Abstract
With the continuous production from Kuwait oil reservoirs, a clear decline in reservoir pressure is observed. Subsequently, the demand for artificial lift is increasing to sustain production. Maintenance of those wells requires frequent interventions and continuous presence of workover rigs, which affects overall cost of production. Change of the electrical submersible pump (ESP) deployment method represents one of the cost reduction initiatives undertaken by the operator to reduce well intervention time and improve asset utilization.
To minimize deferred production generated by the ESP replacement operation, a novel rigless approach leveraging coiled tubing (CT) was introduced in southeast and west Kuwait. It reduces operating costs and eliminates disruptions to operations by enabling rigless retrieval and redeployment of a standard ESP assembly. To evaluate the efficiency of using CT as rigless ESP retrieval and conveyance method, two candidate wells were selected to recover and redeploy a 108-ft-long ESP system. The intervention methodology relied on CT equipped with optical line and real-time downhole telemetry, a high-pressure rotary jetting tool, and a specific ESP deployment assembly.
The retrieval and redeployment of the ESP was executed in a single rigless intervention, averaging less than 72 hours of operational time per well. This represents five times improvement over the standard practice using a workover rig. The intervention was executed in several stages, according to the well intervention program, and included tubing drift and cleanout runs, retrieval, inspection, and redress of the ESP assembly, followed by its successful redeployment. The high-pressure rotary jetting tool was used to condition the wellbore tubulars across the fishing area, while downhole real-time data enabled by the 1 3/4-in. CT equipped with optical telemetry were instrumental to eliminate uncertainties associated with changing downhole conditions. The casing collar locator allowed live depth control and ensured accurate positioning of the ESP. Its careful retrieval and redeployment were monitored thanks to the downhole axial force readings, which allowed controlling the weight applied on the fishing assembly. Internal and external downhole pressure data, along with downhole temperature, helped in controlling actuation and use of the high-pressure rotary jetting nozzle under nominal conditions for maximum efficiency.
This enhanced rigless ESP replacement technique, made possible by the joint use of CT and real-time downhole measurements, was confirmed as a robust workover method for retrieval and redeployment of rigless ESPs in southeast and west Kuwait. The experience gained in the first two wells brings a new level of confidence to Kuwait operators about this technique, which certainly can be expanded to other fields in the Middle East and elsewhere.
