U.S. patent application number 10/949623 was filed with the patent office on 2005-02-17 for microbial growth inhibiting material and method of forming.
Invention is credited to Dooley, Kirk J., Lee, Brady D..
Application Number | 20050034856 10/949623 |
Document ID | / |
Family ID | 32991512 |
Filed Date | 2005-02-17 |
United States Patent
Application |
20050034856 |
Kind Code |
A1 |
Lee, Brady D. ; et
al. |
February 17, 2005 |
Microbial growth inhibiting material and method of forming
Abstract
The invention includes methods of inhibiting microbial growth in
a well. A packing material containing a mixture of a first material
and an antimicrobial agent is provided to at least partially fill a
well bore. One or more access tubes are provided in an annular
space around a casing within the well bore. The access tubes have a
first terminal opening located at or above a ground surface and
have a length that extends from the first terminal opening at least
part of the depth of the well bore. The access tubes have a second
terminal opening located within the well bore. An antimicrobial
material is supplied into the well bore through the first terminal
opening of the access tubes. The invention also includes well
constructs.
Inventors: |
Lee, Brady D.; (Idaho Falls,
ID) ; Dooley, Kirk J.; (Shelley, ID) |
Correspondence
Address: |
Alan D. Kirsch
BBWI
PO BOX 1625
IDAHO FALLS
ID
83415-3899
US
|
Family ID: |
32991512 |
Appl. No.: |
10/949623 |
Filed: |
September 23, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10949623 |
Sep 23, 2004 |
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09991331 |
Nov 14, 2001 |
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6810957 |
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Current U.S.
Class: |
166/246 |
Current CPC
Class: |
Y10S 166/902 20130101;
E21B 37/06 20130101; E21B 41/00 20130101 |
Class at
Publication: |
166/246 |
International
Class: |
E21B 043/22 |
Goverment Interests
[0002] This invention was made with United States Government
support under Contract No. DE-AC07-99ID13727 awarded by the United
States Department of Energy. The United States Government has
certain rights in the invention.
Claims
We claim:
1. A method of forming a well packing material comprising: mixing
an antimicrobial agent with one or both of sand and gravel, wherein
the antimicrobial agent comprises one or more of a dissolved form,
a powdered form, a granular form, a pellet form, and a tablet form;
and wherein the antimicrobial agent content in the packing material
is from about 0.5% to about 30%, by volume.
2. The method of claim 1 wherein at least some of the antimicrobial
agent is encapsulated.
3. The method of claim 1 wherein the antimicrobial agent comprises
one or more of a chlorine release compound, an antimicrobial amine,
and a metal inhibitor.
4. The method of claim 1 wherein the antimicrobial agent comprises
a powdered form and wherein the mixing comprises coating the one or
more of sand and gravel with the powdered form.
5. The method of claim 1 wherein the antimicrobial agent comprises
a dissolved form, the method further comprising; adding a solution
comprising the dissolved form of antimicrobial agent to the one or
both of sand and gravel, wherein the mixing comprises mixing the
one or more of sand or gravel with the solution; and forming a
precipitate from the dissolved form of antimicrobial agent, wherein
the precipitate forms a coating on the one or more of sand and
gravel.
6. A microbial growth inhibiting material comprising: at least one
of sand or gravel; and an antimicrobial agent, wherein the
antimicrobial agent comprises one or more of a precipitate form, a
powder form, a tablet form, a granular form, and a pellet form, and
comprises one or more of a chlorine releasing compound, an
antimicrobial metal, and an antimicrobial amine.
7. The material of claim 6 wherein the antimicrobial agent
comprises one or more of a precipitate form and a powder form, and
wherein the at least one of sand or gravel is coated with one or
both of the precipitate and the powder.
8. The material of claim 6 wherein at least some of the
antimicrobial agent is delayed release.
9. The material of claim 6 wherein the antimicrobial agent
comprises a chlorine releasing compound selected from the group
consisting of calcium hypochlorites, trichloroisocyanurate,
dichloroisocyanurate.
