Liquid-Dominated Reservoir Typical of the large proportion of conventional geothermal resources in which wells are self-flowing or pumped depending on reservoir temperature. Self-flowing...

Lost Circulation Refers to the loss or escape of drilling fluid into permeable zones made up of fractured or porous rock encountered during drilling.

Mafic A geological term referring to igneous rocks that are equivalent to basalt and diorite in composition.

Magma Molten rock typically having a temperature between 800° and 1100° C (~1500-2000° F). Magma is the source of high-grade geothermal energy in conventional resources.

Magnetotelluric (MT) Geophysical Method Makes use of naturally occurring electromagnetic waves to image the resistivity structure of the subsurface. The results can reveal the locations of...

Microseismicity Tiny earthquakes that result from slip or shear along a fracture caused by an uneven distribution of stress. The displacements are very small scale and unfelt at the...

Mineral Geothermometer A secondary mineral phase whose stability is defined by a lower and sometimes an upper temperature threshold. Common mineral geothermometers comprise clays, zeolites...

Mud Pots and Mud Pools Depressions filled with hot bubbling mud commonly associated with steaming ground. The mud is mostly made up of clay minerals which form as an alteration product and...

MWD 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...

Numerical Modeling Application of computational methods to solve complex problems that predict the behavior or the outcome of a real-world or physical system that evolves in space and time.

Normal Fault High angle fault that results from extensional stress and forms a steeply dipping planar structure. Slip movement during an earthquake is vertical and down dip. The...

Packers and Plugs Downhole devices emplaced into a well to seal zones and intervals so they can be pressurized by pumping fluid from the surface in order to stimulate fractures at a...