AAPG Southwest Section

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Nano-Petrophysics of the Prairie Canyon/Mancos “B” Zone of the Mancos Shale Rio Blanco, Colorado


Production of oil and natural gas in North American has been increasingly focusing on exploiting unconventional shale formations. The limited matrix permeability of shale formations induces a significant decline from initial production even after the fracture network has been produced from hydraulic fracturing. Thus understanding fluid flow through the matrix pore network may lead to better hydrocarbon recovery of unconventional shale formations. Specifically this study intends to analyze the impacts of maturity and mineralogy on pore size distribution and pore connectivity, properties of the rock matrix significant to fluid flow and storage. Three wells from Rio Blanco, Colorado were sampled each for a different maturity of the Mancos “B” zone of the Mancos Shale. A combination of techniques, including wettability/contact angle, X-ray diffraction, imbibition tests and mercury injection capillary pressure (MICP), are used to achieve research goals. Preliminary results suggest two types of pore size distributions, related to maturation, mineralogy and grain size. Areas higher in silt content may serve as potential reservoirs with larger pore throats that maintain greater production rates.