Gneiss metamorphic rock

Gneiss

Metamorphic rock that forms under intense pressure and high temperature and that is made of quartz, feldspar, amphibole and mica. Gneiss represents the highest grade of metamorphic rock, which is characterized by alternating bands of dark and light-colored minerals, foliation (i.e., parallel alignment of planar minerals) and tight folding. This rock type is common at mid to deep levels of continental crust.

Geothermal Glossary

Word of the Week – Well Casing

Word of the Week – Well Casing

Well Casing Large diameter pipe that is assembled and inserted into newly drilled intervals of a well. The upper portions of a cased well are commonly cemented in place to provide a smooth internal bore, and prevent the inflow of water and/or collapse of the hole.

Word of the Week – Wellhead

Word of the Week – Wellhead

Wellhead Surface equipment at the top of a well (oil, gas, geothermal) that provides a structural and pressure-containing interface for drilling and production equipment. It is used to support and attach the anchor casing via a welded connection. Other flow valves...

Word of the Week – Well Logging

Word of the Week – Well Logging

Well Logging Methods used to survey and characterize the physical and geological characteristics along and near the wall of a well, including the temperature, pressure, fracture density, fracture orientation, porosity, rock type, casing integrity, and fluid...

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