US20120255726A1

US20120255726A1 - In-situ microbial oxygen generation and hydrocarbon conversion in a hydrocarbon containing formation

Info

Publication number: US20120255726A1
Application number: US13/518,231
Authority: US
Inventors: Bartholomeus Petrus Lomans
Original assignee: Individual
Current assignee: Shell USA Inc
Priority date: 2009-12-24
Filing date: 2010-12-23
Publication date: 2012-10-11
Also published as: GB2488937A8; GB201210573D0; GB2488937B; AU2010334769B2; GB2488937A; CA2783297C; WO2011076925A1; AU2010334769A1; CA2783297A1

Abstract

A method for in-situ microbial oxygen generation in an underground hydrocarbon containing formation comprises: injecting into the formation an oxygen generating composition comprising thermophilic chlorate reducing micro-organisms, such as bacteria of the genus Archaeoglobus, Geobacillus and/or Thermus, which multiply at a temperature of at least 60° C.; and inducing the multiplied micro-organisms to convert the hydrocarbons and/or other pore fluid components in-situ into transportable or disposable products

Description

BACKGROUND OF THE INVENTION

The invention relates to a method for in-situ oxygen generation in a hydrocarbon containing formation.
Such a method is known from U.S. Pat. No. 5,163,510.
The method known from this prior art reference comprises:
injecting into the formation a fluid comprising a source of oxygen that chemically releases oxygen into the formation;
inducing micro-organisms present in the formation to multiply using the oil as their carbon source and the chemically produced oxygen in the injection water as their oxygen source; and
allowing the multiplied micro-organisms to convert oil from the environment.
In this known method the source of oxygen is provided by injecting water comprising an oxidizing compound selected from the group consisting of H₂O₂, NaClO₃, KClO₄, NaNO₃and combinations thereof, which are assumed to be chemically converted to result in oxygen. This assumption is based on the fact that oxygen generation from Microbial Chlorate Reduction was for the first time reported in 1996 by van Ginkel at al in 1996, Archives of Microbiology 166:321-326.
In accordance with the teachings of U.S. Pat. No. 5,163,510 the chemically generated oxygen is then used by microbes to convert hydrocarbons.
Limitations of the use of the known oxidizing compounds known from U.S. Pat. No. 5,163,510 for chemical oxygen generation are that H₂O₂may dissociate during or shortly after the injection process, and that chemical conversion of NaNO₃, NaClO₃and KClO₄do not generate oxygen at temperatures lower than 120° Celsius.
Moreover, the microbes Pseudomonas putida, Pseudomonas aeruginosa, Corynebacterium lepus, Mycobacterium rhodochrous and Mycobacterium vaccae disclosed in U.S. Pat. No. 5,163,510 are non-thermophilic micro-organisms, which are unable to reduce chlorate and/or multiply at temperature of at least 60° C. This will prevent the method known from U.S. Pat. No. 5,163,510 to be beneficial for application throughout an entire hydrocarbon containing formation as the ambient temperature in a hydrocarbon containing formation often exceeds 60° C.
The use of microbial chlorate reduction as mechanism for in-situ oxygen generation and thereby stimulating microbial activity using hydrocarbons as carbon and energy source has been reported for the bioremediation of hydrocarbon spills at ambient atmospheric temperatures in the following prior art references:

Coates et al., 1998, Nature 396(6713): 730
Coates et al., 1999, Applied Environmental Microbiology 65(12): 5234-5341
Coates et al., 2004, US patent 2004/0014196A1, which prior art references are collectively referred to as Coates et al (1998, 1999, 2004)
Tan et al., 2006, Biodegradation 17(1): 113-119
Mehboob et al., 2009: Applied Microbiology and Biotechnology 83(4): 739-747
Langenhoff et al., 2009, Bioremediation Journal, 13(4): 180-187

