Dissolver delivers in situ decontamination of radioactive ESPs

By employing BaSOL 2000 HP™ scale dissolver for in situ decontamination of NORM-contaminated equipment, an operator in Kuwait reduced well downtime and remediation time, avoided a topside backlog of equipment awaiting treatment, improved the QHSE profile by eliminating NORM handling at surface, and reduced costs overall.

NORM scale deposits within ESPs and other artificial lift assemblies can cause mechanical failure, shortening ESP service life and hindering production. Conventional remediation techniques entail shutting in wells, removing equipment, and decontaminating NORM before ESP repair and maintenance can be performed. One operator producing onshore Kuwait sought to decontaminate its radioactive ESPs with an in situ solution to prevent unnecessary shut-ins and decrease costs and rig time. The active dissolution and catalysis agents in the scale dissolver ensure a rapid reaction rate and provide a dissolution capacity of up to 80 g/L [067 lbm/galUS].

The lower part of the completion was shut off by a thru-tubing plug and cement. The upper part of the completion with the ESP was flushed with diesel then treated to render the NORM scale containment water-wet. Heated BaSOL 2000 HP scale dissolver was circulated within the ESP assembly, and continual sample analysis was performed topside to confirm optimal dissolution conditions. A production logging tool containing a gamma ray desitometer was run before and immediately after the treatment.

Comparison of the gamma ray densitometer data from before and after the BaSOL 2000 HP scale dissolver application confirmed that no radiation was present after treatment, indicating successful dissolution and removal of NORM scale from the ESP. During the operation, the cleaned ESP required changeout. The failed, but now cleaned, ESP could be returned to the owner for maintenance and refurbishment and changed out without increasing the backlog of tools waiting for topside treatment. Additionally, the QHSE profile improved from avoiding surface handling of NORM-contaminated materials. The scale dissolver helped the operator reduce well downtime, well remediated time, and costs.