Note: Descriptions are shown in the official language in which they were submitted.
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Ihis invention relates to improvements in well bore drilling method
and means and more particularly, but not by way of limitation, to a well bore
drilling method and means whereby oxygen content of well drilling muds is re-
placed by nitrogenJ exhaust gases, or gaseous mixtures of combustible products
for reduction of corrosion.
In the drilling of an oil or gas wellJ the drilling operation nor-
mally comprises the piercing of the earth by means of a drill bit carried at
the lower end of a string of drill pipe. The drill bit penetrates the earth
to create the well boreJ and the drill string is continually lengthened
during the drilling process as the bit cuts or drills deeper into the earth. ~ -
One drilling method in widespread use today utili~es a drilling
fluid for facilitating the drilling operation performed by the drill bit. The
drilling fluid is usually circulated downwardly through the drill pipe to the
drill bit for flushing or washing away cuttings and other debris from the
bottom of the well bore which might hinder the operation of the bit. The ~ ;
drilling ~luid and cuttings and/or particles are then pumped upwardly in the
well bore through the annulus between the outer periphery of the drill pipe
and the walls of the well bore and to the surface of the earth where the
drilling fluid is directed into the mud pits normally provided in the proximi-
2Q ty of the well bore for storage of the fluid in order that the fluid may be
reused. The mud pits are normally open storage pits, and the fluid retained
therein is frequently contaminated by the oxygen presen~ in the atmosphere
adjacent the exposed upper surface of the stored mud. In addition, oxygen
may contaminate ~he drilling fluids during mixing thereof and during removal
of cuttings and the like from the circulated fluid. Of course, oxygen in the `
drilling fluid is a great disadvantage in that the circulation of the ~luid ~ ~ `
in the well bore brings the drilling fluid into intimate contact with sub-
stantially the entire inner and outer peripheries of the drill pipe as well
as the drill bit, and the oxygen in the drilling fluid causes corrosion of
any metallic equipment with which it is in contact. Because of the current
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use of polymer-type drilling fluid utilizing the salts of sodium and potassium,
the problem of corrosion is greatly increased in the presence of oxygen,
making it more necessary than ever to reduce or eliminate the oxygen con~ent
of the drilling fluid.
Various chemicals are frequently used to react with and remove the
dissolved or entrained oxygen in the drilling fluid and are somewhat effective
in the alle~iation of the corrosive condition that occurs, especially on the
inner periphery of the drill pipe. However, any oxygen contained in the
drilling fluid is a disadvantage and any corrosion of the drill pipe is ex-
tremely disadvantageous, particularly in the light of the present-day costs
and scarcity of materials.
There is also increasing demand for delivery of coal and the like
through pipelines, and movement of materials in this manner requires a slurry
in combination with the materials for passing thereof through the pipeline. ;~ ;
Water is normally used in the slurry and the oxygen content of the slurry
increases the corrosion problem of the inner periphery of the pipe.
The present invention provides a method for drilling a well bore
using drilling fluid and which comprises the displacement of substantially
all of the oxygen in the drilling fluid with a suitable inert gas for reduction
2Q of corrosion in the drilling operation, and providing an atmosphere of the -
inert gas adjacent substantially any exposed surface of said drilling fluid -
for reducing contamination of the drilling fluid from the oxygen content of ;
the ambient air. The gas may be injected into the fluid in any suitable
manner, such as, injected into the fluid at a suitably vented station upstream
of the pump suction, sucll as a vented tank, degasifier, or other vessel, and
may be utilized not only Eor the removal of oxygen, but also to reduce or
possibly eliminate the use of other chemicals in connection with the drilling
fluids. Another method or embodiment of the invention is to inject the gas
directly into the mud pits.
Nitrogen is perhaps the preferable gas to inject into the drilling
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fluids in that it is plentiful and readily available. The present method con-
templates utilizing the nitrogen from the exhaust gases of the normal equip-
ment, such as engines and the like, gaseous mixtures obtained by combustion or
the like, present at the well drilling site, and injecting the exhaust gases
of the like into the drilling fluids through a degasser interposed between the
exhaust system of the engines and the suction side of the drilling mud pump-
ing equipment. The exhaust gases of engines using either natural gas or
diesel fuel is substantially eighty-seven percent nitrogen, and thus it will
be apparent that substantially all types of exhaust gases are usable with the
present invention. Of course, nitrogen gas or the like, in and of itself, may
be utilized in the practice of this invention. In addition, the exhaust gases
may be directly injected from an engine or a combustion chamber into the mud
pits.
