2-D Pore Architecture Characterization of a Carbonate Mudrock Reservoir

Berg, Beth Vanden; Grammer, G. Michael

doi:10.1306/13592022m1123698

Cited by 11 publications

(5 citation statements)

References 39 publications

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“…Processes such as cementation, carbonate pressure dissolution, and clay diagenesis that remain active throughout the burial history can create isolated pores that are independent of the pore network created during sedimentation or even fractures from subsequent tectonics. In the Mississippian-age rocks of the study area, such processes have been widely recorded (Vanden Berg and Grammer, 2016;Vanden Berg et al, 2018;Bode et al, 2019). Two factors might together be contributing to the observed increase in V P pressure sensitivity with decreasing pore size.…”

Section: Size Effectsmentioning

confidence: 84%

“…In the core, the start and end of the Meramec formation was identified using color change from the bounding Devonian and the Pennsylvanian shales (LeBlanc, 2014;Vanden Berg and Grammer, 2016). Within the Meramec Formation, the facies interpretation was based on differences in texture, composition, sedimentary structures, trace fossils (MacEachern et al, 2009) and color (Geological Society of America, 1995).…”

Section: Faciesmentioning

confidence: 99%

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How Nanopores Influence Dry-Frame VP Pressure Sensitivity

et al. 2021

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This paper investigates how nanopore size distribution influences dry-frame P-wave velocity (VP) pressure sensitivity. The study uses a set of twenty-three samples belonging to a single vertical core from the Mississippian-age Meramec formation of the mid-continent US. Individual samples had their facies interpreted, composition estimated, He-gas porosity (ΦHe) determined, and P-wave and S-wave transit times systematically measured for dry core-plugs in a 5–40 MPa loading and unloading cycle. Data from the unloading cycle were linearized in the log scale, and the slope of the best fitting line was considered as a representative of the dry-frame VP pressure sensitivity. A series of photomicrographs from each sample were analyzed using image processing methods to obtain the shape and size of the individual pores, which were mostly in the nanopore (10−6–10–9 m) scale. At the outset, the pore-shape distribution plots were used to identify and discard samples with excessive cracks and complex pores. When the remaining samples were compared, it was found that within the same facies and pore-shape distribution subgroups VP pressure sensitivity increased as the dominant pore-size became smaller. This was largely independent of ΦHe and composition. The paper postulates that at the nanopore scale in the Meramec formation, pores are mostly isolated, and an increase in the confining pressure increased the bulk moduli of the fluids in the isolated pores, which in turn increased the VP pressure sensitivity. The study proposes incorporating this effect quantitatively through a dual-fluid model where the part of the fluid in unconnected pores is considered compressible while the remaining is considered incompressible. Results start to explain the universal observation of why the presence of microporosity quintessentially enhances VP pressure sensitivity.

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Section: Size Effectsmentioning

confidence: 84%

Section: Faciesmentioning

confidence: 99%

How Nanopores Influence Dry-Frame VP Pressure Sensitivity

et al. 2021

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“…The factors affecting pores are very complex, but essentially they are affected by sedimentation, tectonic evolution and diagenesis. The pore types of shale can be divided into four types: intergranular pores, intragranular pores, organic matter pores and microcracks (Berg and Grammer, 2016; Fishman et al., 2012; Klaver et al., 2012; Loucks and Rupple, 2007; Slatt and Brien, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…Whole-aperture distribution characteristics of shale samples. (Berg and Grammer, 2016;Fishman et al, 2012;Klaver et al, 2012;Loucks and Rupple, 2007;Slatt and Brien, 2011). Organic matter pores refer to tiny pores developed in organic matter that are formed during the burial and thermal evolution of organic matter, and they are widely distributed in kerogen in shale.…”

Section: Factors Affecting the Porosity Of Marine-continental Transitmentioning

confidence: 99%

Pore characterization of marine-continental transitional shale in Permian Shanxi Formation of The Southern North China Basin

