Pore structure and heterogeneity of shale gas reservoirs and its effect on gas storage capacity in the Qiongzhusi Formation

Chen, Shangbin; Gong, Zhuo; Li, Xueyuan; Wang, Huijun; Wang, Yang; Zhang, Yingkun

doi:10.1016/j.gsf.2021.101244

Cited by 36 publications

(15 citation statements)

References 56 publications

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“…The content of clay minerals of the Lower Cambrian shales in southern China is generally in the range of about 20% to 40%, and clay minerals mainly include illites, illitesmectite mixed layers, and a small amount of chlorites and kaolinites [22,47,118,122,176]. With the increasing burial depth, montmorillonites would be transformed into illites or illite-smectite layers.…”

Section: Tectonic Deformationmentioning

confidence: 99%

Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

Gao

Xiao

et al. 2022

Geofluids

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The Lower Cambrian shales are widely developed in southern China, with greater thicknesses and higher TOC contents. Although the shale gas resource potential has been suggested to be huge, the shale gas exploration and development is not satisfactory. At present, the gas-bearing property evaluation of the Lower Cambrian shale is still a hot spot of concern. According to previous works, this paper systematically summarizes the gas-bearing characteristics and controlling factors of the Lower Cambrian shales in southern China. The buried depth of Lower Cambrian shales mainly ranges from 3000 m to 6000 m, and the thickness of organic-rich shale intervals ( TOC > 2 % ) varies from 20 m to 300 m. The TOC content and EqVRo value are generally up to 2%-10% and 2.5%-6.0%, respectively. The gas content of the Lower Cambrian shales in the Weiyuan-Qianwei block of the Sichuan Basin and the western Hubei area generally exceeds 2 m3/t, and gas composition is dominated by CH4. In southeastern Chongqing, northwestern Hunan, and northern Guizhou areas, the gas content of the Lower Cambrian shales is generally <2 m3/t, and the N2 content is generally >60%. In the Lower Yangtze region, the Lower Cambrian shale reservoirs basically contain no gas. Higher maturity, lower porosity, and less-no organic pores are suggested to be responsible for low gas contents and/or the predominate of N2 in shale gas reservoirs. Strong tectonic deformation is an important factor leading to the massive gas loss from shale reservoirs, thus resulting in no gas or only a small amount of N2 in the Lower Cambrian shales. In a word, the Lower Cambrian shale gas plays with low maturity and relatively stable tectonic condition, especially deep-ultradeep zones, may be the favorable targets for shale gas exploration.

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Section: Tectonic Deformationmentioning

confidence: 99%

Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

Gao

Xiao

et al. 2022

Geofluids

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“…Previous studies suggested that the rift was the sedimentary center of high-quality source rocks in the lower Cambrian (Han et al, 2013;Wei et al, 2015;Zheng et al, 2014), the generated hydrocarbon could migrate laterally to the reservoirs on both sides of the rift (Figure 1C). Now, the Weiyuan and Anyue gas fields have been found on both sides of the rift, and shale gas is also under exploration (Zou et al, 2014(Zou et al, , 2020Wei et al, 2017;Chen, et al, 2021).…”

Section: Geological Settingmentioning

confidence: 99%

The Fluid Evolution of Ancient Carbonate Reservoirs in Sichuan Basin and Its Implication for Shale Gas Exploration

