In many Brownfield developments, toward the end of a well's life cycle, the primary production zone(s) commonly waters out or depletes, or the well sits idle with no alternative means of returning back to production. At this stage, as a normal course of action, the wells are re-evaluated for potential reserves that might have been bypassed during the original completion. For zones that do not appear promising or could be marginal in terms of delivery, the recompletion costs can be prohibitive. It is in such situations that "cement packer" completions performed rigless in offshore environments provide an economic alternative to workover operations. This technique can be cost-effective and has the potential to increase the producing life of a well.
This paper describes the successful application of a "cement packer" to recover bypassed reserves located above the production packer in an offshore field in the Mediterranean Sea. The technique allows zonal isolation between the various upper zones by placing cement slurry in the production tubing and casing annulus.
Conceptually, it might appear simple to perform such a job, but the planning and execution must be well formulated to ensure well integrity is maintained at all times. In this case history, the challenges of executing the job were examined from many different angles (i.e., high angle well, small platform, short weather window for operations, and multiple job sequences). The average cost was only 20 to 60% of conventional workover jobs, which is a savings of up to USD 400,000. The production results have also been encouraging. These successful results have revealed opportunities for reactivating many more shut-in wells with bypassed reserves that are currently considered economically marginal.