4252 KB)
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451
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Macro-correction method and application of seismic pseudo-well velocity point: a case study from M gas field in Pearl River Mouth Basin
LUO Ze, XIE Mingying, LIANG Jie, TU Zhiyong, HOU Kai
2020, Vol.32(3): 115–121
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242 )
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(6212 KB)
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465
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Prediction of tight sandstone permeability based on high-pressure mercury intrusion（HPMI）and nuclear magnetic resonance（NMR）
CHENG Hui, WANG Fuyong, ZAI Yun, ZHOU Shuxun
2020, Vol.32(3): 122–132
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320 )
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(0 KB)
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(3683 KB)
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434
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Pore structure characterization and its impact on waterflooding development in Khasib reservoir in Ahdeb Oilfield，Iraq
CHEN Mingjiang, CHENG Liang, LU Tao
2020, Vol.32(3): 133–143
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424 )
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(8806 KB)
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426
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Architecture characterization of single distributary channel sand bodies restricted by architecture interface of Yan 8 member in Y116 well area，Yanwu Oilfield
TONG Qiang, YU Jianguo, TIAN Yunji, HU Kelai, YANG Hongmei, CHENG Xuming, ZHU Yushuang
2020, Vol.32(3): 144–158
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240 )
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(10243 KB)
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318
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Experiment on the mechanism of low salinity waterflooding in carbonate reservoir
QIAN Zhen, LI Hui, QIAO Lin, BAI Sen
2020, Vol.32(3): 159–165
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353 )
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368
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Experimental study on the surface feature of acid-etched fractures in carbonate rocks
FENG Wei, YANG Chen, TAO Shanxun, WANG Caizhong, LU Yanying, ZHANG Lufeng, ZHOU Fujian
2020, Vol.32(3): 166–172
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377
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Assessment of glutenite reservoirs and optimization of prospects of Zhenzhuchong Formation in Jiulongshan gas field，Sichuan Basin
ZHANG Manlang, KONG Fanzhi, GU Jiangrui, GUO Zhenhua, FU Jing, ZHENG Guoqiang, QIAN Pinshu
2020, Vol.32(3): 1–13
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336 )
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316
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doi: https://doi.org/10.12108/yxyqc.20200301
Zhenzhuchong Formation in Jiulongshan gas field is known as fractured tight glutenite reservoir with strong heterogeneity. In order to make clear the development layer series and predict the favorable areas,high resolution stratigraphic sequences were divided and systematic studies were conducted on sedimentary microfacies, petrologic features,reservoir space types and fracture distribution of Zhenzhuchong Formation,by means of core description,casting thin section observation,imaging logging,full diameter core analysis,and thus to realize fine reservoir evaluation of fractured glutenite of Zhenzhuchong Formation. The results show that:(1) Zhenzhuchong Formation can be divided into three middle-term cycles and six short-term cycles,and favorable reservoirs were developed in hugely thick glutenites formed by superposed subaqueous distributary channels of fan deltaic front in middle-period cycle Ⅱ.(2) Zhenzhuchong Formation is fracture-pore type reservoir,comprised of inter-gravel and intra-gravel dissolved pores,fracture-expansion solution pores,with porosity mainly of 2.0%- 4.5%,horizontal permeability of 1-100 mD,vertical permeability of 0.1-10.0 mD,and the permeability of Zhenzhuchong Formation was highly improved by low angle fractures and fracture-networks.(3) Short-term cycle Ⅱ 3 and Ⅱ1 were selected as two favorable development layer series in which fractures were well developed and the reservoir permeability was higher than others.(4) Two first class favorable areas and three second class favorable areas were selected through single layer reservoir evaluation and integrative evaluation of multilayer composite. The study results have guiding significance for the development deployment of Jiulongshan gas field.
