Improved Fault and Fracture Imaging Using GRT Depth Migration in West Rustavi, Georgia.

KEY POINTS:

  • GRT delivers superior imaging in land environment compared to Kirchhoff

  • No offset-to-angle transform required

  • More accurate angle versus azimuth outputs (AVAZ)

  • Higher resolution fault and fracture information obtained

Block Energy PLC's West Rustavi concession contains a proven oil field in the Middle Eocene with production being predominantly from natural fractures. The study performed by SIP obtains a high resolution data set, in both a temporal and spatial sense, and derives fault/fracture information to assist horizontal well planning.

West Rustavi, Georgia

West Rustavi concession location.

Map of source (red) and receiver (blue) locations. The area contained numerous zones of restricted access, rivers, highways, railroads and buried infrastrcuture.

SIP has a proven track record of improving image quality using multi-arrival travel time algorithms in the angle domain. The uplift in accuracy of amplitudes and elastic properties derived from these migrations has de-risked many prospects worldwide.

For this multi-azimuth 3D land example, SIP employed true-amplitude GRT migration using a velocity field built with our proprietary auto-focusing based method - completely data driven and unbiased by well information. The use of GRT imaging has generated meaningful geo-mechanical properties such as Young's Modulus and brittleness which will be incorporated into the fracture model for the field.

GRT vs. Kirchhoff PSDM

Kirchhoff pre-stack depth migration of Middle Eocene section. Reservoir zone highlighted.

GRT pre-stack depth migration. Note the well resolved faults at the top of and within the reservoir.

Azimuth output bins with central azimuths 18, 54, 90, 126, and 162 degrees. Kirchhoff (bottom) has failed to maintain amplitudes and shows obvious migration swings.

GRT Diffraction Imaging for Faults

GRT can be used for both specular and diffraction imaging. Diffraction imaging is a natural extension of imaging and restores 5% of the energy due to small scale diffractions from bedding fault planes. The following sections and slices show the added value of diffraction imaging for micro-faults.

GRT PSDM. Standard specular reflection image.

GRT PSDM. Diffraction term of the wave field illuminating small scale faulting which impacts well positioning.

Our P&I Services

Pre-Processing

  • Processing from field tapes

  • eMULT proprietary de-multiple

  • eBAND proprietary de-ghost

  • Broadband

  • Multi-azimuth

  • Multi-client. multi-licence

  • Land and Marine

Velocity Modelling

  • AutoImager data-driven modelling

  • Iterative and migration-based

  • Accurate anisotropic velocity and Eta

  • Geologically consistent velocities

  • Beam Tomography

  • FWI

Depth Imaging

  • GRT true amplitude, AVA compliant

  • eGWM ultra-fast wave equation migration

  • Traditional migrations, e.g RTM, Kirchhoff

  • VTI/TTI

© 2020 Seismic Image Processing UK Ltd. All rights reserved. Banchory Business Centre, Burn O'Bennie Road, AB31 5ZU, United Kingdom. Tel: +44 1330 825 505

  • LinkedIn