Formation of commercial microbial gas accumulations requires specific migration and
accumulation conditions which can be effectively provided by groundwater flow systems.
Namely, if microbial methane can be gathered and transported in aqueous solution over
large lateral distances, great amount of free gas can be exsolved where flows turn
upward causing a decrease in solubility. Based on this concept and the flow pattern
of regional scale topography-driven groundwater flow systems, the present study built
a simplistic 2D model in MS Excel including a methane solubility database with 32000
data. The model can calculate the required flow pathway length to saturate groundwater
with methane, the amount of free gas that can be released in a potential accumulation
zone, and the necessary time interval for the whole process. Application of the model
was demonstrated based on the geological and hydrogeological conditions of a study
area in the Central Pannonian Basin (Hungary) focusing on the Hajdúszoboszló gas field.
In light of the upscaled results of the 2D model, the known microbial gas accumulations
of the study area could be charged according to the model. In addition, parameter
sensitivity analysis also provided valuable insights into the complex mechanisms of
microbial gas migration.
