Variation Of CBM Reservoir Contribution Rate And Its Optimizational Techniques For The Development Plan In Tiefa Daxing Mining Area

The research objectives were the coal seam groups of low coal rank, thin coalseam in coalbed methane development area in Daxing Mine. The field tracking,indoor analysis, theoretical research and numerical simulation were used duringresearch process. The characteristics of the coalbed methane production Wells and thegas from the upper and lower coal group were discussed, the gas outputingcharacteristics of coal reservoir was studied, and then each layer’s gas productingvolume and contribution rate variation of pay zones within10-Years was simulated. Inthe end, the development plan of CBM outputting was advised in this area.The study results indicate that the main influencing factors of coalbed gas wellproductivity in Daxing field include reservoir pressure, thickness of coal seam and thereservoir permeability; the main influencing factors of division of production payzones and their combination were: reservoir permeability, production pay zonesspacing, magmatism, fracturing fracture development, coal and rock macroscopiccharacteristics of coal and the production pay zones’s thickness and interlayer’slithology. the ability of gas production in the above coal seam group is good, Pay zonecontribution rate was mainly controlled by the igneous rock and coal thickness, thelarger the thickness of reservoir is, the more gas was producted, also is its recession isslower. reservoir subjected to the igneous rock, Not only its Pay zone contribution ratecan improve greatly, but also its gas-producting time can be earlier; the ability of gasproduction in the under coal seam group is bad, pay zone contribution rate was mainlycontrolled by the igneous rock and depth Coal thickness, compared with this twofactors, the depth of the pay zone matters. With the increasing of its depth, pay zonecontribution rate fell sharply; the first CBM development selection of reservoir wasthe above coal seam group, when divide and combine the production pay zones, theair content, total reservoir thickness and coal bearing rate Should be first considered,and pick up the part with the characteristics of high permeability, large air content andhigh coal rate containing; the ability of gas production in the under coal seam group isbad, Not recommended for a wide range of development. when developing, the coalseam’s buried depth, igneous rock, reservoir thickness should be considered,Especially the first two factors. pick up the part with priority igneous rock affectedand higher coal bearing rate. In addition, according to the main control indicators ineach well of coal-bed methane mining operation, reasonable drainage technology should be abided. In addition, it is suggested that the multiple fracturing sand fillingperiod of progressive perforation, stratification of ball-off fracturing process incoalbed methane Wells fracturing to increase production, high rank should accordingto each row of each phase of the control target for Wells of coal-bed methane miningoperation.