Inefficient postfracturing cleanout on coiled tubing runs would extend wellsite operations

Vista Energy wanted to improve the efficiency of multistage fracturing operations in its Vaca Muerta horizontal wells. With four wells per pad and typically up to 40 stages per well, a significant amount of time would have been required to mill out conventional composite frac plugs on coiled tubing. Vista Energy wanted to streamline operations to running only a quick cleanout trip after fracturing.

Fully dissolvable frac plugs simplify and accelerate cleanout

Although composite frac plugs are readily available and relatively low cost, the time required to mill them out in wells with a high number of fractured zones would delay putting the wells into production.

To streamline operations, Schlumberger designed a high-efficiency plug-and-perf solution that employs a KickStart rupture disk valve for the toe stage and ReacXion fully dissolvable frac plugs for the remainder of the wellbore. The KickStart valve is an interventionless technology that remotely kicks off the toe stage. After the KickStart valve opens the well for circulation, the remaining stages are reliably isolated with the ReacXion plugs delivered simply with conventional pumpdown techniques. After fracturing, the plugs dissolve without
further intervention.

Analysis of the fracturing fluids used by Vista Energy indicated that the freshwater alloy version of ReacXion plugs would deliver optimal dissolution for accelerated cleanout and faster time to production. Vista Energy now uses reliably performing ReacXion plugs exclusively.

Nearly 2,000 ReacXion plugs deployed with 100% reliability

Vista Energy first deployed the KickStart rupture disc valve and ReacXion fully dissolvable frac plugs at a four-well pad and completed 143 frac stages in the four wells in less than 19 days, including 11 stages in a 24-h period, setting the shortest completion time for the region. The operational efficiency was a significant improvement over the typical rates. One contributor to the efficiency improvement was the antipreset feature of the ReacXion plugs, which enables rapid pumpdown with consistent setting and isolation performance.

After stimulation, CT was run into the wells for sand cleanout. The shortest time between setting the last plug and running CT was about 4 days, which was sufficient time for the ReacXion plugs to dissolve. The excellent dissolution performance meant that the cleanout operations tagged only a few plug remnants at the heel stage of the wells.

Since that highly successful first deployment, Vista Energy now uses only ReacXion frac plugs for Vaca Muerta fracturing operations. Nearly 2,000 ReacXion plugs have been run across 11 well pads, with zero incidents attributable to plug operations or dissolution performance. On average, Vista Energy is now completing more than eight stages per day. Schlumberger continues to improve on the plug design by incorporating a simplified wireline adapter kit and optimized brine-degradable elastomer in these operations.

Time saved and emissions reduced

An estimated 6,000 L [1,585 galUS] of diesel is consumed per day for coiled tubing milling operations on these pads. The diesel is used for pumps, injector head, water treatment, cranes, and other ancillary support. Reducing the time necessary for cleanout operations equates to less coiled tubing operating time, less time on the wellsite, and therefore less diesel consumed. Because 1 L of diesel adds 2.712 kg [0.26 galUS of diesel adds 6 lbm] of CO2 equivalent (CO2e) emissions to the atmosphere, the resulting savings in diesel consumption significantly reduce CO2e emissions across the well pads.

Specifically, exclusive use of ReacXion frac plugs for Vaca Muerta operations delivers an estimated savings for Vista Energy of 424 t of CO2e emissions per 1,000 plugs deployed. This equates to 222 t of CO2e emissions saved in 2020 and 361 t of CO2e emissions saved in 2021 versus using conventional composite frac plugs.