Dissolvable Frac Plugs Set Below Casing Patch | SLB

Slim Dissolvable Frac Plugs Enable Multistage Hydraulic Fracturing Below Casing ID Restriction, Eagle Ford Shale

Published: 01/26/2022

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Operator required slim dissolvable frac plugs for a well with restricted ID

Damaged casing in a Prime Rock Resources well in Louisiana’s Masters Creek Field had necessitated using a casing patch near the heel. The well was scheduled for plug and perf, and because of the high downhole temperature—300 degF [150 degC]—Prime Rock preferred using degradable frac plugs to avoid potential problems with postfrac intervention.

However, the patch had a drift diameter of 3.195 in [81.153 mm], and the operator’s usual provider was unable to supply plugs with an OD small enough to pass through the restriction. Prime Rock approached Schlumberger for a solution. Stimulation pressures were as high as 12,000 psi [83 MPa], so the plug had to be robust, yet still dissolve within a reasonable time period. And despite its smaller OD, it had to expand and seal effectively against fracturing pressure in 4.5-in casing.

ReacXion Slim frac plugs provided the solution

Schlumberger proposed its ReacXion Slim high-expansion fully dissolvable frac plugs. These plugs require minimal field assembly and have a proprietary field-proven coating that prevents early dissolution, enabling plug placement in the well several hours before isolation is required. An antipreset design eliminates the risk of presetting while pumping into the well.

The plug OD of 3.190 in [81.026 mm] was just slightly less than the drift tolerance of the patch. Prior to starting operations, detailed discussions were held to identify operating constraints, including entry limitations at the start of the patch, flow-by restrictions inside it, and velocity control while moving through the patch.

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Despite a difference of just 0.005 in between the plug OD and the drift tolerance of the casing patch, all 23 ReacXion Slim dissolvable frac plugs passed through the restriction and were set at the prescribed depths without incident.

Frac job proceeded according to plan after all 23 plugs were set at requisite depths

Extensive coordination and contingency planning with Prime Rock enabled job execution without any NPT. The plugs were set at the prescribed depths across 4,000 ft [1,220 m] of lateral without incident, despite substantial increase in speed as they passed through the patch, with fluid bypass speeds as high as 4,700 ft/min [1,433 m/min]. No plug movement was observed during stimulation.

Although the coiled tubing cleanout crew was deployed just two days after stimulation was completed, only 3 of the 23 plugs were tagged during cleanout; the rest had dissolved fully. Each tag lasted for <1 min, indicating near-complete dissolution of the remaining plugs. The 0.005-in [0.127-mm] clearance between the plugs and casing patch was a record for US and Canadian operations.

Eagle Ford Shale, United States, North America, Onshore

When a casing patch restricted well ID at the heel, prompt availability of ReacXion Slim high-expansion fully dissolvable frac plugs enabled Prime Rock Resources to proceed with its 23-stage plug-and-perf program, with zero stuck events, swabbing events, or NPT.

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