U.S. patent application number 13/847756 was filed with the patent office on 2014-02-06 for dispersion of compounds for the stimulation of biogenic gas generation in deposits of carbonaceous material.
This patent application is currently assigned to LUCA Technologies, Inc.. The applicant listed for this patent is Luca Technologies, Inc.. Invention is credited to Jordan A. Bradfish, Lisa Greaser, Shelley A. Haveman, William Mahaffey, Benjamin C. Sutton.
Application Number | 20140034297 13/847756 |
Document ID | / |
Family ID | 49223332 |
Filed Date | 2014-02-06 |
United States Patent
Application |
20140034297 |
Kind Code |
A1 |
Mahaffey; William ; et
al. |
February 6, 2014 |
DISPERSION OF COMPOUNDS FOR THE STIMULATION OF BIOGENIC GAS
GENERATION IN DEPOSITS OF CARBONACEOUS MATERIAL
Abstract
Methods of dispersing an activation agent, nutrient, or both to
a carbonaceous material to stimulate production of a biogenic gas
are described. The methods may include accessing a subterranean
geologic formation containing the carbonaceous material, and
supplying a mixture to the formation. The mixture may include an
activation agent or nutrient mixed with a dispersed phase and a
continuous phase. The method may also include contacting the
carbonaceous material with the mixture, and distributing at least a
portion of the activation agent or nutrient over and/or into the
carbonaceous material from the dispersed phase. The production of
biogenic gases is increased by microorganisms that are stimulated
by the distributed activation agent or nutrient to convert a
portion of the carbonaceous material into the biogenic gases.
Inventors: |
Mahaffey; William;
(Evergreen, CO) ; Bradfish; Jordan A.; (Arvada,
CO) ; Haveman; Shelley A.; (Lakewood, CO) ;
Sutton; Benjamin C.; (Arvada, CO) ; Greaser;
Lisa; (Denver, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Luca Technologies, Inc.; |
|
|
US |
|
|
Assignee: |
LUCA Technologies, Inc.
Golden
CO
|
Family ID: |
49223332 |
Appl. No.: |
13/847756 |
Filed: |
March 20, 2013 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61613380 |
Mar 20, 2012 |
|
|
|
Current U.S.
Class: |
166/246 |
Current CPC
Class: |
C09K 8/58 20130101; Y02E
50/30 20130101; C12P 3/00 20130101; C12N 1/20 20130101; C12P 5/023
20130101; E21B 43/295 20130101; Y02E 50/343 20130101 |
Class at
Publication: |
166/246 |
International
Class: |
E21B 43/295 20060101
E21B043/295 |
Claims
1. A method of dispersing an activation agent to a carbonaceous
material to stimulate production of a biogenic gas, the method
comprising: accessing a subterranean geologic formation containing
the carbonaceous material; supplying a mixture to the geologic
formation, wherein the mixture comprises the activation agent mixed
with a dispersed phase and a continuous phase; contacting the
carbonaceous material in the formation with the mixture, wherein
the dispersed phase distributes at least a portion of the
activation agent over and/or into the carbonaceous material; and
increasing the production of the biogenic gas from microorganisms
stimulated by the distributed activation agent to convert a portion
of the carbonaceous material into the biogenic gas.
2. The method of claim 1, wherein the dispersed phase comprises a
non-polar liquid and the continuous phase comprises water.
3. The method of claim 1, wherein the mixture comprises a multiple
emulsion comprising water-in-oil-in-water, and wherein the
dispersed phase comprises a non-polar liquid surrounding an aqueous
solution and the continuous phase comprises water.
4. The method of claim 3, wherein the activation agent is present
in the aqueous solution in the dispersed phase.
5. The method of claim 1, wherein the activation agent comprises at
least one compound selected from the group consisting of an acetate
compound, a yeast extract, an algal extract, and a phosphorus
compound.
6. The method of claim 1, wherein the activation agent comprises an
aromatic compound including an ether linked group.
7. The method of claim 1, wherein the activation agent comprises an
aromatic compound including an ester linked group.
8. The method of claim 1, further comprising metabolizing the
non-polar dispersed phase by the microorganisms, wherein the
metabolizing produces an acetate compound.
9. The method of claim 1, wherein the non-polar dispersed phase
comprises a fatty acid.
10. The method of claim 1, wherein the contacting the carbonaceous
material with the emulsion disperses at least a portion of the
activation agent over a greater area of the formation.
11. The method of claim 1, wherein the non-polar dispersed phase
allows the emulsion to travel over and/or into the carbonaceous
material without being absorbed therein.
12. The method of claim 1, wherein the activation agent comprises
sodium phosphate, potassium phosphate, a phosphorus oxyacid, a salt
of a phosphorus oxyacid, an alkali metal salt of acetic acid, or an
alkali metal earth metal salt of acetic acid.
13. A method of providing a nutrient to a carbonaceous material to
stimulate production of a biogenic gas, the method comprising:
accessing a geologic formation containing the carbonaceous
material; delivering to the geologic formation a mixture comprising
a dispersed phase and a continuous phase, wherein the nutrient is
incorporated into at least one of the phases; contacting the
carbonaceous material in the geologic formation with the mixture,
wherein the nutrient becomes accessible to microorganisms; and
increasing the production of the biogenic gas by stimulating the
microorganisms with the nutrient to convert a portion of the
carbonaceous material into the biogenic gas.
14. The method of claim 13, wherein the dispersed phase is
homogenously distributed in the mixture.
15. The method of claim 13, wherein the dispersed phase comprises a
non-polar liquid surrounding an aqueous solution and the continuous
phase comprises water.
16. The method of claim 13, wherein at least a portion of the
nutrient is located in the dispersed phase.
17. The method of claim 13, wherein the continuous phase comprises
an aqueous solution in which the nutrient is partially
dissolved.
18. The method of claim 17, wherein the microorganisms consume a
portion of the nutrient that is not fully incorporated in the
homogenous mixture.
19. The method of claim 15, wherein microorganisms consume the
non-polar dispersed phase as an additional nutrient source.
20. The method of claim 19, wherein consuming the non-polar
dispersed phase delays the consumption of a second portion of the
nutrient incorporated in the liquid mixture.
21. The method of claim 14, wherein the homogenous mixture is an
emulsion.
22. The method of claim 21, wherein the emulsion is a
microemulsion, and wherein the emulsion further comprises a
surfactant.
23. The method of claim 13, wherein the nutrient comprises an
aromatic compound including an ether linked group.
24. The method of claim 13, wherein the nutrient comprises an
aromatic compound including an ester linked group.
25. The method of claim 13, wherein the nutrient comprises
methanol, ethanol, n-propanol, n-butanol, 2,3butanediol,
ethanolamine, 3,4,5-trimethoxybenzoate, syringate, vanillate,
glycine, cysteine, formate, yeast extract, hydrogen, or carbon
dioxide.
26. A method of introducing multiple portions of a compound to
microorganisms in a geologic formation, the method comprising:
accessing a geologic formation that contains carbonaceous material;
supplying an emulsion to the formation, wherein the emulsion has a
continuous phase and a dispersed phase, and wherein a first portion
of the compound is incorporated into the continuous phase and a
second portion of the compound is incorporated in the dispersed
phase; introducing the first portion of the compound in the
continuous phase to the microorganisms when the emulsion contacts
the microorganisms, and introducing the second portion of the
compound after the microorganisms contact the dispersed phase;
wherein the compound stimulates the microorganism to covert the
carbonaceous material to one or more biogenic gases.
27. The method of claim 26, wherein the compound comprises an
activation agent or a nutrient.
28. The method of claim 26, wherein the compound is selected from
the group consisting of methanol, ethanol, n-propanol, n-butanol,
2,3butanediol, ethanolamine, 3,4,5-trimethoxybenzoate, syringate,
vanillate, glycine, cysteine, formate, yeast extract, hydrogen,
carbon dioxide, sodium phosphate, potassium phosphate, a phosphorus
oxyacid, a salt of a phosphorus oxyacid, an alkali metal salt of
acetic acid, and an alkali metal earth metal salt of acetic
acid.