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Multi-scale joint characterization of micro-pore structure of low-rank coal reservoir
YANG Fu, HE Dan, MA Dongmin, DUAN Zhonghui, TIAN Tao, FU Deliang
2020, Vol.32(3): 14–23
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325 )
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515
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doi: https://doi.org/10.12108/yxyqc.20200302
The multi-scale micro-pore structure is of great significance to the study of the adsorption/desorption process of coalbed methane in low rank coal reservoirs. Taking Jurassic Huanglong coalfield and Shaanbei coalfield as examples,the pore size distribution andpore types of low-rank coal reservoirs were measured by mercury injection, liquid nitrogen adsorption and CO2 adsorption. Combined with nuclear magnetic resonance,the pore size and multi-scale pore size distribution characteristics of low-rank coal were quantitatively analyzed. The results show that the pores of low-rank coal are mainly micropores,followed by macropores. The contribution rate of micropores,macropores and mesoporous pores to specific surface area decreased in turn.The pore types of low-rank coal reservoirs are mainly "columnar pore" and "ink bottle hole",which have good pore connectivity. The T2c cut-off value of the samples obtained by NMR method is 1.4-155.2 ms,which varies greatly. The bound fluid saturation(BVI) is 79.21%-96.96%,and the movable fluid saturation is low. The pore structure of low-rank coal reservoirs is complex and diverse,and there are great differences between single test technique and combined computing characterization method in the characterization of pore structures of low-rank coal reservoirs.
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Hydrocarbon generation kinetics of source rocks of the first member of Nantun Formation in peripheral sags of Hailar Basin
XIE Mingxian, CHEN Guangpo, LI Juan, MA Fengliang, SONG Xiaowei
2020, Vol.32(3): 24–33
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doi: https://doi.org/10.12108/yxyqc.20200303
In order to clarify the hydrocarbon generation potential and present hydrocarbon generation evolution stage of the source rocks of the first member of Nantun Formation in Hongqi,Dongming and Yimin sags on the periphery of Hailar Basin,the hydrocarbon generation kinetics of the source rocks of the first member of Nantun Formation was studied by using a confined system gold tube autoclave. The results show that the kinetic parameters of gaseous hydrocarbons in each sag are quite different,and the main frequency activation energy increases orderly from Dongming sag to Hongqi and Yimin sags. Among the kinetic parameters of liquid hydrocarbon,the average and main frequency activation energy in Hongqi sag are the lowest,the distribution of activation energy in Yimin sag shows double peak characteristics,and the main frequency activation energy increases orderly from Hongqi sag to Yimin and Dongming sags. The possibility of searching for gas reservoirs in the study area is very low. The result of hydrocarbon generation history recovery indicates that the K1 n1 source rocks entered the oil generation threshold in early Cretaceous,and are still in the early stage of low maturity to maturity. The oil conversion rate is 12.67%-39.50%,and only a small amount of hydrocarbon expulsion occurs. The key factor restricting oil generation is that organic matter has not reached the peak of hydrocarbon generation, resulting in limited hydrocarbon generation and resources. The focus of oil and gas exploration is to find source rocks of Tongbomiao Formation and Tamulangou Formation in the lower part with relatively high paleotemperature and strong oil generation potential or local mature areas of source rocks of Nantun Formation.
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Diagenetic characteristics and quantitative porosity restoration of Chang 61 tight sandstone reservoir in Hujianshan area，Ordos Basin
WANG Jiwei, ZHU Yushuang, RAO Xinjiu, ZHOU Shuxun, WU Yingqiang, YANG Hongmei
2020, Vol.32(3): 34–43
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doi: https://doi.org/10.12108/yxyqc.20200304
Based on the analysis of a large number of cores and casting thin slice,the diagenetic characteristics of Chang 61 reservoir in Hujianshan area of Ordos Basin and its influence on reservoir physical properties were systematically analyzed by means of SEM,cathodoluminescence and high-pressure mercury injection,and the pore evolution was quantitatively restored. The results show that the Chang 61 reservoir in Hujianshan area was in the middle diagenetic phase A,mainly underwent compaction-pressure dissolution,cementation and dissolution,resulting different influences on the pore development of the reservoir. The compaction destroyed a large number of primary intergranular pores,which was the most important factor for reservoir compaction in the study area. The average porosity decreased by 18.41%,and the loss rate of pore space reached 56.62%. The cementation not only blocked the pore space,but also enhanced the anti-compaction strength of particles to a certain extent. The porosity decreased by 10.38% on average,and the loss rate of pore space reached 19.78%. The dissolution dissolved unstable components such as clastic particles and interstitial materials,resulting in a large number of secondary pores,thereby improving the physical properties of the reservoir,and the increased porosity was 2.26% on average. According to the impact of the diagenesis on reservoir properties and logging response characteristics,six types of diagenetic facies were identified,namely chlorite film phase-residual intergranular pore facies,residual intergranular pore facies,feldspar dissolution facies,clay mineral cementation facies,carbonate cementation facies and compaction facies. Chlorite film phase-residual intergranular pore facies is the most favorable diagenetic facies for oil enrichment,followed by residual intergranular pore facies.
