U.S. patent application number 11/283335 was filed with the patent office on 2007-05-24 for anti-oxidizing process for non-cryogenic nitrogen.
Invention is credited to Danny Kent Daniels, Vernon Dale Daniels.
Application Number | 20070114024 11/283335 |
Document ID | / |
Family ID | 38052348 |
Filed Date | 2007-05-24 |
United States Patent
Application |
20070114024 |
Kind Code |
A1 |
Daniels; Vernon Dale ; et
al. |
May 24, 2007 |
Anti-oxidizing process for non-cryogenic nitrogen
Abstract
Downhole equipment oxidation and injection well plugging
consequential of non-cryogenic nitrogen utilities is prevented or
alleviated by injecting a residual oxygen scavenging compound such
as ammonium bisulfite into the predominately nitrogen and residual
oxygen flow stream emerging from a non-cryogenic nitrogen
concentration process.
Inventors: |
Daniels; Vernon Dale;
(Tishomingo, OK) ; Daniels; Danny Kent;
(Tishomingo, OK) |
Correspondence
Address: |
W. ALLEN MARCONTELL
P.O. BOX 800149
HOUSTON
TX
77280-0149
US
|
Family ID: |
38052348 |
Appl. No.: |
11/283335 |
Filed: |
November 18, 2005 |
Current U.S.
Class: |
166/267 ;
166/305.1 |
Current CPC
Class: |
E21B 43/40 20130101;
E21B 41/02 20130101; C09K 8/54 20130101 |
Class at
Publication: |
166/267 ;
166/305.1 |
International
Class: |
E21B 43/25 20060101
E21B043/25; E21B 43/34 20060101 E21B043/34 |
Claims
1. A conditioning process for a subterranean well utility gas
containing free oxygen, said process comprising the step of mixing
an oxygen scavenging compound with said utility gas prior to well
injection.
2. A well utility gas conditioning process as described by claim 1
wherein said oxygen scavenging compound is selected from the group
comprising ammonium bisulfite.
3. A well utility gas conditioning process as described by claim 1
wherein said oxygen scavenging compound is selected from the group
comprising ammonium bisulfite solution, ammonium hydrogen sulfite
solution, ammonium acid sulfite solution, monoammonium sulfite
solution and sulfurous acid monoammonium salt solution.
4. A process for extracting fluid from a subterranean well
comprising the steps of: a. generating a flow stream of
non-cryogenic nitrogen containing residual quantities of oxygen. b.
mixing an oxygen scavenger compound with said flow stream; c.
injecting the mixed flow stream comprising non-cryogenic nitrogen
and oxygen scavenger into a subterranean well; d. recovering fluids
extracted from said well; and e. separating said extracted well
fluids by phase and gravity.
5. A process for extracting fluid from a subterranean well as
described by claim 4 wherein said oxygen scavenging compound is
selected from the group comprising ammonium bisulfite.
6. A process for extracting fluid from a subterranean well as
described by claim 4 wherein said oxygen scavenging compound is
selected from the group comprising ammonium bisulfite solution,
ammonium hydrogen sulfite solution, ammonium acid sulfite solution,
monoammonium sulfite solution and sulfurous acid monoammonium salt
solution.
7. A process for extracting fluid from a subterranean well as
described by claim 4 wherein portions of separated fluid containing
water are returned to a subterranean formation
8. A process for conditioning a non-cryogenic nitrogen drilling
fluid containing residual oxygen, said process comprising the step
of mixing an oxygen scavenging compound with said drilling
fluid.
9. A process as described by claim 8 wherein said oxygen scavenging
compound is selected from the group comprising ammonium
bisulfite.
10. A process as described by claim 8 wherein said oxygen
scavenging compound is selected from the group comprising ammonium
bisulfite solution, ammonium hydrogen sulfite solution, ammonium
acid sulfite solution, monoammonium sulfite solution and sulfurous
acid monoammonium salt solution.
11. An apparatus for supplying utility gas to a subterranean well,
said apparatus comprising: a. a first compressor of atmospheric air
having a first discharge flow stream; b. a semi-permeable membrane
bundle receiving said first discharge flow stream for substantial
separation of oxygen from said atmospheric air, said membrane
having a second discharge flow stream substantially comprising
nitrogen mixed with a substantially reduced quantity of oxygen; c.
a second compressor receiving said second discharge flow stream and
discharging a third flow stream; d. a proportional mixing valve
receiving said third flow stream and a forth flow stream comprising
an oxygen scavenging compound for generating a fifth discharge flow
stream, said mixing valve combining said oxygen scavenging compound
with said third flow stream at a rate sufficient to substantially
preempt the reactive potential of residual oxygen in said third
flow stream; and, e. utilizing said fifth discharge flow stream in
a subterranean well development.
12. An apparatus as described by claim 11 wherein said subterranean
well development is a well drilling operation.
13. An apparatus as described by claim 11 wherein said subterranean
well development is a well fluid extraction operation.
14. An apparatus as described by claim 11 wherein said oxygen
scavenging compound is ammonium bisulfite.
15. An apparatus as described by claim 11 wherein said oxygen
scavenging compound is selected from the group comprising ammonium
bisulfite.
