Mineralogical characterization and diagenetic history of Permian marine tuffaceous deposits in Guangyuan area, northern Sichuan basin, China

Fang, Xiang-Min; Yu, Xiantao; Huang, Hengxu; Zhang, Deyan; Zhu, Xiaomin

doi:10.1016/j.marpetgeo.2020.104744

Cited by 5 publications

(4 citation statements)

References 46 publications

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“…When there is an aqueous medium, after hydrolytic devitrification, some of the components are lost with the pore water, and the remaining components are recrystallized and transformed into crystals or microcrystals. The formation process of devitrification includes a series of geochemical effects, such as dissolution-precipitation of volcanic glass, recrystallization, and migration and transformation of metal ions [66,67], and the volume of the newly formed minerals are smaller, thus forming a large number of micropores between different minerals [68][69][70][71]. Devitrification pores can account for approximately 70% of all types of pores in tuffs [68].…”

Section: Primary Pores Devitrification Poresmentioning

confidence: 99%

“…The pyroclastic rocks of the Huoshiling Formation in the study area are mainly com- The tuff has high surface porosity, and the pore type is dominated by devitrified and dissolved pores (Figure 10). Secondary dissolution pores easily form under the condition of dissolution by acidic formation water after devitrification of volcanic ash, and its recrystallization will also lead to the development of intergranular pores and improve the porosity of reservoirs [68][69][70][71]. The coarse-grained tuff has a higher feldspar content and lower clay mineral content than the fine-grained tuff (Figure 3), which provides a good material basis for dissolution, and the effective support of the coarse-grained tuff clastic particle framework is conducive to the formation of more effective pore space, so the coarse-grained tuff reservoir has more favorable physical properties.…”

Section: Devitrification Of Volcanic Ashmentioning

confidence: 99%

“…The process of devitrification involves a series of geochemical actions, including the recrystallization, dissolution, precipitation, migration, and transformation of metal ions. The vitric fragments undergo crystallization and shrink in volume, micropores will be formed in this series of processes, and then devitrification pores will be developed [68][69][70][71]. The pore size of the micropores formed by devitrification is small, but the number of micropores is large, resulting in a larger overall porosity.…”

Section: Devitrification Of Volcanic Ashmentioning

confidence: 99%

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Reservoir Characteristics and Development Model of Subaqueous Pyroclastic Rocks in a Continental Lacustrine Basin: A Case Study of the Chaganhua Subsag in the Changling Fault Depression, Songliao Basin

Shi,

Yi,

Bian

et al. 2023

Energies

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Industrial oil and gas eruptions underwater have been found in the pyroclastic rocks of the Huoshiling Formation in the continental lacustrine basin of the Changling fault depression, Songliao Basin. This paper investigates the reservoir space characteristics, physical characteristics, and pore structure differences of subaqueous pyroclastic reservoirs in the Huoshiling Formation, and the causes of physical property differences of different types of reservoirs and their formation and evolution processes are analyzed. (1) The content of volcanic glass in tuff is higher, the reservoir space is dominated by devitrification pores and dissolution pores, and the coarser the grain size, the more favorable the physical properties, with larger pore sizes and higher porosities. The content of clay minerals in sedimentary tuff is high, the pores between clay minerals are the main pores, and the physical properties of sedimentary tuff are poor. The content of soluble components such as feldspar, debris, and laumontite is high in tuffaceous sandstone, which is dominated by dissolution pores. (2) Primary pores are not developed in the pyroclastic reservoirs in the study area, and the reservoirs are relatively dense, with an average porosity of 2.43% and an average permeability of 0.076 mD. The coarse-grained tuff has the highest porosity, followed by tuffaceous sandstone and fine-grained tuff, and the sedimentary tuff has the least favorable physical properties. (3) Devitrification was an important cause of the high-porosity and ultralow permeability of tuff reservoirs. Two oil and gas charges in the middle diagenetic stage led to the organic acid dissolution of rocks. In addition, fractures can provide migration channels for organic acids and deep hydrothermal fluids, leading to late dissolution, and can connect various scattered dissolution pores to improve the effectiveness of the reservoir space. (4) Coarse-grained tuff reservoirs that developed in the proximal facies are favorable targets for hydrocarbon exploration.

