天然气勘探与开发2026，Vol.49Issue(2)：233-243,11.DOI:10.12055/gaskk.issn.1673-3177.2026.02.015
深层页岩地层拉张破裂特征及破裂压力预测
Tensile fracture characteristics and fracture pressure prediction of deep shale formations
摘要
Abstract
Wellbore instability is induced by tensile fracture propagation during drilling in deep shale formations of the Sichuan Basin.Taking the deep shales of the Lower Silurian Longmaxi Formation in the Penglai gas field of this basin as an example,by integrating mineral composition analysis,mechanical property experiments,and theoretical modeling,the propagation mechanism of tensile fractures was systematically revealed,and a corresponding formation fracture pressure prediction model was established.Results indicate that(i)under large burial depth and strong in-situ stress conditions,the Longmaxi Formation shales exhibit significant heterogeneity in mineral composition and microstructure,with obvious presence of bedding structures.The fracture propagation paths are jointly controlled by bedding structures and mineral distribution;(ii)shale failure modes are categorized into three types:propagation along bedding planes,composite propagation along bedding planes and loading directions,and penetrating propagation along loading direction.The tensile fracture propagation process sequentially undergoes three stages:crack initiation,propagation,and coalescence,with low-angle bedding planes being more prone to induce crack initiation and propagation;(ii)the classical fracture pressure prediction model was modified by introducing a structural correction coefficient m and considering the heterogeneity of mineral distribution and the anisotropy of tensile strength.Field validation demonstrates that the revised model can more realistically reflect the properties of shale reservoirs in the study area,providing a reliable basis for determining the safety drilling fluid density window adaptable to deep shales.关键词
四川盆地/蓬莱气区/深层页岩/张裂缝扩展/抗张强度/破裂压力/结构修正系数/钻井液安全密度窗口Key words
Sichuan Basin/Penglai gas field/Deep shale/Tensile fracture propagation/Tensile strength/Fracture pressure/Structural correction coefficient/Safety drilling fluid density window分类
能源科技引用本文复制引用
李柱正,李洪玺,杨兆亮,范翔宇,马勇,张千贵,蒙承,王秋彤..深层页岩地层拉张破裂特征及破裂压力预测[J].天然气勘探与开发,2026,49(2):233-243,11.基金项目
四川省自然科学基金项目"体积压裂多场耦合作用下页岩气储层井周地质弱面失稳机理及套损评价方法研究"(编号:2026NSFSC0335),中国石油天然气集团有限公司科研项目"万米超深层取心技术与工具研究"(编号:2023ZG19),中国石油西南油气田公司科研项目"万米特深井钻井加深可行性研究"(编号:25XNYTSJ023). （编号:2026NSFSC0335）
