Combination Drive Reservoir

Oil Saturation Adjustment Due to Combination Drive

For the case of combination drive, both water and gas invasion zone is incorporated

in the saturation equation given as: 

Determination of Present GOC and OWC from

Material Balance Equation

Step 1: Determine the bulk volume of the reservoir rock at each depth interval

Step 2: Make a plot of depth versus the bulk volume

Step 3: Calculate the cumulative water influx from the general material balance

equation (We)

Step 4: Calculate the volume of oil displaced by water (Net water influx into the

reservoir) (OW ¼ We Wp)

Step 5: Calculate the reservoir volume liberated gas (GL)

GL¼ NRsi N Np

 Rs

 Bg

Step 6: Calculate the expansion of the primary gas cap (Ge)

Ge ¼ mNBoi

Bg

Bgi

 1

 

Step 7: Calculate the gas drive (GD)

GD ¼ GL þ Ge

Step 8: Calculate the produced excess gas (Gpe)

Gpe ¼ Np Rp Rs

    Bg

Step 9: Calculate the volume of oil displaced by the gas (Og)