29. The method of claim 26, wherein the continuous phase comprises
water and the dispersed phase comprises a non-polar liquid.
30. The method of claim 26, wherein the biogenic gases comprise
hydrogen (H.sub.2) or methane (CH.sub.4).
31. The method of claim 26, wherein the microorganisms consume the
dispersed phase as an additional nutrient source.
32. The method of claim 31, wherein consuming the non-polar
dispersed phase produces an acetate compound.
33. The method of claim 26, wherein the dispersed phase comprises
two or more phases.
34. The method of claim 33, wherein the dispersed phase comprises a
polar-phased droplet surrounded by a non-polar-phased droplet.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/613,380, filed Mar. 20, 2012, entitled
"Dispersion of Compounds for the Stimulation of Biogenic Gas
Generation in Deposits of Carbonaceous Material." The entire
disclosure of which is incorporated herein by reference for all
purposes.
BACKGROUND OF THE INVENTION
[0002] As the price of oil rises, along with economic and
environmental pressures to find local and alternative energy
sources, the use of natural gas as a safe and reliable energy
source continues to grow. Natural gas is used as an energy source
for heating, electric power generation, and transportation fuel.
Natural gas is also used for the production of hydrogen, and in
many manufacturing processes.
[0003] The majority of natural gas is found in underground
deposits, many of which are the same geologic formations that
contain liquid and solid carbonaceous material such as oil fields
and coal beds. Much of the production of natural gas is believed to
occur by biogenic processes, such as by methanogenic microorganisms
that exist in the geologic formations and metabolize the
carbonaceous material into substances such as natural gas as a
metabolic product. The work of these microorganisms over thousands
and millions of years has produced deposits of natural gas that
measure in the trillions of cubic feet.
[0004] As natural gas use increases globally, these reserves will
be depleted creating new types of energy crises. Fortunately, the
same biogenic processes that originally produced many of these
deposits may be utilized to continue producing natural gas on a
globally significant scale. Furthermore, if biogenic processes may
be improved or enhanced to convert even a small fraction of the
carbonaceous material in current formations to natural gas, the
quantities produced could be enormous. For example, the Powder
River Basin in northeastern Wyoming is estimated to contain over 1
trillion short tons of coal. If even 1% of this coal could be
converted to natural gas, it could supply the current annual
natural gas usage in the United States (about 23 trillion cubic
feet) for four years. Many previously mined coal and oil fields in
the United States alone that have become economically prohibitive
to continued mining still contain these quantities of residual
carbonaceous materials.
[0005] Among the challenges faced in the biogenic conversion of
these carbonaceous materials to natural gas and other hydrocarbons
is providing an ample and continued source of nutrients and
activation agents to the microorganisms that metabolize the
carbonaceous materials. The standard spacing of wells for natural
gas production is typically forty or eighty acre spacing (i.e., 1
well/40 acres 1 well/80 acres). Due to the depths and spacing of
these wells, as well as the underground distances covered by the
formations, gas produced through methanogenesis may take a
substantial amount of time to travel to the surface for collection.
Nutrients and activation agents that have been introduced into the
formation to activate or stimulate methanogenesis may be exhausted
long before it has had sufficient opportunity to be widely
distributed by the advective dispersion processes within the
formation. This may slow, or even prevent, the enhanced conversion
of carbonaceous material into natural gas, because only a small
portion of the subsurface microorganism populations' growth and
activity.
[0006] Thus, there is a need for improved nutrients and activation
agents for stimulating the biogenic production of natural gas and
other metabolic products. There is also a need for improved ways of
delivering nutrients and activation agents into the formation
environment. These and other needs are addressed by the present
invention.
BRIEF DESCRIPTION OF THE INVENTION
[0007] Additional production of biogenic gases from carbonaceous
materials found in geologic formations may be realized by supplying
mixtures to microorganisms in the formations that stimulate their
conversion of the carbonaceous materials to gases like hydrogen and
methane. The mixtures may include one or more liquid dispersed
phases surrounded by a liquid continuous phase that is
characteristic of an emulsion. The mixtures may also include solid
phase materials characteristic of a suspension. The compounds in
the mixtures that stimulate biogenic gas production from the
microorganisms may include activation agents and/or nutrients.
These compounds may be at least partially dissolved in one or more
liquid phases of the mixture that is supplied to the
microorganisms. In some instances the materials that form a liquid
phase (e.g., a dispersed phase) may also act as a nutrient or
activation agent for the microorganisms.
[0008] Exemplary mixtures may include oil-in-water and water-in-oil
emulsions. The "oil" phase may be made of a non-polar liquid at the
working temperatures of the mixture, and the "water" phase may be
made from a polar liquid such as water or an aqueous solution,
though other polar liquids may be used instead of (or in addition
to) water. Exemplary mixtures may also include more complex
multiple emulsions where the dispersed phase includes two or more
liquid phases that are not completely miscible. Examples of these
multiple emulsions may include water-in-oil-in-water (W/O/W)
emulsions which have a dispersed phase that includes a core polar
"water" droplet surrounded by a non-polar "oil" droplet surrounded
by a polar "water" continuous phase.
[0009] Embodiments of the invention may include methods of
dispersing an activation agent to a carbonaceous material to
stimulate production of a biogenic gas. The methods may include
accessing a subterranean geologic formation containing the
carbonaceous material, and supplying a mixture to the formation.
The mixture may include the activation agent mixed with a dispersed
phase and a continuous phase. The method may also include
contacting the carbonaceous material with the mixture, and
distributing at least a portion of the activation agent over and/or
into the carbonaceous material from the dispersed phase. The
production of biogenic gases is increased by microorganisms that
are stimulated by the distributed activation agent to convert a
portion of the carbonaceous material into the biogenic gases.
[0010] Embodiments of the invention may also include methods of
providing a nutrient to a carbonaceous material to stimulate
production of biogenic gas from the material. The methods may
include accessing a geologic formation containing the carbonaceous
material, and delivering a mixture to the formation that includes a
dispersed phase, a continuous phase, and the nutrient incorporated
into at least one of these phases. The mixture may contact the
carbonaceous material and become available to microorganisms in
proximity to the material. The nutrient stimulates the
microorganisms to convert at least a portion of the carbonaceous
material into biogenic gas, increasing the production of the
biogenic gas.
[0011] Embodiments of the invention may still further include
methods of introducing multiple portions of a compound or a mixture
of compounds to microorganisms in a geologic formation. The methods
may include accessing a geologic formation containing carbonaceous
material, and supplying an emulsion to the formation. The emulsion
may have a continuous phase and a dispersed phase, and a first
portion of the compound or a single component of a mixture of
compounds is incorporated into the continuous phase while a second
portion of the compound or a component of the mixture of compounds
is incorporated into the dispersed phase. The first portion of the
compound in the continuous phase is introduced to the
microorganisms when the emulsion contacts the microorganisms, and
the second portion of the compound is introduced after the
microorganisms make contact with the dispersed phase. The compound
stimulates the microorganisms to convert the carbonaceous material
into one or more biogenic gases.
[0012] Additional embodiments and features are set forth in part in
the ensuing detailed description and accompanying drawings, and in
part will become apparent to those skilled in the art upon
examination of the specification, or may be learned by the practice
of the invention. The features and advantages of the invention may
be realized and attained by means of the instrumentalities,
combinations, and methods described in the specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention is described in conjunction with the
appended figures:
[0014] FIG. 1 is a flowchart illustrating a method of dispersing a
mixture within a geologic formation according to embodiments of the
invention;
[0015] FIGS. 2A-C are flowcharts illustrating methods of producing
a multiple emulsion incorporating a compound according to
embodiments of the invention;
[0016] FIGS. 3A-C are flowcharts illustrating methods of producing
an emulsion according to embodiments of the invention;
[0017] FIG. 4 is a block diagram showing a process for creating a
multiple emulsion according to embodiments of the invention;
[0018] FIG. 5 shows a system for supplying an encapsulated compound
to a formation environment according to embodiments of the present
invention.
