Mapping of Organic Matter Distribution in Shales on the Centimeter Scale with Nanometer Resolution.

Curtis, Mark E.; Goergen, E. T.; Jernigen, Jeremy; Sondergeld, Carl H.; Chandra, Shekhar S.

doi:10.15530/urtec-2014-1922757

Cited by 8 publications

(6 citation statements)

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“…There are two types of ion milling: Broad Ion Beam (BIB) which typically utilizes argon ions and Focused Ion Beam (FIB) imaging which typically utilizes gallium ions. BIB is preferred for most 2D SEM imaging and analysis of sedimentary rocks because of the relatively large area, upwards of an inch diameter, that can be milled in a few hours, provided sufficient mechanical polishing of the sample has been done beforehand (Curtis et al, 2014;Goergen et al, 2014). FIB ( Figure 8) is primarily reserved for 3D FIB-SEM and TEM sample preparation because of the relatively small area that can be milled in a given time.…”

Section: Imaging Methods For Sedimentary Rocksmentioning

confidence: 99%

Imaging pores in sedimentary rocks: Foundation of porosity prediction

Milliken

Curtis

2016

Marine and Petroleum Geology

121

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This review examines the history and current practice of technologies for imaging of pores in sedimentary rocks. Pores are that portion of the rock volume occupied by components of relative mobility such as water of various salinities, microbial life, petroleum liquids, gases, and supercritical fluids. Through a rock's history the contained pores evolve as the primary detrital assemblage responds chemically and mechanically to changing conditions in the subsurface. Description and classification of pores based upon their paragenesis depends upon inspection by imaging that allows the pores to be seen and interpreted in the context of historical processes responsible for formation of the pore walls. Since the late 1960s, sample preparation and imaging methodologies that clarified our understanding of pores in their correct historical context have been at the root of important advances in prediction of porosity and related bulk properties in the subsurface. These older approaches are now joined by new technologies that serve current efforts to extend predictive capabilities to nm-scale pores in the fine-grained, low-permeability rocks that dominate in the deeper parts of sedimentary basins, and indeed, in the sedimentary record as a whole. Placing the smallest pores into their proper paragenetic context presents a challenge in the quest to develop predictive models for porosity evolution in fine-grained rocks.

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Section: Imaging Methods For Sedimentary Rocksmentioning

confidence: 99%

Imaging pores in sedimentary rocks: Foundation of porosity prediction

Milliken

Curtis

2016

Marine and Petroleum Geology

121

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“…This study focuses on one sample from within the section of Barnett shale whole core which has been extensively characterized by the University of Oklahoma and FEI (Curtis et al, 2014). In particular, from within the 1 foot section shown in Figure 1, the current study deals with the horizontal and vertical core plug #2.…”

Section: Methodsmentioning

confidence: 99%

“…Software developments for acquisition, processing and analysis provide the means to generate huge datasets and to extract statistical measures, e.g. pore size distributions (Milliken et al, 2013;Lemmens et al, 2013;Curtis et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Registration of this higher resolution structural information into its corresponding section of the tomogram provides pore sizes, shapes and connectivities to supplement the porosity map. The current study uses plugs and sub-plugs of Barnett shale (Curtis et al, 2014) to demonstrate the utility of this multi-scale imaging workflow to guide upscaling of transport properties in future studies.…”

Section: Introductionmentioning

confidence: 99%

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Applications of Multi-Scale Imaging Techniques to Unconventional Reservoirs

et al. 2015

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Understanding and prediction of hydrocarbon transport within the matrix of unconventional tight reservoirs demands an integrated imaging strategy spanning from the smallest nanoscale pores to plug scale and beyond. Recent developments in multi-scale imaging are presented for Barnett shale samples to illustrate this approach to upscaling. The utility of micro-CT imaging for shales can be extended by X-ray contrast enhancement techniques coupled with tomogram registration. In particular, saturation of a shale plug with a highly attenuating liquid and subtraction of this tomogram from the registered dry-state tomogram yields a 3D voxel map of connected porosity over the plug. The same procedure can be applied to sub-plugs sampled from the parent plug to capture micron-scale variations in porosity. This approach does not directly provide the size, shape and connectivity of individual pores, since the vast majority of shale pores remain below tomogram resolution even for small sub-plugs. Two approaches to access this higher-order information are addressed. The first uses the state of the shale sub-plug saturated with X-ray dense liquid as the starting point for dynamic micro-CT imaging of the diffusion of a second, miscible, X-ray transparent liquid into the sub-plug. This can reveal the presence of faster pathways of transport through pores of larger size or lower tortuosity. The second approach involves broad beam ion-milling of the sub-plug for acquisition of 2D BSEM image mosaics and mineral maps, and their registration into the corresponding section of the 3D tomograms. This provides a registered basis for upscaling of transport properties, e.g. simulated from small FIB-SEM cubes, to sub-plug and in turn to plug via their micro-CT porosity maps. Very high resolution SEM imaging of broken surfaces can provide useful complementary information as to the finest scale of organic-hosted nanopores. The Barnett shale samples exhibited fairly homogeneous distributions of porosity on the plug and sub-plug scales, and also displayed relatively uniform diffusion across the sub-plug, suggesting that they are amenable to characterization and upscaling using only a limited set of parameters. This homogeneity is thought to be due in significant part to the predominance of organic-hosted porosity and to the structural uniformity of these nano-scale organic pore networks.

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“…These framboidal pyrites are commonly found with organic matter around and between the euhedral crystals of the framboid. The Unconventional Shale Gas Consortium at the University of Oklahoma has found porosity in organic matter in the Wolfcamp Shale (Bocangel et al, 2013;Curtis et al, 2014;personal communication with Mark Curtis, 2016). Authigenic barite is found in one interval, clustered as a horizontal layer in the mudstone matrix (Figure 8b).…”

Section: Diagenesismentioning

confidence: 99%