Safeguarding Well Integrity in a Deepwater Field – The Bonga Field Experience

Abstract

Bonga oil producer wells are capable of delivering high rates in excess of 20 Mbopd; thus, any breach of well safety critical barriers could potentially lead to significant people asset and environmental damages. In addition, deferment caused by well integrity would also significantly impact production. Therefore, well integrity management remains an integral part of Shell's "Must Wins" and the Bonga team is focused on ensuring that we can demonstrate that the Bonga wells remain "safe and healthy" while delivering against production targets. One of the key challenges faced in the deepwater environment is the prohibitive high cost of rig intervention for diagnosis and remediation of well equipment failures; hence the well integrity management approach in the Bonga field places a lot of emphasis on use of alarm settings to operate wells within defined operating envelopes; proactive monitoring of the well operating parameters and consistent high compliance on preventive maintenance. This has resulted in the early detection of well integrity issues and minimal shut-in periods of wells for well integrity related failures. Also, innovative and cost effective methods of integrity repairs using an ROV deployed by the field intervention vessel have been implemented in the Bonga field. This article describes the application of Well Integrity Management in the Bonga deepwater environment and highlights some of the challenges and lessons learned in safeguarding the integrity of deepwater wells through the operational phase.

Subsurface Containment Assurance Program - Key Element Overview and Best Practice Examples

“…Loss of well integrity can occur from several causes including repurposing, poor cement jobs, aging or abandoned wells, and overburden or reservoir deformation (e.g., Nagel, 2001;Ebitu et al, 2011). BP's Macondo deepwater containment loss in the Gulf of Mexico in April 2010 at the Deepwater Horizon rig demonstrates the importance of well integrity to subsurface containment assurance (e.g., Hopkins, 2012;Skogdalen and Vinnem, 2012).…”

“… The Field Management and Surveillance element can establish hard controls such as pressure and volume limits for individual wells along with more integrated assessment of injector and producer clusters. Various production and geophysical monitoring approaches (e.g., Ebitu et al, 2011;Gu et al, 2011) that may shed light on containment form an important part of reservoir surveillance and can inform field management decisions.  The Operations element ties shorter-term, more day-to-day decisions to the wider context of field management, sometimes with explicit communication and feedback loops between operators and engineers.…”