Development and application of a geothermal bio-tracer resistant to extreme environments

Abstract

Tracers are key to acquiring data on fluid transport behavior and hydrological parameters. In particular, in the harnessing of geothermal energy, it is used to determine the connections between production and injection wells, the hydrological parameters of geothermal reservoirs, and the efficiency of thermal recovery. Traditional tracers are expensive and may pollute the environment. In response to these challenges, we developed a composite bio-tracer that is thermally stable, environmentally friendly, easy to detect, inexpensive to produce, and suitable for environments with temperatures more than 120 °C.The composition of our composite bio-tracer includes a specific artificial DNA (Synthetic hybrid-DNA sequence fragments are implanted into the plasmid) that serves as the tracer label, a label-immobilized carrier and is encapsulation in a protective shell. The overall particle size can be controlled average of about 52 nm, enabling migration along the main channels of the reservoir through fluid flow. Laboratory verification indicated that the bio-tracer remains detectable for more than 30 days in extreme environments (geothermal water environments with temperatures of 120 °C and pH ranging from 1.5 to 13.0). The developed composite bio-tracer has been put into actual geothermal site testing and verification, and after 28 days of on-site testing, the tracer recovery reached 83.1 %.