Quartz types and origins of the Upper Permian Dalong Formation shale of the Sichuan Basin: Implications for pore preservation in deep shale reservoirs

Gao, Ping; Xiao, Xianming; Meng, Guangming; Lash, Gary G.; Li, Shuangjian; Han, Yueqing

doi:10.1016/j.marpetgeo.2023.106461

Cited by 7 publications

(6 citation statements)

References 69 publications

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“…During the early burial stage, large-grained quartz particles can protect larger pores from compaction, thus preserving the pore space. However, the filling of pores by authigenic biogenic quartz precipitates hinders pore preservation . Previous studies have shown that the quartz in the Dalong Formation shale is mainly derived from biogenic sources, and the pore development in the Dalong Formation shale is inhibited by quartz.…”

Section: Discussionmentioning

confidence: 99%

“… (a) Late Permian global paleogeographic map [adapted with permission from ref ( 38 ) Copyright (2017) (Elsevier)] and (b) late Permian lithofacies paleogeography of the South China plate [adapted with permission from ref ( 39 ) Copyright (2023) (Elsevier)]. (c) Modern tectonic map of western Hubei [adapted with permission from ref ( 40 ) Copyright (2020) (Elsevier)].…”

Section: Geological Settingmentioning

confidence: 99%

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Pore Structure and Fractal Dimension in Marine Mature Silicon-Rich Shale of the Dalong Formation in Western Hubei

Liu,

Zhu,

Qiao

et al. 2024

ACS Omega

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How shale reservoirs and gas contents are affected by the pore structure of shale is very important. Low-temperature nitrogen isothermal adsorption experiments were conducted by us to investigate the pore structure of the Dalong Formation shale. We measured the specific surface area and fractal dimension of the pores and also considered the mineral fraction and organic matter content of the rock. The results show that the Dalong Formation shale contains a lot of organic carbon, with a total organic carbon (TOC) value between 1.20 and 10.82% (mean: 5.02%). Quartz and clay minerals are the main components of the shale, with quartz making up 40.30 to 85.60% (mean: 67.21%) and clay minerals making up 9.20 to 34.10% (mean: 20.26%) of the shale. Most of the pore space in the shale of the Dalong Formation is formed by intragranular and intergranular pores, organic matter pores, and some microfissures. The pore structure is complex, with parallel-plate and ink-bottle pores being the most common types. Most of the pores are 0−2 or 2−5 nm in size. D 1 and D 2 are the fractal dimensions, with averages of 2.66 and 2.81, respectively. D 1 can range from 2.55 to 2.78, while D 2 can range from 2.66 to 2.94. The TOC content, mineral composition, and pore structure characteristics determine the fractal dimension. Higher levels of the TOC content, quartz mineral content, and specific pore surface area result in a higher fractal dimension, while higher levels of feldspar content result in a lower one. There is no apparent correlation to clay minerals or other mineral compositions.

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Section: Discussionmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Pore Structure and Fractal Dimension in Marine Mature Silicon-Rich Shale of the Dalong Formation in Western Hubei

Liu,

Zhu,

Qiao

et al. 2024

ACS Omega

View full text Add to dashboard Cite

show abstract

“…(a) Late Permian global paleogeographic map (adapted with permission from ref . Copyright [2017] [Elsevier]), (b) late Permian lithofacies paleogeography of the South China Plate (adapted with permission from ref . Copyright [2023] [Elsevier]), and (c) modern tectonic map of western Hubei (adapted with permission from ref .…”

Section: Geological Settingmentioning

confidence: 99%

Origin of Authigenic Quartz in Organic-Rich Shales of the Dalong Formation (NW Middle Yangtze Basin), South China: Implications for Pore Network Development

