Shear-Wave Tomographic Images Of An Oil Reservoir At MIT's Michigan Test Site

Abstract

We conducted a P- and S-wave crosswell survey with Conoco's orbital vibrator source and three-component receivers at M.LT.'s Michigan Test Site. The receiver and source wells bracket a known oil reservoir. Applying a nonlinear crosswell traveltime tomography method, we reconstruct the velocity structures in the oil reservoir using P- and S-wave data separately. The P-wave tomogram shows a similar image to the one by Matarese (1993), and it does not present much velocity variations in the oil producing zone. However, the S-wave tomogram clearly shows the image of the reservoir zone, which is characterized with low velocities in a pinnacle reef. The S-wave velocities in the reservoir are about 20% lower than those of the surrounding carbonates.