Methane adsorption characteristics of overmature Lower Cambrian shales of deepwater shelf facies in Southwest China

Gai, Haifeng; Li, Tengfei; Wang, Xing; Tian, Hui; Xiao, Xia; Zhou, Qinling

doi:10.1016/j.marpetgeo.2020.104565

Cited by 19 publications

(15 citation statements)

References 55 publications

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“…The relationship between TOC values and V L is presented in Figure 7a, showing an evident positive correlation between the two key parameters, which is consistent with previous studies based on limited data [24,27,53]. The findings indicated that a positive correlation still exists, even when the data become larger.…”

Section: Effect Of Toc On Adsorption Capacitysupporting

confidence: 89%

Clarifying the Effect of Clay Minerals on Methane Adsorption Capacity of Marine Shales in Sichuan Basin, China

Wang

Zhou

Zhang³

et al. 2021

Energies

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The effect of clay minerals on the methane adsorption capacity of shales is a basic issue that needs to be clarified and is of great significance for understanding the adsorption characteristics and mechanisms of shale gas. In this study, a variety of experimental methods, including XRD, LTNA, HPMA experiments, were conducted on 82 marine shale samples from the Wufeng–Longmaxi Formation of 10 evaluation wells in the southern Sichuan Basin of China. The controlling factors of adsorption capacities were determined through a correlation analysis with pore characteristics and mineral composition. In terms of mineral composition, organic matter (OM) is the most key methane adsorbent in marine shale, and clay minerals have little effect on methane adsorption. The ultra-low adsorption capacity of illite and chlorite and the hydrophilicity and water absorption ability of clay minerals are the main reasons for their limited effect on gas adsorption in marine shales. From the perspective of the pore structure, the micropore and mesopore specific surface areas (SSAs) control the methane adsorption capacity of marine shales, which are mainly provided by OM. Clay minerals have no relationship with SSAs, regardless of mesopores or micropores. In the competitive adsorption process of OM and clay minerals, OM has an absolute advantage. Clay minerals become carriers for water absorption, due to their interlayer polarity and water wettability. Based on the analysis of a large number of experimental datasets, this study clarified the key problem of whether clay minerals in marine shales control methane adsorption.

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Section: Effect Of Toc On Adsorption Capacitysupporting

confidence: 89%

Clarifying the Effect of Clay Minerals on Methane Adsorption Capacity of Marine Shales in Sichuan Basin, China

Wang

Zhou

Zhang³

et al. 2021

Energies

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“…Previous studies have shown that in addition to the physicochemical properties of shale, external factors such as temperature and pressure also have important effects on the methane adsorption capacity of shale (Gasparik et al, 2014;Tian et al, 2016;Hu H. et al, 2018;Gai et al, 2020). As shown in Figure 1A, at a given pressure, the absolute methane adsorption amount decreases with temperature.…”

Section: Effect Of Temperature and Pressure On Methane Adsorption Capacitymentioning

confidence: 87%

“…As nano-scale pores are most developed in shales (Zou et al, 2017;Chen et al, 2019a;Liu et al, 2020), the adsorbed gas content generally accounts for 20-85% of the total gas content (Curtis, 2002;Chen et al, 2019b;Qiao et al, 2020). The research of gas adsorption capacity forms the foundation for effective and efficient development of shale gas because it is paramount to appraising gas content in-situ as well as pinpointing the target areas (Gai et al, 2020). Shales have extremely low permeability, so more than 90% of shale gas wells need to rely on hydraulic fracturing and other stimulation measures to connect natural fractures for improving the conductivity of the reservoir in order to promote the economic development of shale gas (Zou et al, 2017;Gao et al, 2021;Liu et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Effect of Pre-Adsorbed Water on Methane Adsorption Capacity in Shale-Gas Systems

Chen

Jiang

et al. 2021

Front. Earth Sci.

