Oil & Gas Glossary 1.0

An instrument for measuring the resistivity of drilling fluids and their cakes.

2. a mud with a resistivity less than or equal to the formation water resistivity.

One-millionth of a meter, a metric unit of measure of length equal to 0.001 meter.

2. an observed change, usually uncontrolled, in meter performance, meter factor, etc., that occurs over a period of time.

The electrical resistance offered to the passage of current; the opposite of conductivity.

A mechanical fluid-measuring device that measures by filling and emptying chambers of a specific volume. The displacement of a fixed volume of fluid may be accomplished by the action of reciprocating or oscillating pistons, rotating vanes or buckets, rotating disks, or tanks or other vessels that automatically fill and empty. Also called a volume meter or volumeter.

A well-servicing unit whose mast consists of two steel tubes. Double-pole masts provide racking platforms for handling rods and tubing in stands and extend from 65 to 67 feet (20 meters) so that rods can be suspended as 50-foot (15 meter) doubles and tubing set back as 30-foot (9-meter) singles. See pole mast.

A record of certain electrical characteristics (such as resistivity and conductivity) of formations traversed by the borehole. It is made to identify the formations, determine the nature and amount of fluids they contain, and estimate their depth.

1. a scale of pressure differences in which there is a uniform variation of pressure from point to point. For example, the pressure gradient of a column of water is about 0.433 pounds per square inch per foot (9.794 kilopascals per meter) of vertical elevation. The normal pressure gradient in a formation is equivalent to the pressure exerted at any given depth by a column of 10 percent salt water extending from that depth to the surface 0.465 pounds per square inch per foot or 10.518 kilopascals per meter).

See direct-indicating viscometer, vibrating screen; see shale shaker.

An instrument to measure the amount of voltage needed to break down invert emulsions.

A measure of the speed at which the bit drills into formations, usually expressed in feet (meters) per hour or minutes per foot (meter).

A chart made by a recording meter which shows rate of production.

A unit of length equal to one millionth part of a meter, or one thousandth part of a millimeter.

The amount of moisture present in the air, usually expressed in grains of water per 100 cubic feet of air (milligrams of water per cubic meter of air).

1. a measure of volume for petroleum products in the United States. One barrel is the equivalent of 42 U.S. gallons or 0.15899 cubic meters (9,702 cubic inches). One cubic meter equals 6.2897 barrels.

Commonly called a "V-G meter." A rotational device powered by means of an electric motor or handcrank. Used to determine the apparent viscosity, plastic viscosity, yield point, and gel strengths of drilling fluids. See direct-reading viscometer

A measure of the density of a drilling fluid expressed as pounds per gallon, pounds per cubic foot, or kilograms per cubic meter. Mud weight is directly related to the amount of pressure the column of drilling mud exerts at the bottom of the hole.

The mass or weight of a substance per unit volume. For instance, the density of a drilling mud may be 10 pounds per gallon (ppg), 74.8 pounds per cubic foot (lb/ft), or 1,198.2 kilograms per cubic meter (kg/m3). Specific gravity, relative density, and API gravity are other units of density.

Commonly called a "V-G meter." The instrument is a rotational-type device powered by means of an electric motor or handcrank, and is used to determine the apparent viscosity, plastic viscosity, yield point, and gel strengths (all of which see) of drilling fluids. The usual speeds are 600 and 300 revolutions per minute. See API RP13B for operational procedures. Also see direct-indicating viscometer.

Pressure exceeding or falling below the normal pressure to be expected at a given depth. Normal pressure increases approximately 0.465 psi per foot of depth (10.5kPa per meter of depth). Thus, normal pressure at 10,000 feet is 4,650 psi; abnormal pressure at this depth would be higher or lower than 4,650 psi. See pressure gradient.

The force exerted by a body of fluid at rest. It increases directly with the density and the depth of the fluid and is expressed in pounds per square inch or kilopascals. The hydrostatic pressure of fresh water is 0.433 pounds per square inch per foot of depth (9.792 kilopascals per meter). In drilling, the term refers to the pressure exerted by the drilling fluid in the wellbore. In a water drive field, the term refers to the pressure that may furnish the primary energy for production.