Abstract
From experiments performed with outcrop and overburden shales it is observed that dynamic elastic moduli measured at ultrasonic frequencies by far exceed static moduli. The data do, however, indicate a relation between static and dynamic moduli. If properly established, this would facilitate estimation of in situ static parameters such as e.g. strength and brittleness from seismic or sonic log data. This may enable improved characterization of potential reservoirs and/or cap rock in terms of identifying optimum drilling sites and procedures during subsequent drilling and possible hydraulic fracturing. Our experiments point to strain amplitude effects and frequency dependence as primary sources of discrepancy that need to be understood in order to establish the required relationships.