[0019] FIG. 6 is a chart detailing various amendment compounds and
methane produced over time in a controlled lability experiment.
[0020] FIG. 7 is a chart detailing various amendment compounds and
methane produced over time in a nutritional experiment including
carbonaceous substrate.
[0021] FIG. 8 is a chart detailing various amendment compounds and
acetate turnover over time in a controlled lability experiment.
[0022] FIG. 9 is a chart detailing various amendment compounds and
acetate turnover over time in a nutritional experiment including
carbonaceous substrate.
[0023] FIG. 10 is a microscope image showing a view of the produced
compounds after formation.
[0024] FIG. 11 is a microscope image of the produced compounds one
day after formation.
[0025] FIG. 12 is a microscope image illustrating various of the
produced emulsion types according to the present technology.
[0026] In the appended figures, similar components and/or features
may have the same numerical reference label. Further, various
components of the same type may be distinguished by following the
reference label by a letter that distinguishes among the similar
components and/or features. If only the first numerical reference
label is used in the specification, the description is applicable
to any one of the similar components and/or features having the
same first numerical reference label irrespective of the letter
suffix.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Methods, systems and compositions are described for
stimulating production of biogenic gases in geologic formations
with activation agent and/or nutrient mixtures that may include two
or more liquid phases that are not fully miscible (e.g.,
emulsions). The emulsions may allow agents and nutrients to be
dispersed over a larger portion of carbonaceous material located in
the formation, and/or may allow a controlled release of the agents
and nutrients over a longer period of time. This allows the agents
and nutrients to be accessible to a larger number of microorganisms
in the carbonaceous material, and for longer periods. In some
instances, one or more of the liquid phases may themselves
constitute agents and/or nutrients for microorganisms.
[0028] The stimulation effects of the agents and nutrients may
include increasing the rate of production of the biogenic gas
and/or an intermediary in a metabolic process that produces the
gas. The effects may also include activating a consortium of
microorganisms in the formation to start producing the biogenic
gas. They may further include stopping or decreasing a "rollover"
effect such as when the concentration of one or more metabolic
products starts to plateau (or even drop) after a period of
monotonically increasing.
[0029] In some instances, microorganisms may be provided in the
mixtures themselves, and/or in separate solutions introduced to the
geologic formation. The microorganisms may be provided to areas of
the geologic formation (such as the carbonaceous material) that
show little or no biological activity. They may also be provided to
increase the microorganism population in areas where microorganisms
are already present (e.g., where there is already a native
microorganism population.) The added microorganisms may be selected
to work in concert with the agent/nutrient mixture supplied to the
formation.
[0030] Compounds used in the methods described may act as
nutrients, activation agents, initiators, or catalysts for
increasing the production of biogenic gases including hydrogen and
methane. As nutrients, the microorganisms may consume the compounds
allowing the microorganism populations to grow more rapidly than
without the compounds. As activation agents, the compounds may
lower an activation barrier, open a metabolic pathway, modify a
carbonaceous material, change the reaction environment, and may or
may not be rapidly consumed as a nutrient.
[0031] When the compound is acting primarily like a nutrient,
consumption of the nutrient by the microorganisms may increase the
production of biogenic gas by a stoichiometrically proportional
amount to that of the compound used. Alternatively, when a compound
is acting primarily as an activation agent, the increased amount of
biogenic gas may be much larger than the amount of the compound
added. Thus, in such a scenario, introducing small quantities of
the compound may produce much more than stoichiometric quantities
of the biogenic gases. When the compound acts as an activation
agent, the compound may or may not act as a catalyst, and may be
fully, partially, or not consumed while increasing the production
of biogenic gas.
[0032] Turning now to FIG. 1, a flowchart illustrating methods 100
of dispersing a mixture within a geologic formation according to
embodiments of the invention is shown. The methods 100 may include
accessing the geologic formation 110. The geologic formation may be
a previously explored, carbonaceous material-containing
subterranean formation, such as a coal mine, oil field, natural gas
deposit, carbonaceous shale deposit, etc. In many instances, access
to the formation may involve utilizing previously mined or drilled
access points to the formation. For unexplored formations,
accessing the formation may involve digging or drilling through a
surface layer to access the underlying site. The geologic
formations may include native carbonaceous materials that were
formed in the formation through natural processes instead of being
supplied to the formation through a human-directed process (e.g.,
dumping or pumping the carbonaceous material into the
formation).
[0033] Accessing the geologic formation 110 may also include
accessing microorganisms present in the formation. These
microorganisms may include methanogenic microorganisms that convert
adjacent carbonaceous material into hydrogen (H.sub.2), methane
(CH.sub.4), and/or other metabolic products that have
hydrogen-to-carbon ratios higher than the starting carbonaceous
material. The microorganisms may also include species of
methanogenesis inhibitors that slow or inhibit methanogenic
metabolic processes by consuming methanogenic precursors and/or
producing compounds that inhibit methanogenesis.
[0034] The method 100 may include a biological analysis 112 of the
microorganisms. This may include a quantitative analysis of the
population size determined by direct cell counting techniques,
including the use of microscopy, DNA quantification, phospholipid
fatty acid analysis, quantitative PCR, protein analysis, etc. The
identification of the genera and/or species of one or more members
of the microorganism consortium by genetic analysis may also be
conducted. For example, an analysis of the DNA of the
microorganisms may be done where the DNA is optionally cloned into
a vector and suitable host cell to amplify the amount of DNA to
facilitate detection. In some embodiments, the detecting is of all
or part of ribosomal DNA (rDNA), of one or more microorganisms.
Alternatively, all or part of another DNA sequence unique to a
microorganism may be detected. Detection may be by use of any
appropriate means known to the skilled person. Non-limiting
examples include restriction fragment length polymorphism (RFLP) or
terminal restriction fragment length polymorphism (TRFLP);
polymerase chain reaction (PCR); DNA-DNA hybridization, such as
with a probe, Southern analysis, or the use of an array, microchip,
bead based array, or the like; denaturing gradient gel
electrophoresis (DGGE); or DNA sequencing, including sequencing of
cDNA prepared from RNA as non-limiting examples. The identification
of putative metabolic functions that are encoded in the DNA of
individual organisms may also be conducted by employing Single Cell
Whole Genome Sequencing (SC-WGS). The isolation of hundreds of
individual cells in a sample from the geologic formation may be
achieved. Hundreds of individual cells may be isolated using
fluorescence-activated cell sorting to separate and deposit each
cell into its own well in a microtiter plate. The deposited cell
may be lysed, its entire genome amplified then screened for
identity using SSU rRNA census sequencing techniques and
appropriate amplified genomes selected for genome sequencing. Gene
annotation of SC-WGA samples can be done using the Integrated
Microbial Genomes (IMG) and RAST databases to provide a
comprehensive comparative analysis of putative gene function and
uncover the dominant metabolic and degradation pathways for the
most abundant and active bacteria within the samples. Additional
details of the biological analysis of the microorganisms is
described in co-assigned U.S. patent application Ser. No.
11/099,879, filed Apr. 5, 2005, the entire contents of which is
herein incorporated by reference for all purposes. By determining
characteristics of the microorganisms and dominant metabolic
functions, activation agents and nutrients may be provided that
target particular microorganisms or metabolic pathways in order to
stimulate or favor metabolism of the carbonaceous material to make
particular metabolic products or biogenic gases.
