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

The number of hydrogen atoms per unit volume divided by the number of hydrogen atoms per unit volume of pure water at surface conditions. The hydrogen index (HI) is thus the density of hydrogen relative to that of… Read more →

A type of corrosion produced when a metal absorbs hydrogen atoms. This phenomenon can cause undesirable effects such as blistering, cracking, methaneformation above 400oF [204oC] and hydrogen embrittlement. Read more →

A corrosion test instrument mainly used in sour systems (for example, hydrogen sulfide or other sulfide rich environments) to determine qualitatively or semiquantitatively the corrosion of a structure.A hydrogen probe… Read more →

What Is H2S? H2S (hydrogen sulfide) is a colorless, acutely toxic gas that forms naturally during the anaerobic decomposition of organic matter and occurs alongside hydrocarbons in many oil and gas reservoirs worldwide.… Read more →

Any chemical reaction with water (H2O), such as degradation of lignite by decarboxylation of humic acid (a major component of lignite), which is driven by hydrolysis at high pH and begins at modest temperature. Read more →

A weighted, hollow glass bulb with a long, graduated tube attached for measuring the density of a liquid. A hydrometer is placed in the liquid and the bulb sinks according to the density of the liquid. Graduations on… Read more →

A number on the scale of one to 40 according to the HLB system, introduced by Griffin (1949 and 1954). The HLB system is a semi-empirical method to predict what type of surfactant properties a molecular structure will… Read more →

Pertaining to an attraction for water by the surface of a material or a molecule. Clays and most other natural minerals used in drilling fluids, such as barite and hematite, are hydrophilic. They are spontaneously wet… 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 device designed for use in detecting seismic energy in the form of pressure changes under water during marineseismic acquisition. Hydrophones are combined to form streamers that are towed by seismic vessels or… Read more →

A slickline tool generally used for the removal of sand or similar small particles around the fishing necks of downhole tools or equipment. The hydrostatic bailer incorporates a sealed atmospheric chamber and a shear… Read more →

The vertical height of a fluid column, regardless of the length or other dimensions of that fluid column. For example, a deviated wellbore has a longer length than vertical depth. The hydrostatic head at any point in… Read more →

The pressure at any point in a column of fluid caused by the weight of fluid above that point. Controlling the hydrostatic pressure of a mud column is a critical part of mud engineering. Mud weight must be monitored and… Read more →

Pertaining to hot fluids, particularly hot water, or the activity of hot water, or precipitates thereof. Hydrothermal alteration can change the mineralogy of rock, producing different minerals, including quartz, calcite… Read more →

A change of preexisting rocks or minerals caused by the activity of hot solutions, such as fluids accompanying or heated by magma. Quartz, serpentine and chlorite are minerals commonly associated with hydrothermal… Read more →

A nonionic starch derivative, analogous to hydroxyethylcellulose in its method of manufacture and most applications for drilling, workover and completion fluids. Rather than using a cellulosic starting material, such as… Read more →

A nonionic cellulose derivative with hydroxyethyl groups attached to the polymerstructure. HEC is used as a viscosifier in brines and saline fracturing fluids, workover fluids, completion fluids and drill-in fluids. It… Read more →

Hydroxypropyl starch is a derivative of natural starch, used primarily for fluid-loss control in drilling muds, drill-in, completion and workover fluids. Being nonionic, it is only slightly affected by salinity and… Read more →

A device for measuring the moisture in a gaseous atmosphere, such as the air, usually as percent relative humidity. Mechanical hygrometers detect moisture by elongation and shrinkage of a fiber or sheet or by a device… Read more →

Pertaining to a property of a substance that allows the substance to take up water from the surrounding atmosphere. Many materials used in drilling muds are hygroscopic, for example, high-purity grades of calcium… Read more →