滇东北地区煤储层现今地应力分布特征及渗透性预测

Distribution of present-day in-situ stresses and permeability prediction within coal reservoirs of northeastern Yunnan region

现今地应力分布与煤储层渗透性特征是影响煤层气勘探与开发效果的关键因素,但对滇东北地区二叠系煤储层而言,区域地应力与渗透性分布样式尚不清晰,影响着该区煤层气的高效开发。为此,本次研究在注入/压降地应力实测的基础上,利用有限元数值模拟分析了滇东北地区二叠系C5煤层现今地应力分布特征,结果显示:地应力分布呈现强非均质性特点,研究区北部和东南部的应力值较高,西部、东部以及构造带内的应力值较低。在地应力与渗透率量化关系构建的基础上,预测了煤储层渗透率,呈现东西高、南北低的格局。研究区内现今地应力对煤储层渗透性具有一定的控制作用,亦受埋藏深度等其他因素影响。研究成果期望能为滇东北地区煤层气勘探开发提供有益地质参考。

Distribution of present-day in-situ stresses and characteristics of coal permeability are important factors influencing coalbed methane exploration and development;however,in the Permian coal reservoir of northeastern Yunnan region,regional distribution patterns of in-situ stresses and coal permeability are unclear,which affects high efficient of coalbed methane development in the study area.Hence,in this study,based on measured injection/falloff and in-situ stress data,in-situ stress distribution in the Permian C5 coal seam is analyzed using finite element numerical simulation.The results indicate that in-situ stress distribution in C5 coal seam shows high anisotropy with high stress values in northern and southeastern parts and low stress values in western and eastern parts.The quantitative relationship between in-situ stress and coal permeability is estabilished,and coal permeability distribution is predicted based on this relationship.Generally,coal permeability in the northeastern Yunnan region indicates the pattern of“high in east and west and low in north and south”.The present-day in-situ stresses control coal permeability to a certain extent,and many other factors including coal burial depth influence the permeability.The results are expected to provide to some useful geological references for coalbed methane exploration and development in the northeastern Yunnan region.