Force and Control Measures of Pulverized Coal Migration in Coalbe-d Methane Horizontal Wells

Abstract

Pulverized coal production is a common problem in the process of coalbed methane drainage and production, which is one of the key factors restricting the continuous stability drainage and production of coalbed methane. The reasons and characteristics of pulverized coal output are summarized. Through a detailed analysis of the migration and stress of pulverized coal in the borehole, the migration of pulverized coal is controlled by the stress conditions of pulverized coal, which causes the migration position of pulverized coal to change. Under the action of total pressure difference ΔF, pulverized coal particles can be divided into three situations: downward inclination, upward inclination and near horizontal migration. Finally, a solution to the control of pulverized coal is put forward from two aspects: the control of drainage and mining system and the selection of drainage and mining equipment. The research shows that continuous stability drainage and mining is the key of drainage and mining system, and controlling the hydrodynamic difference ΔF is the means to control the migration of pulverized coal. Choosing a pump with strong adaptability to pulverized coal is beneficial to coalbed methane drainage and production and increase productivity. Two horizontal wells in Shizhuang South Area 2 were replaced by membrane pumps, and the diaphragm pump system guide cover scheme was adopted. The coalbed methane production increased by about 1000m3/d, and the number of well repair was significantly reduced.