Analysis on Gas Drainage Features and Influence Factors of Low Rank Coalbed Methane Well

Based on the actual production data and in combination with the reservoir parameters,the gas drainage features and the influence factors of the coalbed methane well were analyzed,and from the gas productivity,structure location,well drilling and completion technique,gas drainage system and others,the factors influence d to the gas production capacity were analyzed. The study showed that the gas productivitydrilling distance of the horizontal gas well in the seam section and the gas p roduction were in a positive correlation relationship and according to the gas productivity and the drilling distance in the seam section,the gas production of the horizont al well could be predicted.The gas drainage features of the coalbed methane well in different structure locations would be different obviously,and the initial gas drainage effect of the coalbed methane well in the high point of the structure would be better than the coalbed methane well in the low point of the structure. The clean water drill ing and the under-balanced drilling technology were applied to reduce the pollution of the reservoir.The gas drainage technology with a high casing pressure and low liq uid level was applied to realize the continuous and stable gas drainage.