Word of the Week – Two-Phase Flow

Two-Phase Flow

A condition that is attained in production wells associated with high temperature (>200°C) geothermal reservoirs, wherein the flowing fluid comprises a mixture of steam and water. As the two-phase fluid depressurizes in the well, it expands causing it to accelerate upwards, negating the need for a pump to produce fluid.

Word of the Week – Helium Isotopes

Helium Isotopes

Helium gas is a trace constituent of groundwater and thermal fluids, and the ratio of 3He to 4He can be measured with a high-precision mass spectrometer to determine whether it is derived from air, from the radioactive decay of uranium and thorium in the crust, or from the mantle. The latter is a characteristic feature of volcanic and geothermal gases.

Word of Week – Conduction


For geothermal applications, this refers to heat transfer in solids where thermal energy flows via microscopic-submicroscopic collisions of particles, which at a macro level is seen as solid-state diffusion. A vertical conductive thermal gradient is linear wherein temperature increases with increasing depth at a constant slope.

Word of Week – INSAR


Interferometric synthetic aperture radar is a technique that is deployed from aircraft or satellites in order to generate interferogram images. These are used to interpret surface deformation resulting from natural and human-related activities.

Word of the Week – DAS


Distributed Acoustic Sensor. Involves the deployment of fiber optic cable on the surface or in a well, and the detection of small variations in the refractive index of the fiber based on the scattering of light pulsed from a laser. Strain and temperature can be determined at fine scale intervals along the length of the fiber.

Word of Week – DFIT


Diagnostic Fracture Injection Test. A subsurface well test in which pressure is monitored as a small volume of fluid is injected into a reservoir to develop a hydraulic fracture. Monitoring continues to produce a pressure versus time plot that is analyzed to determine reservoir properties, formation pressure, and stress regime.