16. An apparatus as described by claim 11 wherein said oxygen
scavenging compound is selected fro the group comprising ammonium
bisulfite solution, ammonium hydrogen sulfite solution, ammonium
acid sulfite solution, monoammonium sulfite solution and sulfurous
acid monoammonium salt solution.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to chemical pretreatments of
oxidizing gases used in subterranean well drilling and production
processes.
[0003] 2. Description of Related Art
[0004] The petroleum drilling and production industry has a growing
reliance on non-cryogenic inert gases for numerous downhole
procedures. Non-cryogenic gas is usually produced by one of two
processes such as described by U.S. Pat. No. 5,388,650. Production
by one procedure includes the continuous transfer of low pressure
(approximately 100 to 350 psi) air through a bundled assembly of
elongated tubes having semi-permeable membrane walls. The
semi-permeable tubes generally comprise a plastic sleeve having a
wall that is perforated by countless, micron sized apertures. This
tube bundle is enclosed within a substantially evacuated vessel. As
air flow traverses the tube bundle length, oxygen and water vapor
pass through the tube wall apertures into the vessel enclosure
volume while nitrogen and other inert gasses continue along the
interior length of the tubes.
[0005] On a global average, atmospheric air comprises approximately
78% nitrogen and about 21% oxygen. The approximate 1% remainder is
a mixture of water vapor, carbon dioxide, argon and other inert
gasses. The above described semi-permeable membrane separation
process effectively removes about 95% of the airborne oxygen from
the original mixture. It is the remaining 5% that is the source of
oilfield difficulty. This remaining atmospheric oxygen is
reactively free. Since most of the downhole equipment in petroleum
production of service wells is fabricated of carbon steel, the iron
constituency of the material has a high reactive affinity for
oxygen. The reaction product is ferrous oxide, i.e. rust. Hence,
the remaining 5% oxygen in the nitrogen flow stream reacts with the
steel equipment and pipe walls downhole to produce rust particles.
These rust particles are returned to the surface with the nitrogen
circulation flow.
[0006] It is the most critical machined surfaces that are most
exposed to aggressive oxidation. These are dynamic or fluid sealing
surfaces that require a high degree of finish for reliable
operation. When these critical surfaces oxidize, downhole valves do
not open or do not close as required on pressure command from the
surface, for example.
[0007] There is another, less publicized but significant,
consequence of iron oxidation generation from non-cryogenic gas
utility in a subterranean well.
[0008] Most, if not all, non-cryogenic gas utilities in the
oilfield are circulation flow utilities. If drilling, the gas
circulation flushes the borehole of bit cuttings. If the utility is
gas lifting crude production, the well effluent is piped into an
appropriately closed tank or tanks for separation of the fluid
phases. In any case, most of the rust particle products of an
oxidation reaction are suspended in the aqueous phase of the well
effluent. The aqueous phase constituent of a well effluent is
usually mostly water but may also contain various dissolved acids
and minerals.
[0009] Environmental concerns dictate that this aqueous phase is
returned to the earth in the approximate region and strata from
which it was extracted. Accordingly, environmental injection wells
are drilled to receive the water portion of the liquid phase
extracted from the production well. As previously explained, this
aqueous portion carries the rust particle products of the
non-cryogenic gas oxidation. Resultantly, these rust particles are
injected into the environmental well. Over time and usage, these
injected rust particles will close or fill the earth formation
interstices surrounding the environmental well injection zone.
Eventually, the injection zone will be sufficiently sealed by the
rust particle accumulation as to effectively prevent continued
water injection. At this point, the well must be abandoned in lieu
of another environmental well or chemically treated to dissolve the
accumulated ferrous oxide.
[0010] It is an object of the present invention to teach a method
and apparatus that, on the one hand, reduces or eliminates the
oxidation of downhole well equipment and fixtures due to residual
oxygen in a non-cryogenic flow stream.
[0011] Also an object of the present invention is a quest to
develop a technology that prevents or mitigates the deposit of
ferrous oxide particle into a water injection well.
SUMMARY OF THE INVENTION
[0012] Damage due to residual oxygen in a non-cryogenic gas utility
in a well drilling or production enterprise may be reduced or
eliminated by blending the non-cryogenic gas flow stream comprising
predominately nitrogen in the presence of residual oxygen with an
oxygen scavenger selected from the family including ammonium
bisulfite.
[0013] A non-cryogenic nitrogen utility pursuant to the present
invention comprises a low pressure, high volume compressor for
atmospheric air. Low pressure discharge from the high volume
compressor is channeled into a bundled, semi-permeable membrane
tank. Following transit through the main flow stream channel within
the bundled tubes, the concentrated main stream, comprising
predominately nitrogen and a small quantity of residual oxygen, is
further compressed to the downhole utility pressure.
[0014] Prior to well injection, however, the high pressure mixture
of nitrogen and oxygen is further mixed with an oxygen scavenger
compound such as ammonium bisulfite binder. Upon circulated return
to the surface, the well effluent is phase and gravimetrically
separated. Some of the gaseous effluent may be recycled back into
the concentrated nitrogen make-up stream. The liquid phase effluent
comprising predominately water and the dissolved oxygen complex,
for example, is preferably injected back into the earth in an
environmental disposal well.
