Schlumberger

Case Study: Advanced Perforating Technologies Restore Declining Production

Combined Schlumberger technologies reverse production decline in PCSB offshore wells

Challenge: Perforate to restore production from highly deviated gas wells, working around existing perforations and tubing ID restrictions.

Solution: Use a combination of HSD high shot density gun systems, PowerJet Omega deep penetrating perforating shaped charges, eFire electronic firing heads, and PURE clean perforations system to achieve maximum reservoir connectivity.

Result: Increased production on the three wells by 72 MMcf/d with no interruption of production.

PCSB had to restore—or shut down—production from an offshore platform

Petronas Carigali Sendirian Berhad (PCSB) put wells in the PMO region offshore Malaysia into production and enjoyed two years of high gas rates.

Although initial reservoir studies had projected production above 100 MMcf/d until a full five years after production began, the platform’s production later projected below 90 MMcf/d—the minimum rate considered economically viable by PCSB. Production would have to be shut down if it could not be restored to at least the rate deemed economically solvent.

Adding to the challenge were high deviations, tubing ID restrictions, and small intervals between existing perforations that would require very accurate gun placement.

Schlumberger applied a combination of perforating technologies to achieve maximum reservoir connectivity

To maximize penetration while minimizing formation damage in wells A, B, and C, Schlumberger proposed TCP operations with 2 7⁄8-in HSD guns, PowerJet Omega deep penetrating charges, and eFire firing heads.

Further, the PURE system was applied in Well B. Unlike conventional perforating, which relies on a large static pressure differential between the wellbore and the formation to remove perforation debris and crushed-zone damage, the PURE system fully exploits the transient underbalance that occurs immediately after perforating. It creates a large dynamic underbalance, then absorbs perforation debris into the gun chambers, minimizing skin and leaving an obstruction-free path for flow from the reservoir to the wellbore.

SPAN Schlumberger perforating analysis simulated the results of perforating operations in all three wells. PURE system design software was used to specify the unique perforating system for Well B based on full consideration of the completions geometry, reservoir fluids, and formation characteristics.

Over a 40-day period, ten gun runs were made to perforate the three wells. Increases in wellhead pressure immediately after gun detonation indicated that the perforation tunnels had reached undamaged formation.

Production increased, and the platform was kept in production

Perforation of Wells A, B, and C reversed the decline in gas production and led to an increase of 72 MMcf/d. A pressure buildup study on Well B indicated negative skin values at the sandface from –1 to –1.5.

Additional benefits were realized in the PURE system well, including
  • elimination of the need to acid wash perforations
  • reduction of initial underbalance requirements, saving the costs of nitrogen, completion fluids, and rig time
  • minimized tendency for sanding in the guns because postperforation surge was controlled
  • reduced risk of damage from shock loading on the perforating gun string.
Most importantly, PCSB was able to continuously produce from the wells with no interruption.

Download: Advanced Perforating Technologies Restore Declining Production (0.12 MB PDF)

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