Buckling Analysis of Non-cementing Casing String in Borehole

摘要

This article is from the cooperation projects of Tarim Oilfield—the sidetracking feasibility analysis of lateral drilling. It analyzed the buckling behavior of non-cementing casing string in the borehole by means of theoretical analysis and modeling analysis. When free section of casing string occurs buckling, casing string bends along the sidewall, leads to additional force and additional bending moment. If casing string’s deformation is too large, it reduces the ability to resist broken of casing string. The study of non-cementing casing string buckling is important to the feasibility of lateral drilling. The free section of casing string is the research objective of this paper. Considering the factors such as self weight of casing string, fluid pressure inside and outside casing, downhole temperature and contact frictional force between casing and shaft lining, the differential equation of buckling is derived by the energy method. The solution of the buckling differential equation has been solved, and the analytical solution of the sinusoidal and spiral buckling of the casing string along the tube column has been obtained. This article analyzed the buckling behavior of non-cementing casing string in the borehole by means of theoretical analysis and finite element analysis. The results show that the difference of the analytical solution and simulation results of the buckling differential equation is <15%.