The Effect of a Free Gas Saturation on the Sweep Efficiency of an Isolated Five Spot

CIM Bulletin, 1962


The objective of the research conducted and presented herein was to determine the effect of a pre-established free gas saturation on the sweep efficiency of an isolated inverted five-spot well pattern. The investigation concluded that the ultimate recovery of an isolated inverted five-spot may be slightly increased by establishing a free gas saturation prior to water flooding; however, of more significance is the extreme deviation of the pattern's performance after water breakthrough from that commonly obtained from developed well patterns. The rapid "water-out" characteristic common to both linear floods and floods conducted in developed well patterns was not evidenced in the isolated inverted five-spot. Instead, the wells continued to produce oil long after breakthrough until ultimate areal sweep efficiencies of four, five, and six hundred percent were obtained prior to the water-oil ratio becoming excessive. '!'he investigation further noted that these large areal sweep efficiencies could only be obtained if fill-up of the reservoir's initial gas saturation was obtained prior to breakthrough; otherwise, the rapid "water-out" characteristic common to linear floods and floods conducted in developed well patterns would prevail.
Keywords: capillary pressure, inches of mercury, injection, saturation, University of Alberta, Efficiency, Flooding, Model, Models, Oil, Oils, Pressure, Water, Waters