Experimental and numerical study on casing wear in a directional well under in situ stress for oil and gas drilling

- Theoretical researches for casing wear in directional well under in-situ stress are studied.
- Casing friction and wear experiments are conducted.
- The dynamic simulation of casing wear process in directional well is realized.
- The rules of casing wear depth and residual strength at different locations and different time are obtained.
- A new prevention method different from previous measures is proposed.

Under the effect of in situ stress in a directional well, the casing wear problem is a highly nonlinear and complicated process. To address this problem, theoretical studies for casing wear in a directional well under in situ stress are studied. Then, casing friction and wear experiments are conducted to obtain the relevant parameters for simulation. Finally, based on the theoretical studies and experimental data, combined with the drilling and well completion data, a finite element model of joint-casing wear for the NP-1 directional well is established. By reprogramming and redeveloping the software with Fortran language, the dynamic simulation of the casing wear process in directional well is realized considering the effects of in situ stress on the wear process. The rules of casing wear depth and residual strength at different locations and different times are obtained, and a new prevention method different from previous measures is proposed. The work presented in this paper can provide a theoretical foundation and technological basis for casing integrity evaluation and casing design in directional wells under in situ stress.