[0035] The method 100 may also include environmental analysis of
the formation environment. For example, extracted geologic
formation samples such as water, rock, and sediment bearing the
carbonaceous material may be analyzed using spectrophotometry, NMR,
HPLC, gas chromatography, mass spectrometry, voltammetry, and other
chemical instrumentation. The tests may be used to determine the
presence and relative concentrations of elements like dissolved
carbon, phosphorous, nitrogen, sulfur, magnesium, manganese, iron,
calcium, zinc, tungsten, cobalt, and molybdenum, among other
elements. The analysis may also be used to measure quantities of
polyatomic ions such as PO.sub.2.sup.3-, PO.sub.3.sup.3-, and
PO.sub.4.sup.3-, NH.sub.4.sup.+, NO.sub.2.sup.-, NO.sub.3.sup.-,
and SO.sub.4.sup.2-, among other ions. The quantities of vitamins,
and other nutrients may also be determined. An analysis of the pH,
salinity, oxidation potential (Eh), and other chemical
characteristics of the formation environment may also be performed.
Additional details of chemical analyses that may be performed are
described in co-assigned PCT Application No. PCT/US2005/015259,
filed May 3, 2005; and U.S. Pat. No. 7,426,960, filed Jan. 30,
2006, of which the entire contents of both applications are herein
incorporated by reference for all purposes.
[0036] Once access to the geologic formation is available, a
mixture may be provided 115 to stimulate the production of biogenic
gas (e.g., methanogenesis). The mixture may take the form of an
emulsion that incorporates one or more activation agents and/or
nutrients that are provided to the geologic formation. Techniques
for providing the mixture 115 may include direct injection
processes that pump and/or pour the mixture into the formation
environment.
[0037] The mixture may be non-homogeneous or homogeneous, and may
include multiple phases, including solid and liquid phases, and two
or more liquid phases. Exemplary mixtures having two or more liquid
phases may include emulsions that have one or more dispersed phases
surrounded by a continuous phase. The lack of miscibility that
causes the separate liquid phases may be due to different
polarities of the liquids. For example, a dispersed liquid phase
may be non-polar while the continuous phase is polar. Conversely
the dispersed phase may have a polar liquid while the continuous
phase is made from a non-polar liquid.
[0038] Exemplary emulsions may include oil-in-water (O/W) emulsions
that have a non-polar dispersed phase incorporated into a
continuous phase that include polar water molecules. They may also
include water-in-oil (W/O) emulsions where droplets of polar water
or an aqueous solution are dispersed in a non-polar
hydrocarbon-containing continuous phase. The emulsions may be
classified as microemulsions and/or nanoemulsions if the size of
the dispersed-phase droplets are the requisite size. The emulsion
may be a single emulsion containing two-phases, such as O/W, or may
alternatively, in some embodiments, be a multiple emulsion
including an emulsion contained in a separate continuous phase,
such as W/O/W for example. The mixture may further contain
surfactants and/or emulisifiers that slow or prevent the dispersed
phases from coagulating and/or forming a separate layer of the
mixture.
[0039] The activation agents and/or nutrients may be dissolved in
the one or more dispersed phases, the continuous phase, or both.
For example, the agents/nutrients may be soluble in a polar solvent
such as water (i.e., an aqueous phase), or a non-polar solvent such
as found in an "oil" phase. Depending on whether the emulsion is
(1) oil-in-water or (2) water-in-oil, the agents/nutrients that are
soluble in the aqueous phase would be found in the continuous phase
of (1), and dispersed phase of (2), respectively. Agents and
nutrients that are at least partially soluble in both polar and
non-polar solvents may be found in both the dispersed and
continuous phases of the emulsions. Examples may further include
agents and nutrients that are partially dissolved in one or more of
the liquid phases of the emulsion, and that also have a solid phase
component suspended and/or precipitated from the liquid phases.
[0040] In exemplary emulsions that include polar aqueous phases and
a non-polar (e.g., "oil") phase, a non-polar "oil" phase may
include compounds having at least a non-polar,
hydrophobic/lipophilic moiety such as a long chain hydrocarbon.
Examples of these non-polar compounds may include mineral oils,
essential oils, and organic oils, among other types of oils. They
may further include lipids and fatty acids that include non-polar,
hydrophobic hydrocarbon tails. Exemplary fatty acids may include
naturally occurring, saturated and/or unsaturated fatty acids such
as myristoleic acid, palmitoleic acid, sapienic acid, oleic acid,
linoleic acid, .alpha.-linolenic acid, arachidonic acid,
eicosapentaenoic acid, erucic acid, docosahexaenoic acid,
ricinoleic acid, etc., among other fatty acids having one or more
double-bonds between carbon atoms in the hydrocarbon chains, and
including configurations with hydrogen atoms being located on the
same or opposite sides of the double bond, such as with cis- or
trans-configurations of the acids. Exemplary saturated fatty acids
may include lauric acid, myristic acid, palmitic acid, stearic
acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid,
etc., among other fatty acids that have no double bonds and are
saturated with hydrogen atoms. Some of the possible combinations of
acids that may be used in the non-polar phase may be from naturally
occurring fats and oils, and may include animal fats including
lard, duck fat, butter, as well as vegetable fats including coconut
oil, palm oil, cottonseed oil, wheat germ oil, soya or soybean oil,
olive oil, corn oil, sunflower oil, safflower oil, hemp oil, canola
oil, among others. Other possible combinations may include
engineered formulations that have been shown to remain dispersed in
oil-in-water emulsions for particular periods of time without
creaming or separation of the dispersed non-polar phase.
[0041] Polar phase compounds may include water, or aqueous
solutions incorporating salts, sugars, proteins, amino acids,
chlorogenic acids, protein hydrolyzates, various cell extracts such
as yeast extract, algal extracts, or other compounds including
volatile fatty acids, or acids such as acetic acid, propionate,
butyrate, oxyphosphorous acids, etc. Additional exemplary polar
phase compounds may include formamide, dimethyl sulfoxide, and
ferulic acid among others. The included algal extracts may include
Chlamydomonaas spp., or Spirulina spp., for example.
[0042] A compound that acts as a nutrient or activation agent may
be contained within one or more phases of the mixture that is
provided 115 to the geologic formation. The compound may stimulate
the microorganisms to metabolize carbonaceous material in the
formation into biogenic gas, such as methane, or into intermediate
metabolites that may further be metabolized into biogenic gases.
The activation agent may contain various compounds for stimulating
microorganisms in the formation environment. Activation agents
provided may include phosphorous compounds, acetate compounds, or
other nutrients for the microorganisms.
[0043] The phosphorus compounds may include phosphorus compounds
(e.g., PO.sub.x compounds were x is 2, 3 or 4), such as sodium
phosphate (Na.sub.3PO.sub.4) and potassium phosphate
(K.sub.3PO.sub.4), as well as monobasic and dibasic derivatives of
these salts (e.g., KH.sub.2PO.sub.4, K.sub.2HPO.sub.4,
NaH.sub.2PO.sub.4, Na.sub.2HPO.sub.4, etc.). They may also include
phosphorus oxyacids and/or salts of phosphorus oxyacids. For
example, the phosphorus compounds may include H.sub.3PO.sub.4,
H.sub.3PO.sub.3, and H.sub.3PO.sub.2 phosphorus oxyacids, as well
as dibasic sodium phosphate and dibasic potassium phosphate salts.
The phosphorus compounds may also include alkyl phosphate compounds
(e.g., a trialkyl phosphate such as triethyl phosphate), and
tripoly phosphates. The phosphorus compounds may further include
condensed forms of phosphoric acid, including tripolyphosphoric
acid, and pyrophosphoric acid, among others. They may also include
the salts of condensed phosphoric acids, including alkali metal
salts of tripolyphosphate (e.g., potassium or sodium
tripolyphosphate), among other salts, and may also include oxides
of phosphorus (e.g., phosphorus trioxide, pentoxide, etc.), among
other compounds.
