Applications of Pore-Scale Image Data to Exploration and Reservoir Characterization
Improved scanning electron microscope technologies have made it possible to capture and quantify information about unconventional mudrock reservoir characteristics at very high resolution. Types of data that can be captured by SEM images of very fine grained samples include pore types, pore shapes, pore size (average diameter and pore size distribution), micro-fabrics, brittleness index, and elemental/mineralogy mapping. Significant progress has been made with respect to upscaling SEM data to one-inch plug scale samples. Tiled images of AR-polished samples are now possible to collect at high resolution, providing the link to routine core analysis sample end-trims. Nano- and micro-pore data, as well as meso-pores and microfractures, can be mapped and distributed within these larger scale samples. This new workflow allows for more informed sample selection for high resolution SEM data collection and reservoir characterization. While the upscaling problem has not been fully solved, information from pore scale images can be applied to log interpretation and combined with other analyses to enhance our understanding of source rock reservoirs and controls on production from these reservoirs. Examples from the Niobrara Formation reveal that pore type and shape characteristics as defined from SEM images affect NMR log interpretation and evaluation of potential target intervals for horizontal wells. Pore sizes and types change with increasing thermal maturity in the Niobrara in the DJ Basin. The relationship of clay morphology to permeability in chalks and marls is also important.
AAPG Datapages/Search and Discovery Article #90193 © 2014 Rocky Mountain Section AAPG Annual Meeting, Denver, Colorado, July 20-22, 2014