Depositional environment and micropore characteristics of the Ediacaran Doushantuo Formation black shale in Western Hube
- PDF / 5,743,794 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 65 Downloads / 196 Views
ORIGINAL PAPER
Depositional environment and micropore characteristics of the Ediacaran Doushantuo Formation black shale in Western Hubei, China Hao Wang 1 & Ziquan Yong 1 & Xuan Zhang 2 & Bo Ran 1 & Di Yang 1 & Chao Luo 1 & Bin Deng 1
Received: 6 July 2015 / Accepted: 26 February 2016 # Saudi Society for Geosciences 2016
Abstract The black shale of the lower Sinian (Neoproterozoic) Doushantuo Formation, located in the Yangtze area (Hubei, China), has a great potential to contain shale gas. The main depositional environments of the region included tidal flats, shelf lagoons, shelf margins, and slopes. While black shale formed from deposits in a shelf lagoon setting, the sediments from the tidal flats were dolomitic. Several factors affect the sediments deposited in these environments, including sediment surface energy (i.e., quiescent or turbulent), salinity, and the presence of either oxic or reducing conditions. The depositional environments of segments B and D of the Doushantuo Formation in the Jiulongwan section were significantly different; specifically, segment D was anoxic to euxinic. As a result, the total organic carbon (TOC) in the segment D shale is higher than that in segment B. This study also used field emission scanning electron microscopy to show that pores in organic matter are the main gas storage space and that the organic matter pores in segment D have diameters less than 100 nm. The increasing of the organic matter content increases organic pore and porosity of the reservoir. TOC is not only the main controlling internal factors of the micropores of the shale in Doushantuo Formation but also provides the important storage space for shale gas. The quiet and hypoxia environment of the black shale in Doushantuo Formation is the main factor controlling the enrichment of organic matter, and the enrichment of
* Ziquan Yong [email protected]
1
Energy College of Chengdu University of Technology, Chengdu, Sichuan 610059, China
2
Exploration and Development Research Institute of Southwest Oil & Gas Field Company, Petro China, Chengdu, Sichuan 610041, China
organic matter is beneficial to improve the physical property of the shale reservoir. Therefore, black shale formed in the quiet and anoxic depositional environment has better reservoir physical property. Keywords Doushantuo Formation . Black shale . Sedimentary environment . Total organic carbon . Geochemistry . Western Hubei
Introduction The western part of Hubei Province is located in the center of the Yangtze Plate, south of the Shennongjia uplift area, north of the Jiangnan thrust belt, east of the Dangyang detachment fold zone, and around Huangling anticline (Fig. 1). Rich in organic matter, the black shale of the lower Sinian Doushantuo Formation in western Hubei is an important formation for shale gas exploration in southern China (Yong et al. 2012). Previous studies that surveyed the Yejiahe (Baokang, China), Jiulongwan (Yichang, China), and Siduping (Zhangjiajie, China) outcrops and conducted geological and geochemical analyses conc
Data Loading...
