Undiscovered Hydrocarbon Resources in Well-Studied Territories and Complexes of the West Siberian Petroleum Province

This paper presents a probabilistic approach to estimating undiscovered hydrocarbon resources within relatively well-studied territories, as well as oil-and-gas-bearing complexes of the West Siberian Petroleum Province. The relevance of this study stems from the region’s high level of development and the need to refine the structure of remaining resources, which are primarily associated with small and very small accumulations. Our method is based on analyzing the size distribution of hydrocarbon accumulations using a truncated Pareto distribution, whose parameters are estimated by the maximum likelihood method from a set of the largest accumulations discovered. Monte Carlo simulation is employed to obtain probabilistic characteristics of initial and remaining resources, allowing one to account for variations in the total number of accumulations and their aggregate reserves. The Jurassic and Cretaceous complexes of the continental part of the West Siberian Petroleum Province were selected as the study object, as they exhibit a high degree of geological knowledge and a representative sample of accumulations. The results obtained confirm the applicability of the probabilistic approach to estimating undiscovered resources in mature oil and gas provinces and permit assessment of their uncertainty.