10. The material of claim 6 wherein the antimicrobial agent
comprises an antimicrobial metal selected from the group consisting
of silver, copper and zinc
11. The material of claim 10 wherein the antimicrobial agent
comprises an antimicrobial amine, wherein the antimicrobial amine
is selected from the group consisting of quaternary ammonia
compounds and N-halamines.
12. The material of claim 1 wherein the at least some of the
antimicrobial agent is encapsulated.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of pending U.S. patent
application Ser. No. 09/991,331, filed on Nov. 14, 2001.
TECHNICAL FIELD
[0003] The present invention pertains to well constructions and
methods of inhibiting microbial growth in wells.
BACKGROUND OF THE INVENTION
[0004] The presence of microbial growth can cause bio-fouling and
plugging of wells. Such plugging can occur both in vadose-zone
wells and in saturated-zone wells. Vadose-zone wells are wells
having a well bore that does not extend into the water table, and
include, for example, vadose-zone monitoring wells, vapor
extraction wells and injection wells. Saturated-zone wells have a
well bore that extends into the water table such as, for example,
ground water monitoring wells, production wells and irrigation
wells. Plugging of a well may occur by plugging of structures
within the well such as the filter pack, screening, piping, or
pumps. Plugging may also occur by the plugging of the surrounding
geological media. Such plugging is caused by an accumulation of
microbial growth, by an accumulation of microbial extracellular
material, or both.
[0005] Once a well has become bio-fouled or plugged, treatment of
the well to eliminate microbial growth and remove plugging is often
difficult and ineffective. Remedial chemical treatments, such as an
introduction of a highly concentrated chlorine solution into the
well, often fail due to the difficulty in forcing the solution
through an already plugged well. Once bio-fouling has occurred,
replacement of the effected structure is often required. Severe
bio-fouling and plugging may require replacement of the entire well
at great expense.
[0006] Accordingly, it is desirable to provide well constructions
and preventative treatment methods designed to minimize unwanted
microbial growth in wells.
SUMMARY OF THE INVENTION
[0007] In one aspect, the invention encompasses a method of
inhibiting microbial growth in a well. A well bore is provided. A
first material is mixed with an antimicrobial agent to form a
packing material. The packing material is used to fill at least a
portion of the well bore.
[0008] In another aspect, the invention encompasses a material for
packing within a well. The material for packing the well includes
either sand or gravel, or both. The material for packing the well
also includes an antimicrobial agent. The antimicrobial agent can
be in powdered form, in granular form, in pellet form, in tablet
form, in precipitate form, or can be a mixture of two or more of
these forms.
[0009] In another aspect, the invention encompasses an additional
method of inhibiting microbial growth in a well. A well bore is
provided that has a depth extending from a ground surface. A casing
is provided within the well bore and is at least partially
surrounded by an annular space. One or more access tubes are
provided within the annular space of the well bore, outside the
casing. The access tubes have a first terminal opening located at
or above the ground surface and have a length that extends from the
first terminal opening at least part of the depth of the well bore.
The access tubes have a second terminal opening located within the
well bore. An antimicrobial material is supplied into the well bore
through the first terminal opening of the access tubes.
[0010] In still another aspect, the invention encompasses a well
construction having inhibited microbial growth. The well
construction includes a well bore and a well casing within the well
bore. The casing has a terminal end within the well bore and has a
screened portion that extends from the terminal end to a first
elevation within the well bore. Multiple access tubes encircle the
casing within the well bore. The access tubes have a terminal end
within the bore and have a perforated segment extending from the
terminal end to a second elevation within the well bore. The well
bore contains a layer of packing material comprising a first
antimicrobial agent mixed with either sand or gravel, or mixed with
both sand and gravel. The layer of packing material fills the well
bore to a third elevation. The well construction includes a second
antimicrobial agent which, when provided through an access tube, is
able to pass from within an access tube into the packing material
through the perforated segment of the access tube.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Preferred embodiments of the invention are described below
with reference to the following accompanying drawings.
[0012] FIG. 1 shows a diagram of a well construction formed in
accordance with the methodology of the present invention.
[0013] FIG. 2 is an enlarged view of the encircled region in FIG.
1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] This disclosure of the invention is submitted in furtherance
of the constitutional purposes of the U.S. Patent Laws "to promote
the progress of science and useful arts" (Article 1, Section
8).
