Abstract: This invention relates to a method and a system of abating carbon dioxide (CO2) and/or hydrogen sulfide (H2S) in a geological reservoir. Water is pumped or transferred from a water source to an injection well. The gasses are merged with the water under conditions where the hydraulic pressure of the water is less than the pressure of CO2 and/or H2S gas at the merging point. The water with CO2 and/or H2S gas bubbles is transferred further downwardly at a certain velocity higher than the upward flow velocity of said CO2 and/or H2S gas bubbles ensuring downward movement of gas bubbles resulting in full dissolution of said CO2 and/or H2S in the water due to elevating pressure. The complete dissolution ensures a lowered pH of the water entering a geological (e.g.