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Geochemical Characterization of Drill Cuttings to Improve Facies Classification Schemes, Refine Depositional Models, and Serve as a Predictive Tool of Rock Properties in the Delaware Basin

Abstract

The Delaware Basin of West Texas is one of the most actively drilled sub-basins in the United States. Current Permian-aged hydrocarbon targets include the Bone Spring and Wolfcamp Formations, which consist of alternating successions of calcareous, siliceous, and argillaceous sediment. The delivery of sediment into this mixed carbonate-siliciclastic system reflects the interplay between four dominant depositional mechanisms (debris flow, density flow, turbidity flow, and suspension settling), coalescing into an extremely heterogeneous rock record that varies on the log to sub-log scale. Traditionally, geophysical well logs and drill cores have been utilized to address the subsurface heterogeneity present in this system. However, with a sparse distribution of modern well log suites and limited access to conventional core, drill cuttings are a pervasive resource that can be utilized to determine rock properties and adequately characterize reservoir units. The goal of this study is to integrate geochemical methods (XRF, XRD, LECO TOC, and programmed pyrolysis) with nuclear magnetic resonance (NMR) techniques on drill cuttings to demonstrate their utility in determining important rock properties, such as organic content, minerology, and porosity. This workflow will be applied on 100 wells across the Delaware Basin to create a comprehensive geochemical framework to test, 1) if a geochemically defined facies classification scheme, from 10ft cuttings, adequately characterizes the lithologic heterogeneity present in the Permian interval of the Delaware Basin, and 2) if this facies classification scheme can be used as a predictive model for rock properties in adjacent wells.