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Application of Geosteering and Log Property Modeling in Unconventional Shale Reservoirs

Abstract

The key to understanding any unconventional shale play is through the use of multidisciplinary tools that facilitate the integration of geological, petrophysical, and production data. Use of a geosteering solution in combination with a unified petrophysical application delivers a simple yet powerful workflow for conducting post-drill analysis by integrating results that are used to explain production data in the Eagle Ford Shale. An integrated approach has been applied with the goal of identifying important stratigraphic units within the unconventional reservoir that are targeted as favorable intervals for oil/gas production in horizontal wells. A stratigraphic framework was established where key sequence boundaries and flooding surfaces were identified based on well logs (DLogR), geochemistry, core descriptions, and biostratigraphy. Petrophysical properties and core measurements offer insight into the mineralogy, brittleness, porosity, permeability, and fluid saturations of the reservoir. Pyrolysis measurements provide valuable information on the total organic content, level of maturity, and oil yield derived from the source rock. The result of this integrated study has helped us confirm that the most productive targets for oil are carbonate-rich facies with good storage capacity that lie stratigraphically above the organic-rich intervals. The carbonate-rich facies are characterized by mechanical properties that are conducive to forming extensive fracture networks during hydraulic fracturing. By integrating the overall stratigraphic framework with the log responses observed in pilot or vertical wells that penetrate the reservoir, forward modeling in true stratigraphic thickness can verify the precise wellbore placement of nearby horizontal wells relative to the target zone. In addition, stratigraphic projection of log properties such as Young's Modulus or Poisson's Ratio can be displayed as a backdrop along the horizontal wellbore to aid with post-drill interpretation.