Initial Data Preparation for Naturally Fractured-cavernous Carbonate Reservoirs of Osinskiy Horizon Geological Modelling

Abstract

A significant part of hydrocarbon resources of Leno-Tungussian oil-and-gas province is confined with carbonate deposits of Osinskiy horizon (O-1 formation, Billirskaya suite), represented by ancient Paleozoic limestones and dolomites, most of which have mixed cavernous-porous and fractured-cavernous type. One of the main difficulties in developing geological models of such complex reservoirs is the selection of modelling algorithms that allow to reproduce the high heterogeneity of their filtration-capacitive properties associated with the impact of post-sedimentation processes and the non-linear geometry of the void space. In this paper, we present the results of the collection, processing and analysis of primary geological and geophysical data that precedes the stage of full-scale geological and hydrodynamic modeling. The main features of the considered object, located in the central part of Nepskiy arch (Nepsko-Botuobinskiy region), are a large size of modeling area and a number of production wells, which makes it difficult to provide the required amount of special researches. An important factor is the significant loss of accuracy during geological model upscaling process and the necessity to maintain adequate duration of hydrodynamic calculations. Thus, a certain compromise is required between the detail level, the size of the model and time costs of its creation.