Reservoir characteristics of different shale lithofacies and their effects on the gas content of Wufeng-Longmaxi Formation, southern Sichuan Basin, China

Qian, Chao; Li, Xizhe; Zhang, Qing; Shen, Weijun; Guo, Wei; Lin, Wei; Han, Lingling; Cui, Yue; Huang, Yize; Pei, Xiangyang; Yu, Zhi-chao

doi:10.1016/j.geoen.2023.211701

Cited by 16 publications

(13 citation statements)

References 90 publications

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“…The mineral composition of shale can be mainly divided into organic and inorganic matter, including quartz, feldspar, calcite, clay minerals, and a small amount of casein. , Generally, there is a difference between the gas adsorption and moisture contents in organic matter pores and clay mineral pores. However, for gas adsorption in shale in a supercritical state, the adsorption mechanism is usually studied intensively based on the adsorption mechanism in pores of different sizes, which researchers widely use.…”

Section: Model Establishmentmentioning

confidence: 99%

“…From those, the mineral composition, total organic carbon, and shale pore structure represent the internal influencing factors. In contrast, the external influencing factors of the reservoir mainly include temperature, pressure, and moisture. − It was shown that the methane adsorption capacity in shale was positively correlated with total organic carbon content. − As the most critical inorganic component in shale, clay minerals were also thought to contribute considerably to methane adsorption owing to their microstructure . In addition, shale adsorption of methane was influenced by forces between the molecules of the internal material and methane gas molecules, with changes in pressure and temperature-induced changes in shale’s adsorption characteristics .…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Study of Shale Gas Adsorption under the Action of Moisture and Temperature, Including Analysis of the Relevant Adsorption Mechanisms and Thermodynamics

Yang,

Li,

et al. 2023

Ind. Eng. Chem. Res.

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Shale reservoirs commonly contain water, and studying the gas adsorption behavior and thermodynamic characteristics in wet shale is of great significance for shale gas resource evaluation and development. However, the influence of water molecules on the adsorption behavior and thermodynamics of methane adsorption in shales remains poorly understood. In this study, we considered the adsorption mechanism and occurrence environment of methane in shale, constructed an adsorption model that considers the combined effects of moisture and temperature, and verified the rationality of the newly constructed adsorption model from a considerable amount of published data. Then, combining the adsorption potential theory and real gas behavior, the absolute isothermal adsorption curves at various temperatures were successfully calculated using the global fitting method, and the mechanism of gas adsorption under the coupling of multiple factors was studied. On this basis, a rigorous framework for analyzing the adsorption thermodynamic characteristics of methane in shale was proposed, and the mechanism of the influence of water on methane gas adsorption was deeply studied, and the adsorption behavior of methane gas in aqueous shale was further analyzed. The results revealed that moisture had a significant inhibitory effect on the adsorption capacity of shale, and the methane adsorption amount decreases with the increase of moisture content. Similarly, temperature has an inhibitory effect on shale adsorption capacity. However, the effect of moisture and temperature on gas adsorption capacity was synergistic and negative, with high pressure helping to reduce the impact of humidity on methane adsorption capacity in terms of gas content. The thermodynamic model concluded that methane adsorbed in dry and wet shale was physical adsorption, with the isosteric heat of adsorption dropping and accompanying an increase in water content and temperature. The increase in water content led to a decrease in the absolute value of the isosteric entropy of adsorption, which proved to be not conducive to forming a stable and orderly arrangement of methane molecules on the shale surface. Water will preferentially occupy high-energy adsorption sites in micropores and hydrophilic water points in mesopores and macropores and fill micropores and some mesopores under capillary condensation as the water content increases. Water molecules on the methane adsorption basically functioned by modifying the interactions between the adsorbate and the adsorbent. The findings of this study can help for better understanding of subsurface supercritical adsorption under reservoir conditions and provide a basis for shale gas's resource assessment and optimal extraction.

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Section: Model Establishmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical Study of Shale Gas Adsorption under the Action of Moisture and Temperature, Including Analysis of the Relevant Adsorption Mechanisms and Thermodynamics

Yang,

Li,

et al. 2023

Ind. Eng. Chem. Res.

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“…Therefore, understanding the adsorption mechanism, particularly the adsorption of CH 4 on shale rock, is significant. The adsorptive capacity of shale is related to the composition and pore structure of shale gas reservoirs, with most of the CH 4 or CO 2 adsorption occurring in the micropores/nanopores of the organic matter . Supercritical CO 2 injection is a dynamic displacement process used for shale gas recovery and is influenced by the pressure gradient and competitive adsorption between CO 2 and CH 4 .…”

Section: Introductionmentioning

confidence: 99%

“…The adsorptive capacity of shale is related to the composition and pore structure of shale gas reservoirs, with most of the CH 4 or CO 2 adsorption occurring in the micropores/nanopores of the organic matter. 10 for shale gas recovery and is influenced by the pressure gradient and competitive adsorption between CO 2 and CH 4 . 11 When supercritical CO 2 is injected into shale gas formations, some CO 2 molecules start accessing unoccupied adsorption sites, while others compete to replace CH 4 from these sites.…”

Section: Introductionmentioning

confidence: 99%

Advances and Prospects of Supercritical CO₂ for Shale Gas Extraction and Geological Sequestration in Gas Shale Reservoirs

