Case Study: ECP Valve Repair, Permian Basin
On a Plug & Perf horizontal well, an external casing packer valve (ECP valve), set at 4,860 ft, had been derated to 6,000 psi by the manufacturer while the formation would require 6,800 psi fracturing pressure.
The client had planned to run plugs with an outer diameter of 4.425in for the stimulation operations with a possibility to switch to a 4.3in plug.
Concerns about setting a casing patch were about the internal diameter (ID) reduction for the plugs to pass through and the cleanout operation to remove the plugs and start to produce.
The solution was to cover the External Casing Packer to make sure its valve would not see the frac pressure using a 5.5in Slimline patch.
The Saltel Patch IDs regarding a 5.5in-20 lbs/ft casing (Nominal = 4.778in / Drift = 4.653in) are 4.427in / 4.296in and would not be sufficient to allow 4.3in Plug OD to pass through.
The client ran a caliper log to define exactly the internal diameter of the casing, in order to have a better projection of the real patch ID. The Caliper log showed a minimum of 4.744in, that gave a Patch ID of 4.391in drift.
The patch was set in 3 hours and fully drifted up to 4.350in Just after pull out of hole (POOH), the well was successfully pressure-tested up to 9,800 psi.
A plug with an ID of 4.425in was ran later but tagged as predicted on top of the patch. The client decided to run 4.3in plugs for the stimulation operations.
All the perforation guns & plugs went through the patch without any issue. All 13 stages of the well were successfully fractured up to 7,000 psi.
4.5 MM lbs of sand - 67,000 bbls of fluid with 36,000 gals of 15% HCl were successfully pumped through the patch. Retrieving the patch from the hole by fishing or milling was not necessary. All the plugs had been milled out successfully with a 4.25in bit, drilling out one plug at a time and applying sweep and short trip to minimize any tagging/dragging issue.
This job was a major success for the client that applied this same remedial solution for others wells on the pad having issues with DV Tools.
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