Propylitic Alteration

Propylitic Alteration

A term borrowed from studies of hydrothermal ore deposits that refers to an assemblage of secondary hydrothermal minerals which forms in igneous rocks. This assemblage is made up of chlorite, illite, feldspar (both Na and K-rich varieties), epidote, calcite and pyrite, imparting a dark green tint to the appearance of altered rocks. It is commonly developed in volcanic-plutonic sequences that host high-temperature geothermal reservoirs.

Geothermal Glossary

Word of the Week – PDC Drill Bit

Word of the Week – PDC Drill Bit

PDC Drill Bit Polycrystalline diamond compact drill bits have been long used in oil and gas drilling, and only recently have they been used in geothermal drilling. The PDC cutters are known for their resistance to wear and impact, including hot crystalline rock. They...

Word of the Week – Peak Load Generation

Word of the Week – Peak Load Generation

Peak Load Generation The amount of power required to maintain an electric grid for short-lived periods (e.g., morning, late afternoon and evening) in response to high demand. Thermal power plants that burn natural gas and hydroelectric dams are two common modes of...

Word of the Week – Perforation

Word of the Week – Perforation

Perforation The process of punching holes through the steel casing liner in a well in order to inject fluid into or produce fluid out of the reservoir rock. Perforations are achieved through deployment of a perforation gun, which is a string of explosive charges.

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