Net Exhumation Estimation Using an Effective-medium Technique Based On Seismic Traveltime Measurements

Abstract

We propose a new seismically based technique for estimating net exhumation magnitudes on sedimentary basin areas. The method uses traveltime measurements mapped from e.g. seismic data, or ray traced well log data, starting at the sea floor on a reference unexhumed area, and on an area suspected to be uplifted. Analogously to the shale compaction depth-trend methodology, where two homogenous shale formations with comparable petrophysical properties are identified, in reference and uplifted areas, we consider the stratigraphic columns instead as effective media with comparable NMO parameters and velocity heterogeneity. Linear P-wave velocity functions of both reference and uplifted areas are derived from dix-type mathematical relations, and compared in a depth dependent scheme. The methodology is applied in nine wells spread across the Norwegian part of the Barents Sea. Our technique provide results in agreement with published net exhumation magnitude estimates derived from standard compaction depth-trends and thermal maturity techniques. Our uplift magnitude estimates are further used to construct time-dependent burial curves for simulating mechanical and chemical compaction of sandstones. The modelling scheme predicts successfully quartz cement volumes quantified from petrographic analysis, and porosity, rock moduli, and velocities measured by wireline well logging.