Oil & Gas Glossary 1.0

A compound that is formed (along with water) by the reaction of an add with a base. A common salt (table salt) is sodium chloride derived by combining hydrochloric add with sodium hydroxide. The result is sodium chloride and water. Another salt is calcium sulfate, obtained when sulfuric acid is combined with calcium hydroxide.

The active ingredient of slaked (hydrated) lime, and the main constituent in cement (when wet). Referred to as "lime" in field terminology.

Dissolved calcium ions in sufficient concentration to impart undesirable properties, such as flocculation, reduction in yield of bentonite, and increased fluid loss, in a drilling fluid. See also calcium carbonate, calcium sulfate, gypsum.

One of the alkaline earth elements with a valence of 2 and an atomic weight of about 40. Calcium compounds are a common cause of water hardness. Calcium is also a component of lime, gypsum, and limestone.

A freshwater drilling mud using calcium oxide (lime) or calcium sulfate (gypsum) to retard the hydrating qualities of shale and clay formation, thus facilitating drilling. Calcium-treated muds resist scale and any anhydrite contamination but may require further treatment to prevent gelation (solidifcation) under the high temperatures of deep wells.

A chemical compound of calcium, sulfur, and oxygen. Although sometimes considered a contaminant of drilling fluids, it may at times be added to them to produce certain properties. Like calcium carbonate it forms scales in water-handling facilities, which may be hard to remove. See gypsum.

A naturally occurring crystalline form of calcium sulfate in which each molecule of calcium sulfate is combined with two molecules of water. See calcium sulfate.

A substance capable of reacting with an acid to form a salt. A typical base is sodium hydroxide (caustic), with the chemical formula MOH. For example, sodium hydroxide combines with hydrochloric acid to form sodium chloride (a salt) and water.

A chemical combination of calcium, carbon, and oxygen. It is the main constituent of limestone. It forms a tenacious scale in water-handling facilities and is a cause of water hardness.

Sodium hydroxide. Used to maintain an alkaline pH in drilling mud and in petroleum fractions.

A designation that is given for basic compounds containing the OH radical. When these substances are dissolved in water, they increase the pH of the solution. See base.

Mined lignite, usually leonardite, to which chromate has been added or has reacted. The lignite can also be causticized with either sodium or potassium hydroxide.

One of the alkali metal elements with a valence of 1 and an atomic weight of about 39. Potassium compounds, most commonly potassium hydroxide (KOH), are sometimes added to drilling fluids to impart special properties, usually inhibition.

Calcium oxide, used in certain oil-base muds to neutralize the organic acid.

Used extensively for treating various types of calcium contamination. Also called soda ash.

A condition in which clay platelets remain stacked by a polyvalent cation, such as calcium, and are deflocculated by use of a thinner.

A moisture-absorbing chemical compound, or desiccant used to accelerate setting times in cement and as a drying agent.

A clay mineral often used as an additive to drilling mud. It is a hydrous aluminum silicate capable of reacting with such substances of magnesium and calcium. See bentonite.

The formation of stable calcium, magnesium, iron complex by treating water or mud with certain complex phosphates.

The replacement of cations associated with the clay surface by those of another species, e.g., the conversion of sodium clay to calcium clay.

Water that is free of calcium or magnesium salts. Compare hard water

Water that contains dissolved compounds of calcium, magnesium, or both. Compare soft water.

1. a drilling mud in which the water has an appreciable amount of salt (usually sodium or calcium chloride) dissolved in it. Also called saltwater mud or saline drilling fluid.

A very soluble salt used to increase the density of water to points more than double that of water. Normally added to a system first saturated with calcium chloride.

Commercial clay chiefly of the calcium montmorillonite type and having a yield of approximately 15 barrels per ton.

Commercial clay chiefly of the calcium montmorillonite type and having a yield of approximately 15 barrels per ton.

The half-neutralized sodium salt of carbonic acid, used extensively for treating cement contamination and occasionally other calcium contamination in drilling fluids.

Substances generally regarded as drilling mud contaminants, such as salt and calcium sulfate, are called inhibitors when purposely added to mud so that the filtrate from the drilling fluid will prevent or retard the hydration of formation clays shells.

Salt of stearic acid that is a saturated, 18-carbon fatty acid. Certain compounds, such as aluminum stearate, calcium stearate, zinc stearate, have been used in drilling fluids for one or more of the following purposes: defoamer, lubrication, air drilling in which a small amount of water is encountered.

A classification of commercial drilling-clay preparations having a yield of 35 to 40 barrels per ton and intermediate between bentonite and low-yield clays. Usually prepared by peptizing low-yield calcium montmorillonite clays or, in a few cases, by blending some bentonite with the peptized low yield clay

A slurry of portland cement and water and sometimes one or more additives that affect either the density of the mixture or its setting time. The portland cement used may be high early strength common (standard), or slow setting. Additives include accelerators (such as calcium chloride), retarders (such as gypsum), weighting materials (such as barium sulfate), lightweight additives (such as bentonite), or a variety of lost circulation materials (such as mica flakes).