项目名称： 煤层压裂复杂裂缝形成机理与压后裂缝导流能力评价研究

项目编号： No.51504068

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 矿业工程

项目作者： 李玉伟

作者单位： 东北石油大学

项目金额： 21万元

中文摘要： 水力压裂是目前煤层气开发的主要技术手段，通过压裂能够在煤层内部形成复杂裂缝，在井筒周围形成大面积的压力下降，保证煤层气迅速并相对持久地泄放。煤岩发育大量的割理裂隙等结构弱面，弹性模量低、泊松比高，易破碎易受压缩，独特的力学特性导致其水力压裂机理与非煤岩石存在较大差别，压裂裂缝的延伸形态极其复杂，使压裂后裂缝形态的描述和裂缝导流能力的测试评价成为难点。本项目基于多场耦合理论，研究煤岩裂缝延伸过程的裂缝周围动态应力场分布，提出复杂裂缝启裂扩展的判别计算方法，结合煤岩裂缝导流能力实验评价，通过模拟分析不同形态裂缝导流能力的变化，从根本上揭示煤层水力压裂复杂裂缝系统形成的物理内涵以及压后复杂裂缝导流能力和渗流特性的变化机理，为现场煤层气田开发方案设计和煤层气井合理快速开采提供科学依据。

中文关键词： 煤层气；多场耦合；复杂裂缝；裂缝演化；导流能力

英文摘要： Hydraulic fracturing is one of the main technical means for the development of coalbed methane, it can form complex fractures in coalbed and make pressure drop in a large area around the wellbore to guarantee the coalbed methane releases quickly and relatively persistent. Coal rock is a kind of fractured rock masses with low elastic modulus and high poisson's ratio in which lots of cleats, fractures and weak planes develop, it breaks and compresses easily. Its unique mechanical properties make the mechanism of hydraulic fracturing different from that of other kinds of rocks. And the extension of fracturing fractures is extremely complex, which makes the description of fracture geometry and the test of fracture conductivity difficult. This research, which is based on multi-field coupling theory, studies the dynamic stress distribution surround the fractures during the extension process of hydraulic fractures, and put forward a discriminant calculation method of the initiation and extension of complex fractures. Combined with the experimental evaluation of fracture conductivity, and through the simulation analysis of the changes of fracture conductivities for different fractures, fundamentally reveals the physical connotation of the hydraulic complex fractures system of coalbed and the changing mechanism of fracture conductivity and seepage characteristics of fractured complex fractures. This research provides a scientific basis for the development project design of coalbed gas fields and the reasonable rapid extraction of CBM Wells.

英文关键词： coalbed methane;multi-field coupling theory;complex fracture;fracture evolution;fracture conductivity