Development of comprehensive methods for multivariate calculations of the effective oil and gas-saturated volume of objects with complex geological structure

Probabilistic assessment of the resource base occupies a central place in the decision-making process at the stages of prospecting and exploration of hydrocarbon deposits. The accuracy of the results of such an assessment directly correlates with the reliability of identifying uncertainty intervals for the calculation parameters and the probability of discovering new deposits, and also affects the determination of the further program of geological exploration work and the calculation of predicted production profiles. In addition to the standard procedures for geological uncertainties evaluation, for example structural framework construction errors (stratigraphic boundaries positions) and fluid contacts, 2D/3D geological models multivariate calculations require accounting variation of lithological boundaries as well as setting trends based on conceptual understanding. This article presents approaches to net pay volume multivariate modeling of lithologically screened deposits confined to the Lower Cretaceous deposits of the Achimov formation and the Middle Jurassic deposits of the Tyumen formation. The developed methods enable taking into account the uncertainties associated with variations in the shape and size of the sedimentary bodies and associated lithological barriers as well as the resolution limitations of geophysical research methods - at the level of parameter map sets. The level of detail of the final maps is comparable to the results of full-scale multivariate calculations based on 3D geological models, but the calculation speed is significantly higher, which is relevant for large-scale exploration projects under tight deadlines.

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