A road map for improving the technical basis for the estimation of petroleum reserves

Reserves estimation can be based on one or more methodologies, each with its associated uncertainty. These include ‘static’ volumetrics, reservoir simulation, material-balance analysis, and/or projections of ultimate recovery according to production decline. The static volumetric method is in focus here, as the most commonly used approach during the development and early production stages when there has been limited petroleum recovery and the uncertainty associated with a reserves estimate can be considerable. There are several key technical aspects of the static volumetric process, including: the issue of minimum data requirements in relation to reservoir complexity; the upscaling of reservoir parameters and the interpretative algorithms through which they are interrelated; the identification of net reservoir and net pay; and the integration of data sources in a manner that is dynamically conditioned, i.e. tied back to permeation properties. This last point is especially important because reserves, by definition, are commercially recoverable. Suggested improvements reveal additional opportunities for cross-validation and groundtruthing. The approach is synthesized into a high-level, yet pragmatic workplan. It is proposed that the adoption of such a workplan will remove some of the uncertainty that is currently inherent in the technical process for estimating reserves.