我国煤层气开发以高阶煤为主,高阶煤脆性较大,在钻井、压裂工程中以及排采过程中易破碎产生煤粉。生产过程中,煤粉被水流搬运从而参与流动。随着产水递减,储层中煤粉的沉降会导致流动通道的堵塞,使得煤储层的渗透率大幅度降低。当煤粉进入气井井筒后,井底的煤粉可能使泵吸入口堵塞,造成卡泵、埋泵等事故,使得气井停产修井。综述了煤层气生产过程中煤粉产生的机理、运移规律以及目前主要的控粉措施,分别论述了煤粉产生的力学模型、水动力学模型,在储层以及井筒中运移机制的研究进展,将煤粉的运移全过程总结为剥蚀产生、流化启动、悬浮运移以及沉降堵塞四个阶段。我国的煤田地质构造复杂,部分含煤盆地的后期改造作用强烈,破碎的煤体加剧了煤粉产出和运移问题,而煤层气井的控粉工艺多借鉴油藏防砂技术,尚未形成针对煤粉特点以及煤层气排采特征的煤层气井防粉控粉技术。

CBM development in China focuses on the high-rank coal, which is brittle and, during drilling, fracturing and drainage, easily crushed into coal fine. During the production, coal fine flows owing to the water flashing effect. As the water production declines, the coal fine will sediment and block the flowing channels, leading to the great reduction of coal permeability. When the coal fine enter the wellbore, it may jam the pump, resulting in accidents in production such as pump stuck or buried pump, and leading to the stop of production for well repair. In order to solve this problems, the generation mechanism, migration rules and current major controlling approaches of coal fine are summarized. And then, the mechanics model, hydraulic model and migration model are investigated respectively. According to the former studies, the coal fine migration process can be summarized as four stages: denudation, detachment, suspension and sedimentation. However, the geology conditions of coal seam in China are extremely complex and the structure changes effect is dramatic on coal basins. These factors enhance the problems of production and migration. Nevertheless, the coal fine controlling approach method primarily learns from the sanding control technology in oil reservoir and is still undeveloped for the CBM reservoirs.