Reducing the Capillary Forces in Tight Gas Reservoirs Using Thermochemical Fluids

This paper presents a new method for stimulating tight gas reservoirs utilizing thermochemical solutions. The used solutions are environmentally friendly and inexpensive. They can react at certain conditions to generate significant pressure and temperature, which will induce multiple fractures and reduce the capillary forces. In this work, the chemical injections were conducted at high pressure and high temperature conditions, and different rock types were used. Also, nuclear magnetic resonance (NMR) and capillary pressure experiments were carried out, before and after the chemical injections. Results showed that thermochemical fluids can reduce the capillary pressure by 60.9%, 65.6%, and 80.8% for sandstone, carbonate, and shale rocks, respectively. NMR measurements showed that multiple fractures were induced in the treated rocks after the treatment. The generated fractures increased the average pore-throat size and thereby reduce the capillary pressure and decrease the remaining fluid saturations by 20% on average. The reduction in capillary pressure and fluid situation can help in mitigating the formation damages such as condensate banking and water blockage. Ultimate, this work will help in the design and application of thermochemical treatment in improving the productivity of tight gas reservoirs.