Oil & Gas Glossary 1.0

A term used to define the quality of a clay by describing the number of barrels of a given centipoise slurry that can be made from a ton of clay. Based on the yield, clays are classified as bentonite, high yield, low yield, etc., types of clays. Not related to yield value below. See API RP 13B for procedures.

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

In drilling-fluid terminology, yield point means yield value (which see). Of the two terms, yield point is more common.

The yield value (commonly called "yield point") is the resistance to initial flow, or represents the stress required to start fluid movement. This resistance is due to electrical charges located on or near the surfaces of the particles. The values of the yield point and thixotropy, respectively, are measurements of the same fluid properties under dynamic and static states. The Bingham yield value, reported in lb/100 square feet, is determined by the direct-indicating viscometer by subtracting the plastic viscosity from the 300-rpm reading.

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.

A dilatant, or inverted plastic, fluid is usually made up of a high concentration of well-dispersed solids that exhibits a nonlinear consistency curve passing through the origin. The apparent viscosity increases instantaneously with increasing rate of share. The yield point, as determined by conventional calculations from the direct-indicating viscometer readings, is negative; however, the true yield point is zero.

A clay to which an agent has been added to increase its initial yield

In drilling-fluid terminology, a chemical is any material that produces changes in the viscosity, yield point, gel strength, fluid loss, and surface tension.

The lowest internal pressure at which a failure (of pipe) will take place.

The yield of an oil or gas well; the branch of the industry that brings the oil and gas to the surface for sale. The phase of the petroleum industry that deals with bringing the well fluids to the surface and separating them and with storing, gauging, and otherwise preparing the product for pipeline. The amount of oil or gas produced in a given period.

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.

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

The greatest longitudinal stress that a metal can bear without tearing apart. A metal's tensile strength is greater than its yield strength.

A substance formed when two or more substances polymerize at the same time to yield a produce which is not a mixture of separate polymers but a complex having properties different from either polymer alone. See polymer. Examples are polyvinyl acetate-maleic anhydride copolymer (day extender and selective and selective flocculant), acrylamide-carboxylic and copolymer (total flocculant).

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.

An immobile offshore structure from which development wells are drilled and produced. Platform rigs may be built of steel or concrete and may be either rigid or compliant. Rigid platform rigs, which rest on the seafloor, are the caisson-type platform, the concrete gravity platform, and the steel-jacket platform. Compliant platform rigs, which are used in deeper waters and yield to water and wind movements are the guyed-tower platform and the tension-leg platform.