An edge-water-drive oil reservoir has the following boundary-pressure history. Time (months) 0 Boundary pressure (psia) 2610 5 2600 12 2580 16 2552 22 2515 The reservoir-aquifer system is characterized by the following data. Aquifer Property Radius (ft) Porosity (%) Permeability (md) Formation compressibility (psi-1) Water compressibility (psil) Net thickness (ft) Water viscosity (cp) Reservoir 2000 17 60 0.2x10-6 0.7x10-6 25 0.55 18 80 0.3x10-6 0.8x10-6 30 0.85 Using the van Everdingen-Hurst method, estimate the water influx as a function of time given that the encroachment angle is 270 degrees