Resource assessment of the Tecuamburro geothermal system using reservoir simulation

Abstract

The Tecuamburro geothermal area is located in southeastern Guatemala along the Central American chain of volcanos. Thermal surface manifestations are found over an area of nearly 400 km2. Major hot springs and fumaroles are located at Laguna Ixpaco, along Rio Los Esclavos, and east and northeast of the volcano. Geothermometry analysis of these manifestations yields temperatures of 150 – 300oC. Previous work done by Los Alamos National Laboratory, the US Geological Survey, and the Instituto Nacional de Electrificacion in geology, geochemistry, geophysics, and the drilling of one cored well, named TCB-1, suggests that there could be a promising geothermal resource. The geoscience information was reviewed, the conceptual model was updated, and a digital conceptual model was developed to create a new reservoir model. This paper describes the model creation based on our geothermal modeling framework; this model can be run either in AUTOUGH2 or Waiwera. The new model integrates geology, geophysics, faults or structures, alteration zones, reservoir engineering and drilling data, resulting in a robust reservoir model. The model produces good results in matching the temperature profile of well TCB-1, surface features, and temperatures below the clay-cap in Tecuamburro and Infiernitos. Base on this new model, an uncertainty quantification analysis was performed with 1000 sample models for the natural state. The models were filtered based on the temperature profile of the well and temperatures below the clay cap using Approximate Bayesian Computation (ABC) resulting in 100 acceptable sample models that were used to perform a resource assesment applying an innovative method that ran each filtered model for a maximum potential production scenario over 25 years. Results provided by this novel approach give a resource assessment that includes the same information used in traditional stored heat calculations but also takes account of reservoir and wellbore physics and a realistic energy extraction and injection strategy, thus providing a more accurate forecast.