دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

PNV;the current time value of an income stream that extends into the future. Various calculation methods and interest rates have been applied.

n: a measuring instrument fitted with a device that automatically terminates the measurement when it reaches a value fixed in advance.

n: the force that a fluid (liquid or gas) exerts uniformly in all directions within a vessel, pipe, hole in the ground, and so forth, such as that exerted against the inner wall of a tank or that exerted on the bottom of the wellbore by a fluid. Pressure is expressed in terms of force exerted per unit of area, as pounds per square inch, or in kilopascals.

force per unit area exerted by a fluid.

n: a factor used in the formula recommended prior to August 1992 for the calculation of gas volume flow. The factor adjusted the volume to a standard atmospheric pressure regardless of the location.

the rate at which pressure builds up after a flow period. It is related to permeability, fluid viscosity, pressure differential, hole volume, zone thickness and time.

n: a logarithmic plot of bottornhole buildup pressure versus time. Pressure buildup plots are useful in analyzing formation test data for values used in calculating reservoir permeability, formation damage, radius or investigation during the formation test, reservoir depletion, and permeability barriers and other flow irregularities near the wellbore.

n: a device with sealed and lubricated bearings that is installed on the leg of a roller cone bit. Its function is to maintain equal pressure inside and outside the bits bearings in spite of the fact that the drilling mud in the hole can exert very high pressure outside the bit.

n: the part that fixed on the tooth palm of sesl bearing cone bit.

n: a loss of pressure that results from friction sustained by a fluid passing through a line, valve, fitting, or other device.

n: 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 col- umn of water is about 0.433 pounds per square inch per foot (9.794 kilopascals per metre) of vertical elevation. The normal pressure gradient in a formation is equiva- lent 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 permebe). 2. the change (along a horizontal distance) in atmospheric pressure. Isobars drawn on weather maps display the pressure gradient.

n: the variation of pressure with depth.commonly used under hydrostatic conditions(e.g. a hydrostatic column of salt water has a pressure gradient of 0.465 psi/ft).

change in pressure with depth.