On-line microscopic imaging investigation on oil charging characteristics in tight reservoirs
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摘要: 致密储层岩石渗透率低,储集空间受其微纳米级孔隙控制,毛管力作用显著增强。认识油气的微观充注特征是分析运聚成藏的基础。利用自研的岩心流体驱替在线三维显微成像系统,开展致密储层样品油充注过程观测,提出样品整体和孔隙两级的含油特征综合定量分析方法。以相同流程的驱替在线核磁共振测试为对照,揭示不同时刻在线二维直接数字化摄影(Digital Radiography,DR)的平均差值,可用于评价样品整体含油量变化;基于高精度孔隙网络抽提的孔隙级流体饱和度计算方法,实现了图像可分辨的孔隙与孔喉油充注程度的定量评价。通过多层次数据、不同方法的组合,可满足不同研究对动态特征捕捉、孔隙分辨能力及成像视野等差异化需要。分析结果表明,鄂尔多斯盆地不同致密储层两块岩石样品的含油饱和度随注油量的增加,均呈现开始上升较快、后期减缓的特点;相同注入流速下,相对高渗样品油充注初期含油饱和度上升速度更快,最终含油饱和度较高;随着注油量的增加,较高渗样品的大孔隙含油饱和度持续增加,低渗样品大孔隙的含油饱和度呈U形变化,表现出油、水反复占据孔隙的特点。Abstract: The reservoir space of tight reservoir with low-permeability is controlled by micro and nano scale pores, making the influence of capillary force significantly enhanced. Therefore, understanding the microscopic charging characteristics of oil and gas is the basis for analyzing the migration and accumulation of reservoirs. In this paper, the self-developed on-line three-dimensional microscopic imaging system for core fluid displacement is used to observe the oil charging process of two tight reservoir samples, and core-level and pore-level quantitative analysis methods for oil content characteristics are proposed. Taking the on-line nuclear magnetic resonance testing with the same process of displacement as a contrast, it is revealed that the average difference of on-line 2D DR (Digital Radiography) images at different times can be used to evaluate the overall oil content change of the sample. The calculation method of pore level fluid saturation based on high-precision pore network extraction algorithm realizes the quantitative evaluation of oil charging degree of the CT resolved pores and pore throats. The combination of multi-level data and different methods can meet the different needs of different researches on dynamic feature capture, pore resolution and imaging field of vision. The analysis results show that the oil saturation of two rock samples from different tight reservoirs in the Ordos Basin increases rapidly at the beginning and slows down later with oil injection increasing. At the same injection flow rate, the oil saturation of the sample with higher permeability increases faster at the initial oil charging stage, making its final oil saturation higher. With the increase of oil injection, the oil saturation of macropores in the sample with higher permeability continuously increases, while that of macropores in the sample with lower permeability shows a U-shaped change, showing the characte-ristics of repeated occupation of pores by oil and water.
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Key words:
- on-line microscopic imaging /
- oil charging /
- Digital Radiography(DR) /
- pore network /
- tight reservoir
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表 1 致密储层油充注实验样品的孔隙度、渗透率以及薄片鉴定结果
Table 1. Porosity, permeability and thin section identification results of the tested samples
样品 孔隙度/% 孔隙体积/mL 渗透率/10-3 μm2 矿物含量/% 石英 长石 塑性岩屑 刚性岩屑 云母 石英胶结 黏土胶结 面孔率 JT403 13.93 2.77 33.36 41.2 6 2.0 20.0 1.2 4.8 6.8 18.0 Y4 10.86 2.22 1.47 33.6 18 7.2 12.8 10.0 3.2 3.6 11.6 注:孔隙度由氦气孔隙度测定方法测定;渗透率为洗油后氦气脉冲法所测,孔压为150 kPa,净围压为3 000 kPa。 表 2 致密储层油充注实验样品采用的油充注步骤
Table 2. Steps of oil charging for the tested samples
