From Bacteria to Barrels: Microbiology Having an Impact on Oil Fields

7/27/2019 From Bacteria to Barrels: Microbiology Having an Impact on Oil Fields

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32 JPT NOVEMBER 2011

The science behind the use of microbesto enhance oil recovery has advancedsignificantly, but it suffers from oldassociations.

After decades of trial and error, thoseworking on microbial enhanced oilrecovery have identified the oil-eat-ing bacteria that laboratory tests sug-gest can change the properties in an oilreservoir, and know better how to putthem to work. The increasing knowl-edge of the role microbial life plays inoil and gas reservoirs has also led tonew approaches for controlling corro-sion, managing bacterially producedhydrogen sulfide, and creating naturalgas from coal.

(In this story, eat is used to describethe metabolic processes of bacteria. Forinstance, oil eating is more preciselyhydrocarbon oxidizing.)

But the greatest potential payoff andthe most debate come from the ideaof microbes for enhanced oil recovery(MEOR). There is a much greaterunderstanding of what microbiology isdoing in a reservoir and how that canbe used to produce more oil, said Stuart

Page, chief executive officer of GloriEnergy, a company that has stakedits future of convincing the industrythat microbes can be used to recover

more oil.MEOR is still often associated

with promoters promising betteroil production by dumping molas-ses into oil wells. From a historicalpoint of view, it is seen as snake oil,Page said.

The image is darker than the history,which has been more hit and miss.For those in small companies, such asGlori, and big ones, such as Statoil, thechallenge has been convincing expertsin the field that promoting bacterial

From Bacteria to Barrels: MicrobiologyHaving an Impact on Oil FieldsStephen Rassenfoss, JPT/JPT Online Staff Writer

The production vessel used on Statoils Norne field in the North Sea.It was the first offshore field where microbial treatments were used toenhance oil recovery.


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JPT NOVEMBER 2011 33

growth can be a consistent and effectiveway to produce more oil.

Work on using microbes to find oilgoes back further than seismic imagingand the history of MEOR goes backmore than 50 years.

Claude ZoBell, the scientist hired bythe American Petroleum Institute whofirst discovered the microbiological ori-

gins of oil, patented his MEOR conceptin 1957. His approach involved intro-ducing high-performing bacteria intoa reservoir. It is one of many that hasbeen tried and failed as people slowlycame to better understand the exoticlife in reservoirs.

Interest in the microbiology of oil ison the upswing because of the needto extend the life of older fields, andindications that a better understandingof the microbiology of a reservoir canhelp do that. Were in a renaissance of

interest in microbiology in explora-tion and production, said Tom Jack, aUniversity of Calgary adjunct profes-sor who has been involved in the fieldsince 1980.

Statoil has long been a leader in thisfield. Shell, BP, ConocoPhillips, andDuPont are among the large compa-nies supporting research and testing inmicrobiology and oil. The Norwegiancompany has effectively used micro-bial methods to treat well souring andenhance production in the North Sea.It was the first to do a MEOR projectoffshore, injecting nitrates, nutrients,and air into its Norne field, aftertesting the idea at an onshore fieldin Austria.

Statoil has formed a research part-nership with Glori, a company found-ed with backing from one of the topventure capital firms in Silicon Valley,Kleiner Perkins. Glori uses technol-ogy initially developed in India andhas added more over the years. Withthe deal, it will have access to Statoilstechnology, and Egil Sunde, its reser-

voir microbiology specialist, will beadvising Glori.

There is growing interest in MEOR,but microbiologists are still a rarityin the industry. Sunde said that whenthe subject of MEOR comes up, hefrequently hears that nobody else isdoing it, so why should we?

Making a Case for MEORThe critiques of MEOR are often moredirect. One skeptical reservoir expertsummed up the challenge: MEOR has

been looked at for decades; none of thereputable scientists back it. There havebeen no validated results other than labtests in tubes.

Sunde has heard and read the argu-ments that promoting microbes in an oilformation will not allow greater recov-ery. He points to case studies by Statoiland Glori that showed greater produc-

tion where it has been tried, and says:The point is MEOR obviously works.

But he admits the results are notexplained by the current theories ofhow waterfloods work in older reser-voirs. They need to understand howresidual oil can be mobilized in waysthat are not presently accepted, saidSunde. He has written a paper explain-

Bringing Back the Dead:Gas Fields Revived Using Microbes

Microbial methods for pulling moreout of oil and gas fields are typi-cally tried on fields in dire straits.In Wyoming, Luca Technologies hastaken it a step further by accumulat-

ing 1,350 coal seam gas wells inthe Powder River Basin with little orno production.

Its plan is to return them to serviceby pumping in water and nutrientsto revive dormant microorganismsthat produce gas from coal, saidBob Cavnar, the companys chiefexecutive officer. Rather than callingthe creatures bacteria, he prefersto use the more productive sound-ing methanogens. The goal is tocreate conditions for the microbes

to eat coal in a process that resultsin methane.

Luca is not alone in its interest.A competitor in Wyoming, CirisEnergy, is using a different coal-to-gas approach. In Canada, aresearch consortium, called theHydrocarbon Metagenomics proj-ect, lists finding ways to speed theconversion of coal into methaneamong its primary goals. The four-year project involves four univer-sities and two provincial science

organizations.Researchers also are working onusing bacteria to turn heavy crudeinto methane. Going from oil to gasis not an attractive option at currentprices, but it could be a useful skillin places where heavy crude wouldnot be produced otherwise.

The challenge is finding ways toproduce gas in real time. Coalseam methane is associated largelyfrom bacterial activity that occursover geologic time, said SeanCaffrey, project manager of the

metagenomics project. It is seek-ing to understand what varieties of

naturally occurring microorganismsdo the work and how to controltheir behavior.

Going from coal to natural gas isa multistage process with microbes

eating coal to create hydrogen,acetates, and carbon dioxide. Ulti-mately this series of digestive eventsyields methane.

Luca, which has spent years onits methods, aims to prove that itcan deliver in the field, starting witha group of 120 wells. Luca addswatercoal seam gas productionrequires removing the water thatmicrobes need to thrivemixed witha small amount of nutrients tailoredto stimulate the varieties involved in

turning coal into gas.New sources of hydrocarbons

come with new regulations. Waterfrom coal seam gas fields can affectthe water table so Wyoming willbe among the first states to writewater protection rules. Cavnar saidthe injected water contains min-ute quantities of nutrients, suchas yeast extracts and phosphates,which are generally consumed bythe microbes. To demonstrate thatthe formula will not harm drinking

