Geochemical comparison between gas in fluid inclusions and gas produced from the Upper Triassic Xujiahe Formation, Sichuan Basin, SW China

Tao, Shizhen; Zou, Caineng; Mi, Jingkui; Gao, Xiaohui; Yang, Chun; Zhang, Xiangxiang; Fan, Jianwei

doi:10.1016/j.orggeochem.2014.05.008

Cited by 20 publications

(5 citation statements)

References 12 publications

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“…The Indosinian movement at the end of the Late Triassic resulted in the collision of the Yangtze plate with the North China plate. The Longmenshan island chain along the western edge of the Sichuan Basin gradually evolved into a strong thrust nappe orogenic belt and entered the stage of foreland basin evolution, and the coal-bearing clastic rocks of the Xujiahe Formation were deposited [17,18,[22][23][24].…”

Section: Methodsmentioning

confidence: 99%

The Origin of Quartz Cement in the Upper Triassic Second Member of the Xujiahe Formation Sandstones, Western Sichuan Basin, China

Ren

Wang

et al. 2021

Water

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High-precision in situ δ18O values obtained using secondary ion mass spectrometry (SIMS) for μm-size quartz cement are applied to constrain the origin of the silica in the deep-buried Upper Triassic second member of Xujiahe Formation tight sandstones, western Sichuan Basin, China. Petrographic, cathodoluminescence (CL), and fluid inclusion data from the quartz cements in the Xu2 sandstones indicate three distinct, separate quartz precipitation phases (referred to as Q1, Q2, and Q3). The Q1 quartz cement was formed at temperatures of approximately 56–85 °C and attained the highest δ18O values (ranging from 18.3 to 19.05‰ Vienna Standard Mean Ocean Water (VSMOW)). The Q2 quartz cement was generated at temperatures of approximately 90–125 °C, accompanying the main phase of hydrocarbon fluid inclusions, with the highest Al2O3 content and high δ18O values (ranging from 15 to 17.99‰ VSMOW). The Q3 quartz cement was formed at temperatures of approximately 130–175 °C, with the lowest δ18O values (ranging from 12.79 to 15.47‰ VSMOW). A portion of the Q2 and Q3 quartz cement has a relatively high K2O content. The dissolution of feldspar and volcanic rock fragments was likely the most important source of silica for the Q1 quartz cement. The variations in δ18O(water) and trace element composition from the Q2 quartz cement to the Q3 quartz cement suggest that hydrocarbon emplacement and water-rock interactions greatly altered the chemistry of the pore fluid. Feldspar dissolution by organic acids, clay mineral reactions (illitization and chloritization of smectite), and pressure dissolution were the main sources of silica for the Q2 and Q3 quartz cements, while transformation of the clay minerals in the external shale unit was a limited silica source.

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Section: Methodsmentioning

confidence: 99%

The Origin of Quartz Cement in the Upper Triassic Second Member of the Xujiahe Formation Sandstones, Western Sichuan Basin, China

Ren

Wang

et al. 2021

Water

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“…In the Late Triassic, the compression of the Early Indosinian Orogeny led to the uplift of the Longmen Mountains on the western margin. The Sichuan Basin was then gradually developed as a foreland basin (Gao, Sun, Zhang, Hu, & Zhu, 2012;Tao et al, 2014;Yue et al, 2018). After the Longmen Mountains uplifted, the basin evolved into an intracontinental depression filled with terrestrial clastic sediments (Li et al, 2011).…”

Section: Geological Settingmentioning

confidence: 99%

Diagenesis and reservoir quality of the second member of the Upper Triassic Xujiahe Formation tight gas sandstones in the Western Sichuan Depression, southwest China

