多场耦合下煤层气鱼骨状水平井增产的数值模拟

摘要

This paper presents an attempt to probe into the types of horizontal multilateral wells tai-lored for the development of the coalbed methane reservoirs of Shizhuang block in Qinshui Basin,Shanxi Province.The research involves the development of a simplified geometric model building on the theory of coupled hydro-geomechanical processes in porous media and combined with the field data of the area;and using COMSOL Multiphysics,a commercial multiphysics coupling software to create a numerical model to study the medium and long-term gas production capacity of different types of the horizontal fishbone wells. The study concludes that fishbone multilateral horizontal well with centrally symmetric double groups of two secondary branches proves to be the most optimal type of well which enables an increase in the diffu-sion speed of the depressurisation gradient, an expansion of the desorption range of coalbed methane in the coal matrix; a significant decrease in the gas breakthrough time; and improvement in the methane production rate of a single well.Our study could serve as a reference for the coalbed methane extraction engineering in this area.%为了寻求适合山西沁水盆地柿庄区块的煤层气藏开发所使用的水平井井形,基于多孔介质变形-扩散-渗流多物理场耦合理论,结合待开发区域的现场资料,建立简化的几何模型,利用COMSOL Multiphysics仿真软件构建其数值模型,研究不同井形的鱼骨状水平井中长期产能.结果表明:最优井形为中心对称双组二次级分支鱼骨状水平井,使用该井形采气可提高降压梯度的扩散速度,扩大煤层气解吸范围,大幅缩短见气时间,提高单井采气量.此研究为该地区的煤层气抽采工程提供了参考.