Energy College of Chengdu University of Technology China United CBM Co,Ltd.

为了减轻煤储层压裂过程中煤粉对煤储层的损害,分析了煤粉的形成机理及其对煤储层损害的机理。以沁水盆地柿庄南区块为例,根据工业分析和X衍射资料,采用DLVO理论分析了煤粉的水润湿性。研究认为,因为煤粉具有一定的亲水性,煤粉运移容易受水流动的影响,因而压裂后的返排阶段与排水采气阶段是煤粉运移的主要阶段。从煤粉的来源和运移堵塞条件看,在近井带裂缝有效应力大、水流速度高的地方,容易形成煤粉运移损害。采取以下措施可减少煤粉运移损害:在压裂时尽量避开原生煤粉发育的软煤层段;压裂液中避免使用阴离子表面活性剂;在顶替液阶段可适量注入阳离子表面活性剂;煤层气井压裂后的排采过程中,应严格控制排水速度。

In order to mitigate the fine migration in coalbed methane wells after fracturing operation,both of the origin and damage of fines were analyzed.Taking the c oalbed methane wells located in southern Shizhuang Block of Qinshui Basin as an example,based on proximate analysis and X-Ray results,the wettability of coal fines wer e concluded with DLVO theory. It was demonstrated that water wetting of coal fines could explain why the flow rate of water accelerated the migration of coal fines.During t he flow back period and the dewatering period,the coal fines were much easier to release.The results also indicated that the blockage of coal fines in near wellbore area W ould do more harm to the productivity of gas wells,because the effective stress and water flow rate in the near wellbore area were higher than other areas.Measures to relie ve the injuries of fines were also proposed,including indirect fracturing to avoid the soft coal, applying cationic surfactant instead of anionic surfactant in fracturing fluid,and slower dewatering rate.

国家科技重大专项资助项目(2011ZX05060-002)；