步骤 样品JT403 样品Y4 注入流速/(mL·min-1) 样品累积注油量/PV 注入流速/(mL·min-1) 样品累积注油量/PV 1 0.1 0.07 0.1 0.09 2 0.1 0.79 0.1 0.99 3 0.1 1.52 0.1 1.89 4 0.1 4.12 0.1 3.69 5 1.0 9.10 0.1 12.70 -
[1] 朱如凯, 邹才能, 吴松涛, 等. 中国陆相致密油形成机理与富集规律[J]. 石油与天然气地质, 2019, 40(6): 1168-1184. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT201906002.htmZHU Rukai, ZOU Caineng, WU Songtao, et al. Mechanism for generation and accumulation of continental tight oil in China[J]. Oil & Gas Geology, 2019, 40(6): 1168-1184. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT201906002.htm [2] 胡渤, 蒲军, 苟斐斐. 基于数字岩心的致密砂岩微观孔喉结构定量表征[J]. 油气地质与采收率, 2022, 29(3): 102-112. https://www.cnki.com.cn/Article/CJFDTOTAL-YQCS202203013.htmHU Bo, PU Jun, GOU Feifei. Quantitative characterization of pore throat microstructure of tight sandstone based on digital core technology[J]. Petroleum Geology and Recovery Efficiency, 2022, 29(3): 102-112. https://www.cnki.com.cn/Article/CJFDTOTAL-YQCS202203013.htm [3] 孙龙德, 邹才能, 贾爱林, 等. 中国致密油气发展特征与方向[J]. 石油勘探与开发, 2019, 46(6): 1015-1026. https://www.cnki.com.cn/Article/CJFDTOTAL-SKYK201906002.htmSUN Longde, ZOU Caineng, JIA Ailin, et al. Development characteristics and orientation of tight oil and gas in China[J]. Petroleum Exploration and Development, 2019, 46(6): 1015-1026. https://www.cnki.com.cn/Article/CJFDTOTAL-SKYK201906002.htm [4] 金之钧, 张金川, 唐玄. 非常规天然气成藏体系[J]. 天然气工业, 2021, 41(8): 58-68. doi: 10.3787/j.issn.1000-0976.2021.08.006JIN Zhijun, ZHANG Jinchuan, TANG Xuan. Unconventional natural gas accumulation system[J]. Natural Gas Industry, 2021, 41(8): 58-68. doi: 10.3787/j.issn.1000-0976.2021.08.006 [5] 邓亚仁, 任战利, 马文强, 等. 鄂尔多斯盆地富县地区长8层段致密砂岩储层特征及充注下限[J]. 石油实验地质, 2018, 40(2): 288-294. doi: 10.11781/sysydz201802288DENG Yaren, REN Zhanli, MA Wenqiang, et al. Reservoir pro-perties and hydrocarbon charging threshold of Chang 8 tight sandstones in Fuxian area, Ordos Basin[J]. Petroleum Geology & Experiment, 2018, 40(2): 288-294. doi: 10.11781/sysydz201802288 [6] 王洋, 陈海峰, 王凤启. 结合高温高压物性实验确定致密油储层充注物性下限新方法[J]. 地质与资源, 2019, 28(1): 66-71. doi: 10.3969/j.issn.1671-1947.2019.01.011WANG Yang, CHEN Haifeng, WANG Fengqi. Determination of the physical property lower limit of tight oil reservoir by high-temperature and high-pressure experiment[J]. Geology and Resources, 2019, 28(1): 66-71. doi: 10.3969/j.issn.1671-1947.2019.01.011 [7] 王浩男, 肖晖, 苗晨阳, 等. 致密砂岩储层油充注下限综合确定方法及其应用: 以鄂尔多斯盆地马岭地区长8油藏为例[J]. 大庆石油地质与开发, 2020, 39(2): 147-156. https://www.cnki.com.cn/Article/CJFDTOTAL-DQSK202002021.htmWANG Haonan, XIAO Hui, MIAO Chenyang, et al. Comprehensive determining method of the lower limit of the oil-charging in tight sandstone reservoirs and its application: a case of Chang-8 oil reservoir in Maling area of Ordos Basin[J]. Petroleum Geology & Oilfield Development in Daqing, 2020, 39(2): 147-156. https://www.cnki.com.cn/Article/CJFDTOTAL-DQSK202002021.htm [8] 刘震, 刘静静, 王伟, 等. 低孔渗砂岩石油充注临界条件实验: 以西峰油田为例[J]. 石油学报, 2012, 33(6): 996-1002. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB201206011.htmLIU Zhen, LIU Jingjing, WANG Wei, et al. Experimental analyses on critical conditions of oil charge for low-permeability sandstones: a case study of Xifeng Oilfield, Ordos Basin[J]. Acta Petrolei Sinica, 2012, 33(6): 996-1002. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB201206011.htm [9] 徐轩, 胡勇, 邵龙义, 等. 低渗致密砂岩储层充注模拟实验及含气性变化规律: 以鄂尔多斯盆地苏里格气藏为例[J]. 