Shen,

Ma,

Zuo

et al. 2024

Energy Fuels

Self Cite

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The advancements in hydraulic fracturing and horizontal drilling techniques have substantially facilitated the large-scale extraction of natural gas from shale gas reservoirs. However, the use of fracking water poses several potential drawbacks including the contamination of groundwater, surface water, and soil, as well as risks to air quality. Due to the unique physical properties of supercritical CO2, shale gas exploitation using this method has been considered a promising technology that can not only improve gas recovery but can also enable CO2 geological storage. This paper clarifies the gas adsorption mechanism in shale formations, including the factors influencing the adsorption of CH4, the differences between CH4 and CO2 adsorption, and various adsorption models. We show that shale inherently exhibits a preference for CO2 adsorption over CH4. Then, the supercritical CO2 fracturing mechanism, including the shale fracking pressure and the factors influencing CO2 fracturing, is analyzed. The mechanisms of CO2 extraction in shale gas and the key factors influencing CO2 geological storage are discussed. The main challenges and future prospects regarding the use of supercritical CO2 for shale gas recovery and geological sequestration in gas shale reservoirs are finally summarized. A more detailed understanding is required to evaluate the efficiency of shale gas recovery and CO2 geological sequestration in shale formations using supercritical CO2. This work provides a basis and serves as a reference for future research investigating the mechanisms of shale gas exploitation using supercritical CO2, as well as the limitations and advantages of CO2 geological sequestration in unconventional shale gas reservoirs.

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“…As an unconventional oil and gas resource integrating source and reservoir, shale gas accounts for an increasing proportion in the international energy structure and has become a hot spot in the field of global oil and gas exploration. − The shale gas resource potential of the Upper Ordovician Wufeng formation (O 3 w) and Lower Silurian Longmaxi formation (S 1 l) in southern China is huge, and it is an important base for shale gas exploration and development in China. , For unconventional oil and gas resources such as shale gas, shale organic matter abundance [total organic carbon (TOC)] controls the hydrocarbon generation and storage capacity of shale, plays a decisive role in shale gas content, and is an important indicator to evaluate whether shale has commercial exploitation value. − Therefore, the research on the enrichment mechanism of shale organic matter is the leading work of the shale gas enrichment mechanism, resource evaluation, and favorable area optimization.…”

Section: Introductionmentioning

confidence: 99%

Constraints of Sedimentary Environment on Shale Organic Matter Enrichment: Insights from Elemental Geochemistry and Multiple Factor Analysis

Shao,

Xu,

Jiang

et al. 2024

ACS Omega

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The organic-rich shale of the Wufeng−Longmaxi formation is an important section for shale gas exploration. The traditional univariate or bivariate analysis causes researchers to have great controversy about its enrichment mechanism. This study explores the combination of multiple factor analysis (MFA) and element geochemistry to calculate the contribution rate of a paleoenvironment to organic matter enrichment and clarify the main controlling factors of organic matter enrichment. Research has shown that there is generally high productivity from the Wufeng (O 3 w)−Longmaxi formation (S 1 l) deposition. The degree of terrigenous clastic input and weathering during the period of the O 3 w is relatively low, and sedimentary water restriction is strong, mainly developing an anoxic−dysoxic sedimentary environment. During the deposition of S 1 l 1 , the input intensity and weathering of terrigenous debris were slightly enhanced, and the increase of the water column led to the development of an anoxic environment at the bottom of the water layer. During the S 1 l 2+3 period, the degree of terrigenous debris and weathering is the largest, and the high oxygen content of the water column is mainly a normal oxic environment. An MFA calculation shows that the paleoproductivity and paleoredox environment of the organic-rich shale section have the highest contribution rate of about 59.57% to the enrichment of organic matter, which is higher than that of paleoclimate conditions and terrigenous clastic input, indicating that the enrichment of organic matter is mainly controlled by paleoproductivity and the preservation environment. This study provides a basis for the application of MFA in element geochemistry and can serve as a model for other studies.

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Reservoir characteristics of different shale lithofacies and their effects on the gas content of Wufeng-Longmaxi Formation, southern Sichuan Basin, China

Cited by 16 publications

References 90 publications

Theoretical Study of Shale Gas Adsorption under the Action of Moisture and Temperature, Including Analysis of the Relevant Adsorption Mechanisms and Thermodynamics

Theoretical Study of Shale Gas Adsorption under the Action of Moisture and Temperature, Including Analysis of the Relevant Adsorption Mechanisms and Thermodynamics

Advances and Prospects of Supercritical CO₂ for Shale Gas Extraction and Geological Sequestration in Gas Shale Reservoirs

Constraints of Sedimentary Environment on Shale Organic Matter Enrichment: Insights from Elemental Geochemistry and Multiple Factor Analysis

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Reservoir characteristics of different shale lithofacies and their effects on the gas content of Wufeng-Longmaxi Formation, southern Sichuan Basin, China

Cited by 16 publications

References 90 publications

Theoretical Study of Shale Gas Adsorption under the Action of Moisture and Temperature, Including Analysis of the Relevant Adsorption Mechanisms and Thermodynamics

Theoretical Study of Shale Gas Adsorption under the Action of Moisture and Temperature, Including Analysis of the Relevant Adsorption Mechanisms and Thermodynamics

Advances and Prospects of Supercritical CO2 for Shale Gas Extraction and Geological Sequestration in Gas Shale Reservoirs

Constraints of Sedimentary Environment on Shale Organic Matter Enrichment: Insights from Elemental Geochemistry and Multiple Factor Analysis

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Product

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Advances and Prospects of Supercritical CO₂ for Shale Gas Extraction and Geological Sequestration in Gas Shale Reservoirs