Optimization of Casing Type in Inter-salt Reservoir via Numerical Simulation of Non-uniform External Load

Based on the present situation of casing damage in the inter-salt reservoirs, the author studied the mechanical parameters which cause the deformation of casing in the well. First of all, the non-uniform load calculation model which is related with the vertical crustal stress, horizontal crustal stress and creep load was established by using the available logging data, rock mechanical parameters and hydraulic fracturing parameters. And then, the equivalent collapse resistance under the condition of the casing deformation and the necessary compressive strength were calculated via using the transformation relationship between the non-uniform load and the yield strength of casing, the equivalent casing strength and the ratio of diameter to thickness. Finally, the casing type suitable for the inter-salt reservoirs in different blocks was optimized. Based on the numerical simulation of non-uniform external load, the author quantitatively analyzed the mechanical mechanism for the casing damage in the inter-salt reservoirs, proposed a theoretical calculation method for the optimization of casing type suitable for the inter-salt reservoirs.