Optimizing Drilling Cost through the Application of Hydraulic Workover Unit to Drill New Wells in Andalan Delta
Authors: Wijaya Ryan Aditya Surya 
Published: January 2023

TN is a mature giant gas field in Andalan Block Contract Area which is operated by PT Surya Energy Company (PT SEC). TN wells are located in the delta of Andalan river and currently already entering production decline phase. Drilling activities in PT SEC itself has entered industrialization phase since early year 2000, resulted by more than 20 years of learning curve creation in the construction of well design architecture. Currently most of the wells drilled are targeting marginal hydrocarbon (HC) reserve. The downturn of oil and gas industry in mid-year 2014 had pushed the Drilling & Well Intervention team in PT SEC to further squeeze the well duration beyond the technical limit in order to meet the economy of wells drilled and continue drilling operation activities in order to maintain hydrocarbon production plateau. Many innovative ideas have been implemented to achieve these objectives such as the implementation of batch drilling, offline drilling activities, well architecture optimization, more rigless operation and other initiatives as alternative solutions have been introduced and will be planned to reduce well duration and operating cost in overall. This article discusses what factors that cause the well cost become high when drilling in TN field especially in TN Shallow development, investigation of the root cause (s), and the alternative solutions that may be feasible and also the implementation of the selected alternative solutions in order to avoid the company loss opportunity to drill and produce new TN Shallow wells. The root cause analysis used the current reality tree (CRT) which identifies main root cause on why the well cost becomes high or premium, which is high site preparation cost specifically to perform dredging activity. The site preparation is needed to allow for Swamp Barge (SB) rig and any other barge access to safely enter the well location and perform drilling activities the fact that the conventional SB rig is considered the only means to drill new wells in TN field. The alternative solutions of the root causes were determined, and then the best alternative solutions were selected using the analytic hierarchy process (AHP). The ultimate criteria for the selection of the alternative are the overall well cost creation, and how immediate means of drilling new wells as a solution can provide impact to the overall well cost reduction. Several alternative solutions are results of study and research of improvement on drilling project management implementation, including but not limited to some efforts in reducing drilling duration and innovative means to drill new wells with the fit-for-purpose design of drilling fleet, without using conventional SB rig which require huge amount of dredging volume thus resulting in high site preparation cost. Selected alternative solution to perform drilling activities using Hydraulic Workover Unit (HWU) is the best solution considering the equipment and working barges' technical capacity requirement point of view which resulting less daily drilling expense than the SB rig has resulted in less overall well cost. Drilling with HWU is a complex project management involving many entities with various competencies requirements within and outside the company organization. Even though the result of implementation may not be measured and obtained in a short period, the ultimate objective of reducing overall well cost to keep the well economy is expected to gain in the first campaign in the year 2023.