[0044] Examples of the acetate compounds may include acetic acid,
and/or an acetic acid salt (e.g., an alkali metal salt of acetic
acid, an alkali earth metal salt of acetic acid, sodium acetate,
potassium acetate, etc.), among other acetate compounds. Other
activation agents that may be provided include nutrients such as
yeasts and yeast extracts, and may include digests and extracts of
commercially available brewers and bakers yeasts. Other activation
agents may include nutrients including carboxylate compounds,
proteins, hydrogen release compounds, minerals, metal salts, and/or
vitamins, among other components. Catalysts may also be provided in
the emulsions to activate the microorganisms or particular
metabolic pathways. Still other compounds that may be included in
the emulsion include cyclic and aromatic compounds that may include
either or both of an ether linked group and an ester linked group,
and may include vanillin and syringic acid, among other compounds
and acids with a phenol group or other aryl group, and functional
groups that may include, in some embodiments, hydroxyl groups,
carboxylates, aldehydes, ethers, esters, etc., among others.
[0045] The emulsion may be provided 115 in several separate
applications over time as opposed to a single application. These
separate applications may provide multiple stages of activation or
stimulation over a period of time that may be monitored either
through the rate of production of biogenic gas, or alternatively
through in situ measurements of the concentrations of the
activation agent or a metabolic byproduct produced during the
conversion of the carbonaceous material. Additionally, these
introductions may be made to the formation over the course of the
activation period to maintain a certain concentration level or
range of the activation agent in the formation.
[0046] Once the mixture has been formed and provided, it may be
dispersed through the geologic formation 120. The dispersion of the
mixture may be done using a variety of techniques, such as
high-pressure pumping that forces the mixture to permeate the
formation environment. The dispersion pattern of a mixture's agents
and/or nutrients with respect to the formation and the carbonaceous
material may be based at least in part on how the liquid phases are
emulsified and how the agents/nutrients are dissolved in the liquid
phases. For example, in a mixture that is an oil-in-water emulsion
having the agent/nutrient dissolved in the non-polar, dispersed
"oil" phase, the agent/nutrient may be transported further by the
aqueous continuous phase across the carbonaceous material before
being absorbed. Moreover, when the same emulsion encounters native
formation water in contact with the carbonaceous material, the
distribution of the non-polar dispersed phase may be more localized
along the boundary of the formation water and carbonaceous
material. It may also distribute the dispersed phase over a larger
area of the carbonaceous material at the water-material boundary.
In this example, more agent/nutrient may be supplied to the
carbonaceous material by localizing the non-polar dispersed phase
close to the surface of the material instead of diluting it
throughout the adjacent formation water.
[0047] As the mixture is introduced to the formation, it may make
direct contact with carbonaceous material and/or indirect contact
by first being dispersed in the formation before reaching the
carbonaceous material. The microorganisms may be found in a variety
of locations in the geologic formation, including the carbonaceous
material and/or the formation water, among other locations. The
mixture may be dispersed within the geologic formation 120 in order
to reach the microorganisms that may then be stimulated by the
activation agent. The microorganisms may access the activation
agent directly, or in some embodiments, may consume the non-polar
dispersed phase to access the activation agent. In consuming or
metabolizing the non-polar dispersed phase, the microorganisms may
be provided with an additional nutrient source in addition to the
activation agent. Metabolizing the non-polar dispersed phase may
produce an acetate compound that may be utilized by the same or
different microorganisms within the formation environment as an
additional nutrient source to stimulate the microorganisms.
Metabolizing the non-polar dispersed phase may also produce
hydrocarbons that are similar in nature and structure to the
carbonaceous material being converted by the microorganisms, and
may produce metabolic products including biogenic gases, among
other products.
[0048] Method 100 may also include measuring the rate of biogenic
gas production 125. For the biogenic gas products, the partial
pressure of the product in the formation may be measured.
Measurements may also be made before providing the activation
agent, and a comparison of the product concentration before and
after the activation agent may also be made. The biogenic gas
products may also be recovered from the formation environment, or
maintained within the formation environment at a concentration
range that has been found to stimulate the microorganisms to
generate more of the biogenic gas product. Based on the rate of
biogenic gas production, more or less activation agents or
nutrients may be added to the geologic formation in order to
maximize biogenic gas output.
[0049] FIG. 2A shows a flowchart illustrating a method 200 of
producing a multiple emulsion incorporating one or more stimulating
compounds according to embodiments of the invention. The method 200
may include providing both a polar aqueous fluid and a non-polar
fluid 210. The non-polar fluid may be any of the previously
mentioned oils or fatty acids, and may additionally be a fluid at
least partially immiscible in water. The added compound may be
combined with a first portion of the polar fluid 212. The compound
may be dissolved, mixed, suspended, or otherwise contacted with the
fluid. The method 200 may also include adding an oil-soluble
surface active agent ("surfactant"), and/or emulsifier to the
non-polar fluid. The surfactant may be chosen based on its
hydrophilic-lipophilic balance ("HLB") number, which is an
indication of the hydro- or lipophilicity of the surfactant. A
higher HLB value describes a compound that is more hydrophilic,
while a lower HLB value describes a compound that is more
lipophilic. The surfactant used in the emulsion may have a lower
HLB value, thus being more lipophilic, and exemplary surfactants
may have HLB values below or about 10, below or about 8, below or
about 6, below or about 4, or below or about 2.
[0050] Once the surfactant has been properly combined with the
non-polar fluid, the method 200 may include producing a primary
emulsion by adding the portion of the polar fluid containing the
nutrient to the non-polar fluid with the surfactant 214. The
emulsion may be produced by agitating the combined fluids in a
blender, magnetic mixer, or another device that applies relatively
high shear to the emulsion components. The emulsion may be further
stabilized by processing the emulsion in a colloid mill or
homogenizer, or a device that applies a very high level of
hydraulic shear to the emulsion. This produced emulsion may have
macro, micro, or nano-sized particles depending on the requirements
of the particular application. The emulsion may also be produced in
a device that raises the temperature of the components above room
temperature during the processing. Raising the temperature of the
emulsion may reduce the viscosity of the dispersed phase which may
facilitate emulsification of the components. The temperature of the
components may be raised during the processing to above or about
25.degree. C., above or about 50.degree. C., above or about
70.degree. C., or above or about 90.degree. C.
[0051] After the primary emulsion has been produced and stabilized,
the method 200 may further include making a multiple emulsion. A
second portion of a polar fluid, which may include a surfactant
and/or emulsifier, may be used as a continuous phase in the
multiple emulsion. The surfactant may have a higher HLB value,
making it more hydrophilic. For example, the surfactant may have an
HLB value above or about 8, above or about 10, above or about 13,
above or about 15, or above or about 18.
[0052] The method 200 may also include adding the primary emulsion
to the second portion of the polar fluid with the surfactant to
produce a multiple emulsion 216. The multiple emulsion may be
produced by agitating the combined fluids using a relatively low
shear device to avoid separating the primary emulsion. For example,
a blender or magnetic mixer may be utilized to produce both the
primary emulsion and the secondary emulsion. The speed used for the
secondary emulsion may be lower than the speed used for the primary
emulsion, and may be, for example, 50% or less of the speed used in
the primary emulsion. The degree of shear used in the preparation
of the primary and secondary emulsion may vary depending on the
polar and non-polar fluids and surfactants used, as well as the
types of encapsulated compounds. A high-shear device may be used to
produce the primary emulsion, such as a high-pressure homogenizer.
A low-shear device may be used to create the secondary emulsion,
such as a combined orifice device, or a device utilizing a membrane
emulsification technique. Regardless of the devices used for
preparing the emulsions, the osmotic gradient between the two
portions of the aqueous fluids may be maintained at a low-enough
threshold such that the encapsulated aqueous portion does not pass
through the non-polar fluid phase into the continuous aqueous
phase. The osmotic pressure between the two aqueous phases may be
adjusted by changing the concentrations of the fluids, which may be
done, for example, with the addition of the surfactants, or
alternatively by adding various salts, sugars, sugar esters, and/or
other compounds.
