Description and recognition of fractures in high-inclination coring well in Qingcheng shale oil hydraulic fracturing test site

doi:10.3969/j.issn.1672-7703.2025.02.010

Abstract

Abstract: In Qingcheng area, Ordos Basin, the interlayered type shale oil reservoir is characterized by high heterogeneity in both lateral
and vertical directions, low degree of natural fracture development, and large two-direction horizontal stress difference. The preliminary microseismic data indicates that there is distinct feature of double-wing fractures, and the fracture pattern is relatively simple. In order to further understand the post-fracturing fracture pattern and spatial distribution, core section has systematically been taken in a high-inclination well in Qingcheng shale oil hydraulic fracturing test site. Using multiple methods such as CT scanning, core observation, microscopic imaging, and well logging data, the fine description of fracture occurrence, fracture surface morphology, and filling characteristics is conducted, and the fractures are classified and identified. Meanwhile, the dye proppant, mud tracer, and spatial distance and distribution law are used to perform corresponding regression and comprehensive analysis on hydraulic fractures. The study results show that different types of fractures show different characteristics. There is a low proportion of natural tectonic fractures, but a high proportion of bedding fractures and hydraulic fractures with significant characteristics. The hydraulic fractures are characterized by clustering features, and the fracture number is much higher than the corresponding stages in adjacent hydraulic fracturing wells. There are differences in fracture propagation in local areas, but they generally extend along the principal stress direction under the influence of stress difference and azimuth. There are few distinctly propped fractures, but the mud proppant is widely distributed in fractures with a higher proportion of small particles. The tracer analysis shows that the number of hydraulic fractures in each stage is the key contributor to oil production. The fracture recognition, classification, and regression
method obtained by integrating multiple methods can be used as a reference for post-fracturing coring fracture analysis of other unconventional oil and gas reservoirs, and the fracture understanding has certain guiding significance for further fracturing optimization.

Key words: shale oil, hydraulic fracturing test site, high-inclination coring well, hydraulic fracture, clustering feature

CLC Number:

TE112

Cao Wei, Ma Yongning, Meng Hao, Bai Jie, Zhang Tongwu, Xian Cheng, Xu Rongli, Zhao Guoxiang, Tu Zhiyong. Description and recognition of fractures in high-inclination coring well in Qingcheng shale oil hydraulic fracturing test site[J]. China Petroleum Exploration, 2025, 30(2): 133-145.

References

[1] 邹才能，翟光明，张光亚，等. 全球常规—非常规油气形成分布、资源潜力及趋势预测[J]. 石油勘探与开发，2015,42(1):13-25.
Zou Caineng, Zhai Guangming, Zhang Guangya, et al . Formation, distribution, potential and prediction of global conventional and unconventional hydrocarbon resources[J]. Petroleum Exploration and Development, 2015,42(1):13-25.
[2] 赵文智，胡素云，侯连华，等. 中国陆相页岩油类型、资源潜力及与致密油的边界[J]. 石油勘探与开发，2020,47(1):1-10.
Zhao Wenzhi, Hu Suyun, Hou Lianhua, et al . Types and resource potential of continental shale oil in China and its boundary with tight oil[J]. Petroleum Exploration and Development, 2020,47(1):1-10.

