Installing the well casing is a vital a
part of the drilling and completion method. Well casing consists of a
series of metal tubes put in within the freshly trained hole. Casing
serves to strengthen the perimeters of the well hole, make sure that
no oil or fossil fuel seeps out because it is dropped at the surface,
and keep different fluids or gases from oozy into the formation
through the well. The designing is important to confirm that the
correct casing for every well is put in. Types of casing used rely on
underground characteristics of the well, as well as the diameter of
the well that again depends on the dimensions of the drilling bit
used and also the pressures and temperatures fully fledged. In most
wells, the diameter of the well hole decreases the deeper it's
trained, resulting in a cone like shape that has to be taken under
consideration once putting in casing.
There are 5 differing types of well
casing. Conductor casing is a method in which casing is done before
the actual drilling to prevent from caving in and to assist in
bringing the lubricator up from the lowest of the well. • Surface
casing is that the next sort of casing to be put in. It is anyplace
from a hundred to four hundred meters long, and is smaller in
diameter to suit within the conductor casing. Its primary purpose is
to shield H2O deposits close to the surface of the well from
contamination by leaky hydrocarbons or salt water from deeper
underground. It additionally is a passage for lubricator returning to
the surface and helps defend the excavation from harm throughout
drilling. • Intermediate casing is sometimes the longest section of
casing found during a well. Its primary purpose is to reduce the
hazards related to underground formations that will have an effect on
the well. These embrace abnormal underground pressure zones,
underground shales and formations which may otherwise contaminate the
well, like underground salt water deposits. Liner strings are
generally used rather than intermediate casing. Liner strings are
sometimes simply hooked up to the previous casing with “hangers”
rather than being cemented into place, and area unit therefore less
permanent. Production casing, as an alternative known as the “oil
string” or '”long string,” is put in last and is that the
deepest section of casing during a well. This casing gives a passage
from the surface of the well to the petroleum-producing formation.
the dimensions of the assembly casing depends on variety of concerns,
as well as the lifting instrumentality to be used, the amount of
completions needed, and also the risk of deepening the well at a
later date. for instance, if it's expected that the well are going to
be concentrated later, then the assembly casing should be wide enough
to permit the passage of a drilling bit shortly. it's additionally
instrumental in preventing blow-outs, permitting the formation to be
“sealed” from the highest ought to dangerous pressure levels be
reached. Once the casing is put in, conduit is inserted within the
casing, from the gap well at the highest to the formation at the
lowest. The hydrocarbons that area unit extracted run up this conduit
to the surface. The assembly casing is often five to twenty-eight cm
(2 -11 in) with most production wells being half-dozen inches or
additional. Production depends on reservoir, bore, pressure, etc.,
and will be but a hundred barrels per day to many thousand barrels
per day. A packer is employed between casing and conduit at the
lowest of the well. oil and gas courses in kerala
