Evaluation of the Geothermal Potential of Produced Water in a Llanos Orientales Reservoir Using Numerical Simulation

Problem, Objective, and Scope:

Produced water in oil reservoirs contains a significant amount of thermal energy that, in most cases, is not utilized. Wells with high water cut are often considered candidates for abandonment due to their low profitability in terms of hydrocarbon production. However, from a geothermal perspective, these same wells can become strategic assets for energy generation. This work aims to evaluate the thermal potential of more than 110 wells in a field located in the Llanos Orientales basin, with average reservoir temperatures of 250 °F, identifying those with the highest cumulative energy contribution and viability for a pilot geothermal utilization test.

Methodology:

A thermal compositional model was used to reproduce the production history of the field, incorporating variations in temperature, water cut, and saturation. A semi-analytical vertical flow model was coupled to each well to estimate thermal losses to the surface and calculate the useful energy content at the wellhead. A comparative analysis of all wells was carried out, classifying them according to their cumulative delivered thermal energy, based on flow rate and produced water temperature. Finally, a technical ranking of the wells with the highest geothermal potential was developed to advance toward a pilot test design stage.

Results:

The results show that several wells exceed 4.5×10⁷ BTU/day of useful thermal energy, making them technically feasible to supply low-enthalpy thermal conversion systems such as ORC cycles or heat exchangers. Thermal simulation enabled quantification of this potential realistically, even considering energy losses in flow from bottomhole to surface. Ten wells with ideal conditions for future implementation were selected, demonstrating that those historically considered of low value due to their high water cut can now be leveraged from a sustainable energy perspective.

Conclusion:

This study demonstrates that wells with high water cut, commonly considered uneconomic and candidates for abandonment, can acquire new strategic value as sources of recoverable thermal energy. The combination of reservoir thermal models with semi-analytical well tools constitutes a robust and replicable methodology for assessing geothermal opportunities in oil fields. This strategy contributes to the industry’s energy transition, optimizing the use of existing resources and reducing the energy footprint of conventional development.