Invited Keynote Address


Reserve estimation can be based on static volumetric data, utilize reservoir simulation, incorporate a material-balance method, and/or draw upon projections of ultimate recovery according to production decline. The static volumetric method is the primary approach during the development and early production stages, when the uncertainty associated with a Reserve estimate is greatest. Here, key technical aspects of the process include; upscaling reservoir parameters and the interpretative algorithms through which they are interrelated; the issue of minimum data requirements in relation to reservoir complexity; identification of net reservoir and net pay; and the integration of data sources in a dynamically-conditioned manner. This last point is especially important, because Reserves are by definition 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 adoption of such a workplan will reduce some of the uncertainty that is currently inherent in the technical process for estimating Reserves.


Different certifiers can generate significantly different Reserve estimates for a particular field using the same database at a given point in time. This is because Reserve estimation has a subjective element, especially in assessing the range of technical uncertainty. The situation is compounded by the absence of generally accepted protocols for addressing some of the more contentious interpretative issues in petroleum geoscience and geoengineering, especially during the early life of a field when uncertainty is greatest. Yet, users of Reserve information often presume that sound technical methodologies underpin the reported numbers. This paper examines some of the key technical aspects of the Reserve estimation process within the context of reservoir maturity and taking due account of data reliability. The aim is to improve the consistency of approach to Reserve estimation and thence to identify ways of achieving a higher degree of confidence in the reported figures. Initially, Reserve definitions and Resource classification are briefly reviewed for completeness. In essence, Reserves must be discovered, recoverable, commercial and remaining (in a reservoir), and there must be a development plan. They are a subset of Resources, which comprise the total volumes of hydrocarbon accumulations.

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