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Restoration of paleokarst geomorphology of Lower Permian Maokou Formation and its petroleum exploration implication in Sichuan Basin
ZHANG Ya, CHEN Shuangling, ZHANG Xiaoli, ZHANG Xihua, XIE Chen, CHEN Cong, YANG Yuran, GAO Zhaolong
2020, Vol.32(3): 44–55
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390 )
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355
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doi: https://doi.org/10.12108/yxyqc.20200305
Karst reservoirs are widely developed in Sichuan Basin. In order to restore the karst paleogeomorphology of Maokou Formation,the studies on drilling core analysis,logging analysis and seismic data interpretation were carried out. The karst paleo-geomorphological features of the Maokou Formation were characterized by well seismic combination,residual thickness method and impression method. The results show that:(1) The Maokou Formation has the paleo-karstic morphology of "high in the west and low in the east". From the west to the east, the paleo-karst geomorphology could be classified into three geomorphic units such as karst highland,karst slope and karst depression,as well as second-level geomorphologic units,such as residual mound,slope,depression and gully.(2) Karst basin are distributed in Guanyuan-Yuanba-Dazhou-Fengjie area,with residual thickness of Maokou Formation of less than 180 m,which is inherited and evolved landform on the basis of Mao-kou rifting trough. There are deep water facies deposits in the rift trough.(3) The area from south of Sichuan to middlenorth is a karst slope. Karsti-fication is well developed,and effective karst reservoirs are well preserved,mainly distributed in karst residual hills and slopes,while most of the dissolved holes in karst gully are filled with mud of Longtan formation.(4) Jiange-Yuanba-Longgang area in northern Sichuan is located at the edge of rift trough, which is shallow high energy platform edge beach facies and an important new exploration field of karst reservoir. The research results are of great theoretical significance and exploration value for the direction of high-quality karst reservoir exploration.
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Natural gas accumulation patterns of Upper Paleozoic in eastern Hangjinqi area，Ordos Basin
LIU Yuzuo, SHI Wanzhong, LIU Kai, WANG Ren, WU Rui
2020, Vol.32(3): 56–67
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doi: https://doi.org/10.12108/yxyqc.20200306
In order to understand the gas accumulation model of the Upper Paleozoic in Hangjinqi area of Ordos Basin,and to guide the oil and gas exploration in this area,based on the depth analysis of the distribution of source rock,natural gas migration and trap distribution,this paper summarized the hydrocarbon accumulation model in this area. The results show that:source rocks in the study area are thick in the south and thin in the north,with high maturity in the south and low maturity in the north. These traps are mainly distributed in the northern region of Boerjianghaizi fault(Shenguhao region). The density of natural gas in the south is higher than that in the north. The whole shows a downward trend from south to north. The natural gas drying coefficient of the study area is also increasing gradually from south to north. The natural gas in Shenguhao area,which reflects the lack of hydrocarbon source rocks,is mainly transported from the south area of Boerjianghaizi fault. Highquality hydrocarbon source rocks are developed in the south area of Boerjianghaizi fault. The distribution characteristics of high natural gas density and low drying coefficient indicate that the natural gas is in situ accumulation in this area. The faults and associated structural traps are the migration channels and gathering places of oil and gas in Azhen area. Near source natural gas reservoir is formed in Shirigaohan area under the control of sandstone reservoir property and the influence of fault nondevelopment. The nature gas accumulation patterns of Upper Paleozoic in eastern Hangjinqi were divided into three types:horizontal long-distance migration,vertical near-distance in-situ accumulation and reservoir forming model of quasi continuous tight sandstone gas. The research results indicate the direction for the next exploration in Hangjinqi area.
