This paper will describe the successful application of cement packers in Offshore Northwest Java Sea (ONWJ) field to recover by-passed reserves that are located above the production packer. Previously, conventional completion techniques required a workover to re-complete these new zones. However, due to their marginal reserves or the well still has good production from existing zones (ex: in dual completion case where long string is still a good producer while short string is already shut-in), a workover is not a good option to recover these by-passed zones. A new treatment technique in ONWJ field, Indonesia, has been developed to re-complete and treat these zones that are located above the production packer without pulling out completion strings. Isolation of potential zones is accomplished by cementing in the tubing-casing annulus above the production packer. The cement above the zone replaces the production packer and conventional perforating is then used to complete the well.

The advantages of this technique are: inexpensive (no rig required), no need to wait for the well to achieve economic limit rates before recovering the zones, and - most importantly - it still allows access into the lower completions. On the other hand, the disadvantages of this technique are: less gun penetration (has to penetrate tubing-cement-casing-cement-formation), and workover/sidetracking below packer is difficult to carry out once the packer has been covered by cement.

To date, a total of 7 wells have been reactivated using this technique to recover the zones/reserves. The jobs have been done successfully in both single and dual completions. The average cost was only 20%-60% of conventional workover jobs and savings of up to US$ 400,000 have been achieved. The production results have also been encouraging. These successful results have brought new opportunities for reactivating many more shut-in wells with by-passed reserves that are economically marginal.

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