Electrical properties of Longmaxi organic-rich shale and its potential applications to shale gas exploration and exploitation

Wang, Xuben; Zhang, Bing; He, Zhongjie; He, Lixia; Yang, Kai; Huang, Tao; Luo, Fangbing; Tang, Jialin; Gan, Lu

doi:10.1016/j.jngse.2016.10.027

Cited by 19 publications

(4 citation statements)

References 11 publications

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“…A rate of 2θ was used to capture diffractograms from 5 • to 90 • . Following the Chinese oil and gas industry standard (SY/T) 5163-2014, samples were prepared, and spectrum identification was performed [34].…”

Section: Mineral Composition and Morphological Analysismentioning

confidence: 99%

Influence of Low-Temperature Hydrothermal Events and Basement Fault System on Low-Resistivity Shale Reservoirs: A Case Study from the Upper Ordovician to Lower Silurian in the Sichuan Basin, SW China

Zhou,

Cai,

Mou

et al. 2023

Minerals

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High graphitization is responsible for low-resistivity shale development with poor reservoir quality. This paper provides an explanation of organic matter graphitization and determines the impact of high graphite content on low-resistivity shale reservoir quality at the Wufeng-Longmaxi Formation in the Southern Sichuan Basin. Fine veins are frequently developed at shale samples with Ro > 3.5%, graphitized organic matter > 25%, and resistivity < 5 Ω•m, which are dominated by three mineral assemblages: brunsvigite, barite-hyalophane-barium feldspar-potassium feldspar-anhydrite, and calcite-ankerite. These filling minerals are characterized by an Eu positive anomaly and high Ba, Fe, and Mn contents, suggesting that low-resistivity shale was modified by magmatic-related low-temperature hydrothermal fluid. Temperature measurements of brine inclusions and a semi-empirical geothermometer of chlorite show that low-temperature hydrothermal fluid experienced the chlorite stage (150–180 °C), the low-sulfidation stage (120–150 °C), and the low-temperature calcitization stage. Paleozoic fault systems and late Permian hydrothermal activities associated with the Emeishan mantle plume control the graphitization of low-resistivity shale. The water formation and seawater infiltrated into the deep crust along the Paleozoic basement faults under gravity, developing alkaline hot brine through mantle plume heating and then causing a water-rock reaction with basement rocks. They migrated upward along deep and large Paleozoic faults through convective thermal circulation in the Tiangongtang area, the Shuanglong-Luochang area, and the Xuyong area. Cation exchange and redox reactions occurred during the interaction between high-temperature hydrothermal fluid and cool wall rocks. The migration of alkaline hot brine via the Wufeng-Longmaxi shale introduced a subsequent water-rock reaction, resulting in the development of hydrothermal mineral assemblages that intricately filled fractures. It increased formation temperature and enhanced thermal maturity and graphitization of organic matter at the Wufeng-Longmaxi low-resistivity shale, resulting in a wide distribution of low-resistivity shale at the Changning Block.

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Section: Mineral Composition and Morphological Analysismentioning

confidence: 99%

Influence of Low-Temperature Hydrothermal Events and Basement Fault System on Low-Resistivity Shale Reservoirs: A Case Study from the Upper Ordovician to Lower Silurian in the Sichuan Basin, SW China

Zhou,

Cai,

Mou

et al. 2023

Minerals

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“…The intergranular pores of rigid minerals are mainly developed between rigid minerals such as quartz, feldspar, pyrite, and calcite, which are triangle, strip, and irregular, and are one of the main types of Quaternary mudstone reservoirs [29]. The pore diameter is mainly distributed in the range of 20~500 nm, and the length of intergranular pores of rigid minerals can reach the micron level.…”

Section: Intergranular Pores Of Rigid Mineralsmentioning

confidence: 99%

Pore Structure Characteristics, Genesis, and Its Controlling Effect on Gas Migration of Quaternary Mudstone Reservoir in Qaidam Basin

