Delaying the effect of an aluminum carbide drying agent in a tight gas reservoir

Water block damage is the core problem in damage to tight gas reservoirs, and the main obstacle to developing these reservoirs. When an ionic carbide (aluminum carbide: Al4C3) drying agent is injected into the reservoir, the water is quickly gasified through a drying treatment to improve the seepage capacity of the gas and the recovery rate of the reservoir. However, under high temperatures and high pressure (HTHP) conditions, it is easy to lose the reactivity due to the high activity of the drying agent, thus preventing the drying effect. In this paper, in order to delay the reaction starting time of the Al4C3 in HTHP conditions with water-cut, a surface modification of aluminum carbide was carried out by using absolute ethyl as the reaction media and polyvinylpyrrolidone (PVP) as a modifier under the reaction of an initiator AIBN. The modified Al4C3 was characterized by SEM, TEM, FTIR, and other detection methods. In addition, a gas evolution experiment compared the starting time of the reaction between unmodified aluminum carbide and formation water to the starting time of the reaction between modified aluminum carbide and formation water. Results show that this method can successfully modify the drying agent and effectively block the reaction activity of the drying agent. Meanwhile, gas production in the process of drying and the consumption of formation water are obviously reduced, which can effectively delay the reaction starting time by 6-8 minutes.