[0053] The surfactants used in the emulsions may be selected based
on the compounds provided to the carbonaceous material. Surfactants
used may include cationic surfactants, such as benzalkonium
chloride; anionic surfactants, such as alkali or amine soaps, and
detergents; and/or Zwitterionic surfactants, such as CHAPS or
sultaines, amino and imino acids, or phosphates such as
lecithin.
[0054] The emulsions may also include nonionic emulsifying agents.
Nonionic emulsifiers that may be used in either of the primary
emulsion or the secondary emulsion may include, for example,
polymeric and non-polymeric compounds, as well as fatty alcohols,
such as cetyl alcohol, stearyl alcohol, cetostearyl alcohol, and
oleyl alcohol, among others. Other examples of nonionic surfactants
that may be used in the formation of the emulsions include glyceryl
monostearate, polyoxyethylene monooleate or monostearate or
monolaurate, and other polyoxyethylene glycol alkyl ethers (PEG-400
emulsifiers), polyoxypropylene glycol alkyl ethers, glucoside alkyl
ethers, potassium oleate, sodium lauryl sulfate, and sodium oleate,
among others. Still other examples of nonionic emulsifiers that may
be used in the formation of the emulsions may include sorbitan
alkyl esters (Spans), including sorbitan monolaurate (Span 20),
sorbitan monopalmitate (Span 40), sorbitan monostearate (Span 60),
sorbitan tristearate (Span 65), sorbitan monooleate (Span 80),
sorbitan sesquioleate (Span 83), and sorbitan trioleate (Span 85),
among others. Other examples of nonionic surfactants that may be
used in the formation of the emulsions may include triethanolamine
oleate, polyoxyethylene derivatives of sorbitan alkyl esters
(Tweens), including polyoxyethylene sorbitan monolaurate (Tween
20), polyoxyethylene sorbitan monolaurate (Tween 21),
polyoxyethylene sorbitan monopalmitate (Tween 40), polyoxyethylene
sorbitan monostearate (Tween 61), polyoxyethylene sorbitan
tristearate (Tween 65), polyoxyethylene sorbitan monooleate (Tween
80), polyoxyethylene sorbitan monooleate (Tween 81), and
polyoxyethylene sorbitan trioleate (Tween 85), among others.
[0055] The emulsions may also incorporate natural emulsifying
agents, and/or hydrocolloids. For example, the emulsions may
include vegetable derivatives, such as acacia, tragacanth, agar,
pectin, carrageenan, lecithin, and others; or animal derivatives,
such as gelatin, lanolin, and cholesterol, among others.
Semi-synthetic agents such as methylcellulose, and
carboxymethylcellulose, and fully synthetic agents such as
Carbopols may also be used.
[0056] Solid particle emulsifiers may be used to form a particulate
layer around the dispersed phase. These agents may include
dispersed particles of bentonite, veegum, hectorite, magnesium
hydroxide, magnesium trisilicate, and aluminum hydroxide, among
others.
[0057] The method 200 may also include transporting the emulsion to
the geologic formation 218. The transporting may be done in such a
way as to maintain the stabilized emulsion, such as by utilizing
transportation equipment and vehicles that will minimize changes in
temperature or pressure on the emulsion. In some embodiments, the
emulsion may be made at the site of the geologic formation where
the compound may be injected, such that transportation may not be a
concern. Where the emulsion must be transported over long
distances, additional surfactants, mixing transportation vessels,
or different amounts of the surfactants used in the preparation of
the emulsion may be utilized to produce a stable emulsion.
[0058] The emulsion may be injected into the geologic formation 220
to contact the carbonaceous material with the encapsulated
compound. The injection may include a pumping mechanism to force
the emulsion into the geologic formation, and disperse the emulsion
over a greater area of the formation. Alternatively, the emulsion
may be poured into the formation and allowed to remain at the site
of the injection. Depending on the relative amounts of the polar
and non-polar fluids used in the emulsion, the non-polar fluid may
allow the activation agent to disperse over a larger area because
the non-polar fluid may not be absorbed into the carbonaceous
material, formation water, or the formation itself.
[0059] As shown in FIG. 2B, a method 230 is described in which a
paused or staged dispersion may be created from the ways in which
the nutrients or other compounds are incorporated within the
emulsion. The method 230 may provide a polar and a non-polar fluid
240 as previously described. The activation agent or nutrient
compound may be disposed 242 within the polar fluid. Portions of
the polar fluid containing the compound may be used both within the
non-polar phase of the mixture in the first emulsion produced 244,
as well as for the continuous phase used for the multiple emulsion
246. This emulsion may then be transported to the geologic
formation 248. Microorganisms may access this portion of the
activation agent directly when the mixture has been injected 250
into the carbonaceous material. The non-polar phase may be consumed
by the microorganisms as a nutrient source, and the consumption of
the non-polar phase may release the portion of the activation agent
or nutrient contained therein. By providing the portion of the
activation agent as encapsulated within the non-polar dispersed
phase, the release of this portion of the activation agent may
occur at a time later than that at which the portion of the
activation agent disposed within the continuous aqueous phase was
consumed.
[0060] A paused or delayed dispersion may allow greater amounts of
nutrients or activation agents to be delivered at lower
concentrations over longer periods of time to the carbonaceous
material than could otherwise be provided. Adding large amounts of
a specific compound to the geologic formation in one dose may in
some circumstances create deleterious effects including the death
or deactivation of microorganisms. However, by creating multiple
emulsions that stage the release of smaller portions of a compound
at a time, an overall greater amount of the compound may be used in
a single injection. The larger amounts may allow fewer applications
of the activation agents to the geologic formation, which may
provide for improved consistency of the applications to create a
more controlled stimulation of the microorganisms within the
formation.
[0061] Paused or staged dispersion may allow time for the
microorganisms to grow or activate before the additional portion of
the activation agent may be released. For example, a greater
portion of the activation agent may be contained in the non-polar
dispersed phase than in the aqueous continuous phase. Thus, after
the microorganisms are activated by the portion of the nutrient
contained in the continuous phase, they may be provided with a
period of time in which they may grow as a consortium. The
non-polar dispersed phase may be consumed as a nutrient by the
microorganisms, the consumption of which may release equivalent or
greater portions of the activation agent. This second dosing with
larger amounts of activation agent may be more effectively utilized
by a larger and/or more robust microorganism population that has
been given time to grow and acclimate to metabolizing coal carbon
to new biogenic methane gas.
[0062] Alternatively, a greater portion of the activation agent may
be contained in the polar continuous phase of the emulsion, and a
lesser amount within the non-polar dispersed phase. Thus, after the
greater portion of the activation agent has been utilized to
activate the microorganisms, and the microorganisms have penetrated
the non-polar dispersed phase, either by its consumption or by the
breakdown of the emulsion due to separation, the lesser amount of
the activation agent may be utilized to maintain the activation of
the microorganisms during their metabolizing of the carbonaceous
material. A potential cost savings may be realized by providing the
correct proportions of nutrients or activation agents based on the
characteristics or dynamics of the microorganisms. Additionally,
fewer follow-on introductions of nutrients or activation agents may
be required.
[0063] As shown in FIG. 2C, a method 260 is described in which a
multiple emulsion may be created that contains both an activation
agent and a nutrient. By providing both an activation agent as well
as a nutrient source to a microorganism population, the
microorganisms may be capable of increased growth and ability to
convert carbonaceous material due to a compound effect provided by
the combination of elements. The method 260 may include the step of
providing a polar and non-polar fluid 270, substantially as
described previously. A nutrient may be combined 274 within a first
portion of a polar fluid, and an activation agent may be combined
276 with a second portion of the polar fluid. An emulsion may be
produced 278 within the non-polar fluid with the portion of the
polar fluid containing the nutrient. The portion of the polar fluid
containing the activation agent may then be used as the continuous
phase of a multiple water-in-oil-in-water emulsion 280 containing
the emulsion produced with the nutrient as the dispersed phase. The
emulsion may then be transported to the geologic formation 282, and
when introduced to a carbonaceous material 284, the activation
agent located in the continuous aqueous phase may stimulate the
microorganisms to metabolize the carbonaceous material. Then, at a
later point than the stimulation by the activation agent, the
microorganisms may either consume as a nutrient source, or surpass
due to separation, the non-polar dispersed phase, thereby releasing
the nutrient contained therein for consumption by the
microorganisms.
