4D modelling of seismic signatures of fluid flow in crystalline rocks

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The main objective of this research is to optimize data acquisition of future seismological time-lapse experiments around the site of the Kontinentale Tiefbohrung (KTB) in Germany by predictive numerical modelling. Second objective is to understand how fluid pressure variations manifest themselves in the recorded elastic wavefields given a specific asquisition geometry. These objectives will be achieved by 6 essential steps: (1) Establishment of a three-dimensional elastic model with a professional software tool (GOCAD) on a scale of 10 x 10 km that incorporates the major reflectors found in previous investigations (SE1 and SE2). (2) Development of a realistic model of the SE1 reflector with variable lateral heterogeneities. The model must be consistent with logging results and previous measurements and consists of an elastic background model and a porosity and permeability model of the SE1 reflector. (3) Development of a two-dimensional elastic model of the area between pilot and main hole. (4) Utilization of Gassmann `theory (low-frequency surface seismic) and Biot`s theory (high-frequency cross-hole seismic) to estabilish the influence of pore pressure variations on elastic parameters. (5) Simulation of three-dimensional low-frequency wave propagation from surface sources for variable fluid pressure evolving in the SE1 reflector due to fluid injection. (6) Simulation of two-dimensional higt-frequency wave propagation for a cross-hole experiment%2