دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: the viscosity of a drilling fluid as measured with a directindicating, or rotational, viscometer.

n: The viscosity a fluid appears to have on a given instrument at a stated rate of shear. It is a function of the plastic viscosity and the yield point. The apparent viscosity in centipoises, as determined by the direct-indicating viscometer, is equal to the

the viscosity at a given shear rate and a given temperature.

n: a process of molecular bridging of polymers with other chemical substances that alters viscosity and shear rates to enhance lifting of bit cuttings and increase drilling rates.

the shear stress measured at low shear rate after the mud has set for a period of time.

the consistency index, is the shear stress or viscosity of the fluid at one sec-1 shear rate. An increasing K raises the effective annular viscosity, increases hole cleaning capacity.

n: a fluid in which the viscosity remains constant for all rates of shear if constant conditions of temperature and pressure are maintained. Most drilling fluids behave as non-Newtonian fluids, as their viscosity is not constant but varies with the rate of shear.

n: the basic and wsimplest fluids from the standpoint of viscosity consideration in which the shear force is directly proportional to the shear rate. These fluids will immediately begine to move when a pressure or force in excess of zero is applied. examples

a fluid whose shear force and response is directly proportional to shear rate. Yield point is zero.

n: a complex, non-Newtonian fluid in which the shear force is not proportional to the shear rate. Most drilling muds are plastic fluids.

n: a complex, non-newtonian fluid in which the shear force is not proportional to the shear rate. A definite pressure is required to start and maintain movement of liquid. Plug flow is the initial type of flow and only occurs in plastic fluids. Most drilling

a complex, non-Newtonian fluid whose shear force is not proportional to the shear rate. Pressure is necessary to start circulation of the static fluid. Main low rate flow is plug flow. Yield point is greater than zero.

adj: having the capability of changing apparent viscosity with a change in shear rate. Pseudoplastic fluids gain viscosity when subjected to a decrease in shear rate, and lose viscosity when the shear rate is increased. See shear

n: this is the relative velocity of the fluid layers, divided by their normal separation distance. See also viscosity.

the rate of shearing of a fluid during a viscosity measurement. The rate of movement between plates.

n: the consistency of a slurry, measured in poise.

n: A property of fluids and slurries that indicates their resistance to flow, defined as the ratio of shear stress to shear rate.

n: The shear stress measured at low shear rate after a mud has set quiescently for a period of time ( 10 minutes in the standard API procedure, although measurements after 30 minutes or 16 hours may also be made).