Calibration of Rock Stress-sensitivity Using 4D Seismic Data

Rock stress-sensitivity is a key aspect of 4D seismic studies, particularly when discriminating the effects of pressure and saturation change. Typically, laboratory measurements on core samples are used to address the rock stress-sensitivity in petro-elastic models. Such measurements are subject to uncertainties and their applicability to the in-situ field-scale reservoir response is questionable. Here, as an alternative to laboratory measurements, a technique is presented to calibrate the rock stress-sensitivity based on the 4D seismic data alone. After years of injection, the variation of the 4D signal in the fully-flooded zone in the vicinity of the injectors can be solely attributed to pore pressure variations. The proposed method utilises comparison of the observed with synthetic 4D seismic response in this fully water flooded zone for a range of rock stress-sensitivity models. The results of the modelling around two injectors, for a deep-water turbidite reservoir in the West of Shetland on the UKCS, suggest higher rock stress-sensitivity compared to the stress-sensitivity determined from laboratory measurements.