Quantitative evaluation of gas generation from the Upper Paleozoic coal, mudstone and limestone source rocks in the Ordos Basin, China. (July 2019)

• Record Type: Journal Article
• Authors: Liu, Jianliang; Liu, Keyu; Liu, Chang
• Is Part Of: Journal of Asian earth sciences. Volume 178(2019)
• Page Start: 224
• Page End: 241
• Publication Date: 2019-07
• Subjects: Geochemical characteristics -- Source-specific kinetics -- Gas generation process -- Gas generation amount -- Upper Paleozoic -- Ordos Basin; Earth sciences -- Asia -- Periodicals; Sciences de la terre -- Asie -- Périodiques; Earth sciences; Asia; Periodicals; 555.05
• DOI: 10.1016/j.jseaes.2018.04.001
• Languages: English
• ISSNs: 1367-9120

Abstract

Graphical abstract: Highlights: Gas yields and kinetics for each source rock were determined using sealed gold tube pyrolysis experiments. Evolution and amounts of gas generation were modeled using basin modeling. Coal seams made a major contributor, followed by the mudstone and limestone to the Upper Paleozoic gas system. Source-specific kinetics basin model is more suitable for simulating gas generations. Abstract: Significant quantities of tight gas resources have been discovered in the Upper Paleozoic interval in the Ordos Basin, central China. The gas is believed to have been derived primarily from the Upper Paleozoic coal, mudstone and limestone source rocks. An integrated organic geochemistry and basin modeling approach was applied to quantitatively evaluate gas generation from the three types of source rocks. Source-specific gas generation kinetics were first established on the basis of sealed gold tube pyrolysis experiments. Gas generation was then modeled in 1D and 3D using the source-specific kinetics obtained. The results show that (1) near the depositional and thermal center (e.g., Well ZT-1), gas generation occurred much earlier and was greater than that of the Sh-360 well, which is away from the depositional and thermal center; (2) C2 -C5 gases in the ZT-1 well underwent thermal cracking, while gases in the Sh-360 well did not experience any secondary thermal alteration; (3) hydrocarbon gases were mainly generated during the Early Cretaceous (135–96 Ma) and the Late Jurassic (161–135 Ma); (4) the cumulative amounts of gas generation from the coal, mudstone and limestone source rocks are 147.23 × 10 12, 57.85 × 10 12 and 12.73 × 10 12 m 3, respectively, with coal seams being a major contributor (about 67.6%) to the Upper Paleozoic gas system, followed by the mudstone (about 26.6%) and limestone (about 5.8%). By comparing with previous work and a default kinetics basin model, our source-specific kinetics basin model is more suitable for simulating gas generation in the Upper Paleozoic source rocks within the Ordos Basin.