Abstract

Workover operations with conventional workover rigs have an enormous impact on the site, adding strain to operational and production targets. Alternative approaches to optimize Electrical Submersible Pump (ESP) replacements were evaluated and a Hydraulic Workover Unit (HWU) was selected as delivering the most advantageous outcome for the field to expedite the workovers efficiently and cost effectively. The HWU is more than capable to overcome any challenges and perform the replacement of failed ESP's, yet at the same time is a more compact & mobile unit than a traditional workover rig resulting in a much reduced impact on the wellsite. Several major benefits are gained including; avoidance of disruption to nearby wells, faster well turn-around, reduced cost, and ultimately an increased production avails. The size and scale of conventional workover rig and well spacing require the candidate well and other nearby wells to remove flowlines and instrumentation to create enough space for the rig and ancillary equipment. One of the primary design features of a standard HWU is the high level of accessibility in tight spaces allowing the unit to be assembled in small multiple individual components. This can be very time consuming so the challenge was to benefit from the superior accessibility but also to minimize the rig time for a more efficient process. To achieve this, a specialized fit for purpose HWU with the modular construction packaged into minimal components allowing for a swift rig up and efficient deployment of the unit. This HWU remains highly accessible and can replace the failed ESP without disturbing the installed production flowline infrastructure and instrumentation.

The HWU has been a key technology enabler transforming the status quo to improve the optimization of resources and reduce operational costs. During the project of 8 pilot wells, the average workover cost reduction was calculated at 61% per well. The improvement in operational efficiency benefited from an overall 69% faster site and well preparation duration with a 13% reduction in rig time. The magnitude of these improvements in efficiency, cost avoidance and the unlocking of earlier production availability is a game changer for ESP replacement operations. The HWU equipped with comprehensive capabilities has proven itself as a viable alternative to conventional workover rigs to replace failed ESP's. The design enhancements of the pre-assembled modular construction for the HWU minimizes the hazardous and labor-intensive assembly onsite, increasing the safety environment for the operational personnel.

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