Study On Gas Production Mechanism And Discipline Of High Rank Coalbed Methane In Southern Of Qinshui Basin

High rank coal resources in our country is hugely, and coalbed methane resources are also very rich, more then 3.58 trillion cubic meters. Because the geological conditions and the tectonic activity of coal-bearing basin are complexity in our country, there is a unique gas production mechanism and discipline of coalbed methane, while there is no theorem of gas production mechanism and discipline of coalbed methane formed by systematic analysis at home and abroad. This paper based on the field data of high rank coal in southern of Qinshui Basin , with the 3# coalbed in Qinshui Basin as the study object, researched the pore system and micropore structure , methane adsorption and desorption law, percolation mechanism of this coal, presented the gas production mechanism and discipline of high rank coalbed in Qinshui Basin; Set up a fluid-dynamic coupling model to reflect adsorption - desorption– diffusion - percolation on the flow behavior of coal-bed methane under gas - water phases seepage field and coalbed stress - strain field.Analysis of gas production law of high rank coal in Qinshui Basin. It has actual guidance meaning of exploration and development to the high rank coalbed methane in China.The main conclusions in this paper are as follows:①Analyzed the study status quo of coalbed microporous structure and methane adsorption– diffusion - percolation and fluid-dynamic coupling model at home and abroad , made sure the meaning and the measure and the content of research in this paper.②On the basis of definite the defined of high rank coalbed, overviewed the resources pattern of high rank coalbed, as well as the methane production and occurrence in major areas of high rank coalbed in China, and proposed a accumulation characteristics of high rank coalbed methane; At the same time, analyzed the fundamental geology in southern of Qinshui basin③Experimental studied the coal porosity characteristics and specific surface area of different coal ranks, the adsorption and desorption characteristics of high rank coalbed methane, analyzed the adsorption and desorption mechanism of high rank coalbed methane on this basis.④Analyzed the basic characteristics of methane seepage in coal reservoirs, and through experimental studied the coal permeability of different coal ranks, experiments obtained that the coal permeability is relatived with coal rank, stress field, temperature field, etc.. A fluid-dynamic coupling mathematical model including pressure, temperature and stress fields was deduced with single methane of high rank coalbed in connected cleats and fractures in coal matrix . And realized the numerical solution with the coalbed gas exploitation as initial and boundary conditions , a flow event of high rank coalbed methane was simulated effectively, and analyzed the single-phase gas production laws of high rank coalbed methane.⑤Experimental studied the seepage characteristics of two phases between high rank coalbed methane and water, developed the rules and characteristics that the relative permeability of methane and water changed with saturation; Set up a coalbed methane seepage model of gas and water phases Fluid-solid coupling that considered with coalbed methane seepage pressure field and coal deformation field, adopted numerical simulation means to analysis the pressure laws around the coal gas producing wells under considering seepage pressure field, coal deformation field and gas-water phases coupling, analyzed the methane– water phases production laws of high rank coalbed methane.