| Under-balanced drilling with lower drilling cost,protecting oil and gas reservoir and improve the capacity of oil and gas layer,is now widely used widely among major oil fields,and downhole isolation method is one of the effective ways to implement underbalanced drilling.Downhole casing valve technology has become the key technology of downhole isolation method,downhole casing valve is a kind of installed on the casing borehole shaft cut-off valve,all of them,and can be used as part of the technology of casing with below into and fixed in the well,through opening and closing of the valve plate to achieve the "isolation"role,enables the tool to trip in the circumstance that does not kill,greatly improve the work efficiency of drilling.Widely adopted at present,each big oilfield is hydraulic casing valve,is to provide hydraulic driving force,through the control system of the ground by hydraulic control with tool connection pipe,open or close the valve plate movement,its due to down to the line is too long,the cost is higher,therefore,the future of the oilfield downhole isolation technology is the developing direction of mechanical casing valve technology.Mechanical casing valve in this paper,9-5/8 "the whole of the design and analysis,first of all mechanical casing valve body parts to carry on the design,finished by AutoCad drawing of each parts of engineering drawings and the depth of casing valve has carried on the theoretical calculation,in combination with different depth effect on the strength of the body,by the workbench software statics analysis on its internal and external pressure and tensile strength on the valve body intensity,and through the analysis of the buckling of the maximum compressive strength.Secondly,due to mechanical casing valve in the downhole gas drilling condition can because of drilling process,the cutting of the return to the wear and tear inside the body,this paper using fluent software for its abrasion area erosion wear analyzed,concluded in the process of gas drilling,cuttings particle size,number of cuttings,detritus erosion velocity on the wear rate of the body wall,and through the theoretical calculation of the compressive strength of the valve body strength prediction.Then in view of the mechanical casing valve valve core has carried on the design,the core of the working parts of all parameters of the valve plate more groups of simulation experiment was carried out and made a response surface optimization design,as the quality of the stress and the response values for the optimization,it is concluded that the optimal design parameters of the valve plate,and through the theoretical calculation of torsional spring of responsible for open the valve plate type selection.Finally,the sealing performance of valve core has carried on the simulation analysis,ABAQUS is used to analyse the structural parameters of the sealing rubber ring response surface optimization,and obtained the influence of different parameters on the sealing contact stress change rule,contact pressure and stress of sealing ring and seat as response values for the optimization.In this paper,the overall structural parameters and performance parameters are designed,which provide valuable reference for the design of the mechanical casing valve. |