Tang

Shao

et al. 2022

Geofluids

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The Sanhu Depression in Qaidam Basin is the largest Quaternary biogenic gas exploration area with the shallowest burial depth in the world. The shallow high abundance of gas reservoirs and high-quality pure methane have become the main production areas. The development characteristics of loose mudstone reservoirs are restricted by extreme heterogeneity. Therefore, the Quaternary Qigequan Formation mudstone in Qaidam Basin is selected as the research object. Based on the study of the sedimentary background, petrological characteristics, and pore structure characteristics, by comparing the characteristics of different mudstone reservoirs, the controlling factors of the development of different mudstone reservoirs and the control of gas migration are clarified. Research shows the following: (1) The mudstone reservoirs of the Qigequan Formation mainly develop intergranular pores, clay mineral pores, and intragranular pores. The pore size distribution varies from nanometers to micrometers, and mesopores mainly contribute to the specific surface area. (2) Rigid minerals and clay minerals are the main controlling factors for the pore structure of mudstone reservoirs. The increase in the content of rigid minerals is conducive to the development of macropores or larger micropores, while the increase in the content of clay minerals is conducive to the development of mesopores and provides an important specific surface area for gas adsorption. (3) The gas migration form of pure mudstone is mainly dominated by Fick diffusion and slippage flow, which has the characteristics of self-sealing accumulation. The gas migration form of silty mudstone is the coexistence of Fick diffusion, slippage flow, and Darcy flow, which has the features of self-sealing and Darcy flow accumulation. The gas migration form of sandy mudstone is mainly Darcy flow, only with Darcy flow accumulation characteristics. The flow form of gas creates different accumulation modes of mudstone biogas. The Quaternary mudstone reservoir shows different particularity under different material components, and the exploration targets should be treated differently according to specific mudstone types.

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“…Through studying the dispersion characteristics of the LMXF shale, it has been discovered that mineral composition is the main factor affecting resistivity (Xiang et al, 2014), especially the content of pyrite and quartz (He et al, 2017). With further research, the impact of porosity on electrical properties has also been found to be substantial, particularly organic matter pores (Wang et al, 2016;Yang et al, 2020;Zhu et al, 2021Zhu et al, , 2022Zhang et al, 2023). Some researchers have employed geochemical methods to reconstruct the paleoenvironment of shale deposition, revealing a connection between mineral and organic matter content and the paleoenvironment (Loucks and Ruppel, 2007;Dowey and Taylor, 2017;Doner et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Controlling mechanism of shale palaeoenvironment on its resistivity and polarizability: A case study of the Longmaxi Formation in Southern Sichuan

Yang,

Zhang,

Wang

et al. 2024

Preprint

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The mineral composition, content, and organic matter enrichment in shale are significantly influenced by the sedimentary environment. However, there is a limited understanding of how the sedimentary environment impacts the electrical resistivity and polarization properties of shale. This study conducts experimental tests on shale from the Longmaxi Formation in the extensively explored Sichuan Basin of China, employing techniques such as complex resistivity, X-ray diffraction, organic geochemistry, porosity analysis, elemental geochemistry, and argon-ion polishing scanning electron microscopy. The experimental findings reveal the following key points: 1) The core resistivity of the Longmaxi Formation shale ranges from 14.56 Ω·m to 115.96 Ω·m, with an average value of 64.08 Ω·m. The polarization rate ranges from 0.07 to 0.32, with an average of 0.15. 2) Redox conditions and paleoproductivity primarily influence TOC content and the formation of biogenic quartz. The content of pyrite is influenced by redox environments, while clay minerals and terrigenous quartz content are affected by paleoclimate and terrigenous input. 3) The interconnected network of organic matter pores with other types of pores and the content of pyrite are the main controlling factors affecting resistivity. The pyrite content also influences the polarization effect of shale. 4) Redox conditions and paleoproductivity positively influence conductivity and polarization, whereas terrigenous input and paleoclimate have inhibitory effects on both. This study provides essential theoretical insights for logging interpretation, electromagnetic exploration of shale gas and subsequent monitoring of hydraulic fracturing.

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Electrical properties of Longmaxi organic-rich shale and its potential applications to shale gas exploration and exploitation

Cited by 19 publications

References 11 publications

Influence of Low-Temperature Hydrothermal Events and Basement Fault System on Low-Resistivity Shale Reservoirs: A Case Study from the Upper Ordovician to Lower Silurian in the Sichuan Basin, SW China

Influence of Low-Temperature Hydrothermal Events and Basement Fault System on Low-Resistivity Shale Reservoirs: A Case Study from the Upper Ordovician to Lower Silurian in the Sichuan Basin, SW China

Pore Structure Characteristics, Genesis, and Its Controlling Effect on Gas Migration of Quaternary Mudstone Reservoir in Qaidam Basin

Controlling mechanism of shale palaeoenvironment on its resistivity and polarizability: A case study of the Longmaxi Formation in Southern Sichuan

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