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Abstract: An Integrated Approach to Model Generation, Migration, and Accumulation of Methane and Molecular Nitrogen in the Northwest German Basin

Gregor H. Neunzert, Ralf Littke, Erdem F. Idiz

In northern Germany, high concentrations of molecular nitrogen in deep Permian reservoirs are a common exploration risk. During the last years, detailed geochemical studies were initiated by the gas industry to investigate possible sources of this molecular nitrogen, and revealed that organic matter - present in great amounts in the underlying, thick, coal - bearing Carboniferous sequence - is the most likely source for the nitrogen-gas, where high levels of maturity are reached. A kinetic model for this process of nitrogen generation was developed. However, this geochemical model had to be tied into a detailed reconstruction of the basin evolution in order to become useful for industrial purposes. Therefore, a 2D basin modeling study, using PetroMod software, was underta en. It took advantage of new information of seismics as well as of new stratigraphic information in order to unravel the structure of the deeply buried pre-Zechstein formations.

The application of this information reveals to what extent local, purely vertical migration systems on the one hand, and long distance lateral migration systems on the other contributed to the gas in the reservoirs. It can also be shown that deep, pre-Variscian basement structures influenced the long distance migration to a great extent.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France