There is a need to provide an method for in-situ thermophilic microbial oxygen generation wherein a controlled amount of oxygen is microbiologically produced in-situ deeper in the hydrocarbon containing formation where the temperature is at least 60° C.
There is furthermore a need to provide an enabling process for the stimulation of in-situ thermophilic microbial conversion of hydrocarbons wherein oxygen is microbiologically produced from the injected oxygen source only at high temperature locations in a hydrocarbon containing formation where injected or indigenous micro-organisms encounter the injected electron acceptor in addition to an electron donor, such as hydrocarbons, volatile fatty acids, etc.
There is also a need for a method for thermophilic microbial oxygen generation through chlorate reduction at the oil water interface, in contrast to chemical generation of oxygen known from U.S. Pat. No. 5,163,510 that can also occur in oil-poor parts of the reservoir.
Utilization of microbes to enhance hydrocarbon recovery is hampered by the limited bioavailability and biodegradability of the hydrocarbons under hot reservoir conditions.
Thus there is also a need to provide a way to improve bioavailability and biodegradability in hot hydrocarbon containing formations where the ambient temperature is at least 60° C.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided a method for in-situ oxygen generation in an underground hydrocarbon containing formation, the method comprising injecting into the formation an oxygen generating composition which releases oxygen (O₂) by reduction of chlorate (ClO₃—), wherein:
the formation has a temperature of at least 60° C.;
the composition comprises thermophilic chlorate reducing micro-organisms, which multiply at an ambient temperature of at least 60° C.; and
the multiplied thermophilic chlorate reducing micro-organisms convert the hydrocarbons and/or other pore fluids in-situ into transportable or disposable products.
In an embodiment the thermophilic chlorate reducing micro-organisms comprise bacteria of the genus Archaeoglobus, Geobacillus and/or Thermus and use hydrogen (H) and electrons (e) provided by hydrocarbons, volatile fatty acids and/or other pore fluids in the formation followed by dismutation of chlorite (ClO₂ ⁻) by the micro-organisms on the basis of the reactions:
ClO₃ ⁻+2H⁺+2e->ClO₂ ⁻+H₂O
ClO₂ ⁻->Cl⁻+O₂
In a suitable embodiment the thermophilic chlorate reducing micro-organisms multiply at an ambient temperature of at least 80° C. and comprise bacteria of the genus Archaeoglobus fulgidis.
Optionally, the method according to the invention furthermore comprises:
injecting into the formation an oxygen generating composition, which comprise or generates chlorate in the formation and which releases oxygen (O₂) by thermophilic microbial reduction of chlorate (ClO₃ ⁻) by the micro-organisms, using hydrogen (H) and electrons (e) provided by the hydrocarbons, volatile fatty acids and/or other pore fluid components, such as oil & gas contaminants such as H₂S, thiophenes and mercaptanes, followed by dismutation of chlorite (ClO₂ ⁻) by micro-organisms on the basis of the reactions:
ClO₃ ⁻+2H⁺+2e->ClO₂ ⁻+H₂O
ClO₂ ⁻->Cl⁻+O₂;
inducing multiplication of the thermophilic chlorate-reducing micro-organisms (Archaeoglobus, Geobacillus, Thermus), other chlorate-reducing thermophilic micro-organisms and other micro-organisms that can use the hydrocarbons, volatile fatty acids and/or other pore fluid components (e.g. oil & gas contaminants as H₂S, thiophenes and mercaptanes) as their carbon source and/or electron donor and the injected composition or the oxygen generated by thermophilic chlorate reduction thereby as their electron acceptor and/or oxygen source; and
inducing the multiplied micro-organisms to convert the hydrocarbons and/or other pore fluid components in-situ into transportable products, such as in Microbial Enhanced Oil Recovery (MEOR) and/or ECBM Enhanced Coal Bed Methane (ECBM) processes.
The multiplied thermophilic micro-organisms generated in accordance with the method according to present invention may be used for in-situ conversion of coal, shale oil, oilshale, bitumen and/or a viscous crude oil into a synthetic crude oil with a reduced viscosity and/or to convert associated contaminants, such as H₂S, thiophenes and mercaptanes, into oxidized sulfur fractions that remain within the reservoir brine.
The method according to the invention may be used to improve bioavailability and biodegradability of hydrocarbons at thermophilic (60-120° C.) & anaerobic conditions in underground formations containing hydrocarbons, volatile fatty acids and other pore fluid components and micro-organisms, by the process of Thermophilic Microbial Chlorate Reduction. The process will generate oxygen in-situ that will enhance bioavailability and biodegradability, which subsequently will enables enhanced recovery of hydrocarbons (of improved quality) via other process like Microbial Enhanced Oil Recovery (MEOR), Microbial Enhanced Coalbed Methane (MECBM) or pretreatment of heavy hydrocarbon crudes (heavy oil, bitumen) prior to processes as Steam Assisted Gravity Drainage (SAGD).