[0064] FIGS. 3A-C show methods of forming a single emulsion
including a polar fluid and a non-polar fluid. FIG. 3A shows a
method 300 in which a polar and non-polar fluid may be provided
310, and a compound may be incorporated into the polar fluid 312.
The polar fluid may be dispersed within the non-polar fluid
producing an emulsion 314. This water-in-oil type emulsion may then
be directly injected into the geologic formation to contact the
carbonaceous material. In some embodiments, the non-polar
continuous phase may be consumed or metabolized by the
microorganisms as a nutrient source. The metabolic products created
by the breakdown of the non-polar continuous phase may include
acetate compounds, as well as other hydrocarbons including biogenic
gases, among other compounds. Metabolizing the non-polar continuous
phase may release the nutrient or activation agent contained in the
polar aqueous phase, which may be further consumed to stimulate the
microorganisms to convert the carbonaceous material into biogenic
gas. Alternatively, as shown in FIG. 3B, a method 320 is described
that also may provide a polar and non-polar fluid 330. The compound
may be combined with the non-polar fluid 332, which may then be
encapsulated in a polar aqueous fluid 334 and injected into a
geologic formation as described previously. In another alternative,
a compound may be disposed in at least one or both of the emulsion
phases, which may allow a staged or paused release of the compound
to the microorganisms within the formation as discussed above.
[0065] As shown in FIG. 3C, a method 340 may provide a polar and
non-polar fluid 350, and may include suspending microorganisms
within the polar fluid 352. This polar fluid may then be
encapsulated within a non-polar fluid to produce an emulsion 354.
This emulsion may be combined with a polar fluid to produce a
multiple emulsion, or alternatively, may be injected directly into
the geologic formation. In another alternative, the polar aqueous
continuous phase of the multiple emulsion may additionally contain
other nutrients or activation agents to be consumed by the
encapsulated microorganisms or by microorganisms native to the
formation.
[0066] The geologic formation environment may be anaerobic, and
thus, the production and transportation of the emulsions may occur
under anaerobic conditions. For example, the encapsulated
microorganisms may be contained in an anaerobic aqueous fluid used
in the primary emulsion. Anaerobic fluid is characterized as having
little or no dissolved oxygen, in general no more than 4 mg/L,
preferably less than 2 mg/L, and most preferably less than 0.1
mg/L, as measured at 20.degree. C. and 760 mmHg barometric
pressure. The microorganisms may be from the same geologic
formation to which they will be injected, and are being reinjected
in order to be dispersed to alternative portions of the geologic
formation, or to a broader area of the geologic formation.
Alternatively, the microorganisms may be from a different geologic
formation and are being transported to the geologic formation
containing the carbonaceous material sought to be converted into
biogenic gas. In these or other cases, the microorganisms may have
been modified, for example genetically, prior to their being
injected or reinjected into the geologic formation. In order to
maintain an anaerobic environment for the microorganisms, equipment
and vehicles that are oxygen impermeable may be used, otherwise the
microorganisms may be damaged in the process.
[0067] FIG. 4 shows a block diagram for selected components of a
system 400 for creating a multiple emulsion according to
embodiments of the invention. Low-HLB surfactant 411 may be
incorporated into non-polar fluid 412 that may be added to mixing
vessel 410. Activation agent 403 may be incorporated into polar
aqueous fluid 407, that may then be incorporated into non-polar
fluid 412 in mixing vessel 410 to create a primary emulsion. Mixing
vessel 410 may be, among other equipment, a high-shear mixer,
blender, or mortar that may create macro, micro, and/or
nanoemulsions. The primary emulsion may be further stabilized and
refined in high-shear device 420, such as a high-pressure
homogenizer, or a colloid mill through which the primary emulsion
may be passed. Either or both of the mixing vessel 410 and the
high-shear device 420 may be heated to a temperature to facilitate
the production of the primary emulsion. Alternative embodiments may
include using only one of the mixing vessel 410 and high-shear
device 420.
[0068] High-HLB surfactant 421 may be incorporated into polar
aqueous fluid 422 in low-shear device 430. The primary emulsion may
be added to the polar aqueous fluid 422 in low-shear device 430 to
create a multiple emulsion 440. Low-shear device 430 may include a
blade-type or magnetic mixer or blender that operates at a speed
lower than mixing vessel 410. Alternatively, low-shear device 430
may include a membrane through which the primary emulsion may be
passed or pressed. Continuous phase, polar aqueous fluid 422 may be
flowed across the membrane of the low-shear device separating
droplets of the primary emulsion and creating a secondary, multiple
emulsion 440.
[0069] FIG. 5 shows selected components of a system 500 for
supplying an encapsulated nutrient to a formation environment
according to embodiments of the present invention. Multiple
emulsion 440 may be produced at geologic formation 510. The
multiple emulsion 440 may be transported to the geologic formation
510 or created at the site of the geologic formation 510. Multiple
emulsion 440 may be injected into geologic formation 510 via pipes
or wells 520 either previously located in or presently placed in an
access point in the geologic formation 510. Pumping mechanism 535
may also be utilized to inject the multiple emulsion into the
geologic formation 510 to disperse the multiple emulsion 440 over a
greater area of the geologic formation. Additionally, pumping
mechanisms may transport make up water to the well head that may
gravity feed into the well 520. A separate pumping mechanism may
supply a steady stream rate of emulsion 440 to the gravity feed
water stream going into well/pipes 520.
[0070] Alternatively, system 500 may include transferring multiple
emulsion 440 into a vehicle 540 to be delivered to one or more
locations at a geologic formation 510. Vehicle 540 may transport
the multiple emulsion 440 to alternative geologic formations. When
the multiple emulsion 440 is maintained under anaerobic conditions,
oxygen impermeable pipes 530 and vehicles 540 may be utilized to
prevent the introduction of oxygen to the emulsion 440.
[0071] Prior to transportation in vehicle 540, additional
emulsifiers, surfactants, or stabilizers may be added to the
multiple emulsion 440 in order to facilitate transporting the
emulsion in its dispersed form, and to resist separation of the
phases. When vehicle 540 arrives at the geologic formation at which
the multiple emulsion 440 is to be introduced, multiple emulsion
440 may be added to mixing device 550 to more uniformly disperse
any of the primary emulsion that has separated from multiple
emulsion 440.
EXPERIMENTAL
[0072] Experiments were conducted to determine the stability of the
emulsion in the presence and absence of coal particles. Into
non-sterile micro-centrifuge tubes, emulsified soybean oil emulsion
was pipetted in varying dilutions with water filtered by reverse
osmosis to a final volume of 1000 mL. Two identical sets were made.
The first set contained emulsified oil only, and was examined at
several concentrations including 100%, 50%, 10%, and 1%. The second
set was prepared by adding 0.5 g of <600 .mu.m ground Anderson
coal to the tubes along with the emulsified oil. After liquid
additions, all tubes were tightly capped and blended by vortex
mixer prior to incubation over night at room temperature. The
samples were viewed under magnification using direct light/oil
emersion microscopy. Distinct round emulsion micelles were observed
at similar numbers in both the coal amended and unamended samples
within the same dilution level. This was true at all dilution
levels, and both sets of samples were then monitored at set periods
of time to determine if and when separation occurred.
