Petrophysical clustering of carbonates by complex analysis of a wide range of geological and geophysical data to clarify the reservoir filtration properties

Background. Evaluation of filtration-capacitance properties of fractured carbonate section in most cases is associated with difficulties due to the high lithological heterogeneity of deposits, heterogeneity of properties both along the section and laterally, the complex structure of the void space of collectors, and most importantly, the presence of a system of fractures that causes fluid filtration in reservoirs of this type. For a more homologous modeling of filtration behavior and achieving the maximum production level, it is important to carry out a differentiated study of the filtration-capacitance properties of the carbonate reservoir

Aim. Within the framework of the work, the methodology of petrophysical typification of complex carbonate deposits of the Bashkir tier was developed. Now there is a wide variety of modern methods for the differentiated assessment of the filtration properties of carbonate reservoirs, including the use of the results of the interpretation of Hi-Tech methods and various statistical algorithms. The purpose of the work was to test the recommended methods by leading manufacturers of downhole equipment and software vendors to identify the most optimal and effective solutions.

Materials and methods. The Bashkir tier reservoirs were typified by integrated analysis of the results of HI-TECH methods, core studies, production data and well logging by involving the appropriate algorithmic base, as well as machine learning methods at the clustering stage

Results. Based on the results of combining the results of fracture assessment using various algorithms for the analysis of borehole materials, petrotypization of the studied carbonate section was performed and an electrofacies model was developed that allows the prediction of selected petrotypes for a specific well logging data complex using machine learning methods in automatic mode.

Conclusions. The identification of reservoir types by well log data is the first step to their differentiated study. Differentiated study is important because it allows you to more accurately determine the characteristics of the formation. Hydrodynamic studies, in which intervals with different types of void space simultaneously participate, lead to an ambiguous interpretation. In the proposed research program in new exploration wells, the typing of reservoirs according to the described methodology is an important element in the scheme of hydrodynamic and core studies. The presence of fractured reservoirs in the section has a significant impact on the drainage of the deposit and approaches to the development of the deposit, which makes it necessary to consider this feature in the hydrodynamic model to reproduce the characteristic effects of the presence of a system of fractures. The goal of differentiated research is to build a hydrodynamic model of a dual porosity and permeability.

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