High-Temperature-Resistant\nand Gelation-Controllable\nSilica-Based Gel for Water Management

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