PERFORMANCE ANALYSIS FOR CASINGS WITH SPECIAL SMALL-CLEARANCE THREADS

Small-clearance casing, playing an important role in cementing, can enlarge the effective cementing clearance, facilitate the casing running-in, and improve the cement bond quality. The WSP-1T-SC casing is taken as an example to introduce the features of this kind of casing, and its operation performance is studied and evaluated by full-scale test. The test results are analyzed by the FEM method. The test and analysis results show that this casing has adopted structural features different from the API joints, with high gas-tight performance and high resistance to internal pressure, and can be used for production in natural gas wells and high-pressure oil wells. However it has disadvantages of low connection efficiency and not enough resistance to internal pressure as the casing body. Sufficient cares should be taken when making decisions.