Enhanced Oil Recovery (EOR) is a tertiary recovery which requires relatively a high cost of CAPEX and OPEX. The current EOR technique is generally stand alone and injected into single reservoir layer without contributing to the other layers (unconnected reservoir layer). For this reason, a breakthrough of low cost EOR technology (CAPEX & OPEX) is needed, especially since oil prices tend to fall low. Vibroseismic EOR is one of the EOR methods (categorized as mechanical EOR) that is inexpensive, fast response / yield, high mobility (can be moved to another place), environmentally friendly, and could be combined with the waterflood method or other EOR methods to get more effective and optimal result. However, the research & implementation on Vibroseismic EOR are still limited. The paper describes the pilot test of Vibroseismic EOR technology in Tempino Field.
The initial stage is to select the suitable field for implementation Vibroseismic EOR. Then, the rock & fluid properties of the selected field are tested and examined by vibration and stimulation in the laboratory to obtain optimum frequency of 20 Hz S waves (circular / transverse) and 35 Hz P waves (longitudinal). The field scale-up process is carried out by measuring or testing field parameters called Vibroseis Field Parameter Test (VFP Test). VFP Test results get the optimum frequency of S and P waves of 20 Hz using 3 trucks and drive level 70% with amplitude value up to 0.024 rms (root mean square). Through the EOR vibroseismic method, the truck is the source of vibrations on the surface will generate acoustic waves propagating through the rock (subsurface) throughout the reservoir layer within the wave penetration range, generally reaching a depth of 6500 ft depending on the amplitude / power source of vibration, thickness of weathered layer, and rock type. The waves that reach the reservoir will affect the rock & fluids properties.
The pilot test results on production wells showed a positive response within 1 month after vibration, especially those around the existing injection wells which the permeability was relatively good. The increased production accumulative of 10 (ten) monitoring production wells about 8% and withhold declining rate up to 20% from base case. Oil drainage around production wells and drainage direction are confirmed by changes in hydrocarbon saturation maps through passive seismic techniques measured before, during, and after vibration.
The results of this pilot test show that Vibroseismic EOR technology is very promising to be developed to the full-scale stage and implemented in other areas.