Fracture types in the lower Cambrian shale and their effect on shale gas accumulation, Upper Yangtze

Yuying Zhang, Zhiliang He, Shu Jiang, Shuangfang Lu, Dianshi Xiao, Guohui Chen, Yuchao Li

Research output: Contribution to journalArticle

Abstract

To reveal the characteristics of fractures in high quality shale reservoir and to find regions that are favorable for shale gas accumulation, the characteristics of fractures and their effect on the shale gas content in the lower Cambrian marine shale from 2 typical shale gas wells in the Upper Yangtze have been analyzed in detail by observing the shale cores, scanning electron microscope photographs and rock slice pictures associated with various geochemical data. Five types of macrofractures (high-angle shearing fracture, tension-shearing fracture, compresso-shearing fracture, low-angle slip fracture, and bedding fracture) and 4 types of microfractures (interlayer fracture, inter-particle fracture, intra-particle fracture, and organic matter-associated fracture) have been identified in the lower Cambrian shale. The fractures in lower Cambrian shale have 5 possible origins: 1 generated by tectonic tension and shearing stresses; 2 cracking due to loading pressure relief; 3 corroded by acidic fluids during hydrocarbon generation; 4 induced by overpressured fluid; 5 formed due to diagenesis-associated shrinkage of mineral crystals. In general, the shale in Sichuan Basin contains more nonstructural fractures (including bedding fractures and microfractures), whereas shale outside the basin contains more structural fractures (including high-angle shearing fractures, tension-shearing fractures, and low-angle slip fractures). Three controlling factors of fracture development be summarized as follows: 1 tectonic setting; 2 mineral components; 3 organic matter content and maturity. In conclusion, structural fractures can be considered as destructive, and nonstructural fractures can be considered as favorable. Shale gas reservoirs can be divided into 3 types: type A with a shale gas content >2 m3/t, destructive/structural fractures <20/m, and favorable/nonstructural fractures >100/m; type B with a shale gas content of 1 m3/t - 2 m3/t, destructive/structural fractures <20/m, and favorable/nonstructural fractures 50/m −100/m; (3) type C with a shale gas content < 1 m3/t, destructive/structural fractures >20/m, or destructive/structural fractures <20/m, and favorable/nonstructural fractures <50/m.

LanguageEnglish (US)
Pages282-291
Number of pages10
JournalMarine and Petroleum Geology
Volume99
DOIs
StatePublished - Jan 1 2019

Fingerprint

Biogeochemistry
biogeochemistry
Petroleum reservoirs
Tectonics
Shale
shearing
organic compounds
Shearing
Organic compounds
Biological materials
tectonics
organic compound
shale
scanning electron microscopy
Scanning electron microscopy
Gases
gases
gas
Shale gas
shale gas

Keywords

  • Fracture type
  • Lower Cambrian
  • Shale
  • Shale gas
  • Upper Yangtze

ASJC Scopus subject areas

  • Oceanography
  • Geophysics
  • Geology
  • Economic Geology
  • Stratigraphy

Cite this

Fracture types in the lower Cambrian shale and their effect on shale gas accumulation, Upper Yangtze. / Zhang, Yuying; He, Zhiliang; Jiang, Shu; Lu, Shuangfang; Xiao, Dianshi; Chen, Guohui; Li, Yuchao.

In: Marine and Petroleum Geology, Vol. 99, 01.01.2019, p. 282-291.

Research output: Contribution to journalArticle

Zhang, Yuying ; He, Zhiliang ; Jiang, Shu ; Lu, Shuangfang ; Xiao, Dianshi ; Chen, Guohui ; Li, Yuchao. / Fracture types in the lower Cambrian shale and their effect on shale gas accumulation, Upper Yangtze. In: Marine and Petroleum Geology. 2019 ; Vol. 99. pp. 282-291.
@article{2f3155d33ab14c44af7e48daefc45a75,
title = "Fracture types in the lower Cambrian shale and their effect on shale gas accumulation, Upper Yangtze",
abstract = "To reveal the characteristics of fractures in high quality shale reservoir and to find regions that are favorable for shale gas accumulation, the characteristics of fractures and their effect on the shale gas content in the lower Cambrian marine shale from 2 typical shale gas wells in the Upper Yangtze have been analyzed in detail by observing the shale cores, scanning electron microscope photographs and rock slice pictures associated with various geochemical data. Five types of macrofractures (high-angle shearing fracture, tension-shearing fracture, compresso-shearing fracture, low-angle slip fracture, and bedding fracture) and 4 types of microfractures (interlayer fracture, inter-particle fracture, intra-particle fracture, and organic matter-associated fracture) have been identified in the lower Cambrian shale. The fractures in lower Cambrian shale have 5 possible origins: 1 generated by tectonic tension and shearing stresses; 2 cracking due to loading pressure relief; 3 corroded by acidic fluids during hydrocarbon generation; 4 induced by overpressured fluid; 5 formed due to diagenesis-associated shrinkage of mineral crystals. In general, the shale in Sichuan Basin contains more nonstructural fractures (including bedding fractures and microfractures), whereas shale outside the basin contains more structural fractures (including high-angle shearing fractures, tension-shearing fractures, and low-angle slip fractures). Three controlling factors of fracture development be summarized as follows: 1 tectonic setting; 2 mineral components; 3 organic matter content and maturity. In conclusion, structural fractures can be considered as destructive, and nonstructural fractures can be considered as favorable. Shale gas reservoirs can be divided into 3 types: type A with a shale gas content >2 m3/t, destructive/structural fractures <20/m, and favorable/nonstructural fractures >100/m; type B with a shale gas content of 1 m3/t - 2 m3/t, destructive/structural fractures <20/m, and favorable/nonstructural fractures 50/m −100/m; (3) type C with a shale gas content < 1 m3/t, destructive/structural fractures >20/m, or destructive/structural fractures <20/m, and favorable/nonstructural fractures <50/m.",
keywords = "Fracture type, Lower Cambrian, Shale, Shale gas, Upper Yangtze",
author = "Yuying Zhang and Zhiliang He and Shu Jiang and Shuangfang Lu and Dianshi Xiao and Guohui Chen and Yuchao Li",
year = "2019",
month = "1",
day = "1",
doi = "10.1016/j.marpetgeo.2018.10.030",
language = "English (US)",
volume = "99",
pages = "282--291",
journal = "Marine and Petroleum Geology",
issn = "0264-8172",
publisher = "Elsevier BV",

