Characteristics and dominant controlling factors of organic-rich marine shales with high thermal maturity: A case study of the Lower Cambrian Niutitang Formation in the Cen’gong block, southern China

Wang, Ruyue; Gu, Yang; Ding, Wenlong; Gong, Dajian; Yin, Shuai; Wang, Xinghua; Zhou, Xiaojin; Li, Ang; Xiao, Zikang; Cui, Zixian

doi:10.1016/j.jngse.2016.05.009

Cited by 71 publications

(29 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Milliken et al also found a similar variation tendency between TOC content and porosity when the TOC content is above 5.6% [59]. Wang et al suggested that the excessive TOC content could decrease the brittleness and fracture density of the shale, which allow for easy compaction of the shale and minimal preservation of the pores [21,60]. Thus, perhaps the fractal dimensions will decrease with increasing TOC content when the TOC content exceeds a certain amount.…”

Section: Effect Of Toc Content On Pore Structurementioning

confidence: 88%

“…Following the success of marine gas shale in the Sichuan Basin, China [15][16][17], exploration and development of shale gas in nearby regions, such as Hunan Province to the northwest, has progressed remarkably in recent years [18][19][20][21]. Lower Cambrian Niutitang shale is widely distributed in the northwestern Hunan Province and was recently selected as the next main target for shale gas resource exploration and industrial development ( Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“…It is typical marine sediment carbonaceous and black shale in the lower section and dark-grey silty shale in the upper section [22,23]. In recent years, many studies have been carried out on the lithofacies, geochemistry and mineralogy of the Niutitang Formation [21,24,25], although there is a lack of information on pore structure and fractal characteristics. Therefore, the aim of this study is to examine the pore structure and fractal characteristics of the Niutitang Formation from northwestern Hunan Province, China.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Pore Structure and Fractal Characteristics of Niutitang Shale from China

Tang

Wang

et al. 2018

Minerals

View full text Add to dashboard Cite

A suite of shale samples from the Lower Cambrian Niutitang Formation in northwestern Hunan Province, China, were investigated to better understand the pore structure and fractal characteristics of marine shale. Organic geochemistry, mineralogy by X-ray diffraction, porosity, permeability, mercury intrusion and nitrogen adsorption and methane adsorption experiments were conducted for each sample. Fractal dimension D was obtained from the nitrogen adsorption data using the fractal Frenkel-Halsey-Hill (FHH) model. The relationships between total organic carbon (TOC) content, mineral compositions, pore structure parameters and fractal dimension are discussed, along with the contributions of fractal dimension to shale gas reservoir evaluation. Analysis of the results showed that Niutitang shale samples featured high TOC content (2.51% on average), high thermal maturity (3.0% on average), low permeability and complex pore structures, which are highly fractal. TOC content and mineral compositions are two major factors affecting pore structure but they have different impacts on the fractal dimension. Shale samples with higher TOC content had a larger specific surface area (SSA), pore volume (PV) and fractal dimension, which enhanced the heterogeneity of the pore structure. Quartz content had a relatively weak influence on shale pore structure, whereas SSA, PV and fractal dimension decreased with increasing clay mineral content. Shale with a higher clay content weakened pore structure heterogeneity. The permeability and Langmuir volume of methane adsorption were affected by fractal dimension. Shale samples with higher fractal dimension had higher adsorption capacity but lower permeability, which is favorable for shale gas adsorption but adverse to shale gas seepage and diffusion.

show abstract

Section: Effect Of Toc Content On Pore Structurementioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Pore Structure and Fractal Characteristics of Niutitang Shale from China

Tang

Wang

et al. 2018

Minerals

View full text Add to dashboard Cite

show abstract

“…Differently trending faults intersect each other. The dip angles of faults are relatively steep, including some well-preserved upright fault planes [33]. The Lower Cambrian succession in the Upper Yangtze Platform was deposited during a major marine transgression from southeast to northwest.…”

Section: Geological Settingmentioning

confidence: 99%

Total Organic Carbon Enrichment and Its Impact on Pore Characteristics: A Case Study from the Niutitang Formation Shales in Northern Guizhou

Liu

Tang

2019

Energies

View full text Add to dashboard Cite

This study analyzes samples from the Lower Cambrian Niutitang Formation in northern Guizhou Province to enable a better understanding of total organic carbon (TOC) enrichment and its impact on the pore characteristics of over-mature marine shale. Organic geochemical analysis, X-ray diffraction, scanning electron microscopy, helium porosity, and low-temperature nitrogen adsorption experiments were conducted on shale samples. Their original TOC (TOCo) content and organic porosity were estimated by theoretical calculation, and fractal dimension D was computed with the fractal Frenkel–Halsey–Hill model. The results were then used to consider which factors control TOC enrichment and pore characteristics. The samples are shown to be dominated by type-I kerogen with a TOC content of 0.29‒9.36% and an equivalent vitrinite reflectance value of 1.72‒2.72%. The TOCo content varies between 0.64% and 18.17%, and the overall recovery coefficient for the Niutitang Formation was 2.16. Total porosity of the samples ranged between 0.36% and 6.93%. TOC content directly controls porosity when TOC content lies in the range 1.0% to 6.0%. For samples with TOC < 1.0% and TOC > 6.0%, inorganic pores are the main contributors to porosity. Additionally, pore structure parameters show no obvious trends with TOC, quartz, and clay mineral content. The fractal dimension D1 is between 2.619 and 2.716, and D2 is between 2.680 and 2.854, illustrating significant pore surface roughness and structural heterogeneity. No single constituent had a dominant effect on the fractal characteristics.

show abstract

“…Exploration found that China's shale gas resources are rich, and the development prospects are broad, which aligns with the strategic goals of China's future oil and gas development. [12][13][14][15][16][17] However, shale gas reservoir formation conditions, storage space, seepage laws, and exploitation mode all have their own characteristics, especially the poor physical properties of shale gas reservoirs, low porosity, and permeability, which bring great difficulties and challenges to its development and utilization. At present, the method of shale gas mining is based mainly on hydraulic fracturing.…”

Section: Introductionmentioning

confidence: 99%