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The presence and content of water will certainly affect the gas adsorption capacity of shale and the evaluation of shale gas content. In order to reasonably evaluate the gas adsorption capacity of shale under actual reservoir conditions, the effect of water on methane adsorption capacity needs to be investigated. Taking the Da’anzhai Member of the Lower Jurassic Ziliujing Formation in the northeastern Sichuan Basin, China as an example, this study attempts to reveal the effect of pre-adsorbed water on methane adsorption capacity in shale-gas systems by conducting methane adsorption experiments in two sequences, firstly at different temperatures under dry condition and secondly at different relative humidity levels under the same temperature. The results show that temperature and relative humidity (i.e., water saturation) are the main factors affecting the methane adsorption capacity of shale for a single sample. The key findings of this study include: 1) Methane adsorption capacity of shale first increases then decreases with depth, reaching a peak at about 1,600–2,400 m. 2) Lower relative humidity correlates to greater maximum methane adsorption capacity and greater depth to reach the maximum methane adsorption capacity. 3) 20% increase of relative humidity results in roughly 10% reduction of maximum methane adsorption capacity. As a conclusion, methane adsorption capacity of shale is predominately affected by water saturation, pore type and pore size of shale. This study could provide a theoretical basis for the establishment of a reasonable evaluation method for shale adsorbed gas content.

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“…where n ab represents the absolute adsorption, n ex represents the excess adsorption, ρ b is the gas phase density, and ρ ad is the adsorbed phase density. At present, the Langmuir model is widely used to characterize the adsorption characteristics of porous media, such as activated carbon, coal, and shale [3,7,47]. The supercritical Dubinin-Radushkevich (SDR) model is used to characterize the high-pressure adsorption under supercritical conditions, which is modified from the classical Dubinin-Radushkevich (DR) equation for subcritical adsorption [31,[48][49][50].…”

Section: Calculation Of Adsorption Gasmentioning

confidence: 99%

“…The predicted recoverable shale gas resources of the Yangtze Plate account for approximately 70% of the terrestrial resources of China [1], which occur in two sets marine shales (the Lower Silurian Longmaxi Formation and the Lower Cambrian Qiongzhusi Formation) and in the marine-terrestrial transitional Permian strata system [2][3][4][5][6][7][8]. Through the past decade of exploration and development, the marine shales in Sichuan Basin and its peripheral areas have been commercially exploited.…”

Section: Introductionmentioning

confidence: 99%

Methane Storage Capacity of Permian Shales with Type III Kerogen in the Lower Yangtze Area, Eastern China

et al. 2022

Self Cite

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Marine–terrestrial transitional Permian shales occur throughout South China and have suitable geological and geochemical conditions for shale gas accumulation. However, the Permian shales have not made commercial exploitation, which causes uncertainly for future exploration. In this study, high-pressure methane (CH4) adsorption experiments were carried out on the Permian shales in the Lower Yangtze area, and the influences of total organic carbon (TOC) content and temperature on adsorption parameters were investigated. The characteristics and main controlling factors of methane storage capacity (MSC) of the Permian shales are discussed. The results show that the maximum adsorption and the adsorbed phase density of these Permian samples are positively correlated with TOC contents but negatively correlated with temperatures. The pores of organic matter in shale, especially a large number of micropores and mesopores, can provide important sites for methane storage. Due to underdeveloped pore structure and poor connectivity, the methane adsorption capacities of the Permian shales are significantly lower than those of marine shales. Compared with the Longmaxi shales, the lower porosity and lower methane adsorption of the Permian shales are reasonable explanations for their lower gas-in-place (GIP) contents. It is not suitable to apply the index system of marine shales to the evaluation of marine–terrestrial transitional shales. The further exploration of Permian shales in the study area should be extended to overpressure stable reservoirs with high TOC contents (e.g., >5%), high porosity (e.g., >3%), and deep burial (e.g., >2000 m).

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Methane adsorption characteristics of overmature Lower Cambrian shales of deepwater shelf facies in Southwest China

Cited by 19 publications

References 55 publications

Clarifying the Effect of Clay Minerals on Methane Adsorption Capacity of Marine Shales in Sichuan Basin, China

Clarifying the Effect of Clay Minerals on Methane Adsorption Capacity of Marine Shales in Sichuan Basin, China

Effect of Pre-Adsorbed Water on Methane Adsorption Capacity in Shale-Gas Systems

Methane Storage Capacity of Permian Shales with Type III Kerogen in the Lower Yangtze Area, Eastern China

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