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Sedimentary characteristics and high-precision sequence division of lacustrine carbonate rocks of BV Formation in L oilfield of Santos Basin，Brazil
LUO Xiaotong, WEN Huaguo, PENG Cai, LI Yun, ZHAO Yan
2020, Vol.32(3): 68–81
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doi: https://doi.org/10.12108/yxyqc.20200307
Santos Basin in Brazil is a famous large-scale petroliferous sedimentary basin in the world in recent years,and its sub lacustrine microbial carbonate reservoir has become a hot spot of oil and gas exploration. There are few researches on high-precision sequence division and sedimentary mechanism of main reservoirs,which restrict the exploration and development of oil and gas fields in this area. Based on the previous research results,combined with the drilling, logging and seismic data in the basin, this paper made high-precision sequence stratigraphic and sedimentary division of Barra Velha Formation in L oilfield in Santos Basin,clarified the evolution law of the sedimentary sequence in the lake basin,and established the sedimentary model of the microbial reef of BV Formation in L oilfield in the basin. The results show that the BV Formation can be divided into one third-order sequence and four fourth-order sequences. As an important reservoir facies belt of BV Formation,lacustrine microbial reef facies was distributed in the steep slope break belt on both sides of the lake basin and developed in high water level environment,which was mainly controlled by paleogeomorphology and volcanism. The research results could provide a geological basis for the exploration of the carbonate rocks in the sub salt lacustrine facies in Santos Basin and even in the whole coastal salt bearing basin in southeastern Brazil.
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Formation mechanism of high-quality sandy-conglomerate reservoir of Triassic Karamay Formation in Mahu area
XU Ziyu, WANG An, HAN Changcheng, TIAN Jijun, ZHANG Junsheng, LIU Lei, ZHANG Nan
2020, Vol.32(3): 82–92
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321 )
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344
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doi: https://doi.org/10.12108/yxyqc.20200308
In order to clarify the formation mechanism of high-quality sandy-conglomerate reservoir of Triassic Karamay Formation in Mahu area of Junggar Basin,core observation,thin section identification,logging data analysis,mercury injection and physical property measurement and scanning electron microscope analysis were carried out,meanwhile the plane distribution and diagenetic evolution of high-quality reservoir were studied comprehensively. The results show that:(1) The Karamay Formation in Mahu area is mainly composed of braided river delta facies and fan delta facies,in which distributary channel conglomerates,dam bodies and sheet sands are the main reservoirs.(2) Three kinds of reservoirs are superposed with each other. The underwater distributary channel sands in delta front subfacies develop truncated river channel sand body and multiple sedimentary composite sand body,with the largest reservoir thickness,the coarsest grain size and the best reservoir properties, while sheet sand is mainly siltstone,with thin reservoir thickness,fine grain size and relatively poor reservoir properties.(3) Diagenetic environment has a certain control over the evolution of reservoir pores. The chlorite precipitation and calcite cementation in the late diagenetic stage reduced the reservoir physical properties,thus forming the present low porosity and ultra-low permeability reservoir. The research results have guiding significance for oil and gas exploration of Karamay Formation in Mahu area.
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Sequence architecture and structural response of the third member of Shahejie Formation in Liuzan area，Nanpu Sag
REN Mengyi, JIANG Qingchun, LIU Zhen, LU Chaojin
2020, Vol.32(3): 93–103
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doi: https://doi.org/10.12108/yxyqc.20200309
With the source to sink system of Nanpu Sag-Matouying uplift,sediments sink to the Liuzan area in Nanpu Sag developed multi-period sequence,whereas the architecture and sedimentary filling characteristic exist a significant difference. On the basis of seismic,drilling,logging and core data,according to Integrated Prediction Error Filter Analysis(INPEFA) and attribute extraction,evolution of sequence architecture was stated. The controls of tectonics on sequence architecture of terrestrial rift basin were emphatically discussed. The results show that:(1) Five 3rd-order sequences were identified in the third member of Shahejie Formation(Es3). And five types of sequence unit were established,namely "ascending", "ascending-dominated", "near-symmetrical", "descending-dominated" and "descending" in 4th-order sequences.(2) Progressing or retrograding fan delta and coastal subsea apron were developed. From sag margin to center(or from TST to RST),the sequence architecture was evolved from "(ascending) ascending-dominated" pattern to "near-symmetrical" pattern and to "(descending) descending-dominated" pattern.(3) Sequence architecture is controlled by episodic tectonic subsidence. The subsidence rate in Es3-Es2 was accelerated in the early period and reduced in the late period. The corresponding sediments supply was limited,followed by a sudden increase during the late period. The hanging wall tilting rotations during the Es1-Ed periods led to the warped stratum. The both type and distribution of sediments were affected by the differential activities of boundary faults. The distribution of large-scale sand-body changed clockwise in a "north- northeast-east" direction. The superpositions of sedimentary units were influenced by the combination of secondary faults and fault slope-break zones.The results provide strong geological theory support for the prediction of sandstone reservoir distribution in Liuzan area,but also deepen the research on the formation mechanism of continental fault basin sandstone reservoir.
