Integração de dados petrofísicos, petrográficos e de técnicas de inteligência computacional para a caracterização litológica de reservatórios de petróleo

Abstract

Lithology is the description of the physical and mineralogical characteristics of a rock unit or rock formation. Its definition in oil wells through multiple electrical and geophysical profiles has an important role in the reservoir characterization process. From the lithology, models can be generated based on which petrophysical calculations are made. Then they can be used in flow simulators to understand the behavior of an oil field. Direct and indirect methods can carry out the identification, but they are not always feasible due to the results’ cost or imprecision. Predictive models for the distribution of heterogeneities and quality in hydrocarbon reservoirs are fundamental for exploring and optimizing the production of oil and gas fields. Heterogeneities are determined employing different petrofacies, a set of petrographic characteristics that specify a group of rocks. The procedure of identifying petrofacies is generally long, which makes automation necessary to speed up the process, and thus the analysis is completed quickly. It is possible to obtain information about the reservoir rocks through its determination, such as their depositional and diagenetic history, pore structure, and mineralogy. In this context, computational intelligence techniques appear as an alternative to discriminate lithology and petrofacies. This work aims to develop a methodology capable of assisting in the characterization of oil reservoirs. Lithology and petrofacies were derived from the recognition of patterns of petrophysical and petrographic characteristics, respectively. The characteristics were analyzed through Principal Component Analysis. Supervised methods were used to classify samples and evaluate how new samples will be distributed. To find the optimal classifiers, the differential evolution method was applied. Techniques to increase dimensionality were used as a way to evaluate the behavior of the methods used. Phylogenetic Analysis was used to understand the process of diagenesis that occurs during the lithification process of sedimentary rock and the identification of the events that occurred during this process. The presented methodology appears as an alternative to assist the geologist/petrologist in characterizing an oil reservoir.