The oxygen generating composition may comprise perchlorate (ClO₄—) from which chlorate (ClO₃—) is generated using electrons released by hydrocarbons, volatile fatty acids and/or other pore fluid components (e.g. oil & gas contaminants as H₂S, thiophenes and mercaptanes) as electron donor on the basis of the following reaction:
ClO₄ ⁻+2H⁺+2e->ClO₃ ⁻+H₂O.
The hydrocarbons may comprise viscous crude oil, coal and/or other long chain hydrocarbons and the micro-organisms may comprise thermophilic (per)chlorate-reducing bacteria or archaea, such as archaea and bacteria of the genus Archaeoglobus, Geobacillus, Thermus and/or other thermophilic genera able to reduce chlorate and convert fatty acids or long chain hydrocarbons into short chain hydrocarbons being indigenous to the formation or introduced by injection.
The other pore fluid components may comprise fatty acids, natural gas contaminants; H₂S, thiophenes, and mercaptanes, in which case the micro-organisms may comprise archaea and bacteria of the genus Archaeoglobus, Sulfolobus, Ferroglobus, Thiobacillus, Thiomicrospira or other genera able to convert natural gas contaminants.
These and other features, embodiments and advantages of the method according to the invention are described in the accompanying claims, abstract and the following detailed description of a non-limiting hypothetical example.
The present invention novelty compared to the inventions previously reported resides in:
Providing a microbial chlorate-reducing and oxygen-generating process (i.e. different from the invention of U.S. Pat. No. 5,163,510, in which oxygen is assumed to be chemically produced (not by chlorate-reducing microorganisms) and only assumes microbial utilization of oxygen);
Providing such microbial chlorate-reducing and oxygen-releasing process that can operate at high temperatures in the range from 60° C. up to 120° C. relevant to hydrocarbon containing reservoirs. The microbial method according to the invention can operate at an elevated temperature of at least 60° C. and is therefore different from the bioremediation method disclosed in US patent application 2004/0014196 A1 (Coates), which releases oxygen at temperatures <40° C. and the method known from U.S. Pat. No. 5,163,510 that enables the use of micro-organisms at a temperature below 60° C. (but not higher) and therefore seriously limits the application of the known method in hot hydrocarbon containing formations.
The thermophilic microbial chlorate-reducing and oxygen-releasing method according to the invention enhances bioavailability and biodegradability of hydrocarbons, which subsequently enables enhanced recovery of upgraded hydrocarbons from hydrocarbon containing formations optionally by:
a) enhanced oil recovery from oil bearing formations (MEOR),
b) enhanced methane production of coal reservoirs (ECBM),
c) pretreatment of heavy oil deposits before SAGD operation; and
d) in-situ conversion of oil and natural gas contaminants; H₂S, thiophenes and mercaptanes, which conversion involves decontamination of hydrocarbons and is therefore different from US patent 2004/0014196A1, which aims to bioremediate hydrocarbons in a shallow low temperature environment or U.S. Pat. No. 5,163,510, which aims to stimulate MEOR only.
The method according to the invention generates oxygen in-situ that will enhance bioavailability and biodegradability, which subsequently will enable enhanced recovery of hydrocarbons (of improved quality) via other process like Microbial Enhanced Oil Recovery (MEOR), Microbial Enhanced Coalbed Methane (MECBM) or pretreatment of heavy hydrocarbon crudes (heavy oil, bitumen) prior to processes as Steam Assisted Gravity Drainage (SAGD). The process can also enable in-situ natural gas contaminant removal resulting in upgraded hydrocarbons. The invention should therefore be considered as a strong enabling process for other subsurface thermophilic microbial processes.
When used in this specification and claims the term thermophilic chlorate reducing micro-organisms means that these micro-organisms multiply at an ambient temperature of at least 60° C.
These and other features, embodiments and advantages of the method according to the invention are described in the accompanying claims, abstract and the following detailed description of non-limiting embodiments depicted in the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows the consumption of lactate as an electron donor and conversion of chlorate to chloride at 85° C. by the thermophilic Archaeoglobus fulgidus DSM4139 microorganism in laboratory experiment that demonstrates the viability of the method according to the invention at an elevated temperature.

