HYBRID THREADED CONNECTION FOR EXPANDABLE TUBULARS

摘要

An expandable threaded connection between segments of expandable tubulars that allows the threaded tubular connection to withstand the stresses and deformations imposed on the connection by the tubular expansion process is disclosed. The present invention is a unique hybrid threaded connection that utilizes two complementary thread segments to form the expandable threaded connection. The first segment of th e threaded connection utilizes standard box and pin threads such that the threads on th e pin member in the area of the first segment fully engage the mating threads on the box member. The second segment of the threaded connection has the threads machined on the pi n member in a manner such that material is removed from the stab flank of the pin threads to reduce the standard width of the pin threads. In contrast to the pin threads of the second segment, the box threads of the second segment are standard thread width and , thus, are the same thread width as the box threads in the first segment. The use of th e reduced thread width in the pin threads of the second segment allows for a loose fit between the pin threads of the second segment and the box threads of the second segment. As the threaded connection is expanded, the loose fit between the pin and box threa ds of the second segment allowsradial and axial movement between the pin and box threads of the second segments of the threaded connection without causing disengagement of the threaded connection. The disclosed hybrid threaded connection thus utilizes multiple thread segments in which the second thread segment accommodates the stresses and deformations generated by the radial expansion process while the threads of the first segment maintain the coupling strength and the pressure integrity of the threaded connection.