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Distribution characteristics and oil-source analysis of Lower Cretaceous source rock in southern trough of Hurenbuqi sag，Erlian Basin
SHAN Xinjie, WANG Feiyu, LIU Nian, FENG Weiping, JIANG Tao, DU Xi, CHENG Zhiqiang, LI Sijia, LI Yue
2020, Vol.32(3): 104–114
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doi: https://doi.org/10.12108/yxyqc.20200310
The Hurenbuqi sag is located in the middle of the Bayinbaolige uplift in the western part of the Erlian Basin. It is one of the many oil-rich sags in the Erlian Basin. The early exploration has found high-quality source rocks and better oil and gas display,but the current research on source rock is weak. The study of source rocks is still relatively weak. Based on the geochemical evaluation of source rock and the organic geochemical analysis of source rock and crude oil samples,the distribution of organic facies and geochemical characteristics of source rocks and oil-source relationships in the southern trough of the Huerenbuqi sag were revealed. The results show that the source rocks of the southern trough in the Huerenbuqi sag are mainly distributed in the eastern belt,and three sets of source rocks in the K1 ba,K1 bt1 and K1 bt2 are developed. The source rocks of the K1 ba are in the stage of low maturation,the source rocks of the K1 bt1 are in a low maturation stage,and the source rocks of the K 1 bt2 are in the immature to lowmature stage. The C source rocks and D/E source rocks are developed in the three layers of the Lower Cretaceous in the southern part of the Hurenbuqi sag. The C source rocks of the main body of the depression are mainly distributed in the K1 bt1,the thickness is 300-400 m,the initial hydrogen index is 400- 800 mg/g TOC,and the maceral is composed of sapropelinite and exinite and vitrinite. The parent material is mainly low level aquatic organisms such as algae,formed in brackish water to salt water and reducing environment. The D/E source rocks are mainly distributed in the K1 ba,with a thickness of 100-200 m,the initial hydrogen index is 200-400 mg/g TOC,and the microscopic composition is mainly composed of exinite,vitrinite and inertinite. The parent material is mainly terrestrial plants formed in fresh water to micro-salt water and weak reducing environment. The hydrocarbon center is located in the eastern belt. According to the oil-source analysis,the mature crude oil of the K1 ba was derived from the source rocks of the K1 ba. The low mature crude oil of the K1 bt1 was derived from the source rocks of the K1 bt1,while the crude oil of the K1 bt2 may be derived from the K1 bt1 source rock.
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Macro-correction method and application of seismic pseudo-well velocity point: a case study from M gas field in Pearl River Mouth Basin
LUO Ze, XIE Mingying, LIANG Jie, TU Zhiyong, HOU Kai
2020, Vol.32(3): 115–121
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465
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doi: https://doi.org/10.12108/yxyqc.20200311
In seismic exploration and development,the selection of velocity research method is the key to timedepth conversion. In view of the complexity of fault system in M gas field of Pearl River Mouth Basin,the transverse velocity variation is obvious due to the influence of faults on the main part of structure,while the error of depth structure map obtained by previous time-depth conversion methods,such as variable velocity mapping or well-time-depth relationship fitting,is obvious. It is too large to meet the needs of high-precision structural research in the development stage. The traditional variable speed mapping method was improved. The optimized pseudo-well velocity point macro-correction method is to use the difference between pseudo-well velocity time function and logging velocity time function to correct the seismic velocity,which combines the advantages of high vertical resolution of wells and high lateral resolution of earthquakes better. It can improve work efficiency and reduce structural uncertainty at the same time. The actual drilling results show that the macro-correction method of pseudo-well velocity points effectively improves the accuracy of time-depth conversion in this area.
