The seismic stimulation for enhanced oil recovery (EOR) was a RPSEA-funded project, with cost-share provided by BGI (Berkeley Geo Imaging) and Unico, and began in October 2008, with the aim of quantifying whether seismic waves can mobilize oil trapped on capillary barriers, thus enhancing oil recovery in older low-production domestic oil fields. This study focused on a field owned by BGI near Foraker in Osage County, Oklahoma. There were two major components of the study: modeling and field tests.
The modeling was aimed at determining a “stimulation potential” that quantifies whether immobile oil can be liberated by a passing seismic wave. To determine this potential using the theory developed at LBNL required numerical models of both the production gradients in the field and the seismic-wave amplitudes. An example of such a stimulation potential for the Foraker field is given in the figure below. The upper panel shows in map view the location of the producers in the field with the pressure gradient shown in color and the flow amplitude with arrows. The lower panel shows the modeled stimulation potential for the field for a seismic source position as shown. Where the potential is zero, there is no chance for the oil to become liberated by the seismic waves, while increasing values of the potential quantify the increasing likelihood of oil to be liberated.
For the field test part of the study, the Foraker field was first equipped to monitor well-by-well production data. However, prior to the start of seismic stimulation, the field was sold by BGI and the project at the Foraker site brought to a close. A new cost share partner, Sandridge Energy, was then identified, and their Fuhrman Mascho field in the Permian Basin near Andrews, TX, was identified as the new field site.
After many delays, the downhole seismic source built by Applied Seismic Research was finally turned on in October 2013. The source was supposed to run continuously for 8 months, but tool output greatly diminished after just one day. Applied Seismic Research thought that well-water precipitates were impeding the stroke of the tool, so the well was flushed, chemical additives were added, and the tool turned on again in February 2014. Unfortunately, the same thing happened; after one day of normal output, the tool’s output power fell off and Sandridge decided to stop the project.
Consequently, this project ended without performing the field-testing component of the efficacy of seismic stimulation. LBNL developed as the main deliverable the software that can make maps of seismic stimulation potential such as those shown here.