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.

The Multi Zone Single Trip Gravel Pack (MZSTGP) system has been proven as the main solution for developing shallow reservoirs and overcoming sand production issues in marginal sand prone wells in the Mahakam Delta, Indonesia. Robust operating procedures and completion equipments have been developed to assure safe and efficient operations through conventional swamp or jack up rig operations since 2006. Due to marginal reserves being available and the high cost of conventional rig utilization to perform MZSTGP completion, Pertamina Hulu Mahakam initiated completion of the well using a rigless technique to install gravel pack completion with Hydraulic Workover Unit (HWU). This alternative solution is the main driving factor as a new frontier of MZSTGP rigless operation and enables the delivery of typical marginal wells economically at the Mahakam Delta swamp area. This has resulted in potential significant well cost saving up to 37% compared to conventional rig cost, or approximately equivalent to half a million USD along the completion phase. Post rigless gravel pack operation, production stabilized at expected rate and the well has no restrictions to keep producing at this rate or even higher. This new frontier solution of MZSTP rigless operation can be considered as the first successful rigless 7” MZSTGP installation at swamp areas worldwide with no NPT and safety issue.

An Operator wanted to perform a Drill Stem Test (DST) using wireless Surface Read Out (SRO) and downhole sampling of a deep wildcat exploration well (∼4200 mMD) with limited reference from adjacent wells. This first high-pressure, high-temperature (HPHT) exploration well to be attempted in the area was particularly challenging, because it lay in a swamp and had to be drilled with a swamp rig. Immediate, fast decisions would be needed during the DST operation. To ensure accurate DST results in this deep, HPHT well with challenging swampy conditions and lack of adjacent well data, Company deployed its newest wireless acoustic telemetry SRO system, in conjunction with the latest generation tubing-conveyed bottomhole sampling system. A globally proven DST tool string was configured with a retrievable cased hole packer, tubing string testing valve, downhole tester valve, multi-cycle circulating valve, and single-shot rupture disk circulating valve. This innovative solution was engineered to meet the Operator's requirement for reliable, real-time downhole data and representative bottomhole samples of the well. The DST system delivered results was met the Operator's expectation, with successful execution and acquisition of all requested downhole data despite interference from well intervention activity, and collection of all bottomhole samples although killing pressure exceeded the original plan. The wireless SRO system, rated up to 20K psi and 350° F (177°C), allowed the Operator to monitor and analyze real-time bottomhole pressure (BHP) and bottomhole temperature (BHT) for quick decision-making while receiving continuous assurance of downhole tool status. The modular concept supports efficient preparation and testing of tools offline, so risk can be reduced compared to other systems available that can only be tested online (on the rig floor before running in hole). The tubing-conveyed bottomhole sampling system captures more bottomhole samples (9x 400c) than traditional, slickline-conveyed sampling (2-3x 600cc in one run). It also minimizes risk as no well intervention is required and does not add additional time to DST operations. The annulus-pressure-activated bottomhole sampling system incorporated enhancements to upgrade internal sampler tubing pressure from 12k to 15k psi. These enhancements enabled higher well kill pressure for more flexibility, without risk to captured samples. This combined solution provided ongoing reservoir insights that enhanced decision-making, avoided wasted rig time (saving 36 hours), and led to significant cost savings. The wireless SRO system increased confidence in well kill operations, due to observation of actual BHP at surface in real time. The tubing-conveyed bottomhole sampling process worked successfully, without losing the contents of any samplers, even with higher than planned well kill pressure. Overall performance improved compared to slickline-conveyed bottomhole sampling runs.

CRA 13%Cr has been used at all Mahakam swamp and offshore gas wells since 1990's for oil country tubular goods (OCTG) particularly for production tubing, due to its excellent CO2 corrosion resistance. By mid of 2000's, when depletion observed in one reservoir level, the new production started from different level, thus reduce the wells design life and increase the completion job frequency. To avoid completion delay due to tubing material delivery, CLAS 3%Cr and Carbon Steel (C-steel) tubing were proposed. By late 2010's, the study was done to develop materials selection guidelines to provide necessary information allowing early selection of the most appropriate and cost effective Steel for lower well completion. And finally, since 2015, C-steel tubing has been applied to all entire tubing (lower and upper completion a few hundred meter below safety valve) on sweet corrosive gas well through systematic corrosion and erosion assessment, which has been verified as well by tubing wall measurement logging. This paper summarizes the outcome of several studies has been done, and demonstrate the optimization on the use of C-steel tubing instead of higher grade material, as part of corrosion management strategy to synchronize fit for service and economical objective.

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