Application Of Iso-wall Thickness PCP In CBM

Coalbed methane(CBM)resource is very rich in China,as a new type of green energy,how to efficiently exploit resources is our concern.At present,the applicable ability of screw pump in the high sand,high gas and high viscosity mining environment is very strong,and it is widely used in the oil wells and CBM wells.Screw pump is composed of stator and rotor,the rotor material is alloy steel generally,and the stator material is NBR which shows strong oil resistance and wear-resisting.Rubber is a kind of hyperelastic materials,relative to the alloy steel,rubber elastic modulus is very small.The rubber with different thickness of the conventional screw pump stator has some problems such as uneven heat dissipation,uneven loading and swelling uneven,which directly affects the service life of the PCP stator.In order to improve the work performance of screw pump and prolong the service life of the pump stator,we can manufacture the iso-wall screw pump stator by changing the pump body structure.Relative to the single screw pump,double-headed single screw pump has the advantages of high efficiency,large displacement,low energy consumption.How to draw a two-headed single screw stator lines and create a two-headed single screw pump model is the important premise to analyze the performance of iso-wall screw pump.This paper used CAD and Solidworks model analysis softwares to design the stator end face profile of the iso-wall two-headed single screw pump under the ideal state.Use traditional way to design the common hypocycloid stator end face profile,and at the same time,use the CAD secondary development software “ObjectARX” with C++ programming language to design the short hypocycloid stator end face profile.Using finite element analysis software “Workbench” to do the simulation analysis of conventional screw pump and the iso-wall screw pump.And the main mechanical performance indexs adopt the maximum Mises stress,maximum shear stress and the maximum displacement.Then do contrastive analysis with the simulation result to compare the performance of conventional screw pump the iso-wall screw pump.Using the same performance to do the analysis of mechanical properties of different thickness of the rubber stator under certain work pressure.Then the most suitable thickness of the rubber can be selected.Although the ground drive screw pump has many advantages,it is not fit the deviated well and the dog leg well,and the depth of the lower is not deep because of the strength of rod string.Based on above reasons,the concept of electric submersible screw pump arises at the historic moment.Electric submersible screw pump not only has strong adaptability in high sand,high gas and high viscosity drainage environment,and it has the very good development prospect in heavy oil wells,horizontal wells and deviated wells.At the same time,the electric submersible screw pump also inherited the advantages of electric submersible pump such as large displacement,high lift and so on.In the later period of CBM drainage,the lack of formation water which affects drainage of coalbed methane(CBM),the paper put forward a set of downhole reflux of electric submersible pump,and designed a downhole backflow valve,and used software to do the performance simulation of the designed backflow valve.