The effectiveness of a permanent abandonment plug is measured by its ability to bridge the wellbore cross section both vertically and horizontally, including all annuli, with a plugging medium which can withstand the rigors of the environment to which it is exposed (Figure 1 – Barrier Requirements). The most common method for placing a plug in cased hole with an uncemented annulus has required section milling of the casing, making a clean out run and underreaming of the open hole prior to placing a balanced cement plug. A new method is presented which creates a permanent abandonment plug through the use of a system which perforates uncemented casing, washes the annular space and then mechanically places the cement across the wellbore cross section in a single run. This paper outlines the design methods, laboratory testing and operational elements that were assessed during the development phase, as well as the results of field trials used to qualify this technique.

The petroleum industry is performing extensive research into rectifying structural well integrity issues, mainly caused by migration of hydrocarbon fluids to surface through microchannels, due to poor cementation, resulting in the inability to provide integral barriers in the 9⅝″ casing × 12¼″ hole annulus. As a consequence, the well life can be extended and the older wells can be restored back to production and injection, resulting in long term fulfilling of the increasing global demand for additional energy requirement. Annulus-B Remediation using HydraWell Technology is one of the innovative approaches that can be utilized in wells to provide strong integral cement barriers behind the 9⅝″ production 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 restoring the well production/injection with minimum workover costs and risk due to less complex operations, mitigate environmental concerns by avoiding excessive steel cuttings like section milling and eliminating the complexity associated to re-entry risk as incase of section milling. The research utilizes a novel technology to execute a repair of wells with failed Annulus-B barrier integrity by providing integral cement barriers in the 9⅝″ × 13⅜″ casing annulus above the reservoir for wells experiencing migration of hydrocarbons from reservoir through the 9⅝″ × 13⅜″ casing annulus. The planned methodology starts with completion recovery followed by running noise, temperature and cement bond logs in order to evaluate the cement quality behind 9⅝" casing above the reservoir. Findings from the noise/temperature logs and oil sample evaluation indicated that oil is migrating from the reservoir, through 9⅝″ × 13⅜″ casing annulus, dripping at surface through the 30″ conductor pipe. The cement bond logs indicate poor cement behind 9⅝″ casing above the reservoir. Therefore, Remediation technology was successfully utilized as it delivers effective jet washing and subsequent cleaning of the annular space using specialized tools and thereafter spraying cement to create a 100-feet competent cement barrier behind the casings for effective isolation and the prevention of pressure communication to the surface via Annulus-B. Furthermore, a 7″ short tie-back was installed over the perforated cemented interval. Hence, the 9⅝" 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 a very cost effective technology as it saves the operator approximately 5-8 days per well with associated significant CAPEX and OPEX savings by avoiding additional costs associated with complexity of operations in section milling. It is feasible to be applied in offshore wells requiring remediation of failed Annulus-B integrity with reduced rig time and the associated costs with minimum environmental risk.

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The petroleum industry has made significant investments and extensive research to rectify well integrity issues, one particular failure mode relates to the migration of hydrocarbon fluids to surface through microchannels, due to poor cementation, resulting in the inability to provide integral barriers in the 95/8" casing x 12¼" hole annulus. Section milling and external casing patches are two of the widely-utilized approaches to restore annulus integrity; however, they add complexity associated with excessive steel cuttings and re-entry risk. Remediation using Hydra System is one of the innovative approaches that can be utilized in wells to provide strong integral cement barriers behind the 95/8" production casing below the 133/8" casing-shoe to prevent reservoir fluids migrating to surface. As a consequence, the well life can be extended and the older wells can be restored back to production and injection. This approach is gaining increased popularity due to a number of economic and environmental advantages such as restoring the well production/injection with minimum workover costs and risk due to less complex operations. The research utilizes a novel technology to execute a repair of wells with failed Annulus-B (95/8" x 133/8" casing annulus barrier) integrity by providing integral cement barriers in Annulus-B above the reservoir for wells experiencing migration of hydrocarbons from reservoir through the this casing annulus. The planned methodology starts with completion recovery followed by running noise, temperature and cement bond logs in order to evaluate the cement quality behind 95/8" casing above the reservoir. Findings from the noise/temperature logs and oil sample evaluation indicated that oil is migrating from the reservoir, through Annulus-B, dripping at surface through the 30" conductor pipe. The cement bond logs indicate poor cement behind 95/8" casing above the reservoir. Therefore, the aforementioned remediation technology was successfully utilized as it delivers effective jet washing and subsequent cleaning of the annular space using specialized tools and thereafter spraying cement to create a 100-feet competent cement barrier behind the casings for effective isolation and the prevention of pressure communication to the surface via Annulus-B. Furthermore, 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 well's injection rate to be restored. This strategy may be developed as a very cost-effective technology as it saves the operator approximately 16-22 days and $ 1.6-2.3 million per well with associated significant CAPEX and OPEX savings by avoiding additional costs associated with complexity of operations in section milling. It is feasible to be applied in offshore wells requiring remediation of failed Annulus-B integrity as it delivers greater efficiency by reducing the rig time and the associated costs.

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