Retrofit Gas Lift System for Tension-Leg-Platform Wells

Abstract

When oil wells can no longer flow naturally at the desired rate, artificial-lift methods are often employed. Most mechanical installations of artificial-lift equipment require a complete workover of the well, involving pulling the well apart and rerunning the completion with additional artificial-lift components. These methods can prove prohibitively expensive and/or risky, and they may not pass the economic hurdle for implementation. A tubing punch and packoff gas lift system, also known as an "econo-gas lift" or retrofit gas lift system, may provide a less risky and more economically viable means of bringing dead wells back on production or optimizing flowing wells. To the best of our knowledge, the use of retrofit gas lift systems has been untested in a tension-leg-platform (TLP) environment and poses a new set of challenges as compared to its use onshore or in shallow-water locations. A case of the gas lift retrofit of an oil well on a TLP in the Gulf of Mexico (GOM) demonstrates the usefulness of the proposed method. This paper shows how a retrofit gas lift system was used for capturing remaining reserves from a loaded TLP well. The specific case relates to the Shell Ursa A9 well, and this paper presents the new technologies employed and the successes and challenges associated with bringing the well back on production.