Study on the Effect of “Water Shut-off and Profile Control” Combined Operation and Liquid Diverting Mechanism: A Case Study of SZ36-1 Reservoirs in Bohai Oilfield

SZ36-1 Oilfield, characterized by loose reservoir, serious heterogeneity, high average permeability, high viscosity of crude oil and large amount of water injected in single well, is in an urgent to take the liquid diverting measures to achieve the effect of stabilizing oil production and controlling water cut. In order to meet the technical requirements of the oil reservoir management, the authors, taking SZ36-1 reservoirs in Bohai Oilfield as the object, studied the effect and influence factor of water shut-off (starch graft copolymer as the agent), profile control(Cr³⁺ Polymer gel as the agent) and "water shut-off and profile control" combined operation by indoor physical simulation. The results showed that the effect of "water shut-off and profile control" combined operation were better than that of individual water shut-off or profile control in increasing oil production and decreasing water cut. With the increase of liquid slug size replaced by the plugging agent, the split ratio of the reservoirs with low to middle permeability increased and the effect of increasing oil production and decreasing water cut increased. However, the recovery factor showed the trend of "first increasing and then dropping". Therefore, the reasonable slugging size is about 0.05 PV. Besides, with the increase of oil viscosity in the reservoir, the split ratio and recovery of the reservoir with low to middle permeability by water drive decreased; injection pressure and split ratio of the reservoir with low and middle permeability increased after taking the measures of water shut-off and profile control, but the final recovery still very low.