Petrophysical techniques for asset analysis in the Permian Basin

Abstract

Three things that factor into proving the value of an oil and gas asset are whether or not that asset consists of quality acreage, is accompanied by a solid analysis, and has available producible reserves. By utilizing Petrophysical data, insight can be gained into where an asset holds its current value, and how much potential it may have for future further development. The stratigraphic focus of this investigation is the Wolfcamp Formation and each of its shale benchmarks. By utilizing petrophysical models, log calculations, and cross plotting methods, with available well and log data spanning the Texas counties of Midland, Reagan, and Glasscock, an accurate assessment of the hydrocarbon potential, and key reservoir characteristics of the area can be made. Considering a series of assumptions delineated from previous research methods, (1)organic-rich sediments have a higher resistivity than organic-lean sediments, (2)organic-rich rocks decrease in sonic transit time and increase in resistivity, and (3)organic-rich rocks can have a higher gamma-ray reading than ordinary shale and limestone. Keeping these assumptions in mind, the total organic carbon (TOC) of the Wolfcamp Shale throughout this area can be isolated using log calculations and cross plotting techniques focusing on a modified ∆ log R method that incorporates sonic vs. resistivity data. Petrophysical Log Curves for porosity, volume of shale, permeability, and water saturation are then calculated and generated from available log curve data to further indicate the potential of this area. These log curves are utilized in a zone attribute analysis to calculate the water saturation and porosity at each Wolfcamp benchmark throughout Midland, Glasscock and Reagan counties. Utilizing the modified ∆ log R method, the logs for wells in this area indicate that the Wolfcamp shale benchmarks appear to have good TOC, and therefore, are prospective for hydrocarbon production. Attribute maps of generated porosity and water saturation values throughout the area show an increase in porosity with each subsequent Wolfcamp bench and variable water saturation throughout the Wolfcamp zone, displaying fluid distribution trends. Further analysis of petrophysical log curve data incorporated into area Cross Sections highlights potential pay zones.

AAPG Datapages/Search and Discovery Article #90266 © 2016 AAPG Pacific Section and Rocky Mountain Section Joint Meeting, Las Vegas, Nevada, October 2-5, 2016