Coalbed Methane Enrichment And High-production Rule&Prospectivearea Prediction In Qinshui Basin

Coalbed methane enrichment and high-production pattern as well asprospective area prediction are always theoretical and technical problems whichpuzzles coalbed methane industry. They are not only a theoretic subject, but also amajor practical topic needed to tackle during coalbed methane exploration anddevelopment process. Therefore, Qinshui Basin high-rank coalbed methane is selectedas the study object. CBM exploration and development achievements, large amountsof oil and natural gas exploration achievements, and drilling and research reports ofcoal mining, geology mining systems have been collected. Samples of coal, coal bedmethane, water produced from coal seam and coal roof and floor were taken from thestudy area.Based on tests, experiments and previous study results in terms of coal rockindustry analysis, vitrinite reflectance, maceral quantitative, macro and microstructure observation, water conventional ion, water hydrogen and oxygen isotopes,porosity, permeability, gas composition, gas carbon and hydrogen isotopes, isothermadsorption and rock mechanics, multi-level and multi-means comprehensive studieshave been conducted on Qinshui basin’s reservoir geological conditions, accumulationprocess, main gas-controlling factors of reservoir, and enrichment andhigh-production pattern. Meanwhile, on the basis of assessment of main controllingfactor configuration relationship by multi-level fuzzy evaluation method, optimizedthe favourable blocks, coal reservoir parameters were also evaluated by clusteranalysis method to divide the favorable blocks into different partitions andclassifications. Finally, by combining numerical simulation, log interpretation,three-dimensional geological modeling, key blocks of CBM development werequantitatively evaluated, providing geological basis for the efficient development ofcoalbed methane.Major jobs finished:First, comprehensive analysis of Qinshui Basin CBM reservoir formingconditions: Main coal seam distribution, gas content, coal rock and coal quality,porosity, permeability and other geological features were described in detail. On thebasis of coalbed methane desorption characteristics analysis, combined with on-siteactual dynamic data of drainage and production.Second, from time to space, from macro to micro, from regional to local, main controlling factors such as structure, sedimentary and hydrogeology on coalbedmethane enrichment and high-production were systematically discussed, on the basisof control mechanism analysis, and dissected with actual cases.Third, based on the analysis of the main controlling factor configuration, theweights of main controlling factors such as tectonic, sedimentary and hydrogeologicalwere worked out by hierarchy analytic method; according to indicator characteristicsof main factors, relevant subordinate function and subordinate degree wereestablished; finally, sub-fuzzy evaluation method was used to select enrichment andhigh-production areas preliminarily; base on which and combined with reservoiractual situation, reservoir characteristics were quantified, characteristics parameterswere acquired and normalized; and then system clustering was undertaken by usingcluster analysis to form cluster analysis maps, from which three type-I areas includingPZ, ZZ and FZ, two type-II areas including AZ-TL, YQ-SY, were selected as thebases for subsequent CBM exploration and development.