Yang

Guo

2020

Energy Exploration & Exploitation

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Organic-rich marine-continental transitional shale is widely developed in the Permian Shanxi Formation in the Southern North China Basin. In this study, shale samples from the southern and northern wells of the basin were characterized by X-ray diffraction, high-pressure mercury intrusion porosimetry, low-pressure gas adsorption (N2 and CO2) and argon ion polishing-field emissions scanning electron microscopy. The pore types and structures of shale micropores, mesopores and macropores are qualitatively described; their pore size distribution and volume are quantitatively characterized; and the influencing factors of the pore volume are analyzed. The results show that the marine-continental transitional shale pores exhibit an unbalanced multimodal distribution with four peaks at 0.4–0.8 nm, 2–4 nm, 10–50 nm, and >10 µm. The mesopore volume is dominant, accounting for 40–70% of pores. The mesopores of the samples are slit-shaped pores and ink bottle-shaped pores. Since there is a desorption hysteresis loop on the N2 adsorption-desorption curve, most of them belong to the H4 type, and ye23-8 belongs to the mixed H2 and H4 type according to the IUPAC classification scheme. The slit-shaped pores are mainly interlayer pores and interparticle pores in clays, and the ink bottle-shaped pores are tiny dissolved pores and organic matter pores. Ro has negative correlation with the volumes of the mesopores and macropores, but it does not affect the volume of micropores. TOC has a positive correlation with the macropore and micropore volumes, and it has a negative correlation with mesopore volume. The relative contents of kaolinite and I/S have a positive correlation with the mesopore and macropore volumes. The relative content of illite has a negative correlation with the mesopore and macropore volumes. The relative content of chlorite has a negative correlation with the mesopore volume.

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“…As discussed in Vanden Berg and Grammer (2016), several studies have shown that standard polishing techniques of fine-grained rocks often produce artificial pores as a result of plucking of grains during polishing.…”

Section: Pore System Architecturementioning

confidence: 99%

Multiscale Characterization of the Caney Shale — An Emerging Play in Oklahoma

Wang

Luo²,

Achang³

et al. 2021

MidConGeo

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From a hydrocarbon perspective, the Caney Shale has historically been evaluated as a sealing unit, which resulted in limited studies characterizing the rock properties of the Caney Shale and its suitability for hydraulic fracturing. The objective of our research is to help bridge the current knowledge gap through the integration of multiscale laboratory techniques and to characterize the macro- and microscale rock properties of the Caney Shale. We employed an integrated approach for the characterization of the Caney using 200 ft (61 m) of Caney core from a target well in southern Oklahoma. Core observation and petrographic analysis of thin sections were combined to characterize the general rock types and associated fabrics and textures. Mineralogical composition, pore system architecture, and rock fabric were analyzed using x-ray diffraction (XRD), scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS), and focused ion beam (FIB)-SEM. In addition, rebound hardness and indentation testing were carried out to determine rock hardness (brittleness) and elasticity, respectively. With the integrated multiscale characterization, three mixed carbonate-siliciclastic rock types were identified — mudstone, calcareous siltstone, and silty carbonate — likely representing a spectrum of deposition from low to relatively high energy environments in the distal portions of a ramp system. Silty carbonate contains mostly interparticle pores. The calcareous siltstones and silty mudstones contain a combination of organic matter pores and interparticle pores. Each of the rock types shows unique mineralogical compositions based on XRD. The mudstone lithofacies has the highest clay content and the least carbonate content. Calcareous siltstones show moderate carbonate and clay content. Silty carbonate indicates the highest carbonate content with the least clay content. In an order of mudstone, calcareous siltstone, and silty carbonate, rebound hardness and Young’s modulus show an increasing trend. As a result of rock-fluid interactions, there are potential scaling reactions during completion and production that could ultimately affect permeability and production rates. Overall, the proposed multiscale integration approach is critical for the geologic characterization of most rocks. However, in shale reservoirs dominated by microporosity and microstructure where engineered fractures are expected to provide permeability at a reservoir scale, successful integration is essential. An optimized, integrated geological characterization of the Caney Shale that is well aligned with the engineering designs in drilling, completing, and producing wellbores will ultimately lead to optimal production while providing safe and environmentally responsible operations.

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2-D Pore Architecture Characterization of a Carbonate Mudrock Reservoir

Cited by 11 publications

References 39 publications

How Nanopores Influence Dry-Frame VP Pressure Sensitivity

How Nanopores Influence Dry-Frame VP Pressure Sensitivity

Pore characterization of marine-continental transitional shale in Permian Shanxi Formation of The Southern North China Basin

Multiscale Characterization of the Caney Shale — An Emerging Play in Oklahoma

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