煤层气裸眼洞穴完井造成的应力集中带与煤粉产出的关系

摘要

Based on the elasticity theory and analyzing the characteristics of stress distribution near the cav-ity-completed wells, the paper establishes the limit equilibrium equation, then deduces the“R”which says the dis-tance between the sidewall of the cavity-completed wells and the peak stress. The relation between the stress-concentrated zone caused by cavity-completed wells and the coal powder output is concluded by means of the theory of mechanics of materials and the statistical observations of construction records, the conclusions are as follows: the relationship is positive between the output amount of coal powder and the distance of the peak stress caused by cavity-completed wells if there is not big difference in conditions of the geological environment and the CBM geological parameters. The conclusion confirms that the coal powder may be produced if the original stress state changes. It has certain practical significance to CBM industrial production.%通过对煤层气洞穴完井周围应力分布特征分析，基于弹性理论基础，建立了极限平衡方程，进而推出因造穴而产生的应力集中带峰值点至洞穴壁的距离 R。从材料力学理论和施工作业统计观测实据出发，解释了煤层气洞穴井中应力集中带 R值与煤粉产出量之间的关系：即同等地质环境下，煤层气开采地质参数若无大的差异时，则煤层气裸眼洞穴完井煤粉产出量的多少与应力集中峰值点距井壁值R的绝对值大小呈正相关关系。由此证实了“应力状态改变导致煤基质破裂是煤粉产生的可能原因”，该认识对于煤层气工业生产具有一定的实际意义。