Oil & Gas Glossary 1.0

Hydrogen sulfide

Oil containing little or no sulfur, especially little or no hydrogen sulfide.

Oil containing hydrogen sulfide or another acid gas.

A wellbore or formation known to contain hydrogen sulfide gas.

Gas containing an appreciable quantity of hydrogen sulfide and/or mercaptans.

A flammable, colorless gaseous compound of hydrogen and sulfur (H2S) , which in small amounts has the odor of rotten eggs. Sometimes found in petroleum, it causes the foul smell of petroleum fractions. In dangerous concentrations, it is extremely corrosive and poisonous, causing damage to skin, eyes, breathing passages, and lungs and attacking and paralyzing the nervous system, particularly that part controlling the lungs and heart. In large amounts, it deadens the sense of smell. Also called hepatic gas of sulfureted hydrogen.

2. an indicator of wind direction used during drilling or workover operations where hydrogen sulfide (sour) gas may be encountered.

Embrittlement and subsequent wearing away of metal caused by contact of the metal with hydrogen sulfide.

Containing or caused by hydrogen sulfide or another acid gas (e.g., sour crude, sour gas, sour corrosion).

Lead sulfide (PbS). Technical grades (specific gravity about 7) are used for increasing the density of drilling fluids to points impractical or impossible with barite.

A measure of the acidity or alkalinity of a solution expressed as pH. See pH.

A reaction in which the hydrogen ion of an acid and the hydroxyl ion of a base unite to form water, the other ionic product being salt.

Any substance or combination of substances that, when dissolved in water, produces a solution that resists a change in its hydrogen ion concentration on the addition of acid or base.

An acid compound, HCI, commonly used to acidize carbonate rocks. It is prepared by mixing hydrogen chloride gas in water. Also known as muriatic acid.

Abbreviation: an indicator of the acidity or alkalinity of a substance of solution, represented on a scale of 0-14, 0-6.9 being acidic, 7 being neither acidic or basic (i.e., neutral), and 7.1-14 being basic. These values are based on hydrogen ion content and activity.

A substance occurring naturally in the earth and composed mainly of mixtures of chemical compounds of carbon and hydrogen, with or without other nonmetallic elements such as sulfur, oxygen, and nitrogen. The compounds that compose it may be in the gaseous, liquid, or solid state, depending on their nature and on the existent conditions of temperature and pressure.

2. substances in acid-base that, in solution, change color or become colorless as the hydrogen ion concentration reaches a definite value, these values varying with the indicator. In other titrations, such as chloride, hardness, and other determinations, these substances change color at the end of the reaction. Common indicators are phenolphthalein, and potassium chromate.

The sum of the atomic weights in a molecule. For example, the molecular weight of water is 18, because the atomic weight of each of the hydrogen molecules is 1 and the atomic weight of oxygen is 16. See mole

An explanation of the origin of petroleum, which holds that the hydrogen and the carbon that make up petroleum come from plants and animals of land and sea. Furthermore, the theory holds that more of this organic material comes from very tiny creatures of swamp and sea than comes from larger creatures of land.

Organic compounds of hydrogen and carbon, whose densities, boiling points, and freezing points increase as their molecular weights increase. Although composed of only two elements. hydrocarbons exist in a variety of compounds because of the strong affinity of the carbon atom for other atoms and for itself. The smallest molecules of hydrocarbons are gaseous; the largest are solids. Petroleum is a mixture of many different hydrocarbons.

1. the ratio of the weight of a given volume of a substance at a given temperature to the weight of an equal volume of a standard substance at the same temperature. For example, if 1 cubic inch of water at 39 degrees F weighs 1 unit and 1 cubic inch of another solid or liquid at 39 degrees F weight 0.95 unit, then the relative density of the substance is 0.95. In determining the relative density of gases, the comparison is made with the standard of air or hydrogen.