Tuning fracture hydraulic conductivity can be provided so that high hydraulic conductivity in high temperature zones and low hydraulic conductivity in low temperature zones can be defined in enhanced geothermal systems (EGS). Uniform thermal gradient along flow paths can be provided or defined to help provide such conductivity zones. Experimentation performed to evaluate embodiments showed that embodiments could prevent appearance of dominant flow paths between the wells and maintain high heat extraction rates. Embodiments can greatly increase cumulative heat extraction. Embodiments can also be provided for application solely to the injection wells. Other embodiments can position tuning agents between the wells and still help provide control of the fluid flow in the reservoir and enhance heat extraction.