四川盆地川西坳陷深部致密砂岩储层地应力场预测及分区评价——以新场—丰谷地区须家河组二段为例

Prediction and zoning evaluation of in-situ stress field in deep tight sandstone reservoirs of Western Sichuan Depression, Sichuan Basin: a case study of the second member of Xujiahe Formation in Xinchang and Fenggu area

黄滔 李瑞雪 邓虎成 何建华 李可赛 刘岩 相泽厚 杜奕霏 叶泰然

HUANG Tao LI Ruixue DENG Hucheng HE Jianhua LI Kesai LIU Yan XIANG Zehou DU Yifei YE Tairan

成都理工大学 能源学院(页岩气现代产业学院), 成都 610059 中国石油 大庆油田有限责任公司 成都勘探开发研究院, 成都 610051 成都理工大学 油气藏地质及开发工程全国重点实验室, 成都 610059 中国石化 西南油气分公司 勘探开发研究院, 成都 610041

College of Energy (College of Modern Shale Gas Industry), Chengdu University of Technology, Chengdu, Sichuan 610059, China Research Institute of Chengdu Exploration & Development, Daqing Oilfield Company Limited, CNPC, Chengdu, Sichuan 610051, China State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, Sichuan 610059, China Exploration & Production Research Institute, Southwest Petroleum Branch Company, SINOPEC, Chengdu, Sichuan 610041, China

四川盆地川西坳陷新场构造带三叠系须家河组二段致密气藏资源潜力巨大，但地质构造复杂，勘探开发面临巨大挑战。尤其是对现今地应力状态和展布规律的认识尚不清晰，严重制约了工程甜点选取、井眼轨迹优化以及储层压裂改造工作的开展。为明确研究区须二段致密气藏现今地应力的分布特征，从岩心试验、矿场测试和测井解释等多个角度切入，明确单井地应力特征；充分考虑构造变形和断裂对地应力的扰动特征，采用Rhinoceros和FLAC3D软件，对须二段进行了精细的三维应力场建模与预测；基于地应力分布预测结果，选取对压裂和产量影响较大的最小主应力和应力差作为评价指标，对应力场特征进行了分区评价，并对不同应力区井位部署、井轨迹及压裂改造设计给出了初步建议。新场构造带须二段的现今最大水平主应力方向多在N85°—108°E之间，整体随埋深增加逆时针偏转；现今地应力属于走滑应力机制，中部合兴场三向应力明显高于新场和丰谷地区，构造变形和断裂对局部应力场存在扰动。应力分区结果显示，有利于压裂改造的低应力差—低地应力区主要发育在新场和合兴场的三级东西向断裂和四级南北、北东向断裂带附近，以及丰谷地区的构造张性扰动区域。

The second member of the Triassic Xujiahe Formation (Xu 2 Member) in the Xinchang structural belt of the Western Sichuan Depression in the Sichuan Basin contains tight gas reservoirs with enormous resource potential. However, the geological structure is complex, presenting significant challenges for exploration and development. In particular, the current understanding of its in-situ stress state and distribution patterns is insufficient, severely restricting the selection of sweet spots for engineering, wellbore trajectory optimization, and reservoir fracturing modification. To clarify the current in-situ stress distribution characteristics in the tight gas reservoirs of the Xu 2 Member, the paper analyzed data from core tests, field tests, and well logging interpretation to determine the stress characteristics at individual wells. Considering the disturbances to the stress field caused by tectonic deformation and faults, Rhinoceros and FLAC3D software were used to precisely model and predict the three-dimensional in-situ stress field of the Xu 2 Member. Based on the stress distribution predictions, the minimum principal stress and stress differential, which significantly impacted fracturing and production, were selected as evaluation indicators. The stress field characteristics were zoned and evaluated, and preliminary suggestions were provided for well location deployment, well trajectory, and fracturing modification design in different in-situ stress zones. The results show that the current maximum horizontal principal stress direction in the Xu 2 Member of the Xinchang structural belt mostly ranges from N85° to 108°E, with an overall counterclockwise rotation as burial depth increases. The current in-situ stress regime corresponds to a strike-slip stress mechanism, with the central Hexingchang area showing significantly higher triaxial stress than the Xinchang and Fenggu areas. Moreover, local in-situ stress fields are disturbed by tectonic deformation and faults. The stress zoning results show that the low stress differential and low in-situ stress zones, which are favorable for fracturing modification, mainly develop near the third-order east-west-trending faults and the fourth-order north-south and northeast-trending faults in the Xinchang and Hexingchang areas, as well as in the extensional disturbance areas in the Fenggu area.

国家自然科学基金面上项目 42072182;四川省杰出青年科技人才项目 2020JDJQ0058;四川省科技计划青年基金项目 2023NSFSC076

https://doi.org/10.11781/sysydz2024061198