A REVIEW ON THE DEFORMATION AND FAILURE OF SEALS IN OILFIELD

Oil and gas will still be the major energy resource of human in a long period. Sealing is one of the most important operations in oil and gas exploitation, which plays an essential role in horizontal drilling and hydraulic fracturing, booming the exploitation of unconventional oil and gas like shell gas. The quality of sealing is critical to the performance and safety of wells. The deformation and failure of seals may lead to severe environmental pollution, losses of life and property. Therefore, it is important to study the mechanical behavior of seals in oilfields systematically and deeply for safety assessment as well as better sealing of wells. Cement and swellable elastomers are the most widely used sealing materials in oilfield. Well cementing has been developed for more than 100 years. While swellable elastomeric packer is relatively new. In this review, we present the recent advances in the studies of the deformation and failure of cement sheath and swellable packers. The first part focuses on the cement sheath, including stress evolution during the solidification process and production stage, failure modes, and failure criteria. In the second part, emphasis is placed on the work principle, basic theory, test method, failure modes and instability of swellable packers.