Liu,

Zhu,

Qiao

et al. 2024

Energy Fuels

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To investigate the origin of quartz and its effect on shale reservoirs in the Dalong Formation, we conducted a thorough analysis of shale samples using various techniques including optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), low-temperature N 2 adsorption, and geochemical analysis. Our findings reveal the presence of different types of quartz in the Dalong Formation shale, namely, detrital quartz, siliceous biogenic quartz, and quartz resulting from the transformation of clay minerals (S−I quartz). The geochemical data show that the contents of TiO 2 and Al 2 O 3 in shale are low, with SiO 2 showing a negative correlation with those of TiO 2 and Al 2 O 3 . The average value of Al/(Al + Fe + Mn) was determined to be 0.66, while the average value of δ 30 Si was 0.68‰. The results indicate that the silica in the Dalong Formation shale was mainly derived from biogenic sources and was not influenced by a hot liquid. The contribution of terrestrial silica is minimal. The content of silica from different sources was quantified, with an average of 71.37% biogenic quartz, 20.22% terrigenous detrital quartz, and 8.40% S−I quartz. By investigating the pore loss mechanism and analyzing N 2 adsorption data, we discovered that biogenic quartz and S−I quartz have a significant impact on pore development in shale. Biogenic quartz acts as a rigid particle, resisting shale compaction and facilitating pore preservation. On the other hand, S−I quartz, which forms through the transformation of clay minerals, promotes further rock compaction and acts as cement, inhibiting pore development. The presence of terrestrial detrital quartz hinders the formation of mesopores in the shale.

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“…7 It is a key area for shale gas exploration and development in Block H. The Permian sedimentary environment of the area predominantly comprises early shoreline and late continental shelf facies. 18 The Wu-2 member in the Wujiaping Formation is developed with brown siliceous shale. This shale layer exhibits a consistent spatial distribution, optimal burial depth, and maturity.…”

Section: Geological Settingmentioning

confidence: 99%

“…Specifically, the Jiannan structure is a box-shaped elongated anticline with relatively steep limbs, characterized by compressional thrust faults . It is a key area for shale gas exploration and development in Block H. The Permian sedimentary environment of the area predominantly comprises early shoreline and late continental shelf facies . The Wu-2 member in the Wujiaping Formation is developed with brown siliceous shale.…”

Section: Geological Settingmentioning

confidence: 99%

Study on Key Technologies of Geosteering for Shale Gas Horizontal Wells in the Complex Structural Area of Block H in Western Hubei-Eastern Chongqing

Shi,

Feng,

Zhao

et al. 2024

ACS Omega

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Block H, located in western Hubei-eastern Chongqing, remains at a low exploration degree. Characterized by its complex structural attributes, the area presents adverse conditions such as a thin thickness of high-quality shale reservoir, rapid lateral formation occurrence, and poor stratigraphic correlation, challenging conventional geosteering methods. The primary shale gas reservoir in Block H corresponds to the Upper Permian Wujiaping Formation. To ensure that the shale gas horizontal wells in this block effectively penetrate high-quality gas reservoirs, this study delves into the geological characteristics of this stratigraphic unit, identifies principal challenges faced by current geosteering techniques, and introduces a tailored technical solution. This solution encompasses the application of real-time 3D geological modeling to track while drilling, identification of steering marker layers, optimization of steerable tools, and optimization of the steering trajectory while drilling. In the technology of optimization of the steering trajectory while drilling, a trajectory control calculation model based on the average angle technique was established for the first time. Additionally, a sectional control chart for marker layers and well inclination under different deflecting constraints was established. These methods have solved the problems of large error in target prediction and poor trajectory control effects by using the equal thickness method alone. The findings from this study can significantly enhance target prediction and trajectory control accuracy in complex structural areas, offering pivotal insights for the proficient development of analogous shale gas reservoirs in the future.

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Quartz types and origins of the Upper Permian Dalong Formation shale of the Sichuan Basin: Implications for pore preservation in deep shale reservoirs

Cited by 7 publications

References 69 publications

Pore Structure and Fractal Dimension in Marine Mature Silicon-Rich Shale of the Dalong Formation in Western Hubei

Pore Structure and Fractal Dimension in Marine Mature Silicon-Rich Shale of the Dalong Formation in Western Hubei

Origin of Authigenic Quartz in Organic-Rich Shales of the Dalong Formation (NW Middle Yangtze Basin), South China: Implications for Pore Network Development

Study on Key Technologies of Geosteering for Shale Gas Horizontal Wells in the Complex Structural Area of Block H in Western Hubei-Eastern Chongqing

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