Optimisation of a Geothermal Reservoir: A Case Study for Parryland Field

Abstract

The increasing global demand for energy and the pressing need for sustainable resource utilization have compelled societies to seek cleaner alternatives due to the rapid depletion of fossil fuels and environmental concerns. Despite having benefited substantially from its fossil fuel resources, the country of Trinidad and Tobago (TT) has fallen behind other Caribbean Nations in its transition to cleaner energy.  Geothermal resources can be leveraged using existing infrastructure through the transformation of abandoned oil and gas wells into geothermal wells as an innovative, low cost means of advancing sustainable energy initiatives. This study focuses on optimising this transformation, using the abandoned Parryland Field in Southwestern TT as a case study. The initial geothermal reservoir model, constructed using the Computer Modelling Group (CMG) software, underwent key sensitivity analyses involving well spacing, injection rate, and the selection of working fluids. These analyses led to the development of an optimised model with the implementation of a retrofitted geothermal system, consisting of 3 injector wells and 3 producer wells which yielded 184.8 GWh of electricity over a 30-year period. In terms of the economic viability, the optimised configuration generated a positive Net Present Value (NPV) based on a deterministic cashflow model, which also predicted a favourable investment risk profile when subjected to Monte Carlo Simulations using the Crystal Ball software application by Oracle. Furthermore, harnessing the geothermal energy for power generation resulted in a reduction of 157.1 MMlbs of CO₂ emissions when compared with electricity produced using natural gas. This reduction is projected to occur over a 30-year period, facilitated by the utilization of 5.254 billion BTUs of enthalpy.