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Prediction of tight sandstone permeability based on high-pressure mercury intrusion（HPMI）and nuclear magnetic resonance（NMR）
CHENG Hui, WANG Fuyong, ZAI Yun, ZHOU Shuxun
2020, Vol.32(3): 122–132
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434
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doi: https://doi.org/10.12108/yxyqc.20200312
It is of great significance for the development of tight oil and gas reservoir to analyze the main factors affecting the permeability of tight sandstone and accurately predict the permeability of tight sandstone. Taking the tight sandstone from Yanchang Formation in Ordos Basin as the research subject,the main controlling factors of tight sandstone permeability were studied based on high-pressure mercury intrusion(HPMI) and nuclear magnetic resonance(NMR). The permeability prediction models based on NMR and HPMI were evaluated and optimized respectively. The results show that pore-throat size is the main factor affecting tight sandstone permeability,and the median pore-throat radius size has strongest correlation with tight sandstone permeability. Compared with NMR weighted average T2,geometric mean T2 has stronger correlation with tight sandstone permeability. Among the three different NMR permeability prediction models,SDR-REV model has better permeability prediction results compared with SDR model and KCT2w model. Among the three different HPMI permeability prediction models,the Winland model based on r40 and r45 has the highest permeability prediction results. The research results have guiding significance for the further effective development of tight sandstones of Yanchang Formation in Ordos Basin.
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Pore structure characterization and its impact on waterflooding development in Khasib reservoir in Ahdeb Oilfield，Iraq
CHEN Mingjiang, CHENG Liang, LU Tao
2020, Vol.32(3): 133–143
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424 )
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426
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doi: https://doi.org/10.12108/yxyqc.20200313
Khasib reservoir in Ahdeb Oilfield of Iraq is a typical porous carbonate reservoir in the Middle East, and it is characterized by high porosity, low permeability and strong vertical heterogeneity. To understand the causatives for high water cut and rapid breakthrough of injected water in horizontal wells, this paper focused on the three-dimensional characterization of the multi-modal pore structures. Based on core observation, thin section and SEM identification and quantitative analysis of MICP (Mercury Injection Capillary Pressure) curves, 24 rock types were classified in Khasib reservoir according to lithofacies and petrophysical properties. Spatial distribution of the rock types was characterized by well-log correlation, and effective pore-throat radius was extracted from the MICP curves for each rock type. Thus, the three-dimensional distribution of effective pore-throat radius was visualized. The results show that:(1) Effective pore-throat radius ranging from 0.09 μm to 9.2 μm increased upwards and decreased westwards along the long axis of the anticline(from AD1 block to AD4 block).(2) The layer of Khasib2-1-2 L with its average thickness of 0.8 m is a grainstone dominated by interparticle pores,and its average effective pore-throat radius and permeability are 7.2 μm and 278 mD,respectively,which are ten orders of magnitude higher than that of the adjacent layers.(3) The layer of Khasib 2-1-2 L that is referred to as the highpermeability 'thief zone' is a preferential fluid flow passage and is the control factor of rapid breakthrough of injected water.(4) The results were confirmed by typical water control diagnostic plot,production logging as well as resistivity variation observed in vertical wells drilled through the reservoir. The research results provide a reliable basis for oil stabilization and water control in the reservoir,and based on this,reasonable development adjustment measures were proposed.
