Hydrocarbon and Non-Hydrocarbon WAG Processes: A Simulation Approach

Abstract

Development and application of enhanced oil recovery (EOR) processes in layered heterogeneous carbonate reservoirs has been considered a real challenge and a difficult endeavor. A multi-layered heterogeneous carbonate oil reservoir was screened and selected as a good candidate to investigate the feasibility of Water-Alternating-Gas (WAG) process using both hydrocarbon and non-hydrocarbon gases. An integrated reservoir characterization model and the pertinent transformed reservoir simulation history matched model were developed. The main objective of this work is to define the development process that could provide the maximum ultimate recovery factor of more than 70% IOIP. This could increase the total technical reserves by 30 % over the reserves based on classical water flooding reserves. The attained results are used to conclude that the life of the field could be extended and almost doubled. The results also indicated that the best technical development process that provides maximum ultimate recovery factor of more than 70% was the H 2 S-WAG development process. The enriched-WAG development scheme can be designed to give an equivalent ultimate recovery factor by enriching the gas. The N 2-WAG development process gives a relatively poor recovery factor. This is the lowest of all the Non-hydrocarbon Gas Injection (NHGI-WAG) development processes investigated.