中国矿业大学学报, 2017, 46(6): 1323-1331. https://www.cnki.com.cn/Article/CJFDTOTAL-ZGKD201706016.htmXU Xuan, HU Yong, SHAO Longyi, et al. Experimental simulation of gas accumulation mechanism in sandstone reservoir: a case study of Sulige Gas Field, Ordos Basin[J]. Journal of China University of Mining & Technology, 2017, 46(6): 1323-1331. https://www.cnki.com.cn/Article/CJFDTOTAL-ZGKD201706016.htm [10] 白国帅, 蒋有录, 赵承锦, 等. 元坝地区须二下亚段砂岩储层致密化与天然气充注关系[J]. 断块油气田, 2022, 29(1): 20-25. https://www.cnki.com.cn/Article/CJFDTOTAL-DKYT202201004.htmBAI Guoshuai, JIANG Youlu, ZHAO Chengjin, et al. The relationship between densification of sandstone reservoir and natural gas charging in the lower part of the second member of Xujiahe Formation in Yuanba area[J]. Fault-Block Oil and Gas Field, 2022, 29(1): 20-25. https://www.cnki.com.cn/Article/CJFDTOTAL-DKYT202201004.htm [11] 张安达, 王成, 乔睿. 致密砂岩储层物性下限确定新方法及系统分类[J]. 岩性油气藏, 2014, 26(5): 5-8. https://www.cnki.com.cn/Article/CJFDTOTAL-YANX201405002.htmZHANG Anda, WANG Cheng, QIAO Rui. A new method for determining physical property lower limit of tight sandstone reservoir and reservoir system classification[J]. Lithologic Reservoirs, 2014, 26(5): 5-8. https://www.cnki.com.cn/Article/CJFDTOTAL-YANX201405002.htm [12] 周妍, 孙卫, 白诗筠. 鄂尔多斯盆地致密油地质特征及其分布规律[J]. 石油地质与工程, 2013, 27(3): 27-29. https://www.cnki.com.cn/Article/CJFDTOTAL-SYHN201303007.htmZHOU Yan, SUN Wei, BAI Shiyun. Research on dense oil geologic characteristics and distribution regularity in Ordos Basin[J]. Petro-leum Geology and Engineering, 2013, 27(3): 27-29. https://www.cnki.com.cn/Article/CJFDTOTAL-SYHN201303007.htm [13] 葸克来. 松辽盆地南部白垩系泉头组四段致密砂岩油气成储机制[D]. 青岛: 中国石油大学(华东), 2016.XI Kelai. Genetic mechanism of tight sandstone oil and gas reservoir of the Cretaceous Quantou Formation fourth member in the southern Songliao Basin, China[D]. Qingdao: China University of Petro-leum (East China), 2016. [14] QIAO Juncheng, ZENG Jianhui, JIANG Shu, et al. Heterogeneity of reservoir quality and gas accumulation in tight sandstone reservoirs revealed by pore structure characterization and physical simulation[J]. Fuel, 2019, 253: 1300-1316. http://www.sciencedirect.com/science/article/pii/S0016236119308658 [15] 韩小琴, 房涛, 曹军, 等. 鄂尔多斯盆地延安气田山西组致密砂岩储层天然气充注模拟实验及含气性变化规律[J]. 天然气地球科学, 2019, 30(12): 1721-1731. https://www.cnki.com.cn/Article/CJFDTOTAL-TDKX201912006.htmHAN Xiaoqin, FANG Tao, CAO Jun, et al. Simulation experiment of gas charging and gas-bearing change of tight sandstone reservoir of Shanxi Formation in Yan'an gas field, Ordos Basin[J]. Natural Gas Geoscience, 2019, 30(12): 1721-1731. https://www.cnki.com.cn/Article/CJFDTOTAL-TDKX201912006.htm [16] 李超正. 鄂尔多斯盆地长7段致密砂岩储层石油充注有效性研究[D]. 北京: 中国石油大学(北京), 2020.LI Chaozheng. Research on effectiveness of oil charging in the tight sandstone reservoir of the Chang 7 Member, Ordos Basin[D]. Beijing: China University of Petroleum (Beijing), 2020. [17] 谢增业, 杨春龙, 李剑, 等. 致密砂岩气藏充注模拟实验及气藏特征: 以川中地区上三叠统须家河组砂岩气藏为例[J]. 