Study On The Production Decline Art Analysis For CBM Wells

China has rich coal bed methane resources, which accounts for13%of globalcoal bed methane resources, ranking third in the world. However, China’s coal androck gas reservoir development started late, every year only25×108m3capacity,and the United States540×108m3/a far cry compared. China’s coalfield geologicalconditions compared with foreign countries more complicated, the basic theoreticalresearch of the domestic law of CBM production is still not perfect, and thedevelopment of advanced technology from abroad does not apply on China, whichhas restricted the development and utilization of coalbed methane in China. Bedmethane development is basically still used in conventional gas development theory,but they vary widely, so should be standardized, fine mining CBM, we must startfrom the basic theory, the establishment of CBM well flow mathematical model andmaster control of a single well reserves, the key parameters affecting CBMdevelopment. Therefore, in-depth research CBM “desorption-diffusion-seepage”On the basis of the basic law, the law of diminishing production of coalbedmethane wells, mainly to obtain the following results:(1) In-depth research CBM “desorption-diffusion-seepage” law, theestablishment of a physical model of the coalbed methane vertical wells and verticalfracturing wells;(2) Coalbed methane vertical wells flow mathematical model and solving forthe solution of the model closed at the the downhole production quotas, the top andbottom and outer boundary conditions, the diffusion coefficient, storage capacityratio, langmire coefficient parameters the factors were analyzed, to draw modernproduction decline Plate;(3) The establishment of CBM vertical fracturing wells flow mathematicalmodel, the use of point source function theory to solve the solution of the model, thekey parameters of fracture conductivity, skin factor influencing factors, drawing production decline Plate;(4) The preparation of the corresponding computer program to solve the modeland the actual production data plate fitting, fitting better, the final calculation of asingle well controlled area, permeability, single well controlled reserves and otherrelevant parameters, The result is true and reliable.