DETAILED DESCRIPTION OF THE DEPICTED EMBODIMENT

FIG. 1 shows the results of a laboratory experiments which demonstrated that Archaea from the genus Archaeoglobus can perform chlorate reduction at temperatures up to 85-95° C.
Archaeoglobus have often been encountered in hydrocarbon containing high temperature reservoirs as evident from molecular and cultivation experiments. Moreover, members of this genus have been shown to be able to convert fatty acids and alkanes. Members of this genus therefore are one of the most relevant candidates for the thermophilic microbial chlorate-reduction process.
FIG. 1 illustrates the results of a laboratory experiment in which lactate was consumed as electron donor and chlorate was converted into chloride at 85° C. by the micro-organism comprising bacteria of the genus Archaeoglobus fulgidus DSM4139.
It is observed that thermophilic microbial (Per)Chlorate Reduction at a temperature of at least 60° C. has never been described in the prior art for hot hydrocarbon containing environments with fatty acids or hydrocarbons as electron donor and that the experiment revealed that bacteria of the genus Archaeoglobus fulgidus DSM4139 will have an unexpectedly good performance for thermophilic microbial (Per)Chlorate Reduction in a hot hydrocarbon containing formation at an ambient temperature of at least 60° C.

Example

A suitable embodiment of the method according to the invention, comprises the following steps:
a) Screening whether a target underground crude oil and/or natural gas containing reservoir formation has features, such as temperature, salinity, heterogeneity, oil characteristics, micro-organisms, volatile fatty acids, hydrogen ions, acetate, propionate or butyrate and/or other potential electron donors, etc., which allow use of the method according to the invention;
b) Analyzing the composition of the water, oil and/or natural gas in the formation, for example by screening a sample taken from the formation;
c) Identification of potentially interesting micro-organisms with molecular DNA technologies using either general (16S rRNA-related) primer sets or enzyme/functional group specific primer sets (nitrate/nitrite-reductase, (per)chlorate reductases, chlorite dismutase, or hydrocarbon (alkane) degrading enzymes or using metagenomics;
d) Isolation of potentially interesting indigenous microbes from available core, formation water, and oil samples using VFA's (acetate, proprionate, butyrate, etc.), hydrocarbon components (e.g. long chain alkanes) or typical gas contaminants (e.g. H₂S) as electron donor and nitrate, oxygen or perchlorate, chlorate or chlorite as electron acceptor.
e) Determination of the optimal nutrient mix (electron donor, N/P nutrient, trace elements, SRB-inhibiting chemicals, etc.) using the identified and/or cultivated micro-organisms;
f) Microbial incubations using the potential successful nutrient compositions and gas contaminants, VFA's or oil components (e.g. long chain alkanes) to prove microbial activity on lab scale;
g) Optional middle phase could be to verify chance of success by core flood experiments; and
e) The following actual chemical injection and in-situ conversion procedure:
e1) Shut-in and clean-up of a near wellbore area of the crude oil, tar sand, shale oil, natural gas and/or other hydrocarbon containing reservoir formation (either chemically or by flushing);
e2) Injection of microbial cultures (single species or consortia derived from enrichments inoculated with production fluids from the treated reservoir) into the formation to boost the required indigenous microbial species;
e3) Injection of optimized nutrient mixture (main components being: oxygen, perchlorate and or chlorate and/or nitrate possibly continuously but more likely push-wise to avoid the development of a chlorate-utilizing biofilm limited to the wellbore to ensure deep placement into the reservoir formation and thereby stimulating the required indigenous microbial community; and
e4) Monitoring of the in-situ conversion method according to the invention based on increase in oil production, change in water-cut, change in produced oil and/or natural characteristics and/or composition, detection of target micro-organism(s) using molecular DNA technologies and/or cultivation dependent screening.

Claims

1. A method for in-situ oxygen generation in an underground hydrocarbon containing formation, the method comprising injecting into the formation an oxygen generating composition which releases oxygen (O₂) by reduction of chlorate (ClO₃—), wherein:

the formation has a temperature of at least 60° C.;

the composition comprises thermophilic chlorate reducing micro-organisms which multiply at an ambient temperature of at least 60° C.; and

the multiplied thermophilic chlorate reducing micro-organisms convert the hydrocarbons and/or other pore fluids in-situ into transportable or disposable products.

