The brain of a waterflood project is a geological framework that defines reservoir continuity relative to its transmit fluids as well as restrict fluid movement. The lack of geological knowledge results in the misleading interpretation and understanding of the reservoir behavior. This paper presents an integrated geological aspect, concept and approach to design an effective well pattern and well spacing in waterflooding. This method is proven to improve sweep efficiency and lead us to make an EOR planning in our field. T Field is one of the mature fields where a successful waterflood project has been implemented in Indonesia
Detailed core description with sedimentary structure analysis, paleocurrent analysis in FMI data and various property maps were conducted to identify the relationship between injection and production well. It also gives the information about movement of injected water. The sediment transport suggests some directional anisotropy in permeability. The distribution of geological heterogeneities and their influence on fluid flow characteristics were determined by generating maps and cross sections based on integration of log, core & petrographic data and qualitative information from production data. Parameters mapped included the distribution of porosity, log derived geometric mean permeability, clay content, and Dykstra-Parsons coefficients of permeability variations.
The results of this study showed a good correlation of facies distribution and sedimentation direction with flow of water movement behavior. The direction indicated relatively west to east sediment transport being perpendicular to the structure. It was also matched with tracer survey analysis and simulation model. In our success story, we applied the staggered line of full scale waterflood pattern to maximize the areal sweep efficiency and improve 5-7% recovery factor of total OOIP. This information also strongly supports the building of reliable static and dynamic model.
We proved that an integrated geological approach, including a good understanding of facies and sedimentation characteristics of reservoir will lead us to build successful waterflood and EOR project in the future.