Oil and Gas Terms Beginning with “H” — Page 2

Hardness ions are dissolved divalent cations, primarily calcium (Ca2+) and magnesium (Mg2+), present in the aqueous phase of a water-based drilling fluid that interfere with the hydration and performance of bentonite,… Read more →

A particular frequency at which a data set has a resonance, or the frequency has special significance. Read more →

A nonlinear change in waveform in which simple multiples of (1,2, ... n times) the input frequencies, or harmonics, are generated. Read more →

An opening in the top of a tank through which samples are taken or inspection is made. Read more →

Head, in petroleum engineering and fluid mechanics, is the energy of a fluid expressed as an equivalent vertical height of a column of that fluid, providing a convenient way to express fluid pressure and energy in units… Read more →

A head wave (also called a refracted wave, critically refracted wave, or first arrival) is a seismic wave that travels down from the surface to a high-velocity interface, refracts along that interface at the critical… Read more →

In oil and gas production facilities, a header is a large-diameter manifold pipe that serves as a common collection or distribution point — receiving produced fluids from multiple wells or production streams and routing… Read more →

A header box, sometimes called a possum belly or back tank, is a small open box mounted at the feed end of a shale shaker that receives drilling fluid from the return flow line and distributes it evenly across the full… Read more →

In well logging, the heading is the first page or pages of a log print, the section that records the identifying and reference information about the well, the survey, the mud properties, and the operational conditions… Read more →

In oil and gas processing, a heater is a fired or indirect process vessel that adds thermal energy to oil, gas, or water streams to accomplish a specific production or facility objective such as reducing crude viscosity… Read more →

What Is a Heater-Treater in Oil and Gas? A heater-treater is a surface production vessel that combines applied heat with gravity separation and chemical treatment to break stable oil-water emulsions that cannot be… Read more →

In oilfield chemistry and environmental practice, a heavy metal is a metallic element of relatively high atomic weight and density, conventionally those denser than iron, whose elevated concentrations are toxic or… Read more →

What Is Heavy Oil? Heavy oil (also called heavy crude or viscous oil) is crude oil with an API gravity below 20 degrees and a viscosity typically ranging from 100 to 10,000 centipoise at reservoir conditions, making it… Read more →

Heavy pipe in drilling engineering refers to drill collars and other heavy-weight downhole tubulars placed in the bottom-hole assembly (BHA) above the drill bit to provide the compressive weight needed to advance the… Read more →

What Is Heavyweight Drillpipe? Heavyweight drillpipe (also called HWDP or heavy-wall drillpipe) is a thick-walled tubular with the same outer diameter as standard drillpipe but a significantly smaller inner diameter,… Read more →

Hectorite is a smectite clay mineral similar in crystal structure to bentonite but distinguished by a higher density of negative charges on its surface and a notably lower iron content, which gives hectorite-based… Read more →

What Is Held by Production? Held by production (commonly abbreviated HBP) is a lease status condition in which an oil and gas lease that has expired its negotiated primary term continues in force because the leased… Read more →

Hematite (Fe2O3, iron sesquioxide) in oil and gas drilling operations is a dense, reddish-brown iron oxide mineral used as a weighting agent (density additive) in drilling fluids when conventional barite weighting is… Read more →

The hertz (symbol Hz) is the SI unit of frequency, equal to one cycle per second, named after the German physicist Heinrich Hertz (1857 to 1894), who first generated and detected electromagnetic waves and so confirmed… Read more →

A hesitation squeeze in well cementing is a remedial squeeze cementing technique in which small volumes of cement slurry are pumped in alternating cycles of injection and pressure hold ("hesitation"), with each cycle… Read more →

Heterogeneity in petroleum reservoir engineering is the variation of rock and fluid properties — permeability, porosity, capillary pressure, wettability, and fluid saturation — across different locations within the… Read more →

A heterogeneous formation is a reservoir rock whose petrophysical properties, principally porosity, permeability, fluid saturation, lithology, and pore geometry, change measurably from one location to another within the… Read more →

A hiatus, in stratigraphy and petroleum geology, is a gap in the sedimentary record representing a period of time during which sediment was either not deposited (a non-depositional hiatus, caused by sea level rise that… Read more →

What Is Hierarchical Cluster Analysis? Hierarchical cluster analysis groups well log measurements by computing the distance between every pair of data points and arranging the relationships on a dendrogram.… Read more →

A high explosive in oil and gas operations is a chemical compound or mixture that, when initiated by heat, shock, or an initiating detonator, undergoes rapid detonation — a supersonic exothermic decomposition that… Read more →

Equipment or systems used for completion of wells in thermal production of heavy oil. Read more →

High-gravity solids (HGS) are dense solids added to drilling mud to increase its density, also known as weighting material — the principal HGS materials are barite (BaSO4, specific gravity 4.20 g/cm3, the standard… Read more →

High-Pressure Air Injection (HPAI) is an enhanced oil recovery technique in which compressed air is injected at pressures typically exceeding 3,000 psi into light or medium gravity oil reservoirs where reservoir… Read more →

A high-pressure squeeze is a specialized cement squeeze technique that involves the application of treatment pressure higher than the formation fracture pressure — providing the elevated injection pressure needed to… Read more →

What Is High-Pressure High-Temperature (HPHT)? High-pressure high-temperature (also called HPHT ) is a classification for wells, reservoirs, or oilfield equipment operating at bottomhole pressures exceeding 10,000 psi… Read more →