Biogenic or microbial methane has an increasing share in the global gas resource base,
though its exploration still faces challenges and welcomes innovations. Critical elements
of its migration and accumulation models are the groundwater flows which gather and
transport the gas in aqueous solution, and the seal rocks or aquifers which lead groundwater
flows horizontally over great distances. This paper intends to introduce the hydraulic
trap concept into these models, which is able to drive fluids horizontally without
an overlying seal rock. Since hydraulic traps can evolve as a result of the interplay
of regional groundwater flow systems, the basin-scale hydraulic evaluation methodology
which was developed for the analysis of these systems was further improved by this
study to focus on their interplay. The improved methodology was applied on measured
hydraulic data in a study area in the Central Pannonian Basin (Hungary) around the
Hajdúszoboszló gas field where as a result, the first groundwater flow controlled
dissolved biogenic gas migration and accumulation model could be set up. In addition,
the proposed methodology can be used in any terrestrial sedimentary basin, and in
particular, where topography-driven flow systems are underlaid by an abnormal pressure
regime.
