Coalbed Methane Reservoir Safety Improvement And Evaluation Based On Negative Pressure Reaming Technology

As a new clean energy can replace conventional fossil energy,Coalbed methane(CBM)are increasingly brought attention of the people.Due to the particularity of coal seam characteristics in China,Huabei oilfield company’ multi-branch horizontal well did’t achieve the expected goal.It is necessary to explorate drilling and well completion and reservoir reconstruction integration of high-yield shaft-formirg methods.On the basis of predecessors’ research,the theory of finite element and discrete element method for suction reaming of coalbed methane reservoir reconstruction,improving the permeability of the reservoirs,mainly made several works:On the basis of FanZhuang’coalbed methane reservoir geological characteristics and physical properties,this article was established software-liner-reservoir mechanics model.Analysis the effect of borehole parameters and slotted liner parameters on reservoir stress around wellbore under different pressure fluctuation of pressurization process.And Analysis the reservoir stress distribution around the wellbore fracture zone.Based on discrete element PFC2 D methodology,establish reservoir fracture mechanical model of large diameter particles.Using particle flow theory analysis the effect of particle size,pressure gradient,radial slotted length and slot number on cinder through the migration regularity of slotted liner.Through comparing the different simulation results,bextracting parameters that affecting the effects of coalbed methane reservoir and evaluating the safety of reaming.Analysis the main parameters of the rock collapse and the stability of reservoir reconstruction.Combined with parameters of layer stress distribution and coal cuttings migration through the slotted liner,combination of optimal working conditions is proposed of nitrogen injection pressure,circumferential slotted a number and axial kerf width and borehole diameter.