Journal ArticleDOI
Morphology, Genesis, and Distribution of Nanometer-Scale Pores in Siliceous Mudstones of the Mississippian Barnett Shale
TLDR
In this article, the authors used scanning electron microscopy to characterize the pore system in the Barnett Shale of the Fort Worth Basin, Texas, showing that the pores in these rocks are dominantly nanometer in scale (nanopores).Abstract:
Research on mudrock attributes has increased dramatically since shale-gas systems have become commercial hydrocarbon production targets. One of the most significant research questions now being asked focuses on the nature of the pore system in these mudrocks. Our work on siliceous mudstones from the Mississippian Barnett Shale of the Fort Worth Basin, Texas, shows that the pores in these rocks are dominantly nanometer in scale (nanopores). We used scanning electron microscopy to characterize Barnett pores from a number of cores and have imaged pores as small as 5 nm. Key to our success in imaging these nanopores is the use of Ar-ion-beam milling; this methodology provides flat surfaces that lack topography related to differential hardness and are fundamental for high-magnification imaging.
Nanopores are observed in three main modes of occurrence. Most pores are found in grains of organic matter as intraparticle pores; many of these grains contain hundreds of pores. Intraparticle organic nanopores most commonly have irregular, bubblelike, elliptical cross sections and range between 5 and 750 nm with the median nanopore size for all grains being approximately 100 nm. Internal porosities of up to 20.2% have been measured for whole grains of organic matter based on point-count data from scanning electron microscopy analysis. These nanopores in the organic matter are the predominant pore type in the Barnett mudstones and they are related to thermal maturation.
Nanopores are also found in bedding-parallel, wispy, organic-rich laminae as intraparticle pores in organic grains and as interparticle pores between organic matter, but this mode is not common. Although less abundant, nanopores are also locally present in fine-grained matrix areas unassociated with organic matter and as nano- to microintercrystalline pores in pyrite framboids.
Intraparticle organic nanopores and pyrite-framboid intercrystalline pores contribute to gas storage in Barnett mudstones. We postulate that permeability pathways within the Barnett mudstones are along bedding-parallel layers of organic matter or a mesh network of organic matter flakes because this material contains the most pores.read more
Citations
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Journal ArticleDOI
Spectrum of pore types and networks in mudrocks and a descriptive classification for matrix-related mudrock pores
TL;DR: In this paper, a pore classification consisting of three major matrix-related pore types is presented that can be used to quantify matrix related pore and relate them to pore networks.
MonographDOI
The Rock Physics Handbook
TL;DR: The third edition of the reference book as discussed by the authors has been thoroughly updated while retaining its comprehensive coverage of the fundamental theory, concepts, and laboratory results, and highlights applications in unconventional reservoirs, including water, hydrocarbons, gases, minerals, rocks, ice, magma and methane hydrates.
Journal ArticleDOI
Characterization of gas shale pore systems by porosimetry, pycnometry, surface area, and field emission scanning electron microscopy/transmission electron microscopy image analyses: Examples from the Barnett, Woodford, Haynesville, Marcellus, and Doig units
TL;DR: In this article, the nanometer-scaled pore systems of gas shale reservoirs were investigated from the Barnett, Marcellus, Woodford, and Haynesville gas shales in the United States and the Doig Formation of northeastern British Columbia, Canada.
Proceedings ArticleDOI
From Oil-Prone Source Rock to Gas-Producing Shale Reservoir - Geologic and Petrophysical Characterization of Unconventional Shale Gas Reservoirs
TL;DR: In this paper, total organic carbon (TOC), maturity level (vitrinite reflectance), mineralogy, thickness, and organic matter type are used to classify organic matter that ranges from oil-prone algal and herbaceous to gas-prone woody/coaly material.
Journal ArticleDOI
Effect of organic-matter type and thermal maturity on methane adsorption in shale-gas systems
TL;DR: In this article, the authors developed a quantitative model for estimating the adsorbed gas estimate in the presence of moisture and thermal maturity of the gas-sorption ratio in shales.
References
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Journal ArticleDOI
Unconventional shale-gas systems: The Mississippian Barnett Shale of north-central Texas as one model for thermogenic shale-gas assessment
TL;DR: In this article, the authors estimate that the Barnett Shale has a total generation potential of about 609 bbl of oil equivalent/ac-ft or the equivalent of 3657 mcf/acft (84.0 m 3 /m 3 ).
Journal ArticleDOI
Guidelines for Evaluating Petroleum Source Rock Using Programmed Pyrolysis
TL;DR: In this article, the authors used pyrolysis to rapidly evaluate the petroleum-generative potential and thermal maturity of rocks and found that most coals showed high S2/S3 (>5) and low HI values (< 300 mg HC/g TOC.
Journal ArticleDOI
Fractured shale-gas systems
TL;DR: The first commercial United States natural gas production (1821) came from an organic-rich Devonian shale in the Appalachian basin this article, which is a continuous-type biogenic (predominant), thermogenic, or combined biogenic-thermogenic gas accumulations characterized by widespread gas saturation, subtle trapping mechanisms, seals of variable lithology, and relatively short hydrocarbon migration distances.
Journal ArticleDOI
Pore-throat sizes in sandstones, tight sandstones, and shales
TL;DR: Pore-throat sizes in siliciclastic rocks form a continuum from the submillimeter to the nanometer scale as mentioned in this paper, which provides a useful perspective for considering the emplacement of petroleum in consolidated siliclastics and fluid flow through fine-grained source rocks now being exploited as reservoirs.
Journal ArticleDOI
Natural fractures in the Barnett Shale and their importance for hydraulic fracture treatments
TL;DR: In this article, the authors characterized natural fractures in four Barnett Shale cores in terms of orientation, size, and sealing properties, and they measured a mechanical rock property, the subcritical crack index, which governs fracture pattern development.
Related Papers (5)
Spectrum of pore types and networks in mudrocks and a descriptive classification for matrix-related mudrock pores
Unconventional shale-gas systems: The Mississippian Barnett Shale of north-central Texas as one model for thermogenic shale-gas assessment
The importance of shale composition and pore structure upon gas storage potential of shale gas reservoirs
Daniel J.K. Ross,R. Marc Bustin +1 more