Potential for geothermal heat mining by analysis of the numerical simulation parameters in proposing enhanced geothermal system at bongor basin, chad

In this paper, the feasibility of power generation from an enhanced geothermal system (EGS) located beneath an oilfield at the Bongor basin in Chad was examined through the analysis of numerical simulation parameters. A 3D geometric model is constructed to represent the proposed EGS and a thermo-hydro-mechanical (THM) coupled mathematical model was used in the simulation process to link all inter-dependent parameters of heat mining. Oilfield warm water is anticipated to be the circulating fluid of the thermal reservoir due to its ready availability from high water-cut oil wells. Chad depends heavily on a diesel power plant, thus this work further proposes the utilization of carbon dioxide (CO2) from the power plants to be used as heat mining fluid and likely CO2 sequestration into deep granite formation. The results indicate that the implementation of EGS beneath the current oilfield would have significant advantages both technically, environmentally, and economically. Oilfield produced water at warm temperatures improved heat mining efficiency and utilization of oilfield water in geothermal wells will reduce costs involved in water treatment and disposal. The geothermal gradient is sufficient to produce water at a higher temperature that can be utilized commercially by different binary power plants. Utilizing CO2 as heat extraction fluid showed significant heat extraction, higher than using oilfield produced water. Furthermore, substantial amount of CO2 can be deposited into the formation, thus reducing emission of greenhouse gasses to the atmosphere.

Automated summary

The study found that implementing an Enhanced Geothermal System (EGS) beneath the oilfield in the Bongor basin in Chad presents significant advantages in terms of technology, environment, and economy. The use of oilfield produced water and CO2 as heat extraction fluid can improve heat mining efficiency and reduce costs.