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Section: Primary Pores Devitrification Poresmentioning

confidence: 99%

Section: Devitrification Of Volcanic Ashmentioning

confidence: 99%

Section: Devitrification Of Volcanic Ashmentioning

confidence: 99%

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Reservoir Characteristics and Development Model of Subaqueous Pyroclastic Rocks in a Continental Lacustrine Basin: A Case Study of the Chaganhua Subsag in the Changling Fault Depression, Songliao Basin

Shi,

Yi,

Bian

et al. 2023

Energies

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“…Tuffaceous rock, a transition rock between volcanic rock and sedimentary rock, differs from the latter in terms of its lithological characteristics and mineral composition. It is greatly affected by volcanic alteration and later sedimentary-reworking processes (Streck et al, 1995;Colin and Wes, 2003;Inoue et al, 2004;Ddani et al, 2005;García-Romero et al, 2005;Wang et al, 2005;Bertog et al, 2007;Liu et al, 2007;Carey, et al, 2008;Cheng et al, 2010;Yanik et al, 2010;Wang et al, 2020;Xiang et al, 2021;Fan et al, 2022;Li et al, 2022). To identify the basic characteristics of the tuffaceous section, the author studied the Upper Permian marine tuffaceous rocks in the Sichuan Basin by thin-section identification, scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), X-ray diffraction analysis (XRD), mercury injection capillary pressure (MICP), CT scan and other means.…”

Section: Introductionmentioning

confidence: 99%

Lithofacies, mineralogy, and pore characteristics of Permian marine tuffaceous rocks in the Sichuan Basin

Xiong²,

Wang³

et al. 2023

Front. Earth Sci.

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Alongside volcanic eruptions in the middle and late Permian, the sedimentary environment and process changed, and the lithofacies and mineralogical characteristics varied conspicuously from the marine sediments in this period. Marine tuffaceous rocks beared strong witness to the marine and volcanic actions in this time. With experimental studies relying on field outcrop, thin section, scanning electron microscope, X-ray diffraction (XRD), mercury injection capillary pressure (MICP) and CT scan, the researchers analyzed the lithology, mineralogy, and pore characteristics of marine tuffaceous rocks. Among the Permian marine tuffaceous sections of the Sichuan Basin, three types of lithofacies were identified, namely tuff, sedimentary tuff, and tuffaceous mudstone. The mineral composition of the tuffaceous section includes quartz, feldspar, carbonate minerals, pyrite, clay, etc. The quartz content varies from 4.0% to 27.3%, with an average value of 13.0%; the feldspar content varies from 0 to 21.2%, with an average value of 9.8%; the carbonate mineral content varies from 8.52% to 53.45%, with an average value of 27.6%; the clay mineral content varies from 0 to 75.3%, with an average value of 44.8%; and the pyrite content varies from 0 to 13.4%, with an average value of 5.8%. The porosity of tuffaceous rocks varies from 2.2% to 8.1%, mostly concentrated in the range from 3% to 7% with an average level of 5.24%. There are mainly shrinkage pores, dissolution pores, intercrystalline pores, and organic pores. In terms of scale, the pores can be classified as micron-scale and nano-scale pores, and in terms of size, they are mainly micropores and mesopores, accounting for up to 92.12%. The pores are concentrated in the tuffaceous section and well interconnected, forming a complex organic-inorganic pore-fracture network system and bedding fractures with even better connectivity. The pores of the tuffaceous section are greatly influenced by lithofacies and mineral composition. The porosities of tuffaceous mudstone, sedimentary tuff and tuff rank downward, with average porosities of 6.5%, 5.09%, and 3.86% respectively. The felsic content is inversely correlated with porosity; the clay content and TOC content are positively correlated with porosity; the pyrite content is also inversely correlated with porosity. The marine tuffaceous section is similar to shale to a certain extent as it has relatively dense lithology, its pores are mainly of micron-scale and nano-scale and mainly include micropores and mesopores. It boasts the hydrocarbon-generating capacity and reservoir performance, serving as both a source rock and a reservoir. As a novel reservoir, the tuffaceous section can form a tight reservoir both generating and depositing gas and featuring source-reservoir paragenesis, lithological reservoir-controlling, and large-area stratified distribution, manifesting a promising future for exploration.

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Genesis of the Wangpo bed in the Sichuan Basin: Formation by eruptions of the Emeishan large igneous province

Wang

Cao

Zhang

et al. 2022

Palaeogeography, Palaeoclimatology, Palaeoecology

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Mineralogical characterization and diagenetic history of Permian marine tuffaceous deposits in Guangyuan area, northern Sichuan basin, China

Cited by 5 publications

References 46 publications

Reservoir Characteristics and Development Model of Subaqueous Pyroclastic Rocks in a Continental Lacustrine Basin: A Case Study of the Chaganhua Subsag in the Changling Fault Depression, Songliao Basin

Reservoir Characteristics and Development Model of Subaqueous Pyroclastic Rocks in a Continental Lacustrine Basin: A Case Study of the Chaganhua Subsag in the Changling Fault Depression, Songliao Basin

Lithofacies, mineralogy, and pore characteristics of Permian marine tuffaceous rocks in the Sichuan Basin

Genesis of the Wangpo bed in the Sichuan Basin: Formation by eruptions of the Emeishan large igneous province

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