High-Temperature-Resistant and Gelation-Controllable Silica-Based Gel for Water Management

Chemical water control techniques have been proven to be important for improving the oil recovery of mature water flooding reservoirs. However, for reservoirs with high temperatures and large well spacings, few options are available. In this study, an inorganic gel composed of silica sol as the gelling agent (component A) and potassium silicate as the activator (component B) was developed. By breaking the acid–base balance in the precursor B system, more Q3 or Q2 silica was formed, and the number of reactive sites increased, leading to the enhancement of the cross-linking degree and completion of the sol–gel transition. After optimization of the conditions, the gelation time reached ∼7 days at a reaction temperature of 140 °C, which is about 3.5 times longer than the longest gelation time, as reported in a previous report. It was found that our silica-based gel with a Si–O–Si backbone is highly preferred for high temperature- and high salinity-resistant properties, and the gel strength of both rigid and weak gels was adjusted over a wide range, exhibiting a high plugging efficiency.