| NACE |
abbreviation: National
Association of Corrosion Engineers. |
| nail pin |
a pin shaped like a carpenter's
nail and placed in a pressure relief valve. When the pin shears, it opens the valve
to relieve pressure inside a vessel. |
| National Association of Corrosion Engineers (NACE) |
an organization whose function is
to establish standards and recommended practices for the field of corrosion control. |
| natural
clays |
clays that are encountered when
drilling various formations; they may or may not be incorporated purposely into the mud
system. |
| natural gas |
A mixture of hydrocarbons and
varying quantities of nonhydrocarbons that exist either in the gaseous phase or in
solution with crude oil in natural underground reservoirs. |
| natural
gas liquids |
Those portions of reservoir gas
which are liquefied at the surface in field facilities or gas processing plants. |
| natural
gasoline |
the liquid hydrocarbons recovered
from wet natural gas, i.e., casinghead gasoline. |
| neat cement |
a cement with no additives other
than water. |
| necking |
the tendency of a metal bar or
pipe to taper to a reduced diameter at some point when subjected to excessive longitudinal
stress. See bottleneck. |
| needle
valve |
a globe valve that contains a
sharp, pointed, needle-like plug that is driven into and out of a cone-shaped seat to
control accurately a relatively small rate of fluid flow. In a fuel injector, the
fuel pressure forces the needle valve off its seat to allow injection. |
| neutral |
position of the rig's weight
indicator where hook load is zero. |
| neutralization |
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. |
| Newtonian
flow |
see Newtonian
fluid. |
| Newtonian
fluid |
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. |
| nipple |
a short, threaded tubular coupling
used for making connections between pipe joints and other tools. |
| nipple up |
in drilling, to assemble the
blowout preventer stack on the wellhead at the surface. |
| nitrogen |
an inert gas used for jetting
wells. |
| nitro
shooting |
a formation-stimulation process
first used about a hundred years ago in Pennsylvania. Nitroglycerine is placed in a
well and exploded to fracture the rock. Sand and gravel or cement is usually placed
above the explosive charge to improve the efficiency of the shot. Nitro shooting has
been largely replaced by formation fracturing. |
| no-go |
a gauge run downhole to verify
dimensions. |
| no-go
nipple |
a special nipple made up in the
tubing, casing, or drill pipe string the configuration of which is such that a tool
contacting it can pass through only if the tool is in the proper position or
configuration. |
| nomograph |
a chart that presents an equation
containing a number of variables in the form of several straight lines. The straight
lines are scaled with values of the variables. To use it, a straight edge is placed
across the scaled lines at the appropriate values. A nomograph can be easier to use
than solving the equation. |
| non-associated
gas |
Natural gas which is in reservoirs
that do not contain significant quantities of crude oil. |
| nonconductive
mud |
any drilling fluid, usually
oil-base or invert-emulsion muds, the continuous phase of which does not conduct
electricity, e.g., oil. |
| nonlocator |
term to describe the passage entry
of seal assemblies into a packer seal bore not locking into place. |
| normal
butane |
in commercial transactions, a
product meeting GPA specification for commercial butane and, in addition, containing a
minimum of 95 liquid volume percent normal butane. Chemically, normal butane is an
aliphatic compound of the paraffin series. |
| normal
circulation |
the smooth, uninterrupted
circulation of drilling fluid down the drill stem, out the bit, up the annular space
between the pipe and the hole, and back to the surface. Compare reverse circulation. |
| normal formation pressure |
formation fluid pressure
equivalent to about 0.465 pounds per square foot of depth from the surface. If the
formation pressure is 4,650 pounds per square inch at 10,000 feet, it is considered
normal. |
| normal
pressure gradient |
the normal pressure divided by
true vertical depth. |
| normal
solution |
a solution that contains 1
gram-equivalent of a substance per liter of solution. |
| nozzle |
1. a passageway through jet bits
that causes the drilling fluid to be ejected from the bit at high velocity. The jet of mud
clears the bottom of the hole. Nozzles come in different sizes that can be
interchanged on the bit to adjust the velocity with which the mud exits the bit. 2. the part of the fuel system of an engine that has small holes in
it to permit fuel to enter the cylinder. Properly known as a fuel-injection nozzle,
but also called a spray valve. The needle valve is directly above the nozzle. |
