| Abstract |
In 2017, the Salak 3D Modeling Team completed an update of the Salak 3D Static Model that will be the basis for providing earth science-defined conceptual features and reservoir properties for the new Numerical Model of the Salak Geothermal Field. The updated 3D Static Model incorporates Best Practices for interpreting and distributing matrix porosity (Фmatrix) and permeability (kmatrix) and defining the top and base of the reservoir (ToR and BoR). Also incorporated into the updated 3D Static Model data-driven basis for defining the grid orientation, and the interpretation and fieldwide distribution of fracture permeability, permeability anisotropy, and fracture spacing. The updated 3D Static Model uses a different approach to define the distribution of matrix porosity and permeability properties than used previously at Salak. While the previous Static Model used a kriging approach, the updated Static Model includes formations that were divided into Petrophysical Groups (PG) and porosity and permeability measurements from cores for each PG were averaged. In addition, instead of the low, medium, and high cases for ToR and BoR, previoulsy used, the updated 3D Static Model uses a concept-driven approach for the distribution of commercial and connected fractures. These new criteria were modified to describe the fracture system in the geothermal naturally fractured reservoir that has areas of connected but lower permeability at the reservoir margins and commercial, higher permeability area at the core of the reservoir. For the first time, the orientation of the simulation grid for the numerical model is based on the dominant trend of the Effective Fractures (EFs), or fractures that produce geothermal fluids, as determined from borehole image logs. This provides a quantitative basis for defining the dominant permeability anisotropy in the model. Lastly, 3D distribution of fracture permeability and fracture spacing were included in the updated 3D Static Model, and were not in the previous Static Model. The next step involves a collaborative review and update of the parameters for the new Salak Numerical Model during the initial state and history matching phases by a joint Earth Science (ES) and Reservoir Engineering (RE) team. This is key to reviewing the effectiveness of the new Best Practices for defining ES-based constraints for the Numerical Model. As additional lessons are learned, these Best Practices will be reviewed and modified, as needed. |