Lower Carbon Optimal Development of Heavy Oil: Swamp Niger Delta Case Study

Abstract

Abstract The share of light oil in the global oil reserves continues to decline given that oil and gas producing companies have historically placed more focus on developing the light oil fields. This is because light oils can typically be produced at high rates and low costs. This decline has led to an increasing effort to develop and produce high viscosity oil which accounts for about 15% of the global oil reserves. However, to develop and produce heavy oil at commercial production rates, there is almost always a need to reduce the viscosity of the crude as well as introduce additional energy into the reservoir. The most common methodology implemented to produce such viscous crude involves the injection of superheated steam into the reservoir. This helps to reduce the viscosity of the oil, increase the reservoir pressure, increase the displacement of the oil in the porous rock media as well as achieve partial distillation of the oil. Other methodologies revolve around injection of polymers and surfactants to improve the sweep of oil in the reservoir. These methodologies require significant facility capital to develop the process of generating steam or handling the polymer/surfactant. As such, all these methodologies lead to a significant increase in the carbon footprint of operations as well as increased operational costs when compared to light oil production. There is therefore a need to assess other development strategies that will not require significant cost for development and lead to high carbon intensities. This paper presents practical case studies of development of heavy oil reservoirs in the swamp Niger Delta region without using the traditional super-heated steam or polymer/surfactant injection which lead to increase in carbon footprint. The case studies highlight some of the challenges associated with producing heavy oil (inflow challenges, inadequate vertical lift, early water breakthrough due to adverse mobility ratios, amongst others) and show examples of production optimization methodologies that led to wells achieving peak rates that are comparable to those observed in conventional light oil wells in similar depositional environment and with similar well completion types.