Characterizations of pore, mineral and petrographic properties of marine shale using multiple techniques and their implications on gas storage capability for Sichuan Longmaxi gas shale field in China

Xu, Hao; Zhou, Wen; Zhang, Rui; Liu, Shimin; Zhou, Qin

doi:10.1016/j.fuel.2018.12.035

Cited by 83 publications

(78 citation statements)

References 48 publications

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“…The relative pressure (P/Po) ranges from 0.001 to 0.995 for nitrogen adsorption, whereas from 0.0005 to 0.029 for carbon dioxide adsorption. The N 2 adsorption data (with P/Po of 0.06-0.2) were interpreted using the Brunauer-Emmette-Teller (BET) method to obtain specific surface area (SSA), and Barrette-Joynere-Halenda (BJH) method to obtain pore volume (PV) [9,32,33]. Pore size distributions (PSDs) were obtained using the density functional theory (DFT) method [9].…”

Section: Low-pressure N 2 /Co 2 Adsorptionmentioning

confidence: 99%

“…The organic matter abundance, thermal maturity degree and mineral composition of shale have an important influence on shale pore structure [13,32,63,64]. The analysis of shale geochemical characteristics and mineral composition is the basis for pore structure investigation.…”

Section: Organic Geochemistry and Mineral Compositionmentioning

confidence: 99%

“…Therefore, the indirect methods are commonly combined to comprehensively investigate the shale pore structure characteristics, such as low-pressure N 2 /CO 2 gas adsorption, high-pressure mercury intrusion porosimetry (HMIP) and nuclear magnetic resonance (NMR) experiments [11,[30][31][32][33][34]. These methods can be used to quantitatively investigate the pore structure characteristics, including the total porosity, PV, SSA, pore shapes, and PSD [11,[30][31][32][33][34]. Both advantages and disadvantages exist in direct and indirect methods, therefore, a combination of them is an effective approach for shale pore characterization.…”

Section: Introductionmentioning

confidence: 99%

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Full‐Scale Pore Structure and Fractal Dimension of the Longmaxi Shale from the Southern Sichuan Basin: Investigations Using FE‐SEM, Gas Adsorption and Mercury Intrusion Porosimetry

et al. 2019

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Pore structure determines the gas occurrence and storage properties of gas shale and is a vital element for reservoir evaluation and shale gas resources assessment. Field emission scanning electron microscopy (FE‐SEM), high‐pressure mercury intrusion porosimetry (HMIP), and low‐pressure N2/CO2 adsorption were used to qualitatively and quantitatively characterize full‐scale pore structure of Longmaxi (LM) shale from the southern Sichuan Basin. Fractal dimension and its controlling factors were also discussed in our study. Longmaxi shale mainly developed organic matter (OM) pores, interparticle pores, intraparticle pores, and microfracture, of which the OM pores dominated the pore system. The pore diameters are mainly distributed in the ranges of 0.4–0.7 nm, 2–20 nm and 40–200 μm. Micro‐, meso‐ and macropores contribute 24%, 57% and 19% of the total pore volume (PV), respectively, and 64.5%, 34.6%, and 0.9% of the total specific surface area (SSA). Organic matter and clay minerals have a positive contribution to pore development. While high brittle mineral content can inhibit shale pore development. The fractal dimensions D1 and D2 which represents the roughness of the shale surface and irregularity of the space structure, respectively, are calculated based on N2 desorption data. The value of D1 is in the range of 2.6480–2.7334 (average of 2.6857), D2 is in the range of 2.8924–2.9439 (average of 2.9229), which indicates that Longmaxi shales have a rather irregular pore morphology as well as complex pore structure. Both PV and SSA positively correlated with fractal dimensions D1 and D2. The fractal dimension D1 decreases with increasing average pore diameter, while D2 is on the contrary. These results suggest that the small pores have a higher roughness surface, while the larger pores have a more complex spatial structure. The fractal dimensions of shale are jointly controlled by OM, clays and brittle minerals. The TOC content is the key factor which has a positive correlation with the fractal dimension. Clay minerals have a negative influence on fractal dimension D1, and positive influence D2, while brittle minerals show an opposite effect compared with clay minerals.

