A Model of Hydrothermal Dolomite Reservoir Facies in Precambrian Dolomite, Central Sichuan Basin, SW China and its Geochemical Characteristics

Gu, Yifan; Zhou, Lu; Jiang, Yi; Jiang, Chan; Luo, Mingsheng; Zhu, Xiaomin

doi:10.1111/1755-6724.13770

Cited by 15 publications

(20 citation statements)

References 29 publications

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“…Particularly, the southwest region of Sichuan Basin was the most obvious and the strongest area, which was interacted by collision and uplifting. In this region, the NE-striking Xiongpo Anticline and Longquan Shan Anticline formed complex fold structure belts (Gu et al, 2019, Liu et al, 2003Jia et al, 2003;Wu et al, 2019, Zhang et al, 2011. It is commonly believed that the faulting-slipping at detachment and SE-striking collision from LMSF to Sichuan Basin are the main stress mechanism of Xiongpo-Longquan Shan fold belt (Li et al, 2014).…”

Section: The Southwestern Margin Of the Sichuan Basinmentioning

confidence: 99%

Spatial and Temporal Variations in Earthquake Stress Drops between the 2008 Wenchuan and 2013 Lushan Earthquakes

Feng

Liang

et al. 2020

Acta Geologica Sinica (Eng)

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As a case study of spatial and temporal variations in earthquake stress drops between the 2008 Ms 8.0 Wenchuan and 2013 Ms 7.0 Lushan earthquakes, we computed 1828 stress-drop values for earthquakes with magnitudes 1.7 ≤ M L ≤ 5.0 during an eight-year time span before and after major earthquakes. We divide the study area into three subregions (the southern segment of the Longmen Shan fault zone; the southwestern junction of the Longmen Shan and Sichuan Basin; and the southwestern margin of the Sichuan Basin) and calculate individual event stress drops in each. The results show that regions of alternating high and low stress drop are found on either side of the southwestern segment of the Longmen Shan fault zone. During the two-year period after the 2008 Ms 8.0 Wenchuan earthquake, the stress state of the southern Longmen Shan fault shows no significant change. A marked increase in stress level appears about 18 months before the 2013 Ms 7.0 Lushan earthquake near the Lushan hypocenter zone. Two months after the Ms 7.0 event, the stress drops suddenly attenuate, with significantly less seismic energy release per event. We find that changes in the patterns of high and low stress drop values are consistent with the process of stress accumulation or transfer from the pre-mainshock to postmainshock periods. The results indicate that major earthquakes are the dominant cause of temporal and spatial evolution in stress levels. Stress drop variations show obvious temporal and spatial patterns that may suggests subtle changes in the character of stress fields on faults and spatial variations related to local intense compression and tectonic effects.

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Section: The Southwestern Margin Of the Sichuan Basinmentioning

confidence: 99%

Spatial and Temporal Variations in Earthquake Stress Drops between the 2008 Wenchuan and 2013 Lushan Earthquakes

Feng

Liang

et al. 2020

Acta Geologica Sinica (Eng)

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“…Following a review of relevant geological data and surveys, it was discovered that the stratum of the Dengying Formation of the Upper Sinian system in the Xianfeng profile is relatively complete, with little weathering and no vegetation coverage, providing a solid geological foundation for future research. Predecessors divided Dengying Formation into four sections based on lithology combination and electrical characteristics of logging [48][49][50]. The thickness of the first section of Dengying Formation is 20-70 m. The lithology is mainly micrite-powder crystal dolomite and there are a small number of bacteria and algae.…”

Section: Geological Settingmentioning

confidence: 99%

3D Quantitative Characterization of Fractures and Cavities in Digital Outcrop Texture Model Based on Lidar

et al. 2022

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The combination of lidar and digital photography provides a new technology for creating a high-resolution 3D digital outcrop model. The digital outcrop model can accurately and conveniently depict the surface 3D properties of an outcrop profile, making up for the shortcomings of traditional outcrop research techniques. However, the advent of digital outcrop poses additional challenges to the 3D spatial analysis of virtual outcrop models, particularly in the interpretation of geological characteristics. In this study, the detailed workflow of automated interpretation of geological characteristics of fractures and cavities on a 3D digital outcrop texture model is described. Firstly, advanced automatic image analysis technology is used to detect the 2D contour of the fractures and cavities in the picture. Then, to obtain an accurate representation of the 3D structure of the fractures and cavities on the digital outcrop model, a projection method for converting 2D coordinates to 3D space based on geometric transformations such as affine transformation and linear interpolation is proposed. Quantitative data on the size, shape, and distribution of geological features are calculated using this information. Finally, a novel and comprehensive automated 3D quantitative characterization technique for fractures and cavities on the 3D digital outcrop texture model is developed. The proposed technology has been applied to the 3D mapping and quantitative characterization of fractures and cavities on the outcrop profile for the Dengying Formation (second member), providing a foundation for profile reservoir appraisal in the research region. Furthermore, this approach may be extended to the 3D characterization and analysis of any point, line, and surface objects derived from outcrop photos, hence increasing the application value of the 3D digital outcrop model.

