--> Visualization and Quantification of 3-D pore Networks in Tight Reservoir Rocks Using Confocal Laser Scanning Microscopy
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2018 AAPG International Conference and Exhibition

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Visualization and Quantification of 3-D pore Networks in Tight Reservoir Rocks Using Confocal Laser Scanning Microscopy

Abstract

Imaging micropores from core samples and cuttings is a key building block for accurately evaluating the volumetric pore space of a rock sample. Standard petrographic techniques have limited value for micropore quantification due to the interference of multiple crystallographic layers and limited optical Previous HitresolutionNext Hit. High-Previous HitresolutionNext Hit imaging techniques, such as SEM and micro-CT scanning have played a pivotal role in the characterization of micropores. However, these latter imaging techniques are destructive and/or they cannot easily obtain a wide field of view, thus provide a limited understanding of the variable pore types in a sample. This study discusses the technical and practical aspects of Confocal Laser Scanning Microscopy (CLSM) with application to imaging and quantifying complex micropore networks in tight hydrocarbon reservoirs. In the life sciences, CLSM is an established multidimensional light microscopy technique for imaging fluorescently-labeled specimens. In the geosciences, CLSM recently has been applied as a promising method for generating high-Previous HitresolutionNext Hit 3D datasets of pore networks in conventional and unconventional reservoirs that can help to bridge the Previous HitresolutionNext Hit gap between standard petrographic microscopy and higher-Previous HitresolutionNext Hit techniques. The ability to produce optical sections – a non-destructive imaging approach which uses light rather than a physical method to section the sample – allows the imaging of pore networks in delicate samples and the reproduction of results, thus helping to build confidence in the analysis. In this study, optical sections were captured down to a Previous HitresolutionNext Hit of ~300 nm in the Previous HitverticalTop direction and ~ 200 nm in the horizontal direction to image and quantify the 3D pore volume and 3D pore network of tight reservoir rock samples from a variety of North American basins. The dominant pore size distribution was determined by applying spatial statistics and ranges from <1µm to ~25µm in the analyzed samples. Pore volumes were calculated using image analysis techniques and are confirmed by independent porosity and permeability measurements. Most importantly, the reservoir rocks analyzed as part of this study reveal a complex anisotropic pore network at a scale that is below the resolution limit of standard optical microscopy, but exceeding the boundaries of higher resolution techniques. The results from this study aim to serve as the input parameters for advanced flow models and flow simulations.