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Architecture characterization of single distributary channel sand bodies restricted by architecture interface of Yan 8 member in Y116 well area，Yanwu Oilfield
TONG Qiang, YU Jianguo, TIAN Yunji, HU Kelai, YANG Hongmei, CHENG Xuming, ZHU Yushuang
2020, Vol.32(3): 144–158
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318
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doi: https://doi.org/10.12108/yxyqc.20200314
The fine description of architecture of the sand bodies in a single channel is restricted by the third and fourth order architecture interface,which makes the classification and recognition of the interlayers to be the premise of this study. Guided by the analytic hierarchy process,starting from the core calibration,combined with the comprehensive analysis of logging data,the partition standard of the interlayer in Y116 well area of Yanwu Oilfield was identified by using intersection chart,and the horizontal and vertical distribution characteristics of the interlayer were studied by tracking multiple wells from a single well. Under its constraints,three types of architecture characterization units were depicted,forming the spatial distribution model of the architecture characterization interlayer. The results show that in Yan 8 member of Yanwu Oilfield,three types of architecture interfaces were identified,namely,the architecture characterization interlayer between sand bodies of single channel in vertical direction,the architecture characterization interlayer between sand bodies of single channel in horizontal direction and the interlayer within sand bodies of single channel. Under the genesis of argillaceous,calcareous and physical properties,the sand bodies of compound distributary channel were divided into four stages of single channel sand bodies. Among them,the architecture characterization interlayers are mainly distributed in the middle of the river,the muddy interlayers are common in the edge of the river,and the calcareous interlayers are mostly distributed in the upper part of the river. The research on the vertical superposition pattern and the plane contact pattern of the architecture characterization elements shows that the vertical separation type and cutting superposition type are the main types,and the horizontal side cutting type and flood plain contact type are the main types,forming the independent distributary channel unit,separate fine-grained sedimentary unit and contact accretion unit. All the architecture elements form an "extensive contact,superimposed and intricate" architecture distribution model of braided river delta plain with wide connectivity. This study realized the identification and characterization of interfaces in the study area,which can provide a basis for the fine characterization of single channel sand body architecture characterization unit,and has theoretical and practical significance for the further production and development of oilfield.
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Experiment on the mechanism of low salinity waterflooding in carbonate reservoir
QIAN Zhen, LI Hui, QIAO Lin, BAI Sen
2020, Vol.32(3): 159–165
Abstract
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368
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doi: https://doi.org/10.12108/yxyqc.20200315
Potential of low salinity waterflooding in carbonate reservoir is huge. To better promote its field application,experimental research on its mechanism was carried out. Firstly,core displacement experiment was conducted to study the influence of salinity and determining ions(PDIs) on oil recovery. Then,the influence of salinity and PDIs on wettability of carbonate rock was analyzed according to the contact angle experiments. Finally, the low salinity waterflooding mechanism of carbonate reservoir was established based on the experiment results. The results show that low salinity water can effectively change surface wettability,hence the oil recovery,and have optimum salinity to the highest oil recovery. The effects of Mg2+ and SO42- on wettability and recovery are different. With the increase of Mg2+,the wettability alteration increases and the oil recovery enhances. With the increase of SO42-,the wettability alteration increases first and then decreases,and the oil recovery increases first and then stabilizes. The mechanism of low salinity waterflooding in carbonate reservoirs is the wettability alteration which can be divided into two steps:(1) SO42- adsorbed on the positive carbonate minerals surface,neutralizing surface charges,promoting the movement of Mg2+ to the minerals surface;(2) Mg2+ substituted Ca2+ of carbonate minerals surface,resulting in the dissociation of crude oil.
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Experimental study on the surface feature of acid-etched fractures in carbonate rocks
FENG Wei, YANG Chen, TAO Shanxun, WANG Caizhong, LU Yanying, ZHANG Lufeng, ZHOU Fujian
2020, Vol.32(3): 166–172
Abstract
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262 )
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377
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doi: https://doi.org/10.12108/yxyqc.20200316
Acid fracturing is a common method for stimulating carbonate reservoir. The surface characteristics of acid-etched fracture is unique due to the non-uniform acid-etching. At present,the research on geometric feature of fracture surface before and after etching is not enough. In this paper,advanced experimental devices were used to obtain real acid-etched fracture samples,then the geometric characteristics of the fracture surface were analyzed by using 3D scanning data,and the new parameters hn and εh were defined to quantitatively describe the fluctuation degree. Furthermore,the change of fracture surface patterns before and after acid-etching were compared. The results show that gullies and holes were formed on the fracture surface and the fluctuation degree increased,the tortuosity decreased along the flow direction and increased vertically to flow direction after acid-etching.