It is expected that perhaps 1,000 to 5,000 cubic feet of nitrogen
will be used per hour during a typical well drilling operation in the prac-
tice of the present invention; and as heretofore set forth, since nearly all
of the exhaust gases are useable as nitrogen, a plentiful supply of normally
waste product is usually available at each well site. The exhaust gas is
preferably directed from the exhaust manifold of the engine into a filter ;
section of a degasser, or the like, but not limited thereto. The exhaust gas
passies downwardly through the ~ilter section and into a passageway for dis-
charge into a liquid bath, where the exhaust gas "bubbles upwardly" through
the liquid for withdrawal from the degasser through a riser connected with
the suction side of a suitable compressor. Debris of foreign particles pre-
sent in the exhaust gas are removed through this process, and substantially
clean exhaust gas is directed from the compressor through a suitable flow
meter for injection into the drilling fluid.
The nitrogen present in the exhaust gas is introduced into the
drilling fluid by injection of the nitrogen into the reservoir of the drilling
fluid, through suitable perforated pipes and the like disposed within the
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reservoir and surrounded by the drilling mud. In addition, a nitrogen atmos-
phere is created adjacent the exposed upper surface o the drilling mud
during the circulation process of the drilling mud in order to reduce or sub-
stantially eliminate contamination of the drllling fluid by exposure to the
ambient air. The nitrogen injected into the drilling fluid replaces the oxy-
gen in the drilling fluid, and not only is the oxygen content of the drilling
fluid substantially eliminated or reduced to minute quantities, as for example
1/2 part per million or less, or substantially elimina~ing corrosion of the
drill yipe and other metallic elements used in the drilling operation, but
also gases which are normally wasted are recovered for use, and the venting
of engine exhaust gases into the atmosphere is greatly reduced for reducing
environmental hazards. It is also considered that the nitrogen injected into
the drilling fluid may reduce the catalytic efect the oxygen would have on
hydrogen sulfide which may be present in the drilling fluid, thus further
reducing any corrosive action.
The same principle o replacing oxygen in 1uids by nitrogen for
reduction of corrosion may be applied to the slurry used in pipelines wherein
coal or the like is being transported therethrough.
As an example of the practice of the invention in combination with
substantially any combusti~n chamber producing suitable exhaust gases, it is ;
anticipated that the exhaust gases rom the combustion chamber may be directed
through a suitable heater for assuring a suficiently high temperature or
the gases~ From the heater, the gases may be directed through a suitable
catalytic converter and into a water bath or scrubber for cleaning of the gas
stream, and incidentally reducing the oxygen content of the water in the bath ~
I~ desired, the gas stream may be directed through a ilter prior to passage -
through the water bath in order to remove carbon dioxide, carbon monoxide,
hydrocarbons and the like, from the gas stream. The cleaned gas from the
water bath or scrubber may then be utilized as an additive to the steam in-
jection fluids or may be directed into the drilling 1uids as hereinbefore
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set forth.
In the accompanying drawings:-
Figure 1 is a sectional elevational view of a gas processing unitsuch as may be used in the invention.
Figure 2 is a broken elevational view of a modified embodiment of a
portion of the unit depicted in Figure 1.
Figure 3 is a schematic plan view of a typical arrangement of equip-
ment at an oil or gas well drilling site and illustrates a method of exhaust
gas injection into the drilling fluid which embodies the invention.
Figure 4 is an enlarged plan view of a portion of the equipment and
method shown in Figure 3.
Figure 5 is a schematic elevational view of the portion of the method
and means shown in Figure 4.
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Referrin~ to the drawings in detail and particularly Figure 1, re-
ference character 10 generally indicates a gas processing unit comprising a
first housing 12 having the upper end thereo~ closed by a suitable plate
member 14 and the lower end thereof closed by a suitable bottom 15. A second
housing 16 is secured to the housing 12 above the plate 14 in any suitable
manner, such as by bolts 17, thereby providing chambers 18 and 20 on opposite
sides of the plate 14. The plate 14 is provided with a central aperture 22
having a standpipe 24 extending therethrough. The closed upper end of the
pipe 24 extends into the chamber 18 and is provided with a plurality
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of spaced apertures 26 which provide communication between
the interior of the pipe 24 and the chamber 18. The lower ~
end of the pipe 24 terminates in the proximity of the lower ~, -
portion of the chamber 20, and a transversely extending pipe ~
28 is suitably secured to the lower end of the pipe 24 as ~ ~ `
shown in FIGURE 1. The pipe 28 is provided with a plurality
of spaced apertures 30 providing communication between the
interior of the pipe 28 and the chamber 20.
