Adsorption of methane onto mudstones under supercritical conditions: Mechanisms, physical properties and thermodynamic parameters

Shale strata generally contain a certain amount of pore water that accompanies the whole diagenetic and thermal evolution processes of shales. The distribution and occurrence characteristics of pore water significantly influence the nanopore structures of shales, which subsequently affects the accumulation and production of shale oil and gas resources. Based on a set of fresh Wufeng−Longmaxi (WL) shale samples from the deep marine strata in the southern Sichuan Basin, this study investigated the effects of pore water on the pore heterogeneity of shales by a multifractal method. The results show that (1) the deep WL shales have low pore water content (C PW ) and water saturation (S EW ), with average values of 7.47 mg/g and 35.21%, respectively, and the C PW and S EW of the shales are mainly controlled by clay mineral content. (2) Under dried conditions, the pore heterogeneity of high-probability measure areas has negative relationships with the clay mineral content and pore volumes with pore widths of 4−10 nm, and the pore connectivity is mainly controlled by clay mineral content. Under as-received conditions, however, the pore heterogeneity of low-probability measure areas and pore connectivity have positive relationships with clay mineral content and pore volumes with pore widths less than 4 nm. (3) Under as-received conditions, the pore water mainly occupies the nanopore with pore widths less than 4 nm and reduces the effective pore spaces and connectivity, which reduces the pore heterogeneity of high-probability measure areas and enhances the pore heterogeneity of low-probability measure areas.

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“…The BET and BJH models were used to calculate the pore surface area and volume, respectively. 41,42 3.5. Multifractal Analysis.…”

Section: Raman Reflectancementioning

confidence: 99%

Effects of Pore Water on the Heterogeneity in Nanopore Structures of Deep Marine Shales: A Multifractal Study on As-Received Shale Samples from the Southern Sichuan Basin, China

Gao

Cheng

Wu³

et al. 2023

Energy Fuels

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“…Organic matter (OM) hosted pores are a particular pore type in mudrock reservoirs and have been proven to be important for gas-in-place (GIP). − Therefore, the geological controls on the generation and differential development of OM pores have attracted the attention of many scholars. − Additionally, several studies have been reported in the literature on the dynamic evolution of the pore system during the process of diagenetic transformation and OM thermal maturation. − The basic consensus is that the evolution of OM pores is closely related to OM thermal maturation, while that of the mineral-related pores is controlled by both diagenesis and thermal maturation.…”

Section: Introductionmentioning

confidence: 99%

Advances in Microscopic Pore Structure Characterization of Fine-Grained Mudrocks

Wang

Cheng

2023

Energy Fuels

Self Cite

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The microscopic structure of the pore system in fine-grained mudrocks provides spaces for hydrocarbon percolation, migration, and occurrence. It exhibits strong heterogeneity due to the intimate mingling of organic matter (OM) and inorganic minerals and the intricate architecture of the internal network and dynamic changes along the diagenetic pathway and OM thermal maturation. The present review critically summarizes the advances in structure characterization, geological controlling factors, and heterogeneity of the pore system in mudrocks. The pore system in mudrocks can be divided into micro-, meso-, and macropores by diameters, OM-hosted, interparticles, and intraparticle pores by origin and distribution and connected and nonconnected pores according to whether they are connected. The commonly used pore structure characterization techniques can be classified into three categories: i.e., imaging, fluid invasion, and ray-related techniques. Their principles, experimental conditions, applicability, required sample sizes, detectable pore types and diameter ranges, advantages, and disadvantages have been comparatively summarized. To obtain more precise and comprehensive structural properties, multiple techniques are highly recommended to validate and complement each other. The depositional environment, diagenetic events, and OM thermal maturation jointly control the formation and evolution of the pore system. Differences in provenance and depositional background affect primary grain assemblages and thus changes in physical properties during burial depth. Diagenetic transformations mainly change the morphology and structure of mineral-related pores, while OM thermal maturation mainly controls that of OM-hosted pores. Furthermore, the pore structure of mudrocks generally shows strong heterogeneity, which can be effectively assessed by a point-counting porosity quantification and multifractal theory. Finally, we propose the challenges and prospects of microscopic pore structure characterization of mudrocks. More attention needs to be paid to quantifying OM-hosted and mineral-related pore volume fractions, effectively distinguishing connected and nonconnected pores, and comprehensively quantifying the coupled effect of diagenesis and hydrocarbon generation on pore network evolution. In conclusion, the most important aspect of this review is to summarize modern characterization methods and geological controls on pore structure development and propose prospects for unconventional reservoir characterization, with the hope of providing the ultimate knowledge to researchers engaged in unconventional shale oil and gas resources.

