The Potential of Geothermal Energy Combined with Carbon Capture and Storage in Trinidad and Tobago

Abstract

Even without volcanic formations, Trinidad and Tobago can harness geothermal energy from depleted oil reservoirs with the additional benefit of storing Carbon Dioxide (CO₂) in them. This paper evaluates the combination of CCS technology with geothermal energy production utilizing CO₂ as the working fluid using the EOR 4 depleted oil well in the Forest Reserve Field in South-Western Trinidad. A reservoir model was created using CMG to test the reservoir’s geothermal viability and CO₂ storage capacity. CO₂ storage was done using hysteresis and solubility in water since it would not be trapped while being returned to the surface for energy production. The base model constructed was optimized for maximum energy production using a CMOST sensitivity analysis varying specific parameters (matrix porosity, matrix permeability, fracture spacing, rock permeability, thermal conductivity, heat capacity). The optimal dual permeability model had a well spacing of 400 m with an injection pressure of 20,000 kPa. The CO₂ model had a production rate of 1.87 x 10⁶ kg per day and produced 1.997 x 10¹⁶ J of energy, whereas the H₂O (water) model had a production rate of 1 x 10⁷ kg per day and produced 8.475 x 10¹⁵ J of energy. The amount of CO₂ stored was 4.7004 x 10⁷ kg. The total CO₂ reduction was 1.984 x 10⁹ kg compared to using Natural Gas. The sensitivity analysis showed fracture spacing had the largest impact, increasing enthalpy produced from 7.2 x 10¹⁴ J to 1.57 x 10¹⁵ J. The plant would effectively cost US$ 1,061.24 per kW, which is superior in cost efficiency. This study demonstrated the enormous potential for using CO₂ as the working fluid for geothermal power generation in abandoned oil wells such as EOR 4 and offers a low-carbon energy generation strategy associated with a carbon emission reduction technology.