def calc_oil_drainage_area(oil_produced=2.5, res_height=20, porosity=0.25, avg_water_saturation=0.25, oil_vol_factor=1.2, recoveryfactor=0.10):
    """Returns the estimate for drainage area (Acres) given the oil produced (MBO), reservoir height (ft),
    porosity (fraction), average water saturation (fraction), the oil formation volume factor (RBBL/STB), and the recovery factor."""
    return ((oil_produced*10**(3))*oil_vol_factor)/(7758*res_height*porosity*(1-avg_water_saturation)*recoveryfactor)