Analysis on distribution and its influencing factors of coalbedmethane productivity in Sihe Minefield

This paper studies the distributions and its influencing factors of coalbed methane productivity in Sihe mine field using statistical analysis on historical drainage data.Time nodes in different stages of the whole gas well life cycle are used as the classification method.The changes of gas and water with time and space are also tracked.The main controlling factors for productivity distributions are studied geographically and engineeringly.The results show that the range of high production area of coalbed methane wells gradually expands with drainage time while the range of low production area gradually decreases.The productivity distribution at different regions are varied significant.Geographic structure, gas-bearing properties, and permeability are the main geological factors that control the gas productivity.The gas-bearing and productivity distribution are highly correlated and structure influences gas-bearing, thus affects productivity distribution.When permeability difference is great, productivity and permeability are significantly correlated.Furthermore, fracturing, reservoir damage, and underground mining activities are engineering factors that affect productivity, especially reservoir damage and underground mining activities.To optimize the productivity of gas wells, planning the time order for upper and lower seam injoint production is significantly important.