}

TY - JOUR

T1 - Fracture types in the lower Cambrian shale and their effect on shale gas accumulation, Upper Yangtze

AU - Zhang, Yuying

AU - He, Zhiliang

AU - Jiang, Shu

AU - Lu, Shuangfang

AU - Xiao, Dianshi

AU - Chen, Guohui

AU - Li, Yuchao

PY - 2019/1/1

Y1 - 2019/1/1

N2 - To reveal the characteristics of fractures in high quality shale reservoir and to find regions that are favorable for shale gas accumulation, the characteristics of fractures and their effect on the shale gas content in the lower Cambrian marine shale from 2 typical shale gas wells in the Upper Yangtze have been analyzed in detail by observing the shale cores, scanning electron microscope photographs and rock slice pictures associated with various geochemical data. Five types of macrofractures (high-angle shearing fracture, tension-shearing fracture, compresso-shearing fracture, low-angle slip fracture, and bedding fracture) and 4 types of microfractures (interlayer fracture, inter-particle fracture, intra-particle fracture, and organic matter-associated fracture) have been identified in the lower Cambrian shale. The fractures in lower Cambrian shale have 5 possible origins: 1 generated by tectonic tension and shearing stresses; 2 cracking due to loading pressure relief; 3 corroded by acidic fluids during hydrocarbon generation; 4 induced by overpressured fluid; 5 formed due to diagenesis-associated shrinkage of mineral crystals. In general, the shale in Sichuan Basin contains more nonstructural fractures (including bedding fractures and microfractures), whereas shale outside the basin contains more structural fractures (including high-angle shearing fractures, tension-shearing fractures, and low-angle slip fractures). Three controlling factors of fracture development be summarized as follows: 1 tectonic setting; 2 mineral components; 3 organic matter content and maturity. In conclusion, structural fractures can be considered as destructive, and nonstructural fractures can be considered as favorable. Shale gas reservoirs can be divided into 3 types: type A with a shale gas content >2 m3/t, destructive/structural fractures <20/m, and favorable/nonstructural fractures >100/m; type B with a shale gas content of 1 m3/t - 2 m3/t, destructive/structural fractures <20/m, and favorable/nonstructural fractures 50/m −100/m; (3) type C with a shale gas content < 1 m3/t, destructive/structural fractures >20/m, or destructive/structural fractures <20/m, and favorable/nonstructural fractures <50/m.

AB - To reveal the characteristics of fractures in high quality shale reservoir and to find regions that are favorable for shale gas accumulation, the characteristics of fractures and their effect on the shale gas content in the lower Cambrian marine shale from 2 typical shale gas wells in the Upper Yangtze have been analyzed in detail by observing the shale cores, scanning electron microscope photographs and rock slice pictures associated with various geochemical data. Five types of macrofractures (high-angle shearing fracture, tension-shearing fracture, compresso-shearing fracture, low-angle slip fracture, and bedding fracture) and 4 types of microfractures (interlayer fracture, inter-particle fracture, intra-particle fracture, and organic matter-associated fracture) have been identified in the lower Cambrian shale. The fractures in lower Cambrian shale have 5 possible origins: 1 generated by tectonic tension and shearing stresses; 2 cracking due to loading pressure relief; 3 corroded by acidic fluids during hydrocarbon generation; 4 induced by overpressured fluid; 5 formed due to diagenesis-associated shrinkage of mineral crystals. In general, the shale in Sichuan Basin contains more nonstructural fractures (including bedding fractures and microfractures), whereas shale outside the basin contains more structural fractures (including high-angle shearing fractures, tension-shearing fractures, and low-angle slip fractures). Three controlling factors of fracture development be summarized as follows: 1 tectonic setting; 2 mineral components; 3 organic matter content and maturity. In conclusion, structural fractures can be considered as destructive, and nonstructural fractures can be considered as favorable. Shale gas reservoirs can be divided into 3 types: type A with a shale gas content >2 m3/t, destructive/structural fractures <20/m, and favorable/nonstructural fractures >100/m; type B with a shale gas content of 1 m3/t - 2 m3/t, destructive/structural fractures <20/m, and favorable/nonstructural fractures 50/m −100/m; (3) type C with a shale gas content < 1 m3/t, destructive/structural fractures >20/m, or destructive/structural fractures <20/m, and favorable/nonstructural fractures <50/m.

KW - Fracture type

KW - Lower Cambrian

KW - Shale

KW - Shale gas

KW - Upper Yangtze

UR - http://www.scopus.com/inward/record.url?scp=85055339687&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85055339687&partnerID=8YFLogxK

U2 - 10.1016/j.marpetgeo.2018.10.030

DO - 10.1016/j.marpetgeo.2018.10.030

M3 - Article

VL - 99

SP - 282

EP - 291

JO - Marine and Petroleum Geology

T2 - Marine and Petroleum Geology

JF - Marine and Petroleum Geology

SN - 0264-8172

ER -