An integrated wear prevention technology for casing of the abnormal-pressure gas well in the western South China Sea

High-pressure areas are widely distributed in the western South China Sea. In various working conditions, the internal and external pressure of high-pressure well are higher than those of normal-pressure well, so its casing strength has to reach a higher level. As offshore development wells are mainly directional wells and horizontal wells, casing wear is prominent enough to increases the risk of casing collapse or rupture. The casing wear coefficient in different working conditions was obtained by conducting the wear test on different wear bands. The method to check the casing strength of high-pressure well considering the wear was established. To deal with the casing wear in D Gas Field in the South China Sea, Well B, the deepest well was selected as the research object. Based on its casing program and well trajectory, the lateral force of bottom hole assembly (BHA) to the casing in the process of drilling was calculated, and the influence of wear on casing strength was evaluated. Considering the safety factors of wear, anti-internal pressure and anti-external pressure in the process of drilling comprehensively, a set of wear prevention technical scheme based on wear risk profile and casing check safety factor was proposed. And this scheme has already been applied in D gasfield for casing design, bid and procurement.