Shale Gas Potential of Germany - A Geochemical Evaluation
Berner, Ulrich¹; Stiller, Eva¹; Dohrmann, Reiner¹; Marquardt, Dustin²
¹BGR, Hannover, Germany.
²University of Utrecht, Utrecht, Netherlands.
Gas shale exploration started in Germany in 2007/2008 with initial screening projects of the hydrocarbon extraction industry. With respect to the significantly grown interest in this topic we here present results related to the evaluation of potential shale formations in Germany. Based on experiences of previous hydrocarbon research projects three stratigraphic sections have been investigated in greater detail. The selection of the target sediments and regions relates to information on organic carbon content, quality of organic matter, thermal maturity and sediment thickness. The areas under investigation are located predominantly in northern Germany and the strata of interest belong to the Lower Carboniferous shale sections, the Lower Jurassic (Toarcian) Posidonia Shale, and the Lower Cretaceous (Berriassian) German Wealden Formation.
A larger suite of sediments collected from outcrops, drill sites and samples of BGR's archive have been used in our study. Inorganic as well as organic geochemical methods have been combined with organic petrological analyses to characterize the sediments of interest, and we also incorporate measurements of physical properties in our interpretations.
The Lower Carboniferous sediments have been deposited in marine settings and show highly variable quality of organic matter and reveal generally the highest thermal overprint in the deep basin which would favour gas production when not overcooked. Jurassic sediments were deposited under marine (predominantly oxygen deficient) conditions and contain high quality organic matter suitable for oil and gas production depending on the thermal overprint. The German Wealden has been deposited in a lacustrine basin that occasionally experienced marine ingressions. Though the oxygen content in the waters was highly variable through time the overall quality of the organic matter is excellent, with thermal maturities that would allow the production of oil and gas. Generally, the initial hydrocarbon concentrations of potential shale targets could have been altered after maximum burial of the sediments since parts of the North German region have been uplifted afterwards. The uplift might have caused a loss of light hydrocarbons from the sediments in return. This challenge may be solved by tectonic reconstruction and basin modelling using a combination of geochemical and petrophysical parameters of which examples are given.
AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012