Preparation and Evaluation of an Organosilicon Water Block Inhibitor for Low Permeability Gas Reservoirs

To solve the waterblocking damage caused by water phase invasion during drilling and completion of the low permeability gas reservoir, a cationic silicone surfactant DAT was synthesized by the hydrosilylation and epoxy ring opening reactidouble-endedle ended hydrogenated silicone oil (DHSO), allyl glycidyl ether (AGE), trimethylamine hydrochloride (TMHC), defoamer, and other additives were used to prepare the anti-waterblocking agent DAH. Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance o solve the problem of water block resulted from water invasion in drilling and completion of a low permeability gas reservoir, a cationic organosilicon surfactant DAT was synthesized through hydrosilylation reaction and epoxides ring-opening reaction, and by compounding the DAT with a defoamer, an organosilicon anti-water-block agent DAH was produced. The cationic organosilicon surfactant DAT is synthesized with raw materials such as double-ended hydrogen-containing silicone oil (DHSO), allyl glycidyl ether (AGE) and trimethylamine hydrochloride (TMHC). Characterization of the final product with Fourier infrared spectroscopy and HNMR has proved that the molecular structure of the final product conforms to the expected design. The performance of DAH was evaluated by laboratory tests such as surface tension measurement, contact angle test of cores, self-imbibition test of cores, core displacement test etc. The test results reveal that a 1% DAH solution has a surface tension greatly reduced to 21.28mN/m, the contact angle of the DAH water solution is increased from 20° to 110°, the amount of water imbibed by the core sample tested is reduced by 83.1%, and the percent permeability recovery is increased to 82.68%. These test results have proved that DAH can greatly reduce the surface tension of water, and can form a tight absorptive membrane on the surfaces of a core through electrostatic action, thereby reversing the surface of the core from hydrophilic to hydrophobic, and effectively reducing the invasion of water into the formation during drilling and completion operations. This performance of DAH is also helpful to water flow back, making it an excellent additive for reducing the damage caused by water blocking; this is of great importance to the protection of the productivity of a low permeability reservoir.