Applying Rock Physics Towards Seismic Characterization: Case Study From an Unconventional Resource, Neuquén Basin, Argentina

Abstract

Calibration of seismic amplitudes to known rock properties is the ultimate goal of quantitative interpretation (QI) permitting seismic reservoir characterization away from well control. This paper presents a case study of a mature onshore field within the Neuquén Basin, Argentina where an integrated workflow for QI was defined and implemented with the aim of delineating potential areas for further development. The study area is covered by 3D seismic data and 14 wells with a complete set of elastic logs, providing the basis for quantitative analysis along the Quintuco-Vaca Muerta reservoir section, a complex Upper Jurassic to Lower Cretaceous mixed carbonate-siliciclastic system. A summary of the work performed with reference to rock properties and rock physics over a particular layer is used as an example in this paper. 3D seismic data was reprocessed following a workflow tailored towards QI to preserve relative amplitudes and stable phase across the entire survey. Sensitivities for incident angles were performed during processing to obtain the optimal angle stack design, from 10° to 40°, as the input for simultaneous inversion. Fourteen wells, with complete elastic log information, were used for AVA wavelet estimation and low frequency model construction. A four component multi-mineral petrophysical model was calibrated with neutron induced elemental spectroscopy tools and XRD core data. Porosity and hydrocarbon saturation were afterwards calculated and calibrated with NMR data. Rock physics diagnostics were conducted to find a model that correctly represents the elastic behavior of the rocks in the study area. The Friable Shale rock physics model, a modified version of Dvorkin & Nur's Friable Sand model (Dvorkin and Nur, 1996), is designed with the ability to consider different, including clay rich, mineral combinations and their variability with respect to internal rock stiffness. This makes it a versatile rock physics model for use in unconventional settings. A fine-tuned porosity-based parametric rock physics template was defined in the P and S impedance elastic domain. The use of this rock physics model was crucial to classify seismic inversion results into elastic facies and, finally, to define potential areas for further development.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016