DOI: 10.1007/s00531-014-1081-y
Scopus记录号: 2-s2.0-84940957318
论文题名: Predicted bulk composition of petroleum generated by Lower Cretaceous Wealden black shales, Lower Saxony Basin, Germany
作者: Ziegs V. ; Mahlstedt N. ; Bruns B. ; Horsfield B.
刊名: International Journal of Earth Sciences
ISSN: 14373254
出版年: 2015
卷: 104, 期: 6 起始页码: 1605
结束页码: 1621
语种: 英语
英文关键词: Bulk kinetics
; Lacustrine depositional environment
; Phase behaviour
; PhaseKinetics
; Type I kerogen
; Unconventionals
; Waxy oil
Scopus关键词: black shale
; Cretaceous
; depositional environment
; hydrocarbon generation
; hydrocarbon migration
; kerogen
; lacustrine deposit
; source rock
; thermal maturity
; Germany
; Lower Saxony Basin
; North German Basin
; algae
; Botryococcus braunii
英文摘要: The Berriasian Wealden Shale provides the favourable situation of possessing immature to overmature source rock intervals due to differential subsidence within the Lower Saxony Basin. Hydrocarbon generation kinetics and petroleum physical properties have been investigated on four immature Wealden Shale samples situated in different depth intervals and following the PhaseKinetics approach of di Primio and Horsfield (AAPG Bull 90(7):1031–1058, 2006). Kinetic parameters and phase prediction were applied to a thermally calibrated 1D model of the geodynamic evolution at the location of an overmature well. The immature source rocks of all depth intervals comprise kerogen type I being derived from the lacustrine algae Botryococcus braunii. Bulk kinetics of the lower three depth intervals (sample 2–4) can be described by one single activation energy Ea, typical for homogeneous, lacustrine organic matter (OM), whereas sample 1 from the uppermost interval shows a slightly broader Ea distribution which hints to a more heterogeneous, less stable OM, but still of lacustrine origin. Predicted physical properties of the generated petroleum fluids are characteristic of variably waxy, black oil possessing GOR’s below 100 Sm3/Sm3 and saturations pressures below 150 bar. Petroleum fluids from the more heterogeneous OM-containing sample 1 can always be described by slightly higher values. Based on the occurrence of paraffinic, free hydrocarbons in the uppermost horizon of the overmature well and gas/condensate in the lower 3 depth intervals, two scenarios have been discussed. From the first and least realistic scenario assuming no expulsion from the source rock, it can be deduced that phase separation in the course of uplift can only have occurred in the uppermost interval containing the slightly less stable OM but not in the lower intervals being composed of a more stable OM. Therefore and taking secondary cracking into account, all depth intervals should contain gas/condensate. The free hydrocarbons in the upper horizon are interpreted as impregnation from migrated hydrocarbons. The second scenario assumes nearly complete expulsion due to fracturing by the so-called generation overpressure (Mann et al. in Petroleum and basin evolution. Springer, Berlin, 1997). The expelled petroleum might migrate into lower pressurised source rock horizons and reach bubble-point pressures leading to the exsolution of gas and “precipitation” of very high molecular weight bitumen unable to migrate. Subsequent burial of the latter in the course of the basin evolution would lead to secondary cracking and remaining pyrobitumen explaining the high amounts of pyrobitumen in the overmature well Ex-B and relatively enhanced TOC contents at such high maturity levels. © 2014, The Author(s). URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84940957318&doi=10.1007%2fs00531-014-1081-y&partnerID=40&md5=8be21e1088df2dd6b7fb7954a1eec857
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/70265
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Section 4.3: Organic Geochemistry, Helmholtz Centre, GFZ German Centre for Geosciences Potsdam, Telegrafenberg, Potsdam, Germany; Energy and Mineral Resources Group (EMR), Institute of Geology and Geochemistry of Petroleum and Coal, RWTH Aachen University, Lochnerstr. 4-20, Aachen, Germany
Recommended Citation:
Ziegs V.,Mahlstedt N.,Bruns B.,et al. Predicted bulk composition of petroleum generated by Lower Cretaceous Wealden black shales, Lower Saxony Basin, Germany[J]. International Journal of Earth Sciences,2015-01-01,104(6)