A Hybrid Scheme for the Sustainable Production of High Water Cut Unconventional Extra-Heavy Oil Reservoirs: First Simulation Predictions for the Orinoco Oil Belt-Venezuela Shows Hope!

Abstract

The production of heavy, extra-heavy and bituminous crude oils with high-water cuts is a key challenge that requires applying technologies with high economic value and less environmental impact, especially, water management and CO2 emissions. This study proposes a hybrid production scheme based on chemical enhanced oil recovery (surfactant and polymer flooding), switching wells with high-water cut to produce geothermal energy, together with CO2 injection and eventually storage in a highly viscous oil reservoir in Venezuela. A cluster of wells of the Orinoco Oil Belt with marked variation in water cut and with recovery factors of less than 5% was selected for this study, where the current production methods are cold production, CSS (Cyclic Steam Stimulation) and downhole electrical heating. Laboratory tests were matched with the simulation of surfactant and polymer flooding, and CO2 injection (compositional model), independently. The lab tests were performed using fluid and rock samples from the evaluated cluster. Additionally, some wells were adapted/converted to predict the geothermal energy scope through a smart heat exchange process that is highly recommended to support clean energy production from these deposits. Finally, different injection and production schemes were tested and evaluated, and optimization of scenarios was reached. Results of this study show that the injection of surfactants and polymers in the same mixture, under secondary conditions, allows an increase in oil production in the selected cluster by virtue of mechanisms such as mobility control and mobilization of residual oil. The effect of the injected and stored CO2 on the recovery of hydrocarbons was assessed, as well as the possible mechanisms involved in this immiscible process. The application of deep-low temperature geothermal energy (enhanced by downhole electrical heating) is an appealing option for water management and clean energy production in the evaluated field. One of the greatest challenges of the hybrid method is associated with the simultaneous management of the CEOR, CCUS, and geothermal processes in both reservoir and at surface. This coupled with surface facilities operational challenges related to the management and separation of fluids, complex emulsions, water treatment, corrosion and scales, flow assurance issues, adequate heat-transfer throughout the production system; along with issues of reservoir caprock integrity for the CO2 storage as well as economic and process safety considerations. These real challenges will determine the faith and, hence, the implementation of the proposed hybrid scheme. This study proposes an innovative scheme to produce sustainable energy with low cost and environmental impact in the Orinoco Oil Belt, where the largest reserves of highly viscous crude oil on the planet are located. This study presents a methodology for water management, CCUS and exploitation of the geothermal energy from wells of high water cut and less value, which could be extrapolated to other deposits in Venezuela and worldwide.