Integrated Reservoir Characterization Using Petrophysical and Petrographical Analysis

Abstract

A sizeable chunk of spending in an exploration and production activity is expended to characterize a potential hydrocarbon reservoir. Despite the spectacular advances in reservoir characterization techniques and in 3D and 4D modelling, the risks involved in the exploration of new, deeper or diagenetically complex prospects remain large. However, diversity of reservoir rocks and inherent heterogeneity, methods for reservoir characterization, oil field-dependent pore structural model and varying petrophysical flow units pose a great challenge. There is an emerging trend of integration of petrophysical and petrographical analysis to tackle the challenges in reservoirs. Research shows that more than 60% of world’s oil and 40% of world’s gas reserves are held in carbonates. So, the characterization of carbonate reservoirs becomes a major concern. But producing oil and gas from carbonate reservoir is a challenging task. Since carbonate reservoirs are often naturally fractured that show varying wettability characteristics and complex porosities which significantly affects their multi-phase flow properties, production from such reservoirs pose a challenge. In carbonate reservoirs with time, rocks containing water and oil turns initially water-wet rocks into mixed-wet or even oil-wet rocks which is not the case with a sandstone reservoirs which are mostly water-wet. Therefore, characterization of wettability and its effect on fluid flow for a heterogenous reservoir would be crucial in computing the producible reserves. This paper deals with the analysis of conventional core samples from the Vindhyan Basin of India for reservoir characterization. It is envisaged that the work will provide a model which can be sued to determine the reservoir architecture, establish the fluid flow trend and identify growth potential of a reservoir. Here, the work focuses on reservoir characterization using petrophysical and petrographical analysis. Porosity studies in reservoirs require accurate mineralogical characterization. This is achieved by a petrophysical analysis which involves X-Ray Diffraction (XRD) analysis which will help in determining the properties of reservoir like porosity, permeability, lithology, water saturation and density. The petrographical analysis involves the preparation of samples for the thin section that are then observed under the microscope. These thin sections reveal the detailed description of rocks that provides information about depositional facies, diagenetic history and porosity system. The integrated approach and structured methodology developed in this study will result in developing a good simulation model with adequate resolution of data that simulate the production history with sufficient realism.