Combining catalytic hydropyrolysis and GC–IRMS to reconstruct the geochemical characteristics of source rocks in the Baiyun deep-water area of the Pearl River Mouth Basin, China. (September 2021)

• Record Type: Journal Article
• Authors: Yuan, Liping; Jiang, Wenmin; Li, Yun; Xiong, Yongqiang
• Is Part Of: Marine and petroleum geology. Volume 131(2021)
• Publication Date: 2021-09
• Subjects: Baiyun deep-water area -- Catalytic hydropyrolysis -- GC–IRMS -- Individual n-alkanes -- Sedimentary environment; Submarine geology -- Periodicals; Petroleum -- Geology -- Periodicals; Géologie sous-marine -- Périodiques; Pétrole -- Géologie -- Périodiques; Petroleum -- Geology; Submarine geology; Periodicals; Electronic journals; 551.468
• DOI: 10.1016/j.marpetgeo.2021.105166
• Languages: English
• ISSNs: 0264-8172

Abstract

Abstract: Petroleum exploration has found that the Baiyun deep-water area of the Pearl River Mouth Basin (PRMB), China, holds abundant oil and gas resources with great prospects. However, conditions restricting offshore drilling in this area present significant challenges to the investigation of source rocks. Core samples are lacking, and any cuttings obtained are generally highly contaminated by drilling mud. As a result, the identification and evaluation of hydrocarbon sources in deep-water areas would be greatly aided by new techniques capable of reliably obtaining the geochemical characteristics of potential source rocks. This study combines catalytic hydropyrolysis (HyPy) and gas chromatography–isotope ratio mass spectrometry (GC–IRMS) to determine the carbon isotope composition of individual n -alkanes covalently bound in kerogen framework. Furthermore, it reconstructs the source and depositional environment of sedimentary organic matter in potential source rocks from the Baiyun deep-water area of the PRMB. The results indicate that the optimized degassing (i.e., degassing under high vacuum at 250 °C for 24 h) can effectively eliminate hydrocarbon contaminants in the kerogen. Determination by GC–IRMS of bound n -alkanes released from the degassed kerogen by HyPy can provide the molecular carbon isotope characteristics of the original organic matter in cuttings contaminated by drilling mud. The results improve the understanding of potential hydrocarbon source rocks in the Baiyun deep-water area of the PRMB. Highlights: Optimized off-line degassing process could eliminate contaminants in kerogen. Bound n -alkanes released from kerogen maintain δ 13 C values of their precursors. δ 13 C of n -alkanes for source rocks in the Baiyun Sag are firstly identified. Catalytic hydropyrolysis combined with GC–IRMS can regain original geochemistry.