Research article: Crosshole seismic imaging of a fractured reservoir

Time-lapse crosshole seismic surveys have been conducted over a naturally fractured reservoir to demonstrate the feasibility of obtaining high-resolution seismic images to monitor changing fluid saturation within the reservoir. The experiment was perforrned at the Chalmers Hot Dry Rock (HDR) geothermal research site in Fjällbacka, Sweden, across a fractured reservoir. in crystalline rock at around 450 m depth. Although the survey technique being demonstrated is intended to be applied to oil reservoirs, the Fjällbacka site was selected as the geothermal reservoir there is analogous to a naturally fractured oilfield reservoir but is far more readily accessible for experimental work.