Evaluation of autonomous ICD/ICVs in a thin Oil Rim Reservoir

Abstract

Thin oil rim reservoirs have an oil column thickness of ~10 30 meters and are overlain with a gas cap and underlain by an aquifer. Thin oil rim reservoirs have shown to lead to a relative low oil recovery when being produced. Quite common is an early breakthrough of gas and/or water, also known as coning. This study was initiated in order to perform an evaluation of four different completion types in horizontal wells in thin oil rim reservoirs underlaying a gas cap and overlying a strong aquifer. The completion types studied are: Screens without Inflow Control Devices (modelled as perforated liner here) Nozzle based Inflow Control Devices Autonomous Inflow Control Devices Autonomous Inflow Control ValvesA short review of the reservoir and well modelling is given with special focus on Autonomous Inflow Control Devices and Valves.Four different reservoir models are studied, a homogeneous model with a single horizontal well, a homogeneous model with a slanted well, a simple heterogeneous model with a single horizontal well and a real heterogeneous model with a bi-lateral horizontal well.The study showed that if a well is located partly in a gas cap or very close to it the AICV completion performs an optimal job, by choking back the gas efficiently. NICD/AICD is the second best, while no-ICD is the worst case. In a homogeneous model the four completions gave the same results. A single high permeable channel into the gas cap made a smaller impact than expected, but the AICV showed to choke back the gas here efficiently. NICD and AICD completion results are very similar in all cases, which could be linked to the parameter used in the RCP function from the AICD in this study. In the real heterogeneous case, the AICV does clearly the best job the first years, and is better than the NICD/AICD alternatives. It is interesting that the no-ICD case gave the highest ultimate oil recovery.Most importantly the results point to that the AICV (and possible also the AICD) technology has potential to increase the oil recovery in thin oil rims and it is important to be able to make the field life value of it - like tried in this study.