Extending Life for Offshore Wells by Fixing the Integrity High Annulus-B Pressure and Creating Zonal Isolation Using a Novel Remediation Technique
Authors: Ansari Arsalan A. , Ringrose David , Libdi Ziad , Larsen Arne G. 
Published: August 2016

Increasing global demand for additional energy requirement - forecasted to increase up to 74% by 2030 - has catalyzed the petroleum industry to perform extensive research into rectifying structural well integrity issues in order to extend the life and return older wells to production and injection. These issues are mainly caused by failure of corroded surface casing. Due to the inability to provide integral barriers in the 95/8″ casing x 12¼″ hole annulus, these wells are planned to be abandoned or completed as single zone wells. Perforate, Wash and Cement remediation strategy is one of the innovative approaches that can be utilized in wells to provide strong integral cement barriers behind the 95/8″ casing to prevent reservoir fluids migrating to surface. This approach is gaining increased popularity due to a number of economic and environmental advantages such as reduction in costs for abandonment of current wells and drilling of new wells, mitigate environmental concerns, restoring the well production/injection with minimum workover costs and eliminating the risk with section milling of not being able to re-enter the casing.

The research utilizes a Novel Remediation technique for providing integral cement barriers in the 95/8″ x 133/8″ casing annulus above the reservoir for wells experiencing migration of hydrocarbons from reservoir through the 95/8″ x 133/8″ casing annulus. The planned methodology starts with completion recovery followed by running cement, noise, temperature and corrosion logs in order to evaluate the cement quality behind 95/8″ casing above the reservoir and the corrosion level for 133/8″ casing.

Findings from the noise/temperature logs and oil sample evaluation indicate that oil is migrating from the reservoir, through 95/8″ x 133/8″ casing annulus, dripping at surface through the 30″ conductor pipe. The cement bond logs indicate poor cement behind 95/8″ casing above the reservoir. However, the results from Metal thickness detection logs indicate low corrosion (~10-15%) in the 133/8″ casing, eliminating the necessity for any external casing patch to restore 133/8″ structural integrity. Therefore, Perforate, Wash and Cement remediation strategy was successfully applied and the integrity of the dual water injector well was restored by placing 100-feet cement barrier behind perforations in the 95/8″ casing above the reservoir. In addition a 7″ short tie-back was installed over the perforated cemented interval. Hence, the 95/8″ casing was re-established as a well barrier element in the well, allowing the injection rate for the well to be restored.

This strategy may be developed as an economic saving technology as it saves us approximately 5-8 days per well with associated significant CAPEX and OPEX savings by avoiding additional costs on section milling and solving problems encountered with section milling. It is feasible to be applied in offshore wells having integrity issues as it extends the life of the well without taking on additional environmental risk.