Quantum Resonance Interferometry for Characterizing Complex Carbonates below Seismic Resolution
Gulati, Sandeep¹; DeSantis, John²; Meades, Ian²; Koglin, Donald E.²
¹R&D, ViaLogy, Pasadena, CA.
²Applied Reservoir Management, Chevron, Houston, TX.
Quantum Resonance Interferometry (QRI) significantly increases areal and vertical resolution by exploiting multiple scattering events and full seismic wavefront interactions in new ways. A powerful tool is presented based on recent advances coupling seismic interferometry paradigm, nonlinear signal processing, and, use of quantum resonance algorithms. Resutls show how QRI successfully delineated porosity trends in tight dolomites on a Permian section of Chevron's Vacuum Field in New Mexico, USA.
Interpretation geophysicists lose a critical analytical tool as pre-stack AVO inversions are challenged by complex carbonate geometries below the log or seismic resolution. Due to broad-spectrum of diagenesis the final carbonate porosity may not be related to the depositional environment. The original primary porosity may be totally destroyed and new secondary porosity created. Tight carbonate variations have extremely small expression in the seismic response buried below background noise. QRI processes seismic amplitudes below -24dB (against -10dB for conventional analysis) to assess how coherent and random noise in the data is differentially and directly modulated by subtle changes in porosity and fluid saturation levels.
The Vacuum Field Abo dolomite consists of two producing zones - Abo1 and Abo2 which together are about 200 feet thick between 8700 and 8900 feet MD. Productive core porosities average only 5.4%. QRI predicted porosities over 60 sq. km area yielded an R2 of over 70% at 20 foot vertical sections. The trend of higher porosities highlighted by QRI coincides with the best producing wells. The project used 5 wells for training and 13 wells for test and optimization from a small sub-section. However, QRI output volume spanned the training area, plus a large producing area on the east side of the field which included outcomes from over 300 drilled wells that were blinded to the study. A covariance analysis of surfaces generated by kriging from data at these 300 wells was conducted to assess prediction performance 2 to 3 miles away. The test and training were only done on a small area of the west side of the field, but the realization of the output volume to the east showed a high coincidence between producers and predicted porosities.
Predictions at 20' intervals represent a 2X increase in vertical resolution. QRI generated porosity trends could significantly reduce number of wells drilled using standard gridding while increasing overall recovery.
AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012