A complete workflow applied on an oil reservoir analogue to evaluate the ability of 4D seismics to anticipate the success of a chemical enhanced oil recovery process

Abstract

In an Enhanced Oil Recovery (EOR) process, one of the main difficulties is to quickly evaluate if the injected chemical products actually improve oil recovery in the reservoir. The efficiency of the process can be monitored in the vicinity of wells, but it may take time to estimate it globally in the reservoir. The objective of this paper is to investigate the ability of 4D seismics to bridge this gap and to help predict the success or breakdown of a production strategy at reservoir scale. To that purpose, we consider a complete workflow for simulating realistic reservoir exploitation using chemical EOR and 4D seismic modeling. This workflow spans from geological description to seismic monitoring simulation and seismic attributes analysis, through geological and reservoir modeling. It is applied here on a realistic case study derived from an outcrop analog of turbiditic reservoirs, for which the efficiency of chemical EOR by polymer and surfactant injection is demonstrated. For this specific field monitoring application, the impact of both waterflooding and proposed EOR injection is visible on the computed seismics. However, EOR injection induces a more continuous water front that can be clearly visible on seismics. In this case, the EOR efficiency can thus be related to the continuity of the water front as seen on seismics. Nevertheless, in other cases, chemical EOR injections may have more moderate impacts, or the field properties may be less adapted to seismic monitoring. This points out the importance of the proposed workflow to check the relevance of seismic monitoring and to design the most adapted monitoring strategy. Numerous perspectives are proposed at the end of the paper. In particular, experts of the different disciplines involved in the proposed workflow can benefit from the availability of a complete set of well-controlled data of various types to test and improve their own tools. In contrast, the non-experts can easily and quickly benefit from “hands-on” experiments for understanding the involved phenomena. Furthermore, the proposed workflow can be directly applied to geological reservoirs all over the world.