SWLGS Technical Luncheon- February 17, 2005


Carbonate Reservoir Description Using Poststack Seismic Inversion, Onshore Gulf Coast, USA

Ben Flack*, Azza Halit-Robinson, Richard Salter, Niranjan Banik and Randy Utech, Reservoir Services, WesternGeco, Houston, Texas





A robust poststack inversion method has been successfully applied to a recently acquired seismic survey, to predict seismic reservoir porosity within the Jurassic Smackover Formation, onshore Gulf Coast, USA. Inversion added significant value to conventional surface seismic data, providing a much clearer understanding of the stratigraphic nature of porous pods within a predominately tight dolomitic facies.


Five key wells were edited for geophysical purposes and used for quantitative wavelet estimation throughout the seismic volume. A proprietary workflow was used to broaden the seismic bandwidth and ensure a true zero-phase output. Seismic acoustic impedance was calculated independently of well control and resulted in a high-resolution dataset capable of detailed stratigraphic analysis and more accurate gross interpretation for low-frequency compensation and mapping. Well logs were used to calculate an absolute acoustic impedance volume that - through petrophysical calibration - was converted to porosity. “Blind-well-testing” the seismic porosity volume against well logs not used within the processing steps showed good ties.


Porosity maps were generated and used in conjunction with seismic porosity sections to better define, and quantify existing fields and new prospects.




Ben Flack received his Bachelor of Science degree in Geology from the University of Liverpool, England in 2000.  He gained his Master of Science degree in Petroleum Geology from Imperial College, London in 2001.  He entered WesternGeco in 2001 and worked as a log data analyst in Reservoir Services, Gatwick, UK.  After transferring to Houston in 2002, he undertook his present role as Well Data Specialist.  His main interests are in the conditioning and full integration of borehole information with surface seismic data.  He has experience in the use of advanced technology for detailed reservoir description of both carbonate and clastic environments around the world.