2021

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Sichuan Basin is the only successful basin for shale gas exploration in China. In addition to the main shale in the Lower Silurian Longmaxi formation, the lower Cambrian Qiongzhusi shale is an important potential formation. However, it was once considered that shale gas is difficult to enrich because of its poor sealing conditions and hydrocarbon migration to adjacent reservoirs. With the increasing research on hydrocarbon generation and reservoir in shale of Qiongzhusi Formation in recent years, it has become an important exploration target in Sichuan Basin. The enrichment of oil and gas is closely related to fluid activities. Limited by the degree of exploration, there is little analysis of fluid activities in Qiongzhusi Formation, and there is little analysis of shale gas enrichment potential from the perspective of fluid. The hydrocarbon generated from Qiongzhusi shale in the rift could migrate laterally to the uplift area and form a reservoir in Dengying Formation. The fluid activities from source rock to reservoir are basically the same. Therefore, this paper reconstructed the history of hydrocarbon activities in Dengying reservoirs based on fluid inclusion analysis. Then the fluid activity process in Qiongzhusi shale was studied, and its enrichment conditions of shale gas was discussed. The results show that the hydrocarbon activities of Dengying Formation can be divided into three stages: 1) oil charging stage, 2) oil cracking gas generation stage and 3) gas reservoir adjustment stage. The first stage is under normal pressure, and the second and third stages developed overpressure with pressure coefficients of 1.3 and 1.2, respectively. High pressure coefficient is an important indicator of shale gas enrichment. Because the source rock of Qiongzhusi Formation has always been the main source rock of Dengying Formation, it can supply hydrocarbon to Dengying Formation only with overpressure in gas generation stage. Therefore, overpressure in the last two stages of gas generation indeed existed. As long as the sealing condition of shale itself is not particularly poor, shale gas “sweet points” would be formed. Therefore, the thick shale in Deyang-Anyue rift is the focus of shale gas exploration in Qiongzhusi Formation.

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“…The key parameter in assessing the gas storage potential of unconventional rocks is their mineralogy, porosity, and organic richness. The gas storage IOP Publishing doi:10.1088/1755-1315/1003/1/012040 2 and hydraulic fracturing potential of shale reservoirs requires characterization at various scales due to the heterogeneous nature of these rocks [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Elastic properties and pore structure characterization of selected shales in the sungai Perlis beds, Terengganu, Peninsular Malaysia

Haq

Padmanabhan

Khan

et al. 2022

IOP Conf. Ser.: Earth Environ. Sci.

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Studied drill core of the Sungai Perlis Beds in the Terengganu State, Peninsular Malaysia, consists of a diverse suite of organic rich shale lithofacies at various subsurface depths. Lithofacies were delineated on the basis bedding thickness, mineralogy, and organic richness carried out by X-ray diffraction and (XRD) total organic content (TOC) analysis. Field-emission scanning electron microscopy (FE-SEM) analysis was carried out to identify the pore structure, range of pore sizes and mineral arrangement within each lithofacies unit Elastic geomechanical properties (Young’s modulus and Poisson’s ratio) were measured on core samples from each lithofacies unit using static and dynamic approaches. The identified lithofacies include moderate TOC massive argillaceous shale (MTOCMAS), high TOC massive argillaceous shale (HTOCMAS) and high TOC massive siliceous shale (HTOCMSS). FE-SEM analysis shows that pores in all the lithofacies are mostly intergranular, associated with phyllosilicate minerals, and ranges from <1 micrometer to approximately 8 micrometer. Static and dynamic elastic properties measurement shows that shale lithofacies having a high content of phyllosilicate minerals has a lower Young’s modulus and a high Poisson’s ratio value while lithofacies rich in brittle minerals has a higher Young’s modulus and a low Poisson’s ratio value. A good correlation exists between mineralogical brittleness index of the lithofacies and their plane strain modulus. The plane strain modulus is found higher in lithofacies having abundance of brittle minerals in the matrix suggesting that the high TOC massive siliceous shale (HTOCMSS) would preferably allow formation of dense hydraulic fractures, as observed in the CT scan analysis of triaxially fractured specimen, compared to argillaceous shale lithofacies.

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Pore structure and heterogeneity of shale gas reservoirs and its effect on gas storage capacity in the Qiongzhusi Formation

Cited by 36 publications

References 56 publications

Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

The Fluid Evolution of Ancient Carbonate Reservoirs in Sichuan Basin and Its Implication for Shale Gas Exploration

Elastic properties and pore structure characterization of selected shales in the sungai Perlis beds, Terengganu, Peninsular Malaysia

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