WorldWide Drilling Resource

Synthetic DNA Could Aid Geothermal Exploration Compiled by Amy White, Associate Editor, WorldWide Drilling Resource ® For geothermal engineers, knowing where to drill a well and what takes place after the drilling is complete involves a con- siderable amount of guesswork. Stanford scientists are trying to ease speculation woes with mini fragments of DNA dropped into wells to trace the path of water below the earth’s surface. To establish a geothermal plant, two types of wells must be drilled. The first well is approximately two to three miles deep, and makes fractures in hot rock for water to flow through. Second, pro- duction wells are drilled to intersect fractures and carry hot water to the surface. The hot water makes steam to power turbines and cre- ate electricity. Multiple production wells must be placed very carefully to en- sure each one has a chance to produce hot water. Geothermal drilling contractors do not have a reliable means to detect fractures created during the first phase of drilling. Presently, they rely on unpredictable chemical or radioactive tracers to track water underground. Geothermal engineers at Stanford University developed a po- tentially revolutionary tracer using synthetic DNA. The material has a one-of-a-kind pattern and attaches to silica, enabling engineers to craft balls of silica with DNA inside. The balls are injected into a well to give researchers tracing abilities. An outer shell of silica keeps the tracer from being muddled. The technology is promising. DNA tracers are currently being tested for heat stability. Thus far, the DNA-silica balls have lasted six hours at 300ºF (148ºC) in the lab. If field tests are successful, DNA could give geothermal developers an incentive to invest in projects. The Stanford Geothermal Program has driven geothermal reservoir research for over 35 years, completing more than 150 projects. Individuals with working experience in the geothermal industry are encouraged to apply for the program. Financial aid is available for candidates with strong records. For more information, visit https://earth.stanford.edu/researchgroups/geothermal/ Stanford students conduct laboratory experiments. Photo by Norbert von der Groeben, courtesy of Stanford University. --- *+ )#)('-()$* !(& )(%#'" +)""+ ,'.*,+ -'"/ 0 . 49 WorldWide Drilling Resource ® JULY 2016