[0015] The present invention is described with reference to a well
construction 10 in FIGS. 1 and 2. Referring to FIG. 1, well
construction 10 comprises a well bore 12. A packing material 16 at
least partially fills well bore 12. Packing material 16 comprises a
first material 14 and an antimicrobial agent 15, as shown in FIG.
2. Prior to use in the well bore, packing material 16 can be formed
by mixing first material 14 with antimicrobial agent 15.
[0016] A variety of materials are available for use as first
material 14 for purposes of the present invention. Exemplary
materials include sand, gravel, or a mixture thereof.
[0017] Antimicrobial agent 15 can comprise a solid and can be mixed
with first material 14 such that packing material 16 contains
antimicrobial agent 15 from about 0.5% to about 30% (by volume).
Exemplary solid forms for antimicrobial agent 15 for purposes of
the present invention include precipitate form, powder form, tablet
form, granular form or pellet form.
[0018] Mixing of antimicrobial agent 15 with first material 14 can
comprise coating the first material with the antimicrobial agent.
Coating of first material 14 can be performed by mixing a powdered
antimicrobial agent with the first material. Coating can also be
performed by dissolving any of the solid forms of antimicrobial
agent, mixing the dissolved antimicrobial agent with the first
material, and re-precipitating the antimicrobial agent. The solid
antimicrobial agents can be dissolved in an organic or an inorganic
solvent based upon the solubility properties of the specific agent.
The resulting precipitate can form a coating on first material 14.
Alternatively, the mixing can comprise forming a composite mixture
of the first material and one or more of, for example,
antimicrobial powder, antimicrobial tablets, antimicrobial
granules, and antimicrobial pellets.
[0019] At least some of the antimicrobial agent 15 utilized for
purposes of the present invention can be delayed release. A delayed
release antimicrobial agent can include, for instance, solid forms
of an antimicrobial agent that dissolve slowly in water. For
example, a tablet form, a granular form or a pellet form of
antimicrobial compound can dissolve more slowly than the powder
form of the same antimicrobial compound. In addition, encapsulation
or coating of any of the solid forms listed can further decrease
the rate of dissolving in water. Numerous encapsulating or coating
material is available for utilization in the present invention,
including coating material comprising, for instance; proteins,
polysaccharide, starches, waxes, fats, natural and synthetic
polymers, and resins.
[0020] Numerous compounds from a variety of classes of
antimicrobial compounds of can be utilized for purposes of the
present invention. Exemplary classes of such antimicrobial
compounds include chlorine release type compounds, antimicrobial
amines, and antimicrobial metals. Chlorine release type compounds
include, for instance, compounds that can release chlorine when the
compound reacts with water. Specific chlorine release compounds
include, for example, calcium hypochlorites, trichloroisocyanurate,
dichloroisocyanurate.
[0021] Specific types of compounds within the class of
antimicrobial amines for purposes of the present invention include,
quaternary ammonia compounds and N-halamines such as;
poly-acrylonitrile-co-4(acryloxymethyl- )-4-ethyl-2-oxazolidinone
latex, poly-vinyl chloride-co-4-(acryloxymethyl)-
-4-ethyl-2-oxazolidinone latex,
poly-styrene-co-4-(acryloxymethyl)-4-ethyl- -2-oxazolidinone latex,
poly-vinyl acetate-co-4-(acryloxymethyl)-4-ethyl-2- -oxazolidinone
latex, poly-acrylonitrile-g-4-(acryloxymethyl)-4-ethyl-2-ox-
azolidinone latex, poly-vinyl
chloride-g-4-(acryloxymethyl)-4-ethyl-2-oxaz- olidinone latex,
poly-styrene-g-4-(acryloxymethyl)-4-ethyl-2-oxazolidinone latex,
poly-vinyl acetate-g-4-(acryloxymethyl)-4-ethyl-2-oxazolidinone
latex, poly-vinyl
alcohol-g-4-(acryloxymethyl)-4-ethyl-2-oxazolidinone latex and
poly(1,3,5-trichloro-6-methyl-6-(4'-vinylphenyl)-1,3,5-triazine-
-2,4-dione.
