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.

Pertamina Hulu Mahakam (PHM) has applied the Mono Trip Gas Lift (MTGL) completion technique with 27 wells that have been completed by drilling rigs. To improve efficiency, PHM assigned a Hydraulic Workover Unit (HWU) in September 2020 to execute the first rig-less MTGL in the Mahakam field, which is economically feasible based on an internal study. Since HWU has never performed the MTGL cementing, some collaborative works must be done to identify backlog and establish solid procedures for perfect execution. Besides, top of sediment (TOS) was found 16-21 m inside the tubing, which hindered access to the most bottom production zones. Moreover, this project is the first MTGL conducted inside a 7” casing which allows a maximum of 3 barrels per minute (bpm) flow rate (according to packer specification). The flowrate limitation could potentially create higher TOS inside the tubing. Hence, we agreed to utilize a 3.5” landing joint and to apply a higher flow rate for displacing cement as per simulation with rigorous risk assessment and mitigations. As a result, the job was completed in 11.6 days without a lost-time injury, contributing to 12% PHM saving, while the TOS was tagged 13 m above the top of the landing collar by 1.9” macaroni. Despite its success, some lessons are captured as our recommendations, such as improving the sweeping efficiency of the MTGL wiper plugs, establishing a solid system for vital data of cementing job, and developing the infrastructure by HWU contractor to perform the job more successfully. This paper strongly recommends the rig-less operation as an alternative way to reduce the costs of well construction activity. A proper operation can be achieved by learning the lessons, closely managing and monitoring entire job stages. Finally, it encourages partnership and synergy for a better result.

Under the low commodity prices, the operator of the marginal fields has been constantly initiating the ways to improve efficiency. Re-entry wells technique has been chosen as one of many to achieve the objective. Plug and abandonment (P&A) campaign has become massively conducted to prepare the wells for the re-entry. Moreover, a hydraulic workover unit (HWU) is utilized to support the drilling rigs in executing such projects in the last 3 (three) years. Since the nature of the operation involves multiple stakeholders, careful planning is required to ensure that the company's objectives are well delivered. Therefore, estimating duration of single well P&A is more critical to gain the better perspective in the early stages. This paper explains the probabilistic technique developed in forecasting the project's duration. Historical data are collected and multi-level statistical data analytics are performed to establish a tool for estimating the days, costs and finally providing valuable feedback for the initial planning. Utilizing the probabilistic method in this case for the last 5 (five) wells of P&A campaign has showed significant approximation to the actual days. Therefore, the operator is confidence to continuously use this method for the planning. Besides predicting the main scope of P&A works, the tool has accommodated the duration of the non-productive time (NPT) as well as the wait on weather (WOW) for each P&A well. Hence, the probabilistic method introduced in this paper can be beneficial not only for estimating but also enhancing the performance evaluation as the part of continuous improvement.

In unconsolidated sand reservoirs, proper sand control completion methods are necessary to help prevent reservoir sand production. Failure due to sand production from surface equipment damage to downhole equipment failures which can ultimately result in loss of well integrity and worst-case catastrophic failure. Gravel Packing is currently the most widely used sand control method for controlling sand production in the oil and gas industry to deliver a proppant filter in the annular space between an unconsolidated formation and a centralized integrated screen in front of target zones. Additional mechanical skin and proper proppant packing downhole are the most critical objective when implementing gravel packs as part of a completion operation. This paper presents a case history of Well SX that was designed as single-trip multi-zone completion 7-inch casing, S-shape well type, having 86 deg inclination along 1300 meters, 4 to 5-meter perforation range interval and 54 deg inclination in front of the reservoir with total depth of 3800 mMD. The well consists of 4 zones of interest which had previously been treated with a two-trip gravel pack system. While Well NX was designed as single-trip multi-zone completion in 7-inch casing, J-shape well type, 8-meter perforation interval and 84 deg inclination in front of the reservoir with total depth of 3300 mMD. The well consists of two zones of interest which had previously been treated with a single-trip gravel pack system. Both wells are in the Sisi-Nubi field offshore Mahakam on East Kalimantan Province of Borneo, Indonesia. This paper discusses the downhole completion design and operation as well as the changes to the gravel pack carrier which overcame challenges such as high friction in the 7" lower completion and the potential for an improper annular gravel pack due to the lack of shunt tubes in a highly deviated wellbore. In vertical wellbores, obtaining a complete annular pack is relatively easy to accomplish but in highly deviated wellbores, the annular gravel pack is more difficult to achieve and can contribute additional skin. Tibbles at al (2007) noted that installing a conventional gravel pack could result in skin values of 40 to 50, mostly due to poor proppant packing in perforation tunnels. Therefore, operator required to find a reliable gravel pack carrier fluid optimization for typical highly deviated wells to overcome the potential sand production issues by applying a single-trip multi-zone sand control system across both zones (without shunt tubes) along with the utilization of a high-grade xanthan biopolymer gravel pack carrier fluid. Laboratory testing was conducted to ensure that the gravel pack fluid could transport the sand to the sand control completion, large enough to allow for a complete annular pack and still allow the excess slurry to be circulated out of the hole. Electronic gravel pack simulations were performed to ensure that rate/pressure/sand concentration would allow for a complete gravel pack. All four zones in Both of Well SX and NX were successfully gravel packed with a high rate, relatively high sand concentration slurry. The well has not exhibited any sand production issues to date. The current production from both wells is above expectation and are comingled from the two primary zones. Multiple factors were considered during the design and operation of the sand control treatment. Those factors will be described in this paper, starting with candidate selection, completion strategy, operational challenges and treatment execution along with production monitoring of the well.

As conventional fishing assembly offers a degree of recovery chance, such chance can be increased by utilizing an Oscillating Fishing Tool (OFT). The OFT is a fishing Bottom Hole Assembly (BHA) component that delivers low-magnitude; high-frequency oscillation. The continuous motion that the tool provides complements the impact generated by the fishing jar. This paper reviews the successful case history in Field X, which was in fact the first utilization of OFT for a fishing application in the field. Method of analysis involve comparing fishing sequence without and with the OFT. The OFT was used in Offshore Field X to recover a mechanically stuck 550-meter long Tubing Conveyed Perforating Gun assembly inside 9 5/8" casing that could potentially lead to loss of access into the 6 oil reserves candidate perforation zones. Initially the assembly had been stuck for two days, during which conventional fishing BHA was used to retrieve it to no avail, even after jarring for most of that time. OFT was then incorporated in the final fishing BHA and operated in combination with jarring operation. After around twelve hours of oscillating and jarring, the fish was able to be released from the initial stuck point. When tripping the string out, however, the assembly was stuck at high dog-leg severity area near the surface. At that point, in combination with applying substantial overpull, OFT was utilized further to recover the entire string. Upon fish retrieval, it was evident that post detonation, the TCP gun had swelled into 8.6 inches in diameter. In summary, oscillating and jarring for thirty-six cumulative hours successfully released the swelled TCP gun assembly from the stuck occurrences. In conclusion, the operation showed that the OFT serves as a higher level of fishing tool option that offers a particular excitation mode to the stuck assembly. Stuck assembly in a cased hole presents potential loss of oil reserves. Particularly in offshore application, the situation can also be costly. With reduced chance of recovery as time passes by, operation is hindered from being able to proceed to the next completion phase. The case proved OFT to have played an important role in improving fishing probability of success and should be considered as standard fishing BHA in the future.