Waterflooding has been used as an effective means to enhance oil recovery in mature oil fields for decades. The success of waterflooding is a function of geology, facies changes, and fluid dynamics, specifically, formation porosity and permeability. Within the Loudon oil field (Illinois), waterflooding has been used to increase production, but the degree of success has been variable. We have used 3D facies modeling was evaluate the variables controlling the success or failure of waterflooding. Three leases within the Loudon field exhibiting varying degrees of waterflood success were investigated. The K. Stubblefield lease, with the highest mean porosity of 13.5%, responded most favorably to waterflooding, with an increase of more than . Thick, high-porosity zones are well connected within the lease area, contributing to greater communication among the injection wells and the producing wells. The Rhodes-Williams lease, with porosity of 11.5%, had an increase in production of . The model showed that within this lease area, high-porosity zones were either orientated in directions that provided flow away from production wells or were lower porosity zones that finger with higher porosity zones restricting flow. The George Durbin lease, with porosity of 11.5%, produced only an additional . The model suggests that injector wells may be positioned in low-porosity zones and, as with the Rhodes-Williams lease, the alignment and distribution of the low porosities inhibit recovery within the producing wells. The 3D models indicated that although porosity plays an important role in the success of waterflooding, the alignment and distribution of the high- and low-porosity zones play a greater role in the success of secondary recovery techniques. Our research also demonstrated the utility and workflow of digitizing older paper well logs to incorporate into modern modeling software.