A first discharge port 32 is provided in the lower portion
of the housing 12 and is preferably in communication with a
suitable pump (not shown) for a purpose as will be hereinafter
set forth. An inlet port 34 is provided in the housinq 12
spaced upwardly from the port 32 and preferably extends into
communication with a liquid reservoir (not shown) for admitting
liquid 35 into the chamber 20. A suitable float valve 36 is
preferably interposed in the inlet 34 and extends into the
chamber 20 for control of the level 37 of the liquid 35 in
a manner and for a purpose as will be hereinafter set forth.
A second discharge port 38 is provided in the upper portion of
the housing 12 spaced above the inlet port 34 and is in
communication with the suction side of a suitable compressor
40 through a conduit 42. The discharge side of the compressor
40 is in communication with a conduit 41 preferably having a
float meter 43 interposed therein for discharging gas from the
compressor. A plurality of angularly disposed longitudinally
spaced baffles 44 are carried by the pipe 24 and disposed in
the upper portion of the chamber 20 above the level 37 for a
purpose as will be hereinafter set forth.
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The upper end of the housing 16 is closed by a suitable
cover 44 which is provided with a centrally disposed aperture
46 providing access to the chamber 18. Suitable conduit means :
48 extends from the aperture 46 to the usual exhaust muffler
50 of a suitable engine (not shown) for directing the exhaust
gases from the muffler 50 into the chamber 18. A baffle or -
spreader plate 52 is preferably secured within the chamber 18
in any suitable manner (not shown) and is spaced slightly
downwardly from the aperture 46 for initially receiving the
exhaust gases thereagainst for a purpose as will be hereinafter .
set forth. The chamber 18 is preferably filled with a suitable
filter material 54, such as steel wool, or the like.
When the compressor 40 is activated in the usual manner, a
suction is created through the apertures 10 and in the conduit
48 whereby the exhaust gases moving from the exhaust muffler
50 in the direction of the arrows 56 will be drawn into the
pipe or conduit 48. The exhaust gases are discharged into the
chamber 18 through the port 46 whereby they initially impinge
upon the baffle or spreader plate 52. The gases are thus
discharged into substantially the entire cross-sectional area of ~ -
the chamber 18 and move radially and longitudinally through ;.
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the filter material 54 and through the perforations 26 into the ~ :
interior of the pipe 24. The filtered gases then move downwardly
through the pipe 24 and into the perforated pipe 20 and outwardly i.
through the perforations 30 for discharge into the liquid 35 ;~
contained within the chamber 20. The liquid 35 is preferably ::
water, but not limited thereto; and since the filtered gases
are of lighter weight than the water 35, the filtered gases
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bubble upwardly through the water 38 as indicated at 58, and
accumulate in the upper portion of the chamber 20 above the
level 37 of the liquid 35.
The filter material 54 and liquid 35 remove substantially
all of the debris or foreign particles which may be contained
in the exhaust gas. However, the baffles 44 agitate the flow
of the gases moving from the liquid bath 35 toward the discharge
port 38 in the chamber 20 and "knocks out" any water particles,
or any other particles which might remain in the gaseous stream.
Thus, substantially cIean exhaust gases are drawn upwardly through
the conduit 42 in the direction indicated by the arrow 58
for passing through the compressor 40. As hereinbefore set
forth, substantially eighty seven percent of the exhaust gas
is nitrogen, and the remaining components of the gaseous stream
are readily absorbed or precipitated out of the drilling mud
through the normal reaction therebetween.
The float valve functions in the usual or well-known manner
in response to fluctuations of the position of the water level ~`
37 in the chamber 20 for maintaining the level 37 at the désired
position. The discharge port 32 may be utilized in the usual
or well-known manner for discharge or draining of the water 35
from the chamber 20 as desired or necessary. ~`
The exhaust gases being emitted from the muffler 50 are
normally at a relatively high temperature. However, if it
may be desirable to increase the heat of the exhaust gases, a
suitable heater 60 may be provided for the conduit 48 and
disposed between the muffler 50 and the inlet port 46~ The
heater 60 is preferably an electric heater, but not limited
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thereto, and may be utilized as required for supplying heat
to the gases moving through the conduit 48.
