Avoid reservoir damage to optimize production

TNK-BP had three production wells in a mature oil field in western Siberia that needed to be worked over. To aid in maximizing the reservoir's output, the company decided to reperforate the wells to efficiently communicate between the reservoir and the wellbore. This completion technique posed a challenge, as successful communication—and ultimately production—largely depends on the cleanliness of the perforation, and reservoir damage and skin can negatively affect a well's production.

To maximize the wells' production, two key strategies were implemented for tubing-conveyed perforating (TCP): PURE system dynamic underbalance perforating, which obtains clean perforation tunnels that improve production or water injection, and a nondamaging viscoelastic surfactant- (VES-) based pill after perforation to avoid reservoir damage during the well-kill stage.

Custom solution of deep charges and clean perforating

TNK-BP consulted with Schlumberger regarding their objective to achieve higher well productivity by minimizing perforation damage, and a custom strategy was proposed.

PowerJet Omega charges, which provide on average 20% deeper tunnels compared to conventional charges, would be used to increase the probability of passing through the damaged zone. A dynamic underbalance condition would then be created with the PURE system to improve production. After perforating, a nondamaging pill was used to avoid reservoir damage during well-kill operations. This approach successfully protected the new, clean perforation tunnels against damaging kill fluids for an additional 3–5 days of workover operations.

250% production increase from minimized skin

Results from the fit-for-purpose TCP strategy showed negative skin for reperforated intervals and a slightly positive skin for the new layer interval. After spotting the pill, loss control was improved. Postjob production data indicated a 2.5-fold oil production increase compared to the prework- over rate. The custom-engineered combination of PURE system perforations, the VES-based pill, and PowerJet Omega charges helped bring the skin value down from nearly 6 to less than 1, resulting in optimized production and meeting the client’s objectives.