Laboratory Investigation of P and S Wave Types on Vibroseis EOR Technology for Low Permeability Reservoir

Abstract

Advanced technology, specifically EOR, is needed because the reservoir still contains large amount of oil after the current oil is drained. Vibroseis EOR is one of the promising technologies under development. In its implementation, the attenuation of the S wave is lower than the P wave, so using the S wave as a vibration source will have a greater effect than using the P wave in increasing the oil recovery factor. Previous laboratory studies using circular mode vibration stimulation (S waves) revealed an increase in oil RF, porosity, and permeability as well as a decrease in Sor. The research objectives of increasing the recovery factor using both the vibroseismic method and water injection simultaneously are to explain the effect of transverse and longitudinal waves on vibroseismic and recovery factor (Sor) and also to evaluate the efficiency of water injection under the influence of transverse and longitudinal waves.

According to this research, P-wave has a greater effect on increasing oil recovery than S-wave in low permeability. This experiment used a synthetic core with low to medium permeability at a frequency of 15 Hz and amplitudes of 0.1 µm for the P-wave and 0.2 µm for the S-wave. The Recovery Factor (RF) increment reached 8.3% on low permeability (34.8 md) and 10.29% on mid permeability (115.4 md) at same amplitude for P-wave. The increase in oil RF during vibration stimulation in circular mode occurs only at mid-permeability.

This research was used in laboratory tests as well as the implementation of the EOR Vibroseis Field Trial in one of Pertamina's fields, and it was successful in increasing oil recovery in that field.