|
Oil well
drilling utilizes three-cone roller, fixed-cutter
diamond, or diamond-impregnated drill bits to wear away
at the cutting face. This is preferred because there is
no need to return intact samples to surface for assay as
the objective is to strike a formation containing oil or
natural gas. Sizable machinery is used, enabling depths
of several kilometers to be penetrated. Rotating hollow
drill pipes carry down bentonite and barite impregnated
drilling muds to lubricate, cool, and clean the drilling
bit. The mud travels to the surface around the outside
of the drilling rods. Examining rock chips extracted
from the mud is known as mud logging. Another form of
well logging is electronic and is frequently employed to
evaluate the existence of possible oil and gas deposits
in the well hole. This can take place while the well is
being drilled, using Measurement While Drilling tools,
or after drilling, by lowering measurement tools into
the newly-drilled hole.
The rotary system of drilling was in general use in
Texas in the early 1900s. It is a modification of one
invented by Fauvelle in 1845, and used in the early
years of the oil industry in some of the oil-producing
countries in Europe. Originally pressurized water was
used instead of mud, and was almost useless in hard rock
before the diamond cutting bit.
The drilling and production of oil and gas pose a safety
risk and a hazard to the environment from the ignition
of the entrained gas causing dangerous fires and also
from the risk of oil leakage polluting water, land and
groundwater. For these reasons, redundant safety systems
and highly trained personnel are required by law in all
countries with significant production. |
