Planning of an Offshore Well Plugging Campaign: A Vehicle Routing Approach

Abstract

When a petroleum well no longer serves its purpose, the operator is required to plug and abandon (P&A) the well to avoid contamination of reservoir fluids. An increasing number of offshore wells needs to be P&A'd in the near future, and the costs of these operations are substantial. Research on planning methods in order to allocate vessels that are required to perform these operations in a cost-efficient manner is therefore essential. We use an optimization approach and propose a mixed integer linear programming model based on a variant of the uncapacitated vehicle routing problem that includes precedence and non-concurrence constraints to plan a plugging campaign. P&A costs are minimized by creating optimal routes for a set of vessels, such that all operations that are needed to P&A a set of development wells are executed. In a case study, we show that our proposed optimization approach may lead to significant cost savings compared to traditional planning methods and is well suited for P&A planning purposes on a tactical level.

Data-Driven Joint Chance-Constrained Optimization for the Workover Rig Scheduling Problem

“…Last, wells must be plugged and abandoned (a process in which wells are abandoned and cannot be used again after the installation of well barriers or plugs), which is often performed using rigs. Each of these operations requires a specific rig type (Bakker et al 2017). In what follows, we describe the different types of oil rigs and their purpose.…”

“…The decision-making integrated with other resources is especially important for offshore P&A campaigns, which relies on rigs and lighter vessels, such as light well intervention vessels (LWIVs) and light construction vessels (LCVs). Bakker et al (2017) approached the planning of the offshore P&A campaign, presenting a MILP model based on the VRP that aims to minimize costs of a heterogeneous fleet of semi-submersible rigs, mobile offshore drilling units, and light well intervention vessels. Adapting the model from Bakker et al (2017), Bakker et al (2019) developed a commodity flow type formulation for the P&A planning that allowed to tackle larger instances and consider different assumptions such as multiple routes per ship and reduced operability of lighter vessels in the winter.…”

“…Bakker et al (2017) approached the planning of the offshore P&A campaign, presenting a MILP model based on the VRP that aims to minimize costs of a heterogeneous fleet of semi-submersible rigs, mobile offshore drilling units, and light well intervention vessels. Adapting the model from Bakker et al (2017), Bakker et al (2019) developed a commodity flow type formulation for the P&A planning that allowed to tackle larger instances and consider different assumptions such as multiple routes per ship and reduced operability of lighter vessels in the winter. Bakker et al (2021) adapted these formulations to consider learning curve effects on the vessel's processing times.…”