Experimental Study And Numerical Simulation On Permeability Of Filled Coal Fracture

Fracture is the main channel for gas seepage in coal reservoirs,and coal rock fracture filling by medium is a common phenomenon under natural conditions.Predecessors have done much research on fracture permeability of non filled coal,but little research has been done on the permeability of fractured coal and rock.The study of the permeability of coal and rock fissures has important reference value for further understanding the geological status of gas in coal reservoirs and the exploitation of coalbed methane.In this paper,through,we have studied the permeability change rule of coal and rock fissures.Through the treatment of coal mine coal sample,different kinds of filling coal rock fissure are prepared,and its permeability is analyzed.Different gas pressure and different filling width on the permeability of coal reservoir is studied.Finally,Fluent software is used to simulate the permeability of the fissures in the filling coal rock,and a conclusion is obtained.(1)In the permeability test of the fractured coal rock,laboratory experiments and numerical simulation,we have studied the permeability change rule of coal and rock fissures.Through the treatment of coal mine coal sample,different kinds of filling coal rock fissure are prepared,and its permeability is analyzed.Different gas pressure and different filling width on the permeability of coal reservoir is studied.Finally,Fluent software is used to simulate the permeability of the fissures in the filling coal rock,and a conclusion is obtained.(2)In the experiment,when the confining pressure is certain,the permeability of the coal sample is greater than that of the other filling medium.When the filling medium is pulverized coal,the permeability of the 100~120 mesh pulverized coal sample is less than that of the 60~80 mesh pulverized coal,while the coal sample with 0~40 mesh pulverized coal is the most permeable.When the filling medium is other material,the permeability of coal and rock fissures filled with kaolinite and bentonite is less than that of the calcite coal sample with the filling medium,while thepermeability of the coal and rock fissures filled with square high mixture is the largest.(3)In the experiment,the permeability of calcite,bentonite and old soil as filling material decreases with the increase of the width of the fissures,while the coal samples filled with pulverized coal and square high mixture increase with the widening of the crack width,which shows that the permeability of the coal reservoir is closely related to the characteristics of the filling,especially filling.The porosity and size of the particles.(4)The influence factors of coal reservoir permeability under different conditions were analyzed by numerical simulation.(1)Under the action of the same pore pressure,when the filling is calcite,the permeability of coal samples is the strongest,but for the permeability of different filling materials: calcite > kaolin > square bentonite.(2)When the fracture width and filling medium are the same,the permeability of coal reservoir increases first and then decreases with the increase of gas pressure.(3)The influence of fractures on the permeability of coal reservoirs is very significant.The permeability of coal reservoirs increases with the increase of fracture width.