为研究多层叠置含气系统煤层气合采过程中储层流体动态响应特征，利用具有自主知识产权的多层叠置含气系统煤层气合采物理模拟试验装置，开展层间压差分别0.2、0.4和0.6 MPa的合采试验，分析了合采过程中的储层流体动态响应特征。研究结果表明：储层压力演化具有阶段性变化特征，储层压力变化曲线分为骤降型、屏蔽型和倒灌型。合采初期会发生层间干扰，使得流体运移呈现离心流变化特征，表明煤层气发生反向流动。在进行合采时，井筒连通了不同的能量体，煤储层系统之间能量动态平衡状态遭到破坏，使得流体从高能量含气系统向低能量含气系统转移，使得流体运移被抑制或屏蔽，而随着含气系统间流体能量差异的增大，则高能量系统的流体倒灌进入较低能势系统中。层间压差增大，层间干扰现象显著，合采兼容性变差，储层压力回升幅值增大，储层流场离心流范围增大，储层伤害面积增广。层间压差分别从0.2 MPa增加至0.4 MPa和0.6 MPa时，煤层气倒灌量分别从0.42 L增加至3.73 L和7.97 L，合采累积流量从218.74 L减小至208.61 L和192.21 L。

In order to study the dynamic response characteristics of reservoir fluid during Coalbed Methane (CBM) coproduction in Multi-layer Superimposed Gas Bearing System (MSGBS),using the physical simulation test device of CBM coproduction in MSGBS with independent intellectual property rights,the coproduction tests with interlayer pressure difference of 0.2,0.4 and 0.6 MPa were carried out respectively,and the dynamic response characteristics of reservoir fluid during coproduction were analyzed. The results show that：the reservoir pressure evolution has the characteristics of phased change,and the reservoir pressure change curve can be divided into sudden drop type,shielding type and backflow type. At the initial stage of coproduction,there will be interlayer interference,which makes the fluid migration show the characteristics of centrifugal flow,indicating that the reverse flow of CBM occurs. During coproduction,different energy bodies are connected in the wellbore,and the energy dynamic balance state between coal reservoir systems was destroyed,which makes the fluid transfer from high-energy gas bearing system to low-energy gas bearing system,so that the fluid migration is restrained or shielded. With the increase of fluid energy difference between gas bearing systems,the fluid of high-energy system flows back into lower energy potential system. The interlayer pressure difference increases,the interlayer interference phenomenon is significant,the compatibility of coproduction becomes worse,the amplitude of reservoir pressure rise increases,the centrifugal flow range of reservoir flow field increases,and the reservoir damage area increases. When the interlayer pressure difference increases from 0.2 MPa to 0.4 MPa and 0.6 MPa respectively,the CBM backflow increases from 0.42 L to 3.73 L and 7.97 L respectively,and the cumulative flow of coproduction decreases from 218.74 L to 208.61 L and 192.21 L.

0 引言

1 模拟试验方法

   1.1 模拟试验装置

   1.2 煤层设计及模拟材料

   1.3 模拟试验方案及步骤

2 试验结果及分析

   2.1 合采过程中储层压力动态演化特征

   2.2 合采过程中层间压差对储层压力的影响

   2.3 合采过程中层间压差对煤层气产能的影响

3 结论