火烧煤层提高强水敏储层煤层气采收率初探

Exploration on Enhancing Extraction of CBM in Water-sensitive Reservoir by Combustion of Coal Seams

常规开采煤层气的方法是排水降压开采,即通过排采地层水降低压力促使煤层气解吸。而针对水敏性储层,在常规开采方式采出效率较低的情况下,提出采用火烧煤层的方式进行煤层气增产,并分别从温度、压力、表面积、竞争吸附等方面阐述其在理论上的可行性,温度提高分子活性,压力提供扩散动力,表面积提供扩散路径,竞争吸附促进解吸等,并通过强水敏储层实例验证,在储层经过火烧煤层改造后,煤层气的采收率有了较大的提高。

The conventional way to exploit coalbed methane is pressure lowering through drainage,which means that reducing pressure through water drainage for coalbed methane desorption. While,for water-sensitive reservoir,the recovery by conventional way is low;in order to exploit water-sensitive reservoir,combustion of coal seam is proposed to increase recovery ratio,and then theoretical feasibility is elaborated through four aspects： improving activity of molecules by temperature,diffusion by pressure,migration path by superficial area,promoting adsorption and desorption by competition; then given an example of water-sensitive reservoir,the obtained results show that the recovery is effectively improved through combustion of coal seam.