Study On Productivity Of Coalbed Methane Virtual Production Layer Staged Fracturing Horizontal Well

In view of the low output of single-well coalbed methane in the development of soft and low-permeability coal seams,vertical well fracturing proppant was embedded in serious,multi-branched horizontal wells with poor stability,and the conventional stimulation technology has limited effect,while the coal seam lithology is stable.The horizontal well-stage fracturing technology is implemented in the production layer and the technical concept of efficiently exploiting the coal-bed methane by relying on the crack-through layer to communicate the coal seam has been applied in the domestic and foreign industries.In this paper,the high-rank coal in the southern block of the Qinshui Basin is taken as the research object.The theoretical study,laboratory experiment and numerical simulation method are used to systematically analyze the crack extension law and productivity influencing factors under roof fracturing.Firstly,the mechanical properties of coal rock and its top and bottom rock in the study area are analyzed through experiments.Then,based on the experiment and investigation of true triaxial fracturing model,and the criterion for the crack penetration is established.Then the productivity prediction model is established by the seepage characteristics and seepage mechanics theory of the horizontal fractured roof.Finally,the length of the horizontal section and the length of the crack are respectively determined by CMG numerical simulation software.The parameters such as the conductivity of the fracture are optimized,and the productivity of the three types of fractured horizontal wells at different positions in the roof of the coal seam is compared and analyzed.