Multiscale flow unit characterization in a mature field using capillary pressure curves, well logs, and petrophysical data – an example from the Potiguar Basin, Brazil
mature fields, hydraulic flow unit, reservoir management, rock typing, petrophysics
This study integrates geological/geophysical, petrographic/diagenetic, and petrophysical data to individualize rocks with different flow capacities producing oil in a field in the Potiguar Basin, NE, Brazil. The work used information from more than 800 vertical wells, 19 of which have rock data and petrophysical analysis. Seven wells provided most of the data for the present study because of the greater thickness of cores recovered. Implementing the multiscale approach that we presented was essential in understanding the geological aspects that influence the reservoir production capacity. At the micro scale, for example, through the study of thin sections, it was possible to identify and recognize clay minerals that occur may obstruct pore throats and, consequently, affect the permeability and productivity of the rocks. At the meso scale, the study of cores in different portions of the field allowed us to characterize the depositional systems in the area and identify factors that influence the entry of oil into the reservoir. Finally, through the correlation of rock vs. profile at the macro scale, we estimated the distribution of the flow units defined for the other wells, thus allowing the construction of maps and petrofacies sections with geological and dynamic significance. At this last scale, we visualize the geometry of the sedimentary deposits and their heterogeneities, whose understanding directly influences the planning and development of an accumulation (for example, in the definition of the production wells grid and water or steam injection in case of application of secondary recovery methods). Additionally, we developed a methodology to quantify the production capacity of the rocks from a reservoir quality index (RQI) that we validated with field production data.