Design of an integral casing bow-spring centralizer made of dissolvable material

To mitigate the casing drag and sticking problems in horizontal wells in coalbed methane (CBM) reservoirs, a casing bow-spring centralizer fabricated from dissolvable M-magnesium alloy was designed and structurally optimized. Mechanical property testing on the dissolvable material was conducted in accordance with ISO standards. The results indicate that M-magnesium alloy exhibits an elastic modulus below 45 GPa, with both yield strength and tensile strength exceeding 330 MPa. Dissolution experiments demonstrate a dissolution rate of 129.9 mm/a in a 50.9% KCl solution at 80 ℃, which satisfies the downhole requirements for freeing stuck pipe. Furthermore, a quantitative comparative finite element analysis (FEA) was performed on both double-bow and single-bow centralizers to evaluate their starting and restoring forces under varying parameter configurations. The optimized structure model was determined as follows: a total centralizer length of 350 mm, an outer diameter of 216 mm, 3 bow springs, each with a thickness of 6 mm, and an arc width of 66 mm. Advanced applicability analysis under high-temperature conditions (80 ℃) and cyclic flexural deformation analysis further verify that the centralizer complies with standard testing requirements in an 80 ℃ environment. These findings validate the feasibility of the dissolvable material centralizer and provide crucial technical support for unconventional oil and gas cementing operations.