Geothermal potential of a sedimentary reservoir in Northern Germany -deduced from stochastic modeling

Abstract

We investigate the probability for a successful geothermal heat production installation in a sedimentary reservoir in the Northern German Lowland. The stratigraphy and the target layer are identified in a 3D seismic section of 5 km x 5 km lateral length down to 6 km. We establish histograms for the lithological properties based on logging information and measurements on cutting from a number of drill holes. These histograms are interpreted as probability distributions for the rock properties in a stochastic sense. We use numerical modelling to study the transient flow and temperature variations in a Monte Carlo ensemble of 1 000 realisations where rock properties are assigned according to these histograms using Sequential Gaussian Simulation. We study a single and a double well geothermal installation in the target layer and determine the probability of success based on a projected flow rate of 42 L s-1 and a temperature of 75 °C; this installation is supposed to supply 4000 local households with heat. Even though it turns out that for this particular location the combined probability of success is only 1.6 %, this study demonstrate the capability of stochastic modelling to infer the potential of a reservoir for geothermal use.