Relative Quantification of Diagenetic Processes Using Close-Range Hyperspectral Data in Deltaic Deposits of Frontier Formation, Wyoming.

Abstract:

Compositional variations related to diagenetic processes can alter fluid flow and permeability of underground reservoirs (hydrocarbon and/or groundwater). Portable hyperspectral cameras had opened up new horizons for mineralogical characterization at different scales: from hundreds of meters (outcrop) to millimeters (laboratory specimens). The purpose of this study is to map mineral composition at an outcrop scale and relatively quantify lateral and vertical mineralogical variations caused by diagenetic processes at microscopic scale. Visible Near-Infrared (VNIR) and Shortwave-Infrared (SWIR) hyperspectral cameras were used to scan the mixed-influence, delta-front reservoir analogue in the Cretaceous Frontier Formation, in Wyoming. The uppermost parasequence of Wall Creek Member were scanned at Raptor Ridge and compared with previous sedimentological studies that mapped discrete carbonate concretions. In addition, two cores (10 meters long), located 30-50 meters away from the outcrop wall, were scanned in the laboratory in order to collect very high resolution spectral data (at 0.5 cm interval). The normalized spectra, using continuum removal, at specific band for target minerals were plotted to evaluate the relative abundance of calcite, chlorite and kaolinite cement within the sandstone based on location, depth and width of absorption features. The hyperspectral images were classified using multiple spectral classification techniques: Spectral Angle Mapper (SAM), Linear Spectral Unmixing (LSU) and Mixture Tuned Mached Filter (MTMF) based on spectral data collected by spectroradiometer. Results show fast and precise method for mapping relative abundance of minerals at various scales ranging from outcrop to laboratory\core samples. Data are further used for understanding complex diagenetic processes and for reservoir analogue studies.