Abstract
The presence of oil rim in gas reservoirs could potentially have an impact on the timing and philosophy of gas development in the field. Sound reservoir management strategy requires investigation of the development feasibility of the oil rim as part of the field development planning study. This is also a prerequisite to securing regulatory approval for the resulting field development plan.
Eleju C1000 reservoir contains a proven 10ft oil rim with a huge gascap supported by clearly logged fluid contacts. The field is located onshore Niger Delta, with six well penetrations, leading to the discovery of nine hydrocarbon-bearing sands. The field development concept is based on the gas resource in C1000 reservoir, which holds over 80% of the estimated field gas in-place volume.
Based on the available geoscience and engineering data, analytical and simulation methods were employed to evaluate the feasibility of developing the 10ft oil rim in C1000 reservoir. The operator's Oil Rim Development Guidelines and Wyne et al Matrix (for evaluating oil reservoir feasible concept) were employed in selecting an optimum development concept for the C1000 reservoir.
Analytical and simulation methods resulted in C1000 estimated EUR per well range of 0.3 – 0.4 MMstb with a unit development cost (UDC) of about $100/bbl excluding flowlines and facility. This is not economically favourable to the project which has a UDC of $3.4 per boe for gas development only. Therefore, the optimum development option for reservoir C1000 is gas development only.