[0022] Specific examples of agents within the class of
antimicrobial metals which can be utilized for purposes of the
present invention include, but are not limited to, silver, zinc and
copper.
[0023] The present invention encompasses embodiments of packing
material 16 wherein the packing material comprises a single solid
form of antimicrobial agent and embodiments wherein packing
material 16 comprises multiple solid forms of an antimicrobial
agent. In addition, packing material 16 can comprise a single
antimicrobial compound or can comprise multiple antimicrobial
compounds from one or more of the classes of compounds listed. It
can be beneficial to have multiple forms of solid antimicrobial
present in packing material 16 to provide both short term and long
term microbial growth inhibition. For example, if antimicrobial
agent 15 comprises both a powder form and a tablet form, the powder
form can dissolve quickly, thereby providing an immediate microbial
growth inhibiting effect, while the tablet form can dissolve more
slowly, providing a delayed or long term effect relative to the
powder form. For similar reasons, it can be beneficial for
antimicrobial agent 15 to comprise multiple compounds or classes of
compounds which dissolve at different rates or vary in duration of
microbial inhibiting effects.
[0024] The well construction 10 of the present invention can
comprise a vadose-zone well or a saturated-zone well. Well bore 12
can, therefore, comprise a depth that extends from a ground surface
30 into the vadose-zone 28 (not shown), or, as shown in FIG. 1.,
from ground surface 30 into the saturated-zone 26. Where the well
is a vadose-zone well, because the bore does not extend into the
water table, water for reacting with or dissolving an antimicrobial
agent is provided by for example, condensation, infiltration, or
unsaturated flow. The rate of dissolving of any given form of an
antimicrobial agent, therefore, will be less than the corresponding
rate in a saturated-zone well. The form of solid to be utilized in
a specific well construction can be determined accordingly.
[0025] In the shown embodiment, well construction 10 comprises a
casing 18 within well bore 12. It is to be understood that the
present invention encompasses an open-bore well construction that
lacks casing 18 (not shown). Casing 18 can be at least partially
surrounded by an annular space 20 and can comprise a screened
portion 22 that extends from a terminal end 48, located within well
bore 12, to a first elevation within the well bore. Packing
material 16 can fill at least part of annular space 20 around well
casing 18 to a second elevation within the well bore. The second
elevation can be greater than the first elevation such that packing
material 16 at least covers screened portion 22 of casing 18.
[0026] Additionally, well construction 10 can comprise a seal layer
23 which can seal packing material 16. Seal layer 23 can comprise,
for example, bentonite, concrete, neat cement, or a mixture
thereof. Whether or not well construction 10 comprises seal layer
23, well construction 10 can comprise a fill material 24 such as,
for instance, concrete, bentonite (in dry form or comprised in a
slurry), neat cement, or a mixture of cement and bentonite. Fill
material 24 can at least partially fill any annular space 20
remaining in the well bore beyond the portion filled with packing
material 16.
[0027] In addition to the features described above, the invention
encompasses a well construction 10 comprising at least one access
tube 32 within well bore 12. In embodiments comprising well casing
18, the at least one access tube can be positioned outside casing
18 within annular space 20. Access tubes 32 have a first terminal
opening 34 that is preferably located above ground surface 30.
Access tubes 32 extend at least part of the depth of well bore 12,
from first terminal opening 34, to a second terminal opening 36
within the well bore. Well construction 10 can comprise an
antimicrobial agent 39 that is distinct from the antimicrobial
agent 15 in packing material 16, at least initially.
[0028] Access tubes 32 are not limited to a specific number of
tubes, nor is placement of such tubes limited to a specific
distribution within well bore 12. The number of tubes can be, for
instance, from about 2 to about 10 access tubes. Access tubes 32
can have a diameter from about 0.25 inches to about 1.5 inches. The
access tubes can be distributed, for example, around the
circumference of casing 18 and can be equally spaced around the
circumference with respect to each other.
[0029] In addition to the above features, access tubes 32 of well
construction 10 can comprise a perforated segment 40 extending from
second terminal opening 36 to a third elevation within well bore
12. The third elevation can be less than the second such that
perforated segment 40 is entirely covered by packing material 16.