2. The method of claim 1, wherein the thermophilic chlorate reducing micro-organisms comprise bacteria of the genus Archaeoglobus, Geobacillus and/or Thermus, which use hydrogen (H) and electrons (e) provided by hydrocarbons, volatile fatty acids and/or other pore fluids in the formation followed by dismutation of chlorite (ClO₂ ⁻) by the micro-organisms on the basis of the reactions:

ClO₃ ⁻+2H⁺+2e->ClO₂ ⁻+H₂O

ClO₂ ⁻->Cl⁻+O₂

3. The method of claim 2, wherein the thermophilic chlorate reducing micro-organisms multiply at an ambient temperature of at least 80° C. and comprise bacteria of the genus Archaeoglobus fulgidis.

4. The method of claim 1, wherein the oxygen generating composition comprises perchlorate (ClO₄) from which chlorate is generated using electrons released by the volatile fatty acids, hydrocarbons or other pore fluid components as electron donor on the basis of the following reaction:

ClO₄ ⁻+2H⁺+2e->ClO₃ ⁻+H₂O.

5. The method of claim 4, wherein the hydrocarbons comprise viscous crude oil and/or other long chain hydrocarbons and the bacteria comprise crude oil degrading aerobic bacteria, such as bacteria of the genus Geobacillus, Thermus and/or other bacteria that convert long chain hydrocarbons into short chain hydrocarbons being indigenous to the formation of introduced by injection.

6. The method of claim 5, wherein the multiplied bacteria dissociate crude oil from the formation by microbial dismutation of chlorite for the partial biotic and abiotic aerobic conversion of oil.

7. The method of claim 5, wherein the multiplied bacteria dissociate viscous crude oil from the formation by microbial dismutation of chlorite for the partial biotic and abiotic aerobic conversion of oil and the method is used to enhance crude oil recovery from the formation.

8. The method of claim 1, wherein the other pore fluids comprise natural gas contaminants, such as CO₂and/or H₂S, and the micro-organisms comprise bacteria of the genus Sulfolobus, Ferroglobus, Thiobacillus, Thiomicrospira or other genera able to convert natural gas contaminants.

9. The method of claim 8, wherein the formation comprises a H₂S containing pollutant from which the oxygen generates more oxidized sulfur compounds like elemental sulfur, poly sulfide, poly thionates and H₂SO₄.

10. The method of claim 1, wherein the other pore fluid components comprise hydrogen ions, acetate, propionate or butyrate and/or other volatile fatty acids and the injected chemical comprises perchlorate, chlorate and/or chlorite and another chemical, which can serve as electron acceptor or oxygen source, such as oxygen, nitrate, nitrite and hydrogen peroxide in order to ensure deep placement of the perchlorate, chlorate and/or chlorite into the formation.

11. The method of claim 10, wherein composition is injected either continuously or pulse-wise into the formation to ensure deep placement of the nitrate, nitrite, oxygen, perchlorate, chlorate or alternative electron acceptors into the formation.

12. The method of claim 1, wherein the micro-organisms are bacteria that are either indigenous to the formation and/or introduced by injection into the formation.

13. The method of claim 1, wherein the micro-organisms comprise a single species microorganism or a mixture and/or consortia of micro-organisms.

14. The method of claim 1, wherein the micro-organisms are after a period of time substituted by single or multiple enzyme samples that can be water soluble or added as immobilized structures, such as bio-nano particles and/or the micro-organisms are either present in or introduced into the formation as highly active microbes or as spores, cysts or encapsulated micro-organisms.

15. The method of claim 1, wherein the micro-organisms either perform the microbial conversion of perchlorate via chlorate and chlorite to chloride and oxygen (or parts thereof) or the microbial conversion of hydrocarbons or natural gas contaminants or microorganism that comprise both the perchlorate/chlorate/chlorite as well as the hydrocarbon conversion/natural gas contaminant conversion activity, and/or the micro-organisms contain key enzymes from a nitrate-reduction and/or chlorate-reduction pathway such as perchlorate reductase, chlorate reductase, chlorite dismutase, nitrate reductase or nitrate reductase or combinations thereof.