煤层气-水-固三相流动模型与数值模拟研究

中-高阶煤岩脆性较强,钻完井、增产及生产过程中易产生煤粉.排水采气过程中,煤粉的运移会堵塞地层并造成埋泵、卡泵事故,导致气井产量大幅度下降.为了探索煤粉在储层中的流动机理,本文分析了煤层气生产过程中煤粉的运移过程,将存在状态分为静煤粉与动煤粉,将运移中的物理过程简化为剥蚀产生、流化启动、悬浮运移、沉降堵塞与聚团生长等5...

Tri-phase flow model of coalbed methane-water-solid and numerical simulation study

Middle-high rank coal is relatively brittle,and coal fines are easily generated during drilling/completion,stimulation and production.In the process of drainage and gas production,the migration of coal fines tends to block the formation and cause accidents of buried pumps and stuck pumps,resulting in a significant decline in gas well productivity.In order to explore the flow mechanism of coal fines in the reservoir,this paper analyzes the migration process of coal fines in the process of coalbed methane(CBM)production,divides the existing states of coal fines into the static and dynamic ones,and simplifies the physical processes in the migration as the five processes of denudation generation,fluidization initiation,suspension migration,settlement blockage and agglomeration growth,and establishes a gas-liquid-solid tri-phase flow mathematical model considering coal fines migration on the basis of microemulsion phase model.By means of numerical simulation method,the influence of three drainage strategies(i.e.,pressure managed drainage,moderate powder extraction and rapid drainage)on production performance is analyzed,and the influence of various physical processes on CBM drainage and production during coal fines migration has been analyzed in combination with the field examples.The research results show that for gas well producing coal fines,it is the most reliable way to produce it with pressure managed continuous drainage.Meanwhile,the well shut-in can bring irresistible damage to coal permeability,and the duration and times of well intervention and shut-in should be shortened.The results in this paper can provide a reference for coal fines migration quantitative drainage strategy.