Oil and Gas Terms Beginning with “H” — Page 5

What Is Hydrogen Embrittlement? Hydrogen embrittlement (also called hydrogen-assisted cracking or hydrogen damage) is a form of metal degradation in which atomic hydrogen diffuses into the crystal lattice of steel or… Read more →

The hydrogen index (HI) in nuclear magnetic resonance (NMR) logging is defined as the number of hydrogen atoms per unit volume of a fluid divided by the number of hydrogen atoms per unit volume of pure water at surface… Read more →

Hydrogen induced failures describe a family of damage mechanisms that occur when atomic hydrogen, generated by corrosion reactions at a steel surface, is absorbed into the metal and accumulates at internal trap sites… Read more →

A hydrogen probe is a corrosion monitoring instrument that measures the rate of atomic hydrogen permeation through the wall of metal equipment (typically carbon steel or low-alloy steel pipelines, vessels, or tubulars)… Read more →

Hydrogen sulfide (H₂S) is a colorless, flammable, and acutely toxic gas with the characteristic odor of rotten eggs at low concentrations. It has a molecular weight of 34.08 grams per mole, is slightly heavier than air… Read more →

Hydrolysis is any chemical reaction in which a water molecule splits a chemical bond, with the hydrogen and hydroxyl fragments of water attaching to the two products, and in the oilfield it is one of the most important… Read more →

A hydrometer is a sealed glass or plastic instrument that measures the specific gravity (or density) of a liquid by the depth to which it sinks when floated in the liquid, operating on the Archimedes principle that an… Read more →

What Is the Hydrophile-Lipophile Balance Number? The hydrophile-lipophile balance (HLB) number is a numerical index from 0 to 20 that characterises a surfactant molecule's relative tendency to dissolve in water versus… Read more →

Hydrophilic in oil and gas operations describes a material, surface, chemical, or particle that has a strong affinity for water, preferentially adsorbing water molecules, being wetted by water rather than oil, and… Read more →

(adjective) Describing a surface or substance that repels water and resists wetting by aqueous fluids. In petroleum engineering, hydrophobic materials or coatings are used in sand control screens and other downhole… Read more →

A hydrophone is a pressure-sensitive transducer designed to detect and convert acoustic pressure fluctuations in water (including the reflected and refracted seismic energy used in marine seismic surveys) into… Read more →

A hydrostatic bailer is a slickline-deployed downhole tool used primarily for the removal of sand, fines, debris, or similar small particulate matter from around the fishing necks (the mechanical interface points where… Read more →

What Is Hydrostatic Head? Hydrostatic head is the pressure exerted by a static column of fluid due to its weight, calculated as the product of the fluid density, gravitational acceleration, and the vertical height of… Read more →

What Is Hydrostatic Pressure? Hydrostatic pressure (also called formation pressure balance or fluid column pressure) is the pressure exerted by a static column of fluid at any given depth, equal to the product of fluid… Read more →

Hydrothermal in petroleum geoscience refers to processes, fluids, mineral deposits, and alteration features produced by the circulation of hot water (or water-dominated fluids) through rock at elevated temperatures,… Read more →

Hydrothermal alteration is the chemical and mineralogical modification of rock through interaction with hot water (hydrothermal fluids) that circulates through fractures, faults, and permeable zones in the crust,… Read more →

Hydroxyethyl starch (HES, also abbreviated HE starch) is a chemically modified polysaccharide used as a fluid loss control additive in water-based drilling fluids, derived from natural starch (typically corn, potato, or… Read more →

Hydroxyethylcellulose (HEC) is a non-ionic water-soluble cellulose ether polymer produced by reacting alkali cellulose with ethylene oxide, used extensively in the oil and gas industry as a viscosifier, fluid loss… Read more →

Hydroxypropyl starch (HPS) is a chemically modified starch produced by reacting base starch (potato, corn, or tapioca) with propylene oxide under alkaline conditions to introduce hydroxypropyl ether groups… Read more →

A hygrometer is a measurement instrument used to determine the moisture content (water vapor concentration) in a gaseous atmosphere — typically reported as percent relative humidity (RH, defined as the partial pressure… Read more →

Hygroscopic describes a substance's tendency to absorb moisture from the surrounding atmosphere, with the degree of hygroscopicity ranging from mildly moisture-sensitive (like table salt, which clumps in humid… Read more →