Variations of Rock Resistivity in Water-Flooded Zones of Waterflooding Oilfield

摘要/Abstract

摘要： The changes of electrical properties of water flooded reservoirs are complex, which brings great difficulty to the identification of water flooded zone and the evaluation of remaining oil saturation. In this paper, simulated waterflooding experiments under reservoir conditions are carried out by using sealed coring samples, the variations of rock resistivity are analyzed for the situations when the water of different salinities is injected to displace oil and the influences of changes of pore structures, and formation water salinity on rock electrical parameters are discussed. The experimental results show that when high salinity water or formation water is injected to displace oil, the rock resistivity always monotonously decreases and exhibits a“L”shape, and the better the physical properties are, the larger the decrease amplitude of rock resistivity will be; when low-salinity water is injected to displace oil, the rock resistivity generally displays a“U”or“S”shape and the better the physical properties are, the resistivity will change to monotonous increase from monotonous decrease, and the higher the water saturation at the first inflection point will be. The changes of pore structure resulted from the changes of injected water volume have no significant impact on rock electrical parameter. With the increase of formation water salinity, cementation index and saturation index will gradually increase. The influence of the difference of formation water salinity at different waterflooded stage on rock electrical parameters should be considered when calculating residual oil saturation.

关键词: waterflooding development, reservoir, watered out, resistivity, salinity, rock electrical parameter, rock resistivity experiment, electrical conductivity

Abstract: The changes of electrical properties of water flooded reservoirs are complex, which brings great difficulty to the identification of water flooded zone and the evaluation of remaining oil saturation. In this paper, simulated waterflooding experiments under reservoir conditions are carried out by using sealed coring samples, the variations of rock resistivity are analyzed for the situations when the water of different salinities is injected to displace oil and the influences of changes of pore structures, and formation water salinity on rock electrical parameters are discussed. The experimental results show that when high salinity water or formation water is injected to displace oil, the rock resistivity always monotonously decreases and exhibits a“L”shape, and the better the physical properties are, the larger the decrease amplitude of rock resistivity will be; when low-salinity water is injected to displace oil, the rock resistivity generally displays a“U”or“S”shape and the better the physical properties are, the resistivity will change to monotonous increase from monotonous decrease, and the higher the water saturation at the first inflection point will be. The changes of pore structure resulted from the changes of injected water volume have no significant impact on rock electrical parameter. With the increase of formation water salinity, cementation index and saturation index will gradually increase. The influence of the difference of formation water salinity at different waterflooded stage on rock electrical parameters should be considered when calculating residual oil saturation.

Key words: waterflooding development, reservoir, watered out, resistivity, salinity, rock electrical parameter, rock resistivity experiment, electrical conductivity

ZHANG Hengrong, TAN Wei, WANG Lijuan, DING Lei. Variations of Rock Resistivity in Water-Flooded Zones of Waterflooding Oilfield[J]. 新疆石油地质, 2017, 38(zk(English) ): 73-78.

ZHANG Hengrong, TAN Wei, WANG Lijuan, DING Lei. Variations of Rock Resistivity in Water-Flooded Zones of Waterflooding Oilfield[J]. Xinjiang Petroleum Geology, 2017, 38(zk(English) ): 73-78.

参考文献

[1] DABBOUK C, LIAQAT A, BEATTIE G, et al. Waterflood in vuggy layer of the Middle East reservoir-displacement physics understood [R]. SPE 78530, 2002.
[2] ZHONG Xingshui.The relationship between Archie saturation index and wettability[J]. Logging Technology Information, 1989, 2(6): 47-49.
[3] ZAKHANOV B H.The geophysical method of studying oil and gas reservoir [M]. Translated by LI Zhoubo. Beijing: China Industry Press, 1962.
[4] WALTHER H C.Experimental measurement of logging curve saturation-logging parameters [M]//The Well Logging Corpus. Beijing: Petroleum Industry Press, 1974.
[5] ZHAO Fuzhen.Determination of the formation-resistivity variation patterns during oil reservoir flooded process[J]. Xinjiang Petroleum Geology, 1991, 12(4): 339-343.
[6] ZHOU Boran, LIN Chunzeng.Experimental study of rock physical properties of water injection process [R]. Beijing: The Water Drive Oilfield Development Logging 96 International Academic Seminars, 1996.
[7] ZHOU Boran, LIN Chunzeng, TIAN Zhongyan.Experimental study of rock physical properties of water injection process[J]. Foreign Well Logging Technology, 1997, 12(5): 18-27.
[8] ZHAO Wenjie.Experiment research on the rock resistivity properties of watered-out formation[J]. Oil & Gas Recovery Technology, 1995, 4(2): 32-38.
[9] FAN Yiren, DENG Shaogui, ZHOU Cancan.Experimental study on rock resistivity of Liudong oilfield and digital analogy[J]. Journal of the University of Petroleum, China, 1998, 22(5): 42-44.
[10] SONG Weiqi, GUAN Jiteng, FANG Wenjing.Theoretical study of varying rule for rock resistivity in water injection process[J]. Oil Geophysical Prospecting, 2000, 35(6): 757-762.
[11] YANG Chunmei, LI Hongqi, LU Dawei, et al. The relationship between rock resistivity and water saturation in water-drive-oil and oil-drive-water process[J]. Journal of Jilin University (Earth Science Edition), 2005, 35(5): 668-670.
[12] YONG Shihe, ZHANG Chaomo.Logging data processing and comprehensive interpretation [M]. Dongying, Shandong: China University of Petroleum Press, 2002.
[13] FAN Yiren, DENG Shaogui, LIU Bingkai.Experiment on rock resistivity in the process of fresh water derive[J]. Well Logging Technology, 1998, 22(3): 153-155.
[14] ZHANG Gengji.The electrical resistivity log as an aid in determining some reservoir characteristics[J]. Well Logging Technology, 2007, 31(3): 197-201.
[15] MAO Zhiqiang, TAN Tingdong, LIN Chunzeng, et al. The laboratory studies on pore structure and electrical properties of core samples fully-saturated with brine water[J]. Acta Petrolei Sinica, 1997, 18(3): 51-55.
[16] WEI Bin, ZHANG Yousheng, YANG Guikai, et al. Oil-water displacement experiment of reservoir fluid flow unit[J]. Petroleum Exploration and Development, 2002, 29(6): 72-74.
[17] YANG Chunmei.Study on reservoir properties and changes mechanism of well logging curves in the middle-later period of oilfield development [D]. Beijing: China University of Petroleum, 2005.