Refinement of the petrophysical model of the Achimov formation based on facial analysis of sedimentation conditions

Abstract

Aim. Due to the depletion of reserves of the main oil and gas complexes, the greatest interest is attributed to hard-to-recover reserves, complex-built objects of the sedimentary cover, the development of which was unprofitable until recently. One of these is the oil-bearing complex of the Achimov deposits of the Malobalykskoye field in Western Siberia. This article is devoted to the facies analysis and typification of reservoir rocks of the Achimov deposits in order to increase the reliability of determining the boundaries of the reservoirs, their interpretation and assessment of the petrophysical properties of the reservoirs. At the same time, special attention is paid to the facies analysis, which determines the characteristics of the reservoir. The Achimov deposits are a promising source of increasing resources and maintaining production at a high level. With their increasing importance, there are problems that complicate the search and assessment of deposits. Such problems include a high degree of reservoir compartmentalization, sharp facies variability, complex pore space structure, high clay content, low permeability values, etc. 
 
 Materials and methods. The work is based on a comprehensive interpretation of the data of the lithological description of the core, the results of laboratory studies of the core and well logging data analysis of the Achimov deposits of the Malobalykskoye field. The methods used in the interpretation of GIS data, statistical analysis, comparison. 
 
 Due to the fact that the reservoir properties of sand bodies are determined by the peculiarities of their formation in different conditions of sedimentation, it is necessary to establish a relationship between the petrophysical characteristics of rocks and their facies nature by substantiating petrofacies models. The use of the latter in geological modeling makes it possible to more effectively predict the reservoir properties (reservoir properties) of various facies lithotypes. 
 
 Results. The paper presents the results of facies analysis and typification of the reservoirs of the Achimov deposits of the Malobalykskoye field, on the basis of which the boundaries of the reservoirs and the effective oilsaturated thicknesses were refined. 
 
 Conclusions. Based on the results of the study, it can be concluded that it is necessary to develop refined petrophysical models for reservoirs with complex geological structure that take into account the facies features of rocks.