Joint research project to help hit the geothermal drilling “sweet spot”

Joint research project to help hit the geothermal drilling “sweet spot” Darajat III geothermal plant, Indonesia (source: Thorndon Cook)
Carlo Cariaga 17 Jan 2022

Results of the research by Star Energy Geothermal and Schlumberger will be validated by a drilling campaign in the Darajat geothermal field in Indonesia

Star Energy Geothermal (SEG) and Schlumberger have completed a research project called “Fracture Characterization and Optimized Well Placement” (FCOWP). Through fracture characterization, the research aims to increase the likelihood of successful well drilling, thereby lowering the costs of geothermal drilling and power production.

“This project is one of our ongoing efforts to implement innovation and technology to reduce the LCOE (Levelized Cost of Electricity) of geothermal energy. Drilling costs are one of the main cost components of geothermal energy costs. The application of this technology will allow us to drill in the right place with better accuracy and results, which leads to reduced drilling costs and geothermal energy costs,” said SEG Chief Executive Officer Hendra S Tan.

Modeling approach

In geothermal fields, subsurface permeability is accessed by drilling into naturally occurring fractures. There is low certainty with regards to the locations, orientations, and intensity of these fractures during the initial phases of development. As more wells are drilled, the fracture model for any given field becomes more developed.

For this research, the Darajat Geothermal Field of SGE was identified as the primary study area. Data on known permeability of the drilled part of Darajat was used to generate a model that will then be used to predict the distribution of fractures in the undrilled region.

Modeling is divided into two stages. In the first stage, the orientation and intensity of fracture distribution is modeled. The second stage is automated to generate the model of the width and length of the fractures, and to validate this model with the existing well data.

The role of fracture drivers is considered in the models. Known fracture drivers include the stresses that occur in rocks and the presence of magma intrusions in the geothermal systems.

Model validation

According to SEG Chief Asset Management Officer Ken Riedel, the results of the research will be used to improve drilling results for the three geothermal fields operated by SEG. The first application will be in the 2022 drilling campaign of Darajat. Drilling campaigns in Salak and Wayang Windu will follow.