A section of reservoir can be modeled as a rectangular block, with linear flow of oil through it. The face producing oil is 10 ft high by 120 ft wide. The length over which the pressure drop occurs is 1000 ft. The rock has two layers. The lower 8 ft of the 10-ft thickness has permeability 20 mD. The upper 2 ft has permeability 300 mD. Pressure on the producing face is 3200 psi; pressure on the opposite face is 4500 psi. Viscosity of the oil is 0.85 cp and specific gravity is 0.81. B_o is 0.90 rb/stb. What rate is oil produced in units stb/day?