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“…These hydrocarbons were closely associated with the end-Permian magmatism temporally and spatially. Nonetheless, effects of this worldwide magmatism to underlying hydrocarbon source rocks was unraveled (Luo et al, 2021;Hu et al, 2022aHu et al, , 2022bXu et al, 2022;Wang et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

Episodic magmatism across the Permian-Triassic Crisis Boundary and its effects on underlying source rocks: records from conodont-based high-resolution geochemical proxies in marine carbonate successions, South China

Liu

Ding

Sun

et al. 2023

Preprint

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Magmatism of various magnitudes or intensities was widely recognized worldwide in accompanying with the end-Permian mass extinction (EPME) event across the Permian/Triassic boundary (PTB). Meanwhile, hydrocarbon source rocks were pervasively occurring in later-Permian marine carbonate successions. The EPME-related magmatism and later-Permian source rocks were associated spatially and temporally. However, the features of this magmatism and its effects on underlying source rocks were not elucidated. The current study investigated episodes and magnitudes of the magmatism across the PTB from typical South-China profile (i.e., the Pingdingshan section) using conodont-based geochemical proxies at a high-resolution scale (~50 kyr). Integrated trace elemental (Mn, Sr, Rb, and Th) and stable/radioactive isotopic (δ18O, δ13C, and 87Sr/86Sr) results revealed that conodonts provided an ideal proxy for chemostratigraphic signatures of ancient seawater, largely because it was more resistant to diagenetic alterations or thermal recrystallization. The conodont-based high-resolution 87Sr/86Sr values from studied interval (250.50 Ma to 252.00 Ma) showed three decreasing cycles upwardly against a long-term increasing background across the PTB, reflecting three episodes of magmatism. By contrary, the δ18O of same resolution and from same interval displayed no similar trend. This inconsistency was probably because that the δ18O composition of carbonates from studied section was limitedly altered due to long distance from magmatism center and/or buffering from thick water column. The micrite-based high-resolution δ13C exhibited an evolving pattern consistent with long-term background, revealing that the δ13C signatures of multiple stages of magmatism during this short-term interval were not inherited by micrites. The episodes of magmatism across the PTB can be correlated to underlying Chihsian source rocks from studied section according to the clustering of oxygen and strontium isotopic compositions of two sets of strata that were spatially and temporally related. The EPME-related magmatism across the PTB exerted great influences on formation of underlying marine source rocks by bring massive heat and pervasive oceanic anoxia.

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Adsorption of methane onto mudstones under supercritical conditions: Mechanisms, physical properties and thermodynamic parameters

Cited by 15 publications

References 51 publications

Effects of Pore Water on the Heterogeneity in Nanopore Structures of Deep Marine Shales: A Multifractal Study on As-Received Shale Samples from the Southern Sichuan Basin, China

Effects of Pore Water on the Heterogeneity in Nanopore Structures of Deep Marine Shales: A Multifractal Study on As-Received Shale Samples from the Southern Sichuan Basin, China

Advances in Microscopic Pore Structure Characterization of Fine-Grained Mudrocks

Episodic magmatism across the Permian-Triassic Crisis Boundary and its effects on underlying source rocks: records from conodont-based high-resolution geochemical proxies in marine carbonate successions, South China

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