Photo by Jennifer Boyer: Geothermal Greenhouses in Hveragerði, Iceland. Geothermal Greenhouses: A...

Refers to Measurement While Drilling which for directional drilling includes geospatial information that is used to steer the bottom hole assembly (BHA). Inclination and azimuth are surveyed using accelerometers and magnetometers which are incorporated into MWD tools. Other MWD information includes rotational speed of the drill string, type and severity of downhole vibration, temperature, and torque and weight on bit.
Fumarole A steam vent and surface thermal feature that is commonly associated with steaming ground and mud pots in hydrothermally and volcanically active areas.
Geochemical Tracer An environmentally benign chemical that is injected to trace fluid movement through the geothermal reservoir and that can be easily detected in produced hot fluid.
Geothermal Gradient The increase in temperature with depth below the surface, usually reported in units of °C/km.