低渗透煤层气注热开采热-流-固耦合 数学模型及数值模拟

为得到低渗透煤层气藏注热开采过程中煤层气渗流运移规律，探索原地煤层在注入蒸汽加热后对煤层气产量的影响，基于煤体渗透率、孔隙度随温度、应力，气体导热系数、杨氏模量、泊松比随温度变化的关系，综合运用渗流力学、岩石力学、传热学等相关理论，建立了低渗透煤层气注热开采过程煤层气渗流热-流-固多物理场耦合数学模型，采用多井开采方式进行了注热开采过程煤层气渗流规律的数值模拟。数值模拟结果表明：煤层注热10 d抽采100 d后，由于煤层的导热并伴有煤层气的对流传热，煤层平均传热速度为66.25 mm/h，注热开采造成储层压力降是无注热抽采压力降的2.45倍，在温度应力耦合作用下，煤层气注热抽采量是未注热抽采量的2.2倍，注热开采是低渗透煤层气增产的有效途径。

Numerical simulation of the coupled thermal-fluid-solid mathematical models during extracting methane in low-permeability coal bed by heat injection

In order to obtain seepage rules and production of coal bed methane in the process of heat injection exploitation，a coupled thermal fluid solid mathematical models of coal bed mathane was established based on results that permeability，porosity of coal increases with temperature，stress and thermal conductivity coefficient of gas，Young’s modulus，Poisson’s ratio as a function of the temperature，combined with seepage mechanics，rock mechanics，heat transfer and so on.Multi well exploitation way was used to simulate seepage rules during extracting methane in low permeability coal bed by heat injection after three fields were discreted.The numerical simulation results show that after 10 d heat injection and 100 d coal bed methane mining，the average velocity of heat transfer is 66.25 mm/h in coal bed under the action of conductivity of coal bed and convection of coal bed methane，and pressure drop of reservoir cauesd by heat injection is 2.45 times without heat injection，and production of coal bed methane under the conditons of heat injection is 2.2 time without heat injection.It is a effective way to production improvement of low permeability coal bed methane.