Well integrity is one of the critical concern during the life cycle of wells and impose an enormous challenge to the oil & gas industry. External and/or Internal corrosion of tubing & casing is one of the main reasons of leaks in the wells causing fluid movement from one annulus to other annulus. Complete understanding of the source of pressure communication between different annuli is of prime importance for designing an effective remedial action. Most leaks can worsen with time and therefore, locating and repairing a leak in its early stages is essential otherwise it may sometimes lead to abandonment of the well. Knowing the precise location of a leak prior to executing repair jobs will lead to better planning thus reducing downtime and repair costs. The problem becomes more complicated when the leak diagnosis has to be done using conventional logging techniques without pulling out the tubing string.
Presence of competent barriers is a fundamental imperative of well integrity. Imperfect barriers introduce risks that need assessment and management. Few wells go through their operating life cycle without undergoing material degradation and component failures resulting in imperfect barriers. Therefore, use of contingent barriers is necessary to minimize the likelihood of such failures and the resultant impact.
This paper describes different types of through tubing logging techniques used by Kuwait Oil Company for identifying tubing-casing leak in an oil well and discusses the interpretation of the results. The paper also discusses the probable reasons for occurrence of the leak, remedial actions taken to arrest the leak and future completion philosophy to avoid such failures in the new wells.