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“…Although there have been some successful cases, the exploration and development of deep or ultra-deep dolomite reservoirs still face huge technical and commercial risks. In particular, these dolomite reservoirs are characterized by large burial depth and generally experienced complex diagenetic alteration processes (Du et al, 2018;Peng B. et al, 2018;Gu et al, 2019). Correspondingly, the reservoir rock exhibits extremely complicated characteristics due to the superimposition of multiple diagenetic events (Wang et al, 2014;Xu et al, 2016;Zhu et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…Zhu et al (2015) agreed with this view, but also emphasized the constructive role of recrystallization during supergene karstification. After 2013 (Shi et al, 2013;Liu et al, 2014;Peng J. et al, 2018;Gu et al, 2019), scholars have noticed the existence of multi-stage hydrothermal alteration in deep dolomite reservoir of the Dengying Formation and proposed that hydrothermal alteration increases the porosity of the Dengying Formation matrix dolomite by 3%-5% (Liu et al, 2014). However, Jiang et al (2016) proposed that porosity could only increase by 2% after hydrothermal alteration.…”

Section: Introductionmentioning

confidence: 99%

Effects of diagenesis on quality of dengying formation deep dolomite reservoir, Central Sichuan Basin, China: Insights from petrology, geochemistry and in situ U-Pb dating

Wang

Yang³

et al. 2023

Front. Earth Sci.

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The Ediacaran Dengying Formation in Central Sichuan Basin is the deep dolomite gas reservoir with the largest natural gas reserves in China, providing an excellent example for understanding the effect of diagenesis evolution on deep dolomite reservoir quality. By integrating petrology, geochemistry and in situ U-Pb dating, this study aims to reveal the genesis of different rock fabrics and their corresponding diagenetic events, and to discuss the temporal relationship of diagenetic events and their effects on the reservoir quality of Dengying Formation. Two phases of dolomite and three phases of dolomite cement are identified in Ediacaran Dengying Formation deep dolomite reservoirs of Central Sichuan Basin as follows: 1) matrix dolomites (MD), 2) fine-medium crystalline dolomites (FMD), 3) fibrous dolomites (FD), 4) medium-coarse crystalline dolomites (MCD), and 5) saddle dolomite (SD). By analyzing petrographic and temporal relationships between these fabrics, it is suggested that the deep dolomite reservoir of Dengying Formation in Central Sichuan Basin has experienced six diagenetic stages, including 1) syndiagenetic stage, 2) the first-time early diagenetic stage, 3) epidiagenetic stage, 4) the second-time early diagenetic stage, 5) middle diagenetic stage and 6) late diagenetic stage. Microbial dolomitization during syndiagenetic stage produced limited increase in reservoir porosity, but it is of great significance for preservation of reservoir spaces. Silicification is most unfavorable for reservoir formation, but its duration and influence range are very limited. At epidiagenetic stage, the physical properties of Dengying Formation dolomite reservoir have been greatly improved. Two-time early diagenetic stages are both destructive for preservation of reservoir spaces. During middle diagenetic stage, two-stage of hydrothermal alterations occurred, corresponding to Late Silurian to Devonian and Late Permian, respectively. Hydrothermal alteration of the MD is both constructive and destructive, but overall it is constructive, and the improvement of physical properties is limited. For the karstified MD, both two-stage hydrothermal alterations were destructive, resulting in damage of reservoir physical properties caused by cementation by two-stage SD and one-stage MVT minerals.

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A Model of Hydrothermal Dolomite Reservoir Facies in Precambrian Dolomite, Central Sichuan Basin, SW China and its Geochemical Characteristics

Cited by 15 publications

References 29 publications

Spatial and Temporal Variations in Earthquake Stress Drops between the 2008 Wenchuan and 2013 Lushan Earthquakes

Spatial and Temporal Variations in Earthquake Stress Drops between the 2008 Wenchuan and 2013 Lushan Earthquakes

3D Quantitative Characterization of Fractures and Cavities in Digital Outcrop Texture Model Based on Lidar

Effects of diagenesis on quality of dengying formation deep dolomite reservoir, Central Sichuan Basin, China: Insights from petrology, geochemistry and in situ U-Pb dating

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