Causes analysis of wellhead equipment eccentric wear in Well KXS203

Due to the derrick substructure non-uniform subsidence of Well KXS203, casing head and wear bushing of this well were severely worn during drilling, and then casing string leaked later in pressure testing. In order to figure out the cause of wellhead equipment worn, and to prevent this kind of accident from happening again, the paper gives an investigation on the wearing condition of wellhead equipment and drill pipe, and calculates the eccentric wellhead degree due to derrick foundation settlement, and analyzes the influence of dimension match between drill pipe tool joint and wellhead equipment, wellhead eccentricity, performance of wear bushing and jacking screw, rotation of the drill string, drilling trip, and rotational speed of the drill string on wellhead equipment eccentric wear. It is considered that the wellhead worn is related to all above aspects, but the wear of wellhead in this well is mainly because of the wellhead eccentricity and wearing bush failure. Some measures are suggested to prevent well head equipment from wear.