et al. 2021

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The tight sandstones reservoir of the second member of the Xujiahe Formation (Xu2 member) is gradually becoming the main reservoir for natural gas exploration and exploitation in the Western Sichuan Basin. The tight sandstone is normally deeply buried, where it is controlled by complex diagenetic processes. To gain insights into reservoir exploration of the Xu2 member, the diagenetic history and the impacts of diagenesis on reservoir quality were established using several experimental methods.The sandstones were found to be mainly litharenite, sublitharenite, and feldspathic litharenite. The reservoir quality was characterized by low porosity (3.4% on average), low permeability (0.17 mD on average), low pore throat radius, and high displacement pressure. The tight sandstones experienced a series of significant diagenetic processes, including mechanical compaction, early dissolution, and precipitation of carbonate and siliceous cements during eodiagenesis. They also underwent chemical compaction, late dissolution, and transformation of clay minerals during mesodiagenesis. The silica cementation mainly resulted from chemical compaction, feldspar dissolution, and the transformation of clay minerals. A higher degree of compaction has a vital role in destroying most of the primary pores. Cementation had a significant impact on reducing the porosity and permeability, although chlorite preserved primary pores by slowing the compaction. This study aimed to provide a comprehensive insight into diagenesis and its impact on the reservoir quality of deeply buried sandstone, and provide insights into reservoir exploration and development in deeply buried tight sandstones.

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“…The exploration of the target formation, the Xujiahe Formation in central Sichuan, began in the 1950s. To date, several giant gas fields of Xujiahe Formation, like Guang 'an, Hechuan, Anyue, and Xinchang, have been discovered successively, with proven gas reserves of more than 0.6 × 10 12 m 3 (Tao et al, 2014).…”

Section: Geologic Backgroundmentioning

confidence: 99%

Bi-Fractal Characterization of the Pore Network of Tight Sandstone

et al. 2021

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Fluid seepage performance and accumulation in tight sandstone is a critical research topic for in-depth exploration and development, closely related to the heterogeneity of the pore network. The fractal characterization is one of the most compelling and direct ways for quantitative investigation of heterogeneity. However, only one kind of fractal is used in most studies, and the differences and relations between different fractal dimensions are rarely discussed. This paper chose one of the most representative tight sandstone formations in China, the second member of the Xujiahe Formation, as the research object. First, based on physical analysis and XRD analysis, we carried out a qualitative investigation on pore structure utilizing thin-section and scanning electron microscopy. Then, detailed pore structure parameters were obtained using high-pressure mercury intrusion (HPMI). Lastly, we combined two-dimensional fractal analysis on thin-section images and three-dimensional fractal analysis on HPMI data to characterize the pore network heterogeneity quantitatively. The Xu2 tight sandstone is mainly medium- to fine-grained lithic feldspathic sandstone or feldspathic lithic sandstone with low porosity and permeability. Also, the Xujiahe tight sandstone is mainly composed of quartz, feldspar, and clay. The pore types of Xu2 tight sandstones are primarily intergranular pores, micro-fractures, and intra- and intergranular dissolution pores. Moreover, most of the micro-fractures in gas-bearing formation are open-ended, while most are filled by clay minerals in the dry formation. The r50 (median pore radius) is the most sensitive parameter to seepage capability (permeability) and gas-bearing status. The 2D fractal dimension (Ds) of gas-bearing samples is significantly larger than that of dry samples, while the 3D fractal dimension (D1, D2) of gas-bearing samples is lower than that of dry samples. There is a strong negative correlation between D2 and gas-bearing status, permeability, quartz content, and r50, but a positive correlation between Ds and these parameters. D2 represents the heterogeneity of pore space, while the Ds indicates the development of the pore network. Tectonic movements that generate micro-fractures and clay cementation that blocks the seepage channels are the two main controlling factors on fractal dimensions. Combining 2D and 3D fractal analysis could give a more in-depth investigation of pore structure.

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Geochemical comparison between gas in fluid inclusions and gas produced from the Upper Triassic Xujiahe Formation, Sichuan Basin, SW China

Cited by 20 publications

References 12 publications

The Origin of Quartz Cement in the Upper Triassic Second Member of the Xujiahe Formation Sandstones, Western Sichuan Basin, China

The Origin of Quartz Cement in the Upper Triassic Second Member of the Xujiahe Formation Sandstones, Western Sichuan Basin, China

Diagenesis and reservoir quality of the second member of the Upper Triassic Xujiahe Formation tight gas sandstones in the Western Sichuan Depression, southwest China

Bi-Fractal Characterization of the Pore Network of Tight Sandstone

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