Models & tests of casing wear in drilling for oil & gas

Casing wear is one of the critical problems in drilling operations for oil and gas field development. It is important to be able to predict the casing wear for offering practical advice on casing wear reduction. Currently the wear-efficiency model and the nonlinear casing wear model are used to predict casing wear. Two full-size casing wear tests were conducted in this study, involving the change in tool joint size. Comparisons of the test data with the casing wear models showed that the casing wear condition coefficient in the nonlinear wear model is slightly affected by the wear time and tool joint size change, which is different from the casing wear factor in the wear-efficiency model. Therefore, the nonlinear wear model should be used to predict the casing wear depth with higher accuracy in complex wells. In addition, it was found that the limestone additives (nonabrasive solids) did not affect the casing wear in the film forming & sealing & low invasion reservoir protection drilling fluid. High concentrations of the nonabrasive solids did not further reduce casing wear after a protective layer was formed.