Characteristics of in situ stress field of coalbed methane reservoir and its influence on permeability in western Guizhou coalfield, China

In-situ stress is an important indicator for the preferential selection of coalbed methane (CBM) exploration dessert zones, and a key factor affecting production capacity wells. Coal reservoir permeability one parameters to evaluate recoverability modifiability reflects seepage coal reservoirs. In this study, in situ data were collected from multiple injection/fall-off tests parameter wells western Guizhou province, China The relationships among such as pore pressure (P p ), closure c breakdown b stress, permeability, depth explore. Using Anderson’s classification method, distribution three different states was counted. A new simplified model diagram triaxial principal study area proposed by linearly fitting burial depth. envelope equation median lateral coefficient k-value ratio with obtained Brown Hoek method calculated using hyperbolic regression algorithm. k-values found be discrete at shallower depths converge deeper depths, gradually converging .65. control on reservoirs explored, strong positive correlation between Z-shaped variation shallow 1,000 m. Also, pattern vertical basically corresponds transition zone strike-slip fault mode normal mode. seam has sensitivity effective (EIS). least squares power exponents applied analyze mechanism EIS reveal relationship that considered previous authors. Summarizing above research results, CBM divided into development potential 400–1,000 m most favorable zone.