Access tubes 32 can comprise a cap 42 to close second terminal
opening 36, and a removable cap 44 that covers first terminal
opening 34.
[0030] Antimicrobial material 39 can be supplied into well 10
through the first terminal opening 34 of access tubes 32. Once
antimicrobial agent 39 is added through terminal opening 34,
antimicrobial agent 39 can be able to pass from within access tube
32 into packing material 16 through perforated segment 40 of access
tube 32.
[0031] Antimicrobial material 39 can be supplied at time intervals.
Exemplary time intervals for purposes of the present invention can
be from between about 2 months and about 12 months. During the time
interval between supplying antimicrobial agent 39, the first
terminal opening 34 of access tubes 32 can be reversibly capped
44.
[0032] Antimicrobial agent 39 is not limited to any specific
material or form. Antimicrobial agent 39 can comprise, for example,
one or more of the solid forms discussed above with respect to
antimicrobial agent 15. Antimicrobial agent 39 can also comprise
one or both of a gas antimicrobial agent and a liquid antimicrobial
agent, or can comprise a combination of one or more of a gas
antimicrobial agent, a liquid antimicrobial agent and a solid
antimicrobial agent. Exemplary gas antimicrobial agents for
purposes of the present invention include chlorine and ozone.
Exemplary liquid antimicrobial agents, for purposes of the present
invention include one or more of iodine, bromine or a dissolved
form of any of the chlorine release type compound discussed
above.
[0033] Where antimicrobial agent 39 comprises a gas or a liquid,
supplying of antimicrobial agent 39 through first terminal opening
34 can comprise pressure pumping the gas or liquid through first
terminal opening 34. Alternatively, the gas or liquid may be pushed
through the access tube by utilizing a pressurized air stream that
can be flowed through first terminal opening 34 of access tubes 32,
or by inserting a slotted tube through the first terminal opening
to sift the antimicrobial agent through perforated segment 40 of
the access tubes.
[0034] As shown in FIG. 1, well constructions 10 encompassed by the
present invention include constructions comprising the described
well packing material 16 containing antimicrobial agent 15, and
simultaneously comprising access tubes 32 and the described
antimicrobial agent 39, in a single well. Where a single well
comprises both antimicrobial agent 15 and antimicrobial agent 39,
the two antimicrobial agents can be the same or can differ. As
discussed above, it can be beneficial to provide a multiple forms
of antimicrobial compounds and/or multiple compounds within a
single well.
[0035] Well constructions encompassed by the present invention also
include constructions comprising access tubes 32 and antimicrobial
agent 39 in the absence of packing material 16 and antimicrobial 15
(not shown). The invention also contemplates well constructions
comprising packing material 16 containing antimicrobial agent 15,
and comprising an absence of antimicrobial agent 39, and well
constructions comprising packing material 16 and an absence of
access tubes 32. The use of packing material 16 of the present
invention is not intended to be limited to use within a well.
[0036] It is to be understood that the present invention
contemplates adaptation of the above described methods and well
constructs for bio-remedial and bio-venting wells. Bio-venting and
bio-remedial wells utilize bacteria to perform functions in
furtherance of the purposes of the well. However, growth of these
microbes is preferentially constrained to the surrounding
geological structures rather than within the well bore.
Accumulation of such microbes or extracellular material within the
well bore can detrimentally effect the functioning of the well, and
lead to plugging.
[0037] The above described methods can be used to inhibit microbial
growth within the well bore of a bio-venting or bio-remedial with
limited adverse effects on the microbial population in the
surrounding geological structures. For example, an antimicrobial
with limited diffusion properties due to a low solubility, such as
for instance a polymeric amine, can be utilized within the well
bore to minimize diffusion into the surrounding geological
structures. The antimicrobial effects can thereby be limited to, or
localized within, the well bore.
[0038] In compliance with the statute, the invention has been
described in language more or less specific as to structural and
methodical features. It is to be understood, however, that the
invention is not limited to the specific features shown and
described, since the means herein disclosed comprise preferred
forms of putting the invention into effect. The invention is,
therefore, claimed in any of its forms or modifications within the
proper scope of the appended claims appropriately interpreted in
accordance with the doctrine of equivalents.
* * * * *