天然气工业, 2020, 40(11): 31-40. https://www.cnki.com.cn/Article/CJFDTOTAL-TRQG202011007.htmXIE Zengye, YANG Chunlong, LI Jian, et al. Charging simulation experiment and characteristics of tight sandstone gas reservoirs: a case study of the Upper Triassic Xujiahe Formation sandstone gas reservoir in the central Sichuan Basin[J]. Natural Gas Industry, 2020, 40(11): 31-40. https://www.cnki.com.cn/Article/CJFDTOTAL-TRQG202011007.htm [18] SINGH K, BIJELJIC B, BLUNT M J. Imaging of oil layers, curvature and contact angle in a mixed-wet and a water-wet carbonate rock[J]. Water Resources Research, 2016, 52(3): 1716-1728. http://www.onacademic.com/detail/journal_1000038767068910_8c4c.html [19] DALTON L E, KLISE K A, FUCHS S, et al. Methods to measure contact angles in scCO2-brine-sandstone systems[J]. Advances in Water Resources, 2018, 122: 278-290. http://www.onacademic.com/detail/journal_1000041580604099_2edb.html [20] SCANZIANI A, SINGH K, BLUNT M J, et al. Automatic method for estimation of in situ effective contact angle from X-ray micro tomography images of two-phase flow in porous media[J]. Journal of Colloid and Interface Science, 2017, 496: 51-59. http://www.researchgate.net/profile/Alessio_Scanziani/publication/313504460_Automatic_method_for_estimation_of_in_situ_effective_contact_angle_from_X-ray_micro_tomography_images_of_two-phase_flow_in_porous_media/links/58a5eb5292851cf0e3a143a9/Automatic-method-for-estimation-of-in-situ-effective-contact-angle-from-X-ray-micro-tomography-images-of-two-phase-flow-in-porous-media.pdf [21] 孙先达. 纳米CT技术在水驱后微观剩余油分布形态及量化分析中的应用[J]. 电子显微镜学报, 2015, 34(3): 216-221. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXV201503007.htmSUN Xianda. Application of Nano-CT technology to the study of distribution patterns and quantitative analysis in microscopic residual oil after water flooding and quantitative analysis[J]. Journal of Chinese Electron Microscopy Society, 2015, 34(3): 216-221. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXV201503007.htm [22] 马勇, 曾溅辉, 冯枭. 致密砂岩微米级孔隙网络系统石油驱替实验三维在线模拟[J]. 石油实验地质, 2020, 42(1): 139-146. doi: 10.11781/sysydz202001139MA Yong, ZENG Jianhui, FENG Xiao. Three-dimensional simulation of oil distribution during waterflooding in a micrometer-sized pore network system of tight sandstone[J]. Petroleum Geology & Experiment, 2020, 42(1): 139-146. doi: 10.11781/sysydz202001139 [23] 乔俊程, 曾溅辉, 夏宇轩, 等. 微纳米孔隙网络中天然气充注的三维可视化物理模拟[J]. 石油勘探与开发, 2022, 49(2): 306-318. https://www.cnki.com.cn/Article/CJFDTOTAL-SKYK202202007.htmQIAO Juncheng, ZENG Jianhui, XIA Yuxuan, et al. A three dimensional visualized physical simulation for natural gas charging in the micro-nano pore system[J]. Petroleum Exploration and Development, 2022, 49(2): 306-318. https://www.cnki.com.cn/Article/CJFDTOTAL-SKYK202202007.htm [24] YI Zhixing, LIN Mian, JIANG Wenbin, et al. Pore network extraction from pore space images of various porous media systems[J]. Water Resources Research, 2017, 53(4): 3424-3445. http://www.onacademic.com/detail/journal_1000039863455710_5bab.html [25] JU Yang, XI Chaodong, ZHENG Jiangtao, et al. Study on three-dimensional immiscible water-oil two-phase displacement and trapping in deformed pore structures subjected to varying geostress via in situ computed tomography scanning and additively printed models[J]. International Journal of Engineering Science, 2022, 171: 103615. http://www.sciencedirect.com/science/article/pii/S0020722521001555 [26] ZENG Jianhui, FENG Xiao, FENG Sen, et al. Influence of tight sandstone micro-nano pore-throat structures on petroleum accumulation: evidence from experimental simulation combining X-ray tomography[J]. Journal of Nanoscience and Nanotechnology, 2017, 17(9): 6459-6469.