A well system includes a well extending from a surface into a formation, a Y-tool provided at an end of a tubing string extending through the well, a concentric coiled tubing string extending through the tubing string and through a bypass line of the Y-tool, and a plurality of treatment solutions provided at the surface of the well. The plurality of treatment solutions includes at least one component of a dissolvable gel, a gel dissolving solution, and at least one component of a non-dissolvable gel. A method for plugging a water zone in a hydrocarbon bearing formation and a method for reducing a concentration of produced water from a hydrocarbon bearing formation are also described.