Evaluation of Utilisation a Hydraulic Workover Unit for Gravel Pack Job in Indonesia

Abstract

Abstract In the last 2 (two) years, the operator has been performing gravel pack (GP) completion using a Hydraulic Workover Unit (HWU). Such rigless GP explains that a drilling rig shall drill a well, running the casing and cementing then suspending the well. Next, HWU will perform the completion job to fulfill the scope of the well construction. By May 2021, HWU has done 4 (four) rigless GP with various well designs. The original background is to reduce costs of the well construction and to increase the wells delivery efficiency of a jack-up rig. This paper will compare the duration of rigless GP execution in those wells, even though the value creation of using HWU as an alternative way will also be reviewed. Regarding operational capabilities, HWU has several limitations that differ from a jack-up rig. Several disadvantages range from HWU's construction, tripping performance, lifting practices until contract management. From a construction aspect, HWU is more sensitive to weather thus prone to the operation suspension. In some platforms, HWU has more complexity lifting operations due to the crane's reach limitation, therefore an additional crane is needed to assist. Furthermore, HWU utilizes traveling slips for tripping, as such the length of the cylinder will affect the speed. Moreover, HWU is not in a favorable situation due to some important services are not dedicated to support the operation. For example, the handling equipment for upper completion is managed through a call-out contract and the logistic vessel has to be shared with other fleets. Therefore, it is essential to develop a solid course of action to achieve the objective of utilizing HWU in GP jobs. Related to performance enhancement, some initiatives have been pursued i.e. changing the position of the barge to reduce weather sensitivity, developing the effective logistic plan, and managing some activities to be performed by the jack-up rig (in offline mode). Moreover, adding some pipe racks and enforcing all crew to improve tripping speed safely are also part of the improvement. Also, it is essential to select the equipment as necessary as possible to deal with the call-out contract and to increase the economic value of the project. Finally, performance monitoring and documenting lesson learned are critical to pursue for future improvement. All of those efforts have been paid off as indicated by the learning curve which has been shaped. Referring to the duration and expenses of the first rig-less GP job, the latest well has attained a reduction in costs by 60% and less 66% of time completion. The fact implies that HWU is worth pursuing in executing GP completions as an alternative to the conventional way.