Probabilistic Estimation of Rigless Plug and Abandonment Campaign in Mahakam Offshore Fields

Abstract

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.