Finite element analysis on the sealing performance of the casing premium thread connection

Casing is one of the most used pipes in oil and gas exploration. The casing string, on the one hand, needs to bear large tensile loads generated by its weight. On the other hand, it needs to withstand great internal and external pressures. Tensile loads of the casing connection are being transmitted by its screw thread and sealing function on the fluid is achieved mainly by the interference fit of interior and exterior flank of thread. With the development of new exploration techniques, the exploitation and application of oil and gas wells under complex operating conditions such as deep wells, ultra deep wells, extended reach wells, horizontal wells and HTHP gas wells, urgently demand the premium connections with reliable sealing quality. The sealing performance of a casing premium thread under typical operating conditions using the finite element analysis method was analyzed. The effect mechanism of thread parameters on sealing property is obtained. The analysis results are of great significance on the structure optimization and improvement of air permeability performance of the premium thread.