Well integrity management has been ever present in well construction and wells management since the early 1900’s and the frontier oil exploration wells. With the development of ever more sophisticated cased hole diagnostic tools, standardization of operations across the industry and regulatory bodies driving best in class practice, the management of well integrity and well barrier status, has become a key focus. In the rejuvenation or post cessation of production phase, the status, and remediation to reinstate well barriers is critical, attracting significant cost in many cases. When seeking to reinstate a failed well barrier to isolate an over pressurized water or hydrocarbon bearing formations, there are various techniques available, with low to high cost differentials.
In reservoir isolation for slot re-use operation, and in overburden and surface well abandonment phases, failures to annular well barrier elements can drive the isolation cost to exceed the initial well construction cost. The condition of annular cement is a key pivot point during planning for isolation operations, the qualification criteria for this varies based on international treaty compliance, country specific legislation and operator well integrity standards. Once diagnosed, the remediation operation is selected based on a risk and cost basis, with the most economically advantageous approach to ensure access to the annulus or annuli, for a well barrier to be set. Various approaches based on mechanical removal or perforation of tubulars, ballistic perforation or in cases destruction of tubulars, and various material considerations such as cement, resins, specialist alloys can be used. Naturally occurring formation activation and creep can be identified and utilized as an annular well barrier in certain conditions. The qualification of each is again governed by the countries legislative approach.
This presentation provides and overview of the commonly utilized annular diagnostic and remediation techniques available to petroleum engineers, and how international well integrity governance influences or prescribes approaches. Technical limits and challenges are cited, allied to baseline costs, for comparison in international cases.