[0073] Microcosms tests were performed using fresh coal bed methane
water from the Powder River Basin with and without 0.5 grams of
ground Anderson coal. Emulsified oil amendment was tested for its
ability to activate methanogenic coal conversion and compared to
various nutritional controls. A microscopic examination of samples
from methanogenically active microcosms tests showed the presence
of emulsified oil micelles at significantly reduced particle
numbers at 150 days after test initiation. These results suggest
that amendment materials contained within the emulsion micelles may
still be available for long-term slow-release to microorganism
consortiums. Additionally, the oil that may be included within the
emulsion is also available to the microorganisms for
conversion.
[0074] Experiments conducted also compared methane production by
microorganism consortiums being provided emulsified oil and various
other amendments. FIG. 6 is a chart detailing various amendment
compounds and methane produced over time in a controlled lability
experiment. In this experiment, no carbonaceous material, i.e.
coal, was provided to the microorganisms during the course of the
treatment. As shown, emulsion based amendments were provided in
addition to standard amendments as well as slow-release lactate
amendments. As can be identified, the two amendments of emulsified
oil produced significantly more methane at faster rates over the
experimental period than did any other amendment. Without being
limited to any specific theory, the inventors believe that fatty
acids of the emulsified oils undergo metabolism through beta
oxidation by which acetate units are cleaved from the long chain
hydrocarbons. The derived acetate can be utilized as an activation
agent to stimulate the microorganisms in the production of methane.
Additionally, the emulsions that also contained a phosphate and
yeast extract amendment produced substantially more methane over
the course of the procedure. This may provide both the activation
potential of the acetate source as well as the nutrients that can
be utilized over a longer period of time due to the
encapsulation.
[0075] A similar set of experiments was conducted to those
illustrated in FIG. 6 that compared methane production utilizing
various amendment compounds over time that included a carbonaceous
substrate. The results are included in FIG. 7. Similar to the
results reported for the lability experiment, the methane
production was significantly higher in the samples receiving
emulsified oil based amendments. Similar inferences can be made
from the results of the experiments containing carbonaceous
material as with the experiments without carbonaceous materials.
The difference between the two figures illustrates the carbonaceous
material metabolized by the microorganisms in FIG. 7 that may
result in the increased methane production.
[0076] FIG. 8 illustrates acetate turnover over time in an
additional lability experiment performed with similar amendment
samples. As shown the emulsified oil based samples produced acetate
that was initially accumulated in the system. However, instead of
producing a build-up of metabolic product, the released acetate was
consumed over a course of time for the experiment. Thus, the
microorganism consortium may consume the released acetate after
metabolizing the emulsified oil. Additionally, microorganisms that
may better utilize the acetate, such as acetoclastic methanogens,
may flourish as a result of the acetate available and grow to a
more significant portion of the consortium. As illustrated, the
emulsified oil including the phosphate and yeast extract produced a
greater initial amount of acetate in the system followed by a
faster utilization of the produced acetate by the consortium.
[0077] An additional experiment including carbonaceous material was
conducted with similar amendment samples to determine the amount
and degree of acetate turnover as shown in FIG. 9. As with the
methane production experiments, the inclusion of carbonaceous
material increased the amount of acetate produced in the initial
period of accumulation. Also, the emulsion including phosphate and
yeast extract produced a faster turnover of the accumulated acetate
than did the sample including the emulsified oil alone. This effect
may be a result of the nutrient benefit provided by the phosphate
and yeast amendment.
[0078] Considering FIGS. 7 and 9 together indicates that the
acetate accumulated initially is consumed, followed by enhanced
production of methane. For example, FIG. 9 illustrates that after
an initial accumulation of acetate during the first 50 days, the
acetate is consumed. This consumption correlates to the increase of
methane production beginning at roughly day 50 of FIG. 7. This
phenomenon may be a result of acetoclastic methanogenic organisms
increasing in population followed by a period of activity during
which the organisms consume the acetate thereby producing methane.
The available acetate may activate the growth of the consortium,
and release of the phosphate and yeast extract when the emulsified
oil is metabolized may provide nutrients for stimulating methane
production. As such, the encapsulated nutrients may be utilized in
an improved fashion as compared to a bolus of nutrients as they may
be consumed over a longer period of time due to the encapsulation.
Thus, less of the nutrients may be needed due to a more efficient
utilization by the consortium.
[0079] An additional experiment creates additional emulsion
products useful according to the present technology. Polyglycerol
polyricinoleate ("PGPR") was blended into soybean oil at 8% by
weight (8 g PGPR:100 g Soybean oil) until the solution appeared
visibly homogenized in a first solution. Xanthan gum was blended
into a solution of yeast extract, acetate, and phosphate at 0.2% by
weight to make a second solution. Equal parts of the first and
second solutions were blended in bursts at high speed (>5000
RPM) until a viscous product was formed as a third product.
[0080] An additional solution of yeast extract, acetate, and
phosphate was added to a fresh vessel and stirred at room
temperature. To the stirring solution was added 0.5% by weight of a
1:1 ratio of Tween 20 and Tween 80. The solution was stirred for
several minutes at low speed (<500 RPM) until bubbles developed.
The third product was slowly added to the solution while mixing
continued. The final product was blended for several minutes more
at low to moderate speed (<1000 RPM) to avoid incorporating air
into the mixture.
[0081] FIG. 10 shows a microscope image of the formed emulsions at
400.times. magnification directly after production. The graph shows
formed emulsion droplets at 5 .mu.m and 20 .mu.m respectively as
indicated, and shows the incorporation of yeast extract, acetate,
and phosphate solution within the oil solution. FIG. 11 shows the
same solution after 24 hours has elapsed showing that the yeast
extract, acetate, and phosphate droplets have coalesced into cores
of agent within the oil droplets. FIG. 12 shows additional views of
emulsion species located within certain mixtures of the present
technology. Droplets 1210 show large cores of the extract solution
that are coalesced within the oil droplets. Droplets 1220 show
water-in-oil nanodroplets that are dispersed throughout the
mixture. Droplets 1230 show WOW particles produced in the
mixture.
[0082] It will be understood by one of ordinary skill in the art
that the embodiments may be practiced differently in different
environments. For example, one environment may include wireless
control of processes or machinery from a remote terminal that can
provide automatic instruction, while another environment may
include no such control and is operated locally at the site of the
process based on then current operation conditions.
[0083] Additionally, it will be understood by one of ordinary skill
in the art that the embodiments may be practiced without these
specific details. For example, machinery, systems, networks,
processes, and other elements in the invention may be shown as
components in block diagram form in order not to obscure the
embodiments in unnecessary detail. In other instances, well-known
processes, structures, and techniques may be shown without
unnecessary detail in order to avoid obscuring the embodiments.
[0084] Also, it is noted that individual embodiments may be
described as a process which is depicted as a flowchart, a flow
diagram, a data flow diagram, a structure diagram, or a block
diagram. Although a flowchart may describe the operations as a
sequential process, many of the operations can be performed in
parallel or concurrently. In addition, the order of the operations
may be rearranged. A process may be terminated when its operations
are completed, but could have additional steps not discussed or
included in a figure. Furthermore, not all operations in any
particularly described process may occur in all embodiments. A
process may correspond to a method, a system, a procedure, etc.
[0085] As used herein and in the appended claims, the singular
forms "a", "an", and "the" include plural references unless the
context clearly dictates otherwise. Thus, for example, reference to
"a process" includes a plurality of such processes, and reference
to "the nutrient" includes reference to one or more nutrients and
equivalents thereof known to those skilled in the art, and so
forth.
[0086] Also, the words "comprise", "comprising", "include",
"including", and "includes", when used in this specification and in
the following claims, are intended to specify the presence of
stated features, integers, components, or steps, but they do not
preclude the presence or addition of one or more other features,
integers, components, steps, acts, or groups.
[0087] The description and examples above are not intended to limit
the scope, applicability, or configuration of the application to
only what has been described. It should be understood that various
changes may be made in the function and arrangement of elements
without departing from the spirit and scope of the invention as set
forth in the appended claims.
* * * * *