Physical modeling of in-depth fluid diversion by “gel dam” placed with a horizontal well

Ineffective cycling of injected water in high permeability zones during water flooding processes can be an issue in positive rhythm reservoirs. The “gel dam” in-depth fluid diversion technique is proposed to ameliorate this problem. The technique involves the injection of gel by horizontal wells drilled in the highly permeable and strongly swept zones of thick positive rhythm reservoirs. The injected water then will bypass the “gel dam” and be diverted into the upper, lower permeability zones. As a result, the sweep efficiency and oil recovery from the overlying low permeability zone can both be increased. A 2D visible sand-pack physical model was set up to test the process, and a video camera was used to visualize the “gel dam” fluid diversion effects. The results of the experiments indicated that, with one or two “gel dams”, both the sweep volume and ultimate oil recovery increased greatly, while the rate of water cut decreased. Compared with physical models with no “gel dam”, the ultimate oil recoveries of those with one or two “gel dams” increased by 17.6% and 27.3%, respectively. By applying the “gel dam” in-depth fluid diversion technique, difficulties in the in-depth placement of plugging agents can be resolved, and the sweep efficiency of positive rhythm reservoir can be increased significantly.