煤层气储层有效应力计算方法研究

Study on effective stress calculation method of coalbed methane reservoir

煤层气是赋存于煤储层中的一种具有双重孔隙结构的自生自储型非常规天然气,但开采过程中储层所面临的强应力敏感性问题严重制约着煤层气产量,目前阶段计算有效应力的方法大多是将基质与割理系统共同考虑,忽略了二者内部流体压力的不同。为此,提出了将基质与割理系统的有效应力分开计算的思想,给出了初步的计算方法,并运用实际案例加以印证,强调保持适当的排采速度、缓慢增加有效应力对煤层气产量提高的重要性。

Coalbed methane was a kind of self-generation and self-reserving unconventional gas of dual porosity structure in coal reservoir. However,the strong stress sensitivity of coalbed methane during the mining process restricts its production seriously. Presently,most of the calculation methods of effective stress put the matrix and cleat system together to consider,ignoring the difference of internal fluid pressure. Therefore,puts forward the idea of separating the effective stress of matrix and cleat system and gives the preliminary calculation method. Then uses a practical case to further emphasize the importance of keeping a proper drainage speed for coalbed methane production.