Wellbore stability mechanism and drilling fluid safety density window of horizontal well in lacustrine shale: A case study on the Jurassic Da'anzhai Member in the Sichuan Basin

被引：0
|
作者：
Ma T. [1 ]
Xiang G. [1 ]
Lin Z. [2 ]
Yang B. [3 ]
Chen Y. [4 ]
机构：
[1] State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu
[2] Professional Training Department, Training Center, CNPC Chuanqing Drilling Engineering Company Limited, Chengdu
[3] Drilling & Production Technology Research Institute, CNPC Chuanqing Drilling Engineering Company Limited, Guanghan
[4] Exploration Division, PetroChina Southwest Oil &Gasfield Company, Chengdu
来源：
| 1600年 / Natural Gas Industry Journal Agency卷 / 41期
关键词：
Anisotropy; Drilling fluid safety density window; Horizontal well; Jurassic Da'anzhai Member; Lacustrine shale; Shale oil and gas; Sichuan Basin; Wellbore stability mechanism;
D O I：
10.3787/j.issn.1000-0976.2021.09.012
中图分类号：
学科分类号：
摘要：
Recently, Sinopec and PetroChina have successively achieved oil and gas exploration breakthroughs in the Jurassic lacustrine shale in the Sichuan Basin, and Well Taiye 1, Ping'an 1 and Long'an 1 produce industrial oil and gas flow from shale reservoirs, which further reveals the oil and gas exploration and development potential of lacustrine shale. The lacustrine shale in the Sichuan Basin is an important target of shale oil and gas exploration in China, but the horizontal wells in shale have a higher risk of wellbore instability and tend to suffer wellbore collapse, pipe sticking and pipe burying accidents, which seriously restricts the drilling speed and efficiency improvement and drilling safety and horizontal wells. In order to clarify the wellbore stability mechanism of lacustrine shale, this paper systematically tests and analyzes the mineral composition, microstructure, physical and chemical properties and rock mechanics of shale by taking the lacustrine shale of Jurassic Da'anzhai Member in the Sichuan Basin as the research object. Then, the evaluation model of drilling fluid safety density window is established and the wellbore stability of Da'anzhai Member shale is analyzed. Finally, the accuracy of wellbore stability mechanism and drilling fluid safety density window evaluation results is verified in Well N2H. And the following research results are obtained. First, the wellbore instability mechanism of Da'anzhai shale is mainly the mechanical instability caused by high stress concentration, strength anisotropy and penetration of drilling fluid into the planes of weakness, so it is necessary to pay attention to the physical plugging performance of drilling fluid. Second, the wellbore stability of vertical well and small-angle directional well is the best, and the collapse pressure increases sharply when the well inclination exceeds 45°. Third, the horizontal well along the maximum horizontal in-situ stress has low collapse pressure, high fracture pressure and good wellbore stability, but it isn't conducive to fracturing. Fourth, the horizontal well along the minimum horizontal in-situ stress has high collapse pressure, low fracture pressure and poor wellbore stability, but it is conducive to fracturing. In conclusion, the lower and upper limits of safety density window in Well N2H are 1.91-1.98g/cm3 (mean value of 1.94g/cm3) and 2.37-2.55g/cm3 (mean value of 2.45g/cm3), respectively, the recommended density of oil-based drilling fluid ranges from 2.05 to 2.30g/cm3, and the prediction results are in line with the actual drilling situation. The research results can provide effective guidance for wellbore instability control, design and construction of horizontal well in Da'anzhai Member lacustrine shale. © 2021, Natural Gas Industry Journal Agency. All right reserved.
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页码：114 / 124
页数：10
相关论文
共 37 条
  • [1] YANG Yueming, CHEN Yulong, LIU Shenyang, Et al., Status,potential and prospect of shale gas exploration and development in the Sichuan Basin and its periphery, Natural Gas Industry, 41, 1, pp. 42-58, (2021)
  • [2] YANG Yueming, HUANG Dong, Geological characteristics and new understandings of exploration and development of Jurassic lacustrine shale oil and gas in the Sichuan Basin, Natural Gas Industry, 39, 6, pp. 22-33, (2019)
  • [3] SUN Huanquan, CAI Xunyu, ZHOU Dehua, Et al., Practice and prospect of Sinopec shale oil exploration, China Petroleum Exploration, 24, 5, pp. 569-575, (2019)
  • [4] SUN Huanquan, ZHOU Dehua, ZHAO Peirong, Et al., Geology-engineering integration development direction of Sinopec, Reservoir Evaluation and Development, 11, 3, pp. 269-280, (2021)
  • [5] HU Dongfeng, WEI Zhihong, LIU Ruobing, Et al., Major breakthrough of shale oil and gas in Well Taiye 1 in Bashansi Syncline in the Sichuan Basin and its significance, China Petroleum Exploration, 26, 2, pp. 21-32, (2021)
  • [6] CHEN Mian, JIN Yan, ZHANG Guangqing, Petroleum engineering and rock mechanics, pp. 102-166, (2008)
  • [7] MA Tianshou, WANG Haonan, LIU Mengyun, Et al., Experimental and theoretical investigation on anisotropy of shale tensile mechanical behaviors, Journal of Central South University (Science and Technology), 51, 5, pp. 1391-1401, (2020)
  • [8] MA Tianshou, CHEN Ping, Boundary element method and its application to borehole collapse problems in shale formations, Journal of Central South University (Science and Technology), 47, 3, pp. 839-849, (2016)
  • [9] WAN Xin, WU Jinqiao, YANG Chao, Et al., Study of safe drilling mud weight window for shale gas horizontal well in Yanchang Oilfield, Unconventional Oil & Gas, 3, 5, pp. 121-126, (2016)
  • [10] LIU Shuanglian, Effect analysis of shale bedding on well logging response and rock mechanics parameters, Unconventional Oil & Gas, 6, 4, pp. 1-5, (2019)
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