Downhole Electrical Heating System: Feasibility of Heavy Oil Implementation in Offshore Congo

Abstract

Abstract The heavy oil reservoirs exploitation is one of the future targets of the major oil companies worldwide. Most of the heavy oil fields are produced through cold production methods leaving therefore significant amounts of unproduced reserves. To date different EOR techniques (like for instance steam injection or other thermal methods) are available to achieve higher recovery factors. However, some technologies, like the downhole electrical heating have been recently improved, allowing cold production enhancement therefore maximizing the recovery factor without incurring on the high investments associated to the implementation of EOR. In order to increase the production of the heavy oil reservoir in the offshore Congo, a study of down hole electrical heating application has been carried out showing encouraging results. The aim of the study was to evaluate the benefit associated with the application of this technology through the reservoir modeling. Significant results were achieved in terms of recovery factor increase. The use of heat to increase the reservoir temperature showed good results in terms of heavy oil viscosity reduction starting from 1,000 cP at reservoir conditions (34°C) down to much lower values throughout the production time resulting in increased production rate and consequently, higher recovery factor from this reservoir. The first application of this technology is foreseen in a long horizontal well section of about 600 meters length completed with production sand screen. The electrical heating mineral insulated three phase cables will be deployed throughout the horizontal well section by means of a dedicated completion tail pipe. Several design challenges have been faced to properly centralize the heating cables and clamp the same around the completion tail pipe due to the well size constraints.