Pore characteristics of the lower Sinian Doushantuo Shale in the Mid-Yangtze Yichang area of China: Insights into a distinct shale gas reservoir in the Neoproterozoic formation

Yang, Wei; He, Sheng; Zhai, Gangyi; Tao, Ze; Dong, Tian; Han, Yuanjia; Chen, Ke; Shen, Wei

doi:10.1016/j.jngse.2019.103085

Cited by 11 publications

(14 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…High gas production rate achieved from the Ediacaran shale, as mentioned in the introduction, further implies that the oldest potential shale gas formation could be extended from Cambrian to Ediacaran strata. Currently, with respect to Ediacaran shales, only a few studies exist and mainly focus on the pore types, pore size distribution and their relationship with organic matter and minerals (Chen et al 2016;Yang et al 2020). Our study also indicates that the pore structure of Ediacaran shales could limit the long-term shale gas production.…”

Section: Gas-in-placementioning

confidence: 67%

“…Therefore, an appraisal of the economic potential of Ediacaran shale gas reservoirs is of particular importance. While numerous studies were performed to characterize storage properties of the Wufeng-Longmaxi shales (Yang et al 2015(Yang et al , 2016(Yang et al , 2017Wang et al 2016), only a few studies thus far focused on shales from the Ediacaran (Chen et al 2016;Yang et al 2020). These shales, though extremely high in thermal maturity (approximately 4.0% in equivalent vitrinite reflectance), are rich in organic matter (TOC content of up to 8.0 wt.%) and widely distributed in the area of the Upper Yangtze platform with thicknesses of 200 to 900 m. The well-studied Silurian Longmaxi Shale in the Sichuan Basin has a lower thermal maturity (2.0-3.2%), smaller thickness from 100 to 500 m, exhibits high TOC contents (up to 8.3 wt.%) as well as porosity (3.4-8.2%) (Zou et al 2014;Yang et al 2015;Zhang et al 2019).…”

Section: Article Highlightsmentioning

confidence: 99%

See 1 more Smart Citation

Pore structure and sorption capacity investigations of Ediacaran and Lower Silurian gas shales from the Upper Yangtze platform, China

Gaus

Seemann

et al. 2021

Geomech. Geophys. Geo-energ. Geo-resour.

View full text Add to dashboard Cite

The shale gas potential of Ediacaran and Lower Silurian shales from the Upper Yangtze platform is assessed in this study with a focus on the contributions of clay minerals and organic matter to sorption capacity. For this purpose, a multidisciplinary assessment was carried out using petrophysical, mineralogical, petrographic and geochemical methods. In terms of TOC contents (4.2%), brittle mineral contents (68.6%) and maximum gas storage capacities (0.054–0.251 mmol/g) Ediacaran shales from this study show comparable properties to other producing shale gas systems although the thermal maturity is extremely high (VRr = 3.6%). When compared to lower Silurian shales from the same region, it is evident that (1) deeper maximum burial and (2) a lack of silica-associated preservation of the pores resulted in a relatively lower mesopore volume, higher micropore volume fraction and lower overall porosity (Ediacaran shales: 1.4–4.6%; Silurian shales: 6.2–7.4%). Gas production is therefore retarded by poor interconnectivity of the pore system, which was qualitatively demonstrated by comparing experimental gas uptake kinetics. TOC content exhibits a prominent control on sorption capacity and micropore volume for both shales. However, different contributions of clay minerals to sorption capacity were identified. This can partly be attributed to different clay types but is likely also related to burial-induced recrystallisation and different origins of illite. Additionally, it was shown that variations in sorption capacity due to incorrect estimates of clay mineral contribution are in the same range as variations due to differences in thermal maturity. Article highlights Pore structure and gas storage characteristics are evaluated for the first time for Ediacaran Shales from the Upper Yangtze platform Due to a lower free gas storage capacity and diffusivity, the Ediacaran shale can be regarded as a less favorable shale gas prospect when compared to the Silurian shale Clay mineral contribution to sorption capacity is evaluated taking clay mineralogy into consideration Maturity-related changes of organic matter sorption capacity have been discussed on the basis of a compiled data set

show abstract

Section: Gas-in-placementioning

confidence: 67%

Section: Article Highlightsmentioning

confidence: 99%

Pore structure and sorption capacity investigations of Ediacaran and Lower Silurian gas shales from the Upper Yangtze platform, China

Gaus

Seemann

et al. 2021

Geomech. Geophys. Geo-energ. Geo-resour.

