深层页岩气水平井天然裂缝发育特征及其对精细开发的启示——以川南泸州区块五峰组—龙马溪组为例

Development characteristics of natural fractures in horizontal wells for deep shale gas and their implications for enhanced development: a case study of Wufeng-Longmaxi formations in Luzhou area, southern Sichuan Basin

杨学锋 夏自强 赵圣贤 何沅翰 高瑞琪 曹埒焰

YANG Xuefeng XIA Ziqiang ZHAO Shengxian HE Yuanhan GAO Ruiqi CAO Lieyan

1. 中国石油 西南油气田分公司 页岩气研究院, 成都 610051; 2. 页岩气评价与开采四川省重点实验室, 成都 610091

1. Shale Gas Research Institute of PetroChina Southwest Oil & Gasfield Company, Chengdu, Sichuan 610051, China; 2. Shale Gas Evaluation and Exploitation Key Laboratory of Sichuan Province, Chengdu, Sichuan 610091, China

天然裂缝发育特征分析是深层页岩气勘探开发评价的重要环节，对储层品质综合评价、压裂差异化设计具有指导意义。以四川盆地南部(以下简称川南)泸州区块五峰组—龙马溪组深层页岩为研究对象，综合利用岩心分析化验、水平井成像测井和地震等资料，从岩心天然裂缝描述、水平井成像测井发育特征、水平井天然裂缝与地震预测裂缝带之间的匹配关系等方面进行了系统研究。结果表明：水平井成像测井可准确识别3种天然裂缝类型，即高导缝、高阻缝和微断层；水平井识别裂缝走向与现今最大水平主应力方向一致，裂缝倾角分布规律与处于相同构造部位的评价井直井段总体相似；地震预测裂缝带控制成像测井岩心尺度天然裂缝发育，中强度曲率体裂缝带、低强度曲率体裂缝带、蚂蚁体裂缝带对岩心尺度天然裂缝的影响距离分别为110、80、30~50 m。泸州区块岩心尺度天然裂缝具“双高”特征(倾角高、方解石充填程度高)，揭示的水平井岩心尺度天然裂缝发育特征与直井段、地震预测裂缝带之间的对应匹配关系，可为川南地区海相页岩天然裂缝精细表征、储层分类评价和差异化压裂工艺试验攻关方向提供借鉴。

The analysis of natural fracture development characteristics is crucial for evaluating deep shale gas exploration and development. It provides valuable insights for assessing reservoir quality comprehensively and designing fracturing strategies differentially. This study focused on the deep shale of the Wufeng-Longmaxi formations in Luzhou area of southern Sichuan Basin (hereinafter referred to as southern Sichuan). Using core analysis, horizontal well imaging logging and seismic data, this study systematically investigated aspects such as descriptions of core natural fractures, development characteristics of horizontal well imaging logging, and the correlation between natural fractures in horizontal wells and seismically predicted fracture zones. The results show that horizontal well imaging logging can accurately identify three types of natural fractures: high-conductivity fractures, high-resistance fractures, and micro-faults. The fracture orientations identified by horizontal wells align with the direction of the current maximum horizontal principal stress, with fracture dip distribution patterns similar to those observed in vertical evaluation wells in the same structural positions. Seismically predicted fracture zones control the development of core-scale natural fractures identified through imaging logging. The influence distances of medium-intensity curvature body fracture zones, low-intensity curvature body fracture zones, and ant-track fracture zones on core-scale fractures are 110, 80, and 30-50 m, respectively. The Luzhou area’s core-scale natural fractures exhibit “double-high” characteristics (high dip angle and high degree of calcite filling). The revealed correlations between the deve-lopment characteristics of core-scale natural fractures in horizontal wells, vertical well sections and seismic fracture zones serve as valuable references for the fine characterization of natural fractures, reservoir classification evaluation and differential fracturing technology testing of marine shale in southern Sichuan.

中国石油天然气集团有限公司科技项目“页岩气规模增储上产与勘探开发技术研究”(2023ZZ21)和中国石油西南油气田分公司科研项目“川南页岩气立体开发模式与技术政策研究”(20220304-06)联合资助。

https://doi.org/10.11781/sysydz202404735