Referring now to FIGURES 3, 4 and 5, a typical installation
at the drilling site of a well bore 62 is illustrated which
comprises a reserve pit 64 disposed in the proximity of the - ~
well bore 64 for storage of a quantity of drilling fluid (not ~-
shown) to be used during the well drilling operation. A -
plurality of mud pits, such as shown at 66, 68, 70, and 72 are
provided in the general area of the reserve pit 64, for
10 receiving and storing quantities of the drilling mud or fluid
during the drilling operation, all of which is well-known in
the industry. Normally, the pits 66 and 68 are in communication
through suitable by-pass conduits (not shown), and the pits 68
and 70 are similarly in col~ununication through suitable by-pass
conduits (not shown), as are the pits 70 and 72. Thus,
substantially any necessary quantity of drilling mud is readily
available at all times during the drilling operations for
meeting all drilling requirements. Suitable mud pumps 74 and 76
are provided in communication with the mud pit 72 for directing
20 the mud or drilling fluids therefrom into the drill pipe for
circulation downwa~dly therethrough to the bottom of the well ;~-
bore. A mud house 78 is provided in the vicinity of the well
bore 62 for storing the sack of dry chemicals from which the
drilling mud is made, and a hopper or the like (not shown) is
preferably provided for directing preselected quantities of
the dry ingredients to the mud pits for mixing with suitable
liquids to produce the desired drilling mud product, as is
well known. A suitable substructure 80 is also provided in
the proximity of the well bore 62 for supporting the usual
operating equipment necessary for the performance of the
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drilling operation. In addition, a power plate 82, boiler
house 84, heater 86, fuel storage tank 88, and water tank 90
are provided at the well bore site. A sludge tank 92 and
pumps 92 and 94 are provided in the proximity of the mud pit
72, and a pump 96 is provided in the proximity of the reserve
pits 64 and 70. A suitable shaker 96 is disposed above the
mud pit 66 and in communication therewith through a conduit or
pipe 97. A suitable degasser unit is disposed above the pits
68 and 70 and is in communication with each through conduits
100 and 102.
During the well bore drilling operation, the proper quantity
and quality drilling fluid is pumped downwardly through the
center of the drill pipe (not shown) by directing the fluid
through suitable flexible tubing tnot shown) wh.ich extends over
the pulley (not shown) of the drilling rig (not shown~. The
drilling fluid is pumped downwardly through the drill pipe to i
the bottom of the well bore 62 and is returned or recirculated
upwardly through the annulus between the outer periphery of
the drill pipe and the wall of the well bore. The returning
drilling fluid or drilling mud contains debris washed from ~ ~
the bottom of the well, and is normally contaminated with gas ~ -
absorbed or "picked up" by the drilling mud during the
recirculating operation. The returning drilling fluid is directed
from the annulus of the well bore 6~ to the shaker 96 through ;
suitable piping, as indicated at 104 in FIGURE 3. The shaker 96
normally includes screens 106 (FIGURE 4), and the agitation
of the drilling mud by the shaker 96 causes cuttings, debris, or
other foreign particles to fall out of the drilling mud onto
the screens by gravity, thus partially cleaning the drilling
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mud. The mud leaves the shaker 96 through the conduit 97
and falls by gravity into the pit 66. In the event the mud in
pit 66 is considered to be in condition for reuse, it may be
recirculated downw~rdly through the drill string as required.
However, in most instances, the drilling mud is passed from
the pit 66 into the pit 68 by the usual hy-pass line or pipe
(not shown), and is drawn into the degasser unit 98 by the
suction of the normal compressor or pump (not shown) provided
in combination therewith. The mud passes through the degasser
98 where the fluid is properly treated for removal of ~ ~
substantially any entrained gases "picked up" during the
recirculation of the fluid through the well bore 62, and
the degassed fluid is deposited in the pit 70, from where it
may be passed to the pit 72 by the usual by-pass line (not
shown), and from where the mud may be returned to the drill
string for additional use, all of which is well ~nown in the
art.
