SAGD Reservoir Characterization Considerations – Part 1 of 2 BY MARK SAVAGE, P.L.GEO.
INTRODUCTION The reservoir characterization process (the process) is the foundation for subsurface deliverables. The extent of the detail and focus areas required for the process are influenced by the overall project scope, schedule, and budget. The process should incorporate cross-functional (finance, facilities, etc.) and multidisciplinary (geoscience, reservoir engineering, etc.) input. This process has been used for a range of project decisions, up to significant decision gate (DG) milestones, DG1 (concept), DG3 (sanction), Figure 1, and resource and reserve determination and validation. By following this process, a thorough understanding of the steam-assisted gravity drainage (SAGD) asset potential and uncertainty can be gained. With some minor modifications, the workflow and considerations could be used across different asset types.
A vital component of the process is multidisciplinary collaboration. As a minimum, the following disciplines should be involved: geology, geophysics, petrophysics, geomodelling, and reservoir/production engineering. Depending on the project specifics, other cross-functional disciplines may be required: field operations, facilities, project engineering, drilling and completion engineering, risk analysis, and finance. There are three stages to the process workflow: data collection and geoscience analysis, petrophysical analysis and geomodel development, Figure 2. The 3-D geomodel and simulations are dynamic and may need updates from new learnings and information.
Each stage of this workflow will influence the degree of uncertainty captured in the performance predictions. These predictions are used to assess volumetrics, greenfield or brownfield optimal facility design capacity, number of wells required Figure 1: Simplified Decision Gate Example (Source: Savage, M., 2020) for a field or pad startup, and the schedule for production rate sustaining pads. The schedule should incorporate performance learnings and required modifications from the producing pads, e.g. updated 3-D geomodels, type curves, and simulations.
“A vital component of the process is multidisciplinary collaboration. ”
Figure 2: Reservoir Characterization Workflow (Source: Savage, M., 2020)
This commentary is part one of a two-part paper and addresses the data collection component of the process. Part two of the paper will address the petrophysical analysis and geomodelling components of the process.
