Feasibility Study of Thermal EOR Techniques in Unconventional Heavy Oil Reservoirs in the Niger Delta: An Experimental and Numerical Simulation Approach

Abstract

Abstract The exploration and production of unconventional hydrocarbon reservoirs have gained significant attention in recent years due to their increasing importance as a source of energy. Acquiring a comprehensive understanding of the unique characteristics of unconventional reservoirs is essential to optimize the recovery of these resources. The Niger Delta region, while currently undergoing the secondary recovery phase for some conventional projects, has significant potential for unconventional hydrocarbon reserves. This study employed a combination of laboratory experiments and numerical simulations to evaluate the feasibility and recovery efficiency of steam flooding and hot water injection for heavy oil recovery in unconventional oil reservoirs in the Niger Delta region. Core samples with a porosity range of 7% – 10% were used in the laboratory examination of steam flooding performance. 2D homogeneous reservoir models with two wells were developed using a reservoir simulator to match the steam flooding experiment and to simulate hot water injections for each core sample. Three independent parameters (injection rate, injection temperature, and injection pressure) were used in each model. The Box-Behnken Design was used to generate simulation runs per the observed recovery method using the maximum and minimum values of the independent parameter. Formation's porosity and permeability range variation was accounted for in the model using Uncertainty analysis. The Experimental design software was used to examine the input and output data and generate a Response Surface model (RSM) that correlates recovery efficiency and the independent parameters. Results indicate that steam flooding is a more practical/feasible solution for heavy oil recovery in these types of reservoirs with an average of 11% recovery. The study provides valuable insights for future field development and production planning in low-porosity unconventional reservoirs.