BRIEF DESCRIPTION OF THE DRAWING
[0015] With respect to FIG. 1, the single figure of the drawing, a
flow schematic is represented to illustrate a non-cryogenic gas
production and oilfield utility system that incorporates the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] Referring to the drawing schematic, a low pressure, high
volume compressor 10 draws in atmospheric air and compresses it to
the range of about 100 psi to 400 psi. A conduit or storage vessel
11 transfers the compressed air into a semi-permeable membrane
bundle 14. The membrane bundle 14 is enclosed by an oxygen transfer
vessel 15 for confinement of the oxygen that passes through the
semi-permeable walls of the bundle.
[0017] The oxygen effluent 17 is drawn out of the membrane vessel
by a pump not shown and either released to the atmosphere, bottled
or piped to another utility such as an engine or fuel cell.
[0018] The predominately nitrogen mainstream 19 Is piped into a
high pressure compressor 26. The high pressure compressor charges
the concentrated nitrogen mainstream to the pressure required of
the downhole utility and delivers the concentrated and pressurized
nitrogen mainstream into a conduit or accumulation vessel 28.
Valves 30 or other flow regulation devices regulate flow of the
high pressure stream of concentrated nitrogen through appropriate
conduits 32 into a mixing valve 33.
[0019] The mixing valve 33 proportionally blends a suitable oxygen
scavenging compound with the concentrated nitrogen mainstream 32. A
presently preferred example of oxygen scavenging compound is a
liquid form of ammonium bisulfite (NH.sub.4 HSO.sub.3) having the
essential property of either reacting with the residual oxygen in
the nitrogen mainstream or complexing with the free oxygen present
in the concentrated nitrogen mainstream to bind it from further
reaction with the materials of downhole equipment. Of course, the
reaction product of the additive and the residual oxygen must
remain in fluid suspension throughout the remaining steps of the
process. The additive quantity is determined as a function of the
nitrogen mainstream flow rate and the separation efficiency of the
semi-permeable membrane bundle. These two functions determine the
flow rate quantity of residual oxygen in the mainstream whereby the
reactive potential of the residual oxygen is blocked or preempted.
Other possibly useful compounds may include ammonium hydrogen
sulfite solution, ammonium acid sulfite solution, monoammonium
sulfite solution and sulfurous acid monoammonium salt solution.
[0020] In the case of a production utility, the treated nitrogen
stream 34 may be piped into the casing annulus of well 35 and
returned with formation fluid up the inside flow bore of a
production tube 36. If the treated nitrogen utility is drilling,
the flow route is somewhat reversed. The high pressure delivery
conduit would enter the drill string through a fluid swivel
mechanism not shown and be expelled from the well 35 casing
annulus.
[0021] In either case, the well discharge stream 38 carries the
well effluent to appropriate separation tankage 40. Although such
tankage is conveniently represented by the drawing as a single
vessel 40, in fact, numerous complex vessels are involved in the
effluent separation process.
[0022] The separation vessels 40 receive a mixed phase flow stream
38 and induce separation of the three fluid phases. Traditionally,
the phases are separated gravimetrically. The lighter, gaseous
portion of the return flow stream 38 may contain natural gas
(hydrocarbon fuel gas), helium or any number or naturally occurring
in situ formation gases in addition to the treated nitrogen
originally charged into the well. Some of these natural gasses may
be useful to the downhole utility and therefore recycled with the
treated nitrogen. Others may be corrosive or of greater value in
other utilities and are therefore separated. Those of skill in the
art will be familiar with those separation processes.
[0023] The recycled gases 42 may be directed into a recycle
compressor 44. A flow regulation system 46 meters the recycled gas
flow into the treated nitrogen make-up flow 24.
[0024] Generally, the liquid hydrocarbon products C.sub.xH.sub.y
are lighter than water. Hence, the hydrocarbon liquids may be
decanted through an intermediate flow stream 48.
[0025] Volumetrically, water may be the most abundant fluid product
of a declining well. Although the heaviest liquid is here
characterized as "water", rarely does the liquid consist of the
pure binary compound. No only are numerous dissolved minerals
present but also present are numerous dissolved and immiscible
acids. Hence, this aqueous well effluent characterized as "water"
is, in reality, a toxic liquid cocktail.
[0026] Being the most dense of the phases and therefore the
heaviest, the water separates gravimetrically at the bottom of a
static separation vessel 40 as graphically represented by the
drawing. The water drainage is carried away by conduits 50 into
high pressure injection pumps 52. The high pressure discharge 54
from the pumps 52 is connected into the injection tube 58 flow bore
of an environmental well 60. The injection tube 58 discharges the
water into a suitable earth formation 56.
[0027] Presumptively, the only compound present in the well
injected "water" that was not present in the original production
are the complex products of ammonium bisulfite and oxygen. These,
however, remain in liquid solution with other minerals originally
present and therefore migrate away from the injection zone of the
well 60.
* * * * *