Theoretical Calculation of Tensile Limit Load of Casing Slip Effect in Ultra-deep Well
In view of the excessive hanging weight of the casing at the wellhead of an ultra-deep well in an oilfield in Xinjiang,the damage of the slip tooth to the outer wall of the casing is caused,and the cumulative damage leads to the frequent occurrence of the fracture failure of the slip hanger casing.Therefore,this paper proposes the slip effect tensile limit load to evaluate the strength design of the wellhead slip hanger clamping part of the casing.Based on the third strength theory and the fourth strength theory,the calculation model of the slip effect tensile limit load of the wellhead slip hanger clamping casing is established respectively.The calculation results show that it is more reasonable to use the third strength theory to calculate the slip effect tensile limit load of the slip hanger casing from the safety point of view.However,in order to make full use of the mechanical properties of the material,the fourth strength theory should be used to evaluate the casing strength.In the limited space of the four-way,the optimal slip half cone angle is 23 °～25 °,and the optimal slip effective contact length is 135～145 mm,which can ensure a large slip effect tensile limit load.The research methods and results of this paper will provide theoretical basis for the strength design of slip hanger wellhead casing and various safe construction operations.
deep and ultra-deep wellslip hangercasing fracturemechanical modeltensile limit load
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