View full text Add to dashboard Cite

show abstract

“…The TOC content of the Z 1 d 2 shale averaged 1.95 wt %, ranging from 0.35 to 4.42 wt %. 27,28,31 3. SAMPLES AND ANALYTICAL METHODS 3.1.…”

Section: Geological Settingmentioning

confidence: 99%

“…31 The vitrinite reflectance (R o %) of the Niutitang Shale in well ZD2 ranged from 1.97% to 2.59%, similar to the R o % measured in other wells in the Yichang area, with R o % ranging from 2.26% to 2.70%. 25,26,28,31 When comparing the coexisting two-phase aqueous inclusions Th trend in the calcite and quartz particles (approximately 120−170 and 90−120 °C, respectively) with the burial and thermal maturity models, we can infer that methane inclusions in the calcite and quartz veins were successively trapped during the large-scale rapid uplifting process of the Huangling anticline from approximately 150 to 120 Ma (Figure 11), indicating that the fluid inclusions were trapped after the maximum burial conditions and corresponding petroleum cracking into dry gas. This interesting phenomenon can be explained by the compression of the Z 1 d shale reservoir during the uplifting process, resulting in widespread fracturing and the permeation of methane-rich fluids.…”

Section: Trapping Conditions Of Fluid Inclusionsmentioning

confidence: 99%

“…Geologically, the ancient Z 1 d shale has experienced multiple burials and uplifts and thus a complex thermal evolution history with multiple significant geo-hydrodynamic events. Therefore, this Z 1 d shale has recently received widespread attention and has been researched in terms of its sedimentation and diagenesis, structure and preservation conditions, and reservoir and gas-bearing properties. ,− However, few scholars and studies have focused on the preservation conditions of shale gas in the Yichang area, western Hubei, mainly because of the low density of drilled wells. Furthermore, good preservation conditions are vital to the enrichment of shale gas. ,, …”

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

Paleo-Temperature and -Pressure Characteristics of Fluid Inclusions in Composite Veins of the Doushantuo Shale (Yichang Area, South China): Implications for the Preservation and Enrichment of Shale Gas

Yang

et al. 2021

Energy Fuels

Self Cite

View full text Add to dashboard Cite

The Sinian Doushantuo Formation has been identified as a promising shale gas reservoir in South China and potentially worldwide. This study aims to restore the paleo-temperature and paleo-pressure characteristics of the Doushantuo Formation, found in the Yichang area, western Hubei, and to study the significance of overpressure on shale gas preservation and enrichment using petrographic, cathodoluminescence (CL), microthermometry, and Raman spectroscopy techniques on the composite veins. Single-phase methane inclusions and two-phase aqueous inclusions were consistently observed in the same fluid inclusion assemblage (FIA), indicating that the fluid inclusions trapped during fracture cementation were saturated with methane-rich hydrocarbon fluid. The CL image analysis demonstrated that the formation of veins in the shale occurred in two different stages, consistent with the results of the homogenization temperature (Th) analysis. The trapping pressures of the methane inclusions ranged from 81.95 to 95.00 MPa and from 57.13 to 63.62 Ma in the calcite and quartz veins, respectively, as predicted by the combination of the methane inclusion density and Th of the coexisting aqueous inclusions and the equations of state for the supercritical methane. The calculated pressure coefficient (Pc) of 1.90–2.31 indicates that fluid inclusions were trapped in the medium-to-high overpressure state. The Ths of the fluid inclusions are lower than that of the maximum paleo-temperature (∼230 °C), indicating that these fluid inclusions were trapped after the maximum burial and first rapid uplifting process (∼165 Ma). These trapped diachronous fluid inclusions can provide crucial evidence for the formation and evolution of the identified overpressure. Our results suggest that the paleo-overpressure in the Doushantuo shale was continually released through high-angle fractures during the multistage uplifts, deposition, and reuplifting in the Yanshanian and Himalayan movements, resulting in normal pressure and low gas content.

show abstract

Maturity Assessment of the Lower Cambrian and Sinian Shales Using Multiple Technical Approaches

Yang

Zhai

et al. 2021

J. Earth Sci.

View full text Add to dashboard Cite

Pore characteristics of the lower Sinian Doushantuo Shale in the Mid-Yangtze Yichang area of China: Insights into a distinct shale gas reservoir in the Neoproterozoic formation

Cited by 11 publications

References 19 publications

Pore structure and sorption capacity investigations of Ediacaran and Lower Silurian gas shales from the Upper Yangtze platform, China

Pore structure and sorption capacity investigations of Ediacaran and Lower Silurian gas shales from the Upper Yangtze platform, China

Paleo-Temperature and -Pressure Characteristics of Fluid Inclusions in Composite Veins of the Doushantuo Shale (Yichang Area, South China): Implications for the Preservation and Enrichment of Shale Gas

Maturity Assessment of the Lower Cambrian and Sinian Shales Using Multiple Technical Approaches

Contact Info

Product

Resources

About