The Analysis Of The Casing Contact And Friction In The Process Of Casing Running

In recent years,horizontal wells have been developed rapidly in drilling engineering,which will bring great difficulty to the casing running operation in the horizontal wells.In order to ensure the central degree of casing and the casing running smoothly,the centralizers will be attached to the casing.However,the addition of the centralizer usually changes the contact state between the casing and the wellbore,which increases the difficulty to the analysis of the casing running friction.The casing running is studied through the analysis of the casing flexural deformation,the contact state between the casing and the wellbore,and the casing stress in the horizontal wells(1)According to the structure principle and performance characteristics of the different centralizer,the change conditions of the casing friction of the different centralizer is analyzed.According to the two factors,the casing bending moment and corner angle,not considered in the calculation of casing deflection with energy method,the casing bending deformation is analyzed respectively from the uniform load,concentrated load and bending moment,and the casing deflection and corner angle of the three cases are calculated.Then through the three bending moment equation of vertical and horizontal continuous bending beam model,the calculation method of the casing maximum deflection is established.The casing midpoint maximum deflection difference of the energy method and three bending moment method is analyzed through example.(2)This paper analyzes the three kinds of contact state between casing with the centralizer and wellbore,namely the free state,the point contact and the line contact.According to the contact state and the mechanical condition between casing with the centralizer and borehole,and according to calculating the casing maximum deflection of the vertical and horizontal beam bending moment equation,this paper establishes judgment criterion.of the contact.When three are the contact between casing and borehole,based on iterative method,the critical contact position between casing and borehole is analyzed,and the contact length between casing and borehole can be determined.(3)According to the contact state between casing and borehole,combined with soft-string model and rigid rod model of the casing friction force analysis,the calculation model of casing frictionis established,which can calculate the casing friction and the hook load.Then combined with the calculation of casing friction model,developed the calculation software of casing friction,and compared the casing friction of different distance of adjacent centralizer in horizontal well,it is importantly significant for the casing running operations.