| Conformance problems, such as reservoir heterogeneity can result in a significant decrease in oil recovery, and an excessive water production. Millimeter particle gels (PPG) have been used as conformance control agents to plug open fractures, however, very little research has been conducted to study their ability to plug partially open fractures. This research studies the ability of the PPG to plug partially open fracture to improve conformance and increase recovery in oil reservoirs. Rectangular Sandstone cores were used to conduct the experiments. Fracture widths used include 2, 3.5, 5 mm. For each fracture width, four gel strengths were used; gel strength was varied using 0.05, 0.25, 1, and 10 wt% NaCl brine. The experiments studied the effect of gel strength, and fracture width on oil recovery. The effect of back pressure on the PPG propagation, and plugging efficiency was also studied. The concept of PPG matrix permeability reduction was studied and analyzed using the matrix of the partially open fractures. The gel particles were found to have different gel strengths depending on their location in the fracture. Particles present at the end of the fracture near the sand face were found to have higher gel strengths, whereas particles located near the inlet of the fracture had lower gel strengths. This research studied both the open and partially open fractures, and the difference between them. The concept formation damage was introduced by showing that even though the gel particles managed to plug the fracture, they also extruded into the matrix thus reducing the permeability and affecting oil recovery. These results can help improve future PPG conformance control treatment in the field, and aid in the improvement of hydrocarbon recovery. |
