Short Communication
Sayyad Zahid Qamar
Abstract
Extraction of oil and gas from old and difficult reservoirs is quite challenging, both technically and economically. Some of these challenges have been successfully met through the use of Solid Expandable Tubular (SET) technology. Special petroleum tubular is expanded in-situ by forcing a conical mandrel through it, using hydraulic push or mechanical pull. SET technology has been used for cost reduction and efficiency improvement in well completion operations; separation of water producing and other undesirable zones from the production zone; profitable production from mature and abandoned wells etc. In collaboration with a regional petroleum development company, a full-scale expansion test rig has been designed, fabricated and commissioned at Sultan Qaboos University. The mandrel is made from special material (high-grade tool steel, such as AISI D6). High level of repeated thermo-mechanical stresses requires a specific set of properties for the cone material. This is achieved through an optimal heat treatment sequence, in conjunction with various types of mechanical testing. Heat treatment consists of annealing, hardening/austenitizing, air or oil quenching and single or double tempering. Testing includes hardness, tensile properties (Elastic modulus, yield strength, ultimate strength and ductility) and impact strength. Optimum material properties would ensure dimensional accuracy of the expanded tubulars and a longer mandrel life.