煤层气排采降压理论深化认识及生产问题解释

Understanding of Depressurization Theory of CBM Drainage and Explanation of Production Practice

通过对煤层气排采降压理论的深入理解与认识,认为煤层气井排采降压的过程符合文丘里原理:煤层气井排采降压的作用是形成稳定的流动场,流体在流动的过程中对煤孔及煤表面进行降压,促进煤层气的解吸,实现煤层气的开采。依据该理论对生产实践中的特有现象进行了解释说明:如管压波动对低压低产气井产量影响明显,对高产气井产量影响甚微或不影响;单井累产气量高于控制面积的地质储量;带压作业井产量不降反增等现象。

Based on the further understanding of the depressurization theory of CBM drainage,it is considered that the depressurization process of CBM drainage conforms to Venturi principle.The role of CBM drainage and depressurization is to form a stable flow field,and the fluid depressurizes the pores and the surface of coal during the flowing process,which promotes thedesorption of CBM and realizes the gas extraction.According to this theory,some special phenomena in CBM production practice are explained.For example,the fluctuation of pipe pressure has obvious effect on the CBM production of low pressure and low producing wells,and has little or no effect on the production of high producing wells.The accumulated CBM production of single well is higher than the geological reserves of the control area,and the production of the well with pressure is not decreased but increased.