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Section: Low-pressure N 2 /Co 2 Adsorptionmentioning

confidence: 99%

Section: Organic Geochemistry and Mineral Compositionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Full‐Scale Pore Structure and Fractal Dimension of the Longmaxi Shale from the Southern Sichuan Basin: Investigations Using FE‐SEM, Gas Adsorption and Mercury Intrusion Porosimetry

et al. 2019

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“…Firstly, dry samples were placed in the core clamping device, and helium gas was allowed to isothermally expand into the sample until equilibrium. Porosity was calculated by the grain volume and bulk 2 Geofluids volume of the sample, and the average value after three tests was selected [8]. Gas permeability was measured by the unsteady-state pulse decay technique and the average value was used.…”

Section: Porosity and Permeabilitymentioning

confidence: 99%

“…Many researchers have tried to enhance oil recovery from these tight-rock reservoirs [5,6]. These investigations have included quantitative characterization of pore structure using various techniques [7][8][9], connectivity analysis of tiny pores [10][11][12][13][14], and predictions of migration of movable fluids and oil/gas production [15,16]. Tight sandstone reservoirs have extremely complex pore systems and low recovery.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Characterization of Pore Connectivity and Movable Fluid Distribution of Tight Sandstones: A Case Study of the Upper Triassic Chang 7 Member, Yanchang Formation in Ordos Basin, China

et al. 2020

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The pore connectivity and distribution of moveable fluids, which determines fluid movability and recoverable reserves, are critical for enhancing oil/gas recovery in tight sandstone reservoirs. In this paper, multiple techniques including high-pressure mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and microcomputer tomography scanning (micro-CT) were used for the quantitative characterization of pore structure, pore connectivity, and movable fluid distribution. Firstly, sample porosity and permeability were obtained. Pore morphology and the 3D distribution of the pore structures were analyzed using SEM and micro-CT, respectively. The pore-size distribution (PSD) from NMR was generally broader than that from MIP because this technique simply characterized the connected pore volume, whereas NMR showed the total pore volume. Therefore, an attempt was made to calculate pore connectivity percentages of pores with different radii (<50 nm, 50 nm–0.1 μm, and 0.1 μm–1 μm) using the difference between the PSD obtained from MIP and NMR. It was found that small pores (r<0.05 μm) contributed 5.02%–18.00% to connectivity, which is less than large pores (r>0.05 μm) with contribution of 36.60%–92.00%, although small pores had greater pore volumes. In addition, a new parameter, effective movable fluid saturation, was proposed based on the initial movable fluid saturation from NMR and the pore connectivity percentage from MIP and NMR. The results demonstrated that the initial movable fluid saturation decreased by 14.16% on average when disconnected pores were excluded. It was concluded that the effective movable fluid saturation has a higher accuracy in evaluating the recovery of tight sandstone reservoirs.

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Connectivity of organic matter pores in the Lower Silurian Longmaxi Formation shale, Sichuan Basin, Southern China: Analyses from helium ion microscope and focused ion beam scanning electron microscope

et al. 2022

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As one of the most important energy sources in the world today, shale gas has attracted extensive research. Numerous scholars agreed that the organic matter (OM) pores in shale provide the main space which benefits effective gas occurrence. However, the connectivity provided by OM pores is more important in the development process than their reservoir properties. A comprehensive portrayal of the 3D connectivity of the OM pores is elaborated in this study. The Lower Silurian Longmaxi shale samples were selected as the research subject.The shale samples are subjected to focused ion beam scanning electron microscope, helium ion microscope observation experiments, 2D microscopic characterization of OM pores, and 3D segmentation extraction. The results indicate that the connectivity of shale is mainly contributed by OM pores. The OM pores have the advantageous structural characteristics of large number per unit area, evenly distributed, regular pore morphology, and large pore size relative to the mineral matrix pores. The OM pores structure in shale is complex with a network structure of small pores nested in large pores, which can increase the adsorption capacity of gas. Besides, the small pores nested in large pores can act as a throat to significantly improve the connectivity. OM pores in the pyrobitumen are interconnected in 3D space, providing the main channels for gas percolation in the shale reservoir.

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Characterizations of pore, mineral and petrographic properties of marine shale using multiple techniques and their implications on gas storage capability for Sichuan Longmaxi gas shale field in China

Cited by 83 publications

References 48 publications

Full‐Scale Pore Structure and Fractal Dimension of the Longmaxi Shale from the Southern Sichuan Basin: Investigations Using FE‐SEM, Gas Adsorption and Mercury Intrusion Porosimetry

Full‐Scale Pore Structure and Fractal Dimension of the Longmaxi Shale from the Southern Sichuan Basin: Investigations Using FE‐SEM, Gas Adsorption and Mercury Intrusion Porosimetry

Quantitative Characterization of Pore Connectivity and Movable Fluid Distribution of Tight Sandstones: A Case Study of the Upper Triassic Chang 7 Member, Yanchang Formation in Ordos Basin, China

Connectivity of organic matter pores in the Lower Silurian Longmaxi Formation shale, Sichuan Basin, Southern China: Analyses from helium ion microscope and focused ion beam scanning electron microscope

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