Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

Table 1

Geological and geochemical characteristics of the Lower Cambrian shales.

Regions	Sichuan Basin	Upper-Middle Yangtze Region (excluding Sichuan Basin)				Lower Yangtze Region
Distribution of organic-rich shales	Southern Sichuan, Southwestern Sichuan	Western Hubei	Chongqing	Northwestern Hunan	Northern Guizhou	Southern Anhui-Northern Jiangsu
Sedimentary face	Deep water shelf	Deep water shelf	Deep water shelf	Deep water shelf	Deep water shelf	Deep water shelf
Thickness of organic-rich shales (m)	60-300	20-80	20-200	50-120	40-100	20-100
Burial depth (m)	2500-6000	1000-5500	3500-5500	500-2500	1200-2400	4000-6000
EqVRo (%)	2.5-3.5	2.5-3	2.4-4.3	2-3.5	2.2-4.4	3.0-4.5
TOC (%)	2-3	2.4-3.2	0.4-9.9	0.3-6.4	1.7-9.6	2.3-14.5
Kerogen type	I-II1	I	I-II1	I	I-II1	I
Reference	[12, 54, 57, 59, 63, 83–86]	[44, 45, 58]	[22, 51, 55, 87–90]	[21, 43, 52, 53, 65, 91]	[23, 56, 64, 92]	[24, 75, 93–95]