H
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halite |
An evaporite mineral, NaCl, common salt |
high-resolution dipmeter tool |
A dipmeter tool which records four high-resolution microresistivity curves and has an additional electrode on one pad which yields another curve at displaced depth. The displaced-depth curve is used to correct for variations on sonde speed. Provides not only improved resistivity resolution. but also improved dip resolution or refinement. |
holdup |
In a producing well, the volume fraction of a specific fluid phase (e.g., water holdup, oil holdup) in the upward moving flow stream. The relative quantities of the fluids produced at the surface are related to the holdup and upward velocity of each phase. |
horns |
Spurious high-resistivity anomalies found on induction log curves inside the upper or lower boundary of a resistive bed in which the apparent resistivity markedly contrasts with that of a conductive adjacent bed. A result of improper boundary compensation for the level of formation resistivity being logged. |
hostile environment |
A particularly difficult set of well conditions that may detrimentally affect steel, elastomers, mud additives, electronics, or tools and tool components. Such conditions typically include excessive temperatures, the presence of acid gases (H2S, CO2), chlorides, high pressures and, more recently, extreme measured depths. |
hydraulic fracturing |
The breaking or parting of reservoir rock through the use of injected fluids. Hydraulic fracturing is a method of stimulating production or injection at a specific depth in a formation of low permeability by inducing fractures and fissures in the formation by applying high fluid pressure to its face. Fluids (liquids, gases, foams, emulsions) are injected into reservoir rock at pressures which exceed the strength of the rock and overcome internal stresses of the rock. The fluid enters the formation and parts or fractures it. Sand grains, aluminium pellets, glass beads, or similar materials are carried in suspension by the fluid into the fractures. These are called propping agents or proppants. When the pressure is released at the surface, the fracturing fluid returns to the wellbore as the fractures partially close on the proppants, leaving paths with increased permeability for fluid flow. |
hydrogen embrittlement |
The process whereby steel components become less resistant to breakage and generally much weaker in tensile strength. While embrittlement has many causes, in the oil field it is usually the result of exposure to gaseous or liquid hydrogen sulphide [H2S]. |
hydrogen sulphide |
A gaseous compound, H2S, of sulphur and hydrogen commonly found in petroleum which causes the foul smell of sour petroleum fractions. It is extremely poisonous and corrosive. |
hydrostatic pressure |
That pressure due to the weight of a column of liquid (formation water, drilling mud, etc.) extending from the depth of interest to the liquid level which might or might not be at the surface. |