In the practice of the present invention, the nitrogen
c3enerator or nitrogen source 10 is suitably connected with
the mud pits 66, 68, 70, and 72 through suitable conduits or
piping system generally indicated at 108 in FIGURES 3, 4 and
5, and which is in communication with the conduit 41 for
receiving the exhaust gases therefrom. The piping system 108
is connected with suitable perforated pipes 110 by suitable
branch lines 112. The perforated pipes 110 are disposed
within the mud pits and preferably in the lower portion thereof,
whereby the pipes 110 will be surrounded by the drilling mud.
In addition, suitable perforated pipes 114, as shown in FIGURES
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4 and 5, are in communication with the piping system 108 and
are disposed below the screens 106 of the shaker 96 for
providing a nitrogen atmosphere in the shaker in order to
insulate the mud therein from the ambient air in order to reduce
contact of the drilling mud with the oxygen in the ambient air.
The exhaust gases leaving the apparatus 10 through the
conduit ~1 are directed to the plurality of perforated pipes
110 and 114, whereby the nitrogen content of the exhaust gases ~ ~;
is injected directly into the mud contained in the pits 66,
68, 70 and 72. At the same time, of course, the nitrogen
atmosphere is created below the screens 106 of the shaker. The
nitrogen contained in the exhaust gases replaces the oxygen
in the drilling mud and forces the oxygen upwardly through the
mud ~or escape through the exposed upper surface thereof. In
addition, any excess quantity of nitrogen injected into the
mud will bubble upwardly through the mud for discharge at the
exposed upper surface thereof; and it has been found that
the escaping nitrogen accumulates over t:he entire exposed
sur~ace of the drilling mud, forming a protection layer of
nitrogen between the exposed drilling mud and the ambient air.
Thus, contamination of the drillin~ bit by contact with the
oxygen in the air is substantially eliminated.
Testing procedures using the method of the invention
indicate that the nitrogen injected into the drilling mud ;~
may act as a dispersent, at least it appears to offer a
slight dispersing action. This may be due to the removal of
the entrained air or oxygen. Of course, it is to be understood
that substantially any suitable gases may be utilized in ~-
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the practice of the present invention with substantially
the same results. However, the use of nitrogen present in
the exhaust gases of equipment normally present at a wel] ~
bore drilling site offers other advantages; namely, the ~;
red~ction of contaminates discharged into the atmosphere. -
As hereinbefore set forth, it has also been found that `
hydrogen sulfide appears to be driven off or removed from
the drilling fluid along with the oxygen, thereby removing
another possible source of corrosion of down-hole drilling ~`
equipment.
Experiments have been conducted wherein the injection of
nitrogen into the drilling fluids during the drilling of a
well bore have been documented. In the drilling of one
par-ticular well bore, the injection of nitrogen was initiated ~
for testing purposes subsequent to some drilling under "normal" ~-`
or "standard" mud drilling operation, and the results indicated
a remarkable drop in oxygen content in t:he drilling fluids,
along with a corresponding drop in the corrosion rate. For
example, the oxygen content of the drilling mud dropped from
approximately 5 and 6 parts per million to approximately 0.5
to 1.7 parts per million upon the injection of the nitrogen
into the drilling muds.- Subsequent testing programs have
produced equally remarkable results.
From the foregoing, it will be apparent that the present
invention provides a novel method and means for drilling oil ~ ~
and/or gas well bores wherein corrosion of the drilling ~`
equipment is greatly reduced. A suitable gas is injected
into the normal drilling fluids for replacing substantially all
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of the oxygen content of the drilling fluids, thus substantially eliminating
or greatly reducing corrosion resulting from the drilling fluid contact with
the drill pipe, drill bit, or other metallic "down hole" tools or equipment. `
It is a particular advantage to use nitrogen as the gas in the practice of
the invention since a plentiful supply of nitrogen is usually readily available
at ~he well drilling site in that content of the exhaust gases of the engines,
and the like, utilized during the well drilling operation is largely nitrogen, ~ -
and these exhaust gases may be "cleaned" for injection into the drilling muds
for injection of the nitrogen into the muds for replacement of the entrained
oxygen. The novel method and means not only reduces corrosion but also uti~
lizes gases which are normally waste products, and utilizes these gases in a ~;
manner for reducing contamination of the atmosphere, thus improving the
natural environment surrounding the drilling site. The novel method and means -~ `
is simple and efficient in operation and economical and durable in construc-
tion.
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