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.