[3] 吴奇，胥云，王晓泉，等. 非常规油气藏体积改造技术：内涵、优化设计与实现[J]. 石油勘探与开发，2012,39(3):352-358.
Wu Qi, Xu Yun, Wang Xiaoquan, et al . Volume fracturing technology of unconventional reservoirs: connotation, optimization design and implementation[J]. Petroleum Exploration and Development, 2012,39(3): 352-358.
[4] 付金华，李士祥，牛小兵，等. 鄂尔多斯盆地三叠系长7 段页岩油地质特征与勘探实践[J]. 石油勘探与开发，2020,47(5):870-883.
Fu Jinhua, Li Shixiang, Niu Xiaobing, et al . Geological characteristics and exploration of shale oil in Chang 7 Member of Triassic Yanchang Formation, Ordos Basin, NW China[J].Petroleum Exploration and Development, 2020,47(5):870-883.
[5] 付金华，刘显阳，李士祥，等. 鄂尔多斯盆地三叠系延长组长7 段页岩油勘探发现与资源潜力[J]. 中国石油勘探，2021,26(5):1-11.
Fu Jinhua, Liu Xianyang, Li Shixiang, et al . Discovery and resource potential of shale oil of Chang 7 member, Triassic Yanchang Formation, Ordos Basin[J]. China Petroleum Exploration, 2021,26(5):1-11.
[6] 张矿生，唐梅荣，陶亮，等. 庆城油田页岩油水平井压增渗一体化体积压裂技术[J]. 石油钻探技术，2022,50(2):9-15.
Zhang Kuangsheng, Tang Meirong, Tao Liang, et al . Horizontal Well volumetric fracturing technology integrating fracturing, energy enhancement, and imbibition for shale oil in Qingcheng Oilfield[J]. Petroleum Drilling Techniques, 2022,50(2):9-15.
[7] 石道涵，张矿生，唐梅荣，等. 长庆油田页岩油水平井体积压裂技术发展与应用[J]. 石油科技论坛，2022,41(3):10-17.
Shi Daohan, Zhang Kuangsheng, Tang Meirong, et al . Development and application of shale oil horizontal well volume fracturing technology in Changqing Oilfield[J]. Petroleum Science and Technology Forum, 2022,41(3):10-17.
[8] 慕立俊，拜杰，齐银，等. 庆城夹层型页岩油地质工程一体化压裂技术[J]. 石油钻探技术，2023,51(5):33-41.
Mu Lijun, Bai Jie, Qi Yin, et al . Geological engineering integrated fracturing technology for Qingcheng interlayer shale oil[J]. Petroleum Drilling Techniques, 2023,51(5):33-41.
[9] 何永宏，李桢，樊建明，等. 鄂尔多斯盆地页岩油开发井网优化技术及实践：以庆城油田为例[J]. 石油学报，2024,45(4):683-697.
He Yonghong, Li Zhen, Fan Jianming, et al . Optimization technique of development well pattern of shale oil in Ordos Basin and its application: a case study of Qingcheng oilfield[J].Acta Petrolei Sinica, 2024,45(4): 683-697.
[10] 何永宏，薛婷，李桢，等. 鄂尔多斯盆地长7 页岩油开发技术实践：以庆城油田为例[J]. 石油勘探与开发，2023,50(6):1245-1258.
He Yonghong, Xue Ting, Li Zhen, et al . Development technologies for Triassic Chang 7 shale oil in Ordos Basin:a case study of Qingcheng Oilfield, NW China[J]. Petroleum Exploration and Development, 2023,50(6):1245-1258.
[11] 侯雨庭，杨兆钰，张忠义，等. 鄂尔多斯盆地延长组长73 页岩油地质认识与勘探前景[J]. 中国石油勘探，2024,29(6):16-28.
Hou Yuting, Yang Zhaoyu, Zhang Zhongyi, et al . Geological understanding and exploration potential of shale oil in the third sub-member of the seventh member of Yanchang Formation in Ordos Basin[J]. China Petroleum Exploration, 2024,29(6):16-28.
[12] Ciezobka J, Scott R. Overview of Hydraulic Fracturing Test Sites (HFTS) in the Permian Basin and Summary of Selected Results (HFTS-I in Midland and HFTS-II in Delaware)[C]. Houston: SPE/AAPG/SEG Unconventional Resources Technology Conference, 2020.
[13] Fu P, Schoenball M, Ajo-Franklin J, et al . Close observation of hydraulic fracturing at EGS Collab Experiment 1: Fracture trajectory, microseismic interpretations, and the role of natural fractures[J]. Journal of Geophysical Research Solid Earth,2021,126(7).
[14] Ciezobka J, Courtier J, Joe W. Hydraulic fracturing test site (HFTS) - project overview and summary of results[C]. Houston: SPE/AAPG/SEG Unconventional Resources Technology Conference, 2018.
[15] Li H, Han J, Tan J, et al . A comprehensive simulation study of hydraulic fracturing test site 2 (HFTS-2): Part Ⅰ - modeling pressure-dependent and time-dependent fracture conductivity in fully calibrated fracture and reservoir models[C]. Denver: SPE/AAPG/SEG Unconventional Resources Technology Conference, 2023.
[16] Han J, Zhao Y, Li H, et al . A comprehensive simulation study of hydraulic fracturing test site 2 (HFTS-2): Part Ⅱ -Development optimization in the delaware basin using an integrated modeling workflow[C]. Denver: SPE/AAPG/SEG Unconventional Resources Technology Conference, 2023.
[17] Morris J, Sherman C, Fu P, et al . Multiscale geomechanical analysis of the hydraulic fracturing test site[C]. New York: 53rd U.S. Rock Mechanics/Geomechanics Symposium, 2019.
[18] Liu X, Tan Y, Singh A, et al . Learnings on fracture and geomechanical modeling from the hydraulic fracturing test site in the Midland Basin, West Texas[C]. Brisbane: SPE/AAPG/SEG Asia Pacific Unconventional Resources Technology Conference, 2021.
[19] Gale J, Elliott S, Li J Z, et al . Natural fracture characterization in the Wolfcamp Formation at the hydraulic fracture test site (HFTS), Midland Basin, Texas[C]. Colorado: SPE/AAPG/SEG Unconventional Resources Technology Conference, 2019.
[20] 魏海峰. 非均质性页岩水力压裂裂缝扩展形态研究进展[J]. 油气地质与采收率，2023,30(4):156-166.
Wei Haifeng. Research progress on fracture propagation patterns of hydraulic fracturing in heterogeneous shale[J]. Petroleum Geology and Recovery Efficiency，2023,30(4):156-166.
[21] 张矿生，薛小佳，陶亮，等. 页岩油水平井体积压裂缝网波及体积评价新方法及应用[J]. 特种油气藏，2023,30(5):127-134.
Zhang Kuangsheng, Xue Xiaojia, Tao Liang, et al . New method for evaluating the volume fracturing fracture network sweep volume in shale oil horizontal wells and its application[J] Special Oil ＆ Gas Reservoirs, 2023,30(5):127-134.
[22] 张矿生，慕立俊，陆红军，等. 鄂尔多斯盆地页岩油水力压裂试验场建设概述及实践认识[J]. 钻采工艺，2024,47(6):16-27.
Zhang Kuangsheng, Mu Lijun, Lu Hongjun, et al . Overview and practical understanding of the construction of shale oil hydraulic fracture field labs in the Ordos Basin[J]. Drilling & Production Technology, 2024,47(6):16-27.
[23] 刘合，慕立俊，齐银，等. 基于光纤监测的分段压裂多簇均衡性评价与优化建议[J]. 钻采工艺，2024,47(6):1-7.
Liu He, Mu Lijun, Qi Yin, et al . Evaluation and optimization suggestions of multi-cluster equilibrium of segmented fracturing based on optical fiber monitoring[J]. Drilling & Production Technology, 2024,47(6):1-7.
[24] Fu W, Morris J P, Fu P, et al . Developing upscaling approach for swarming hydraulic fractures observed at hydraulic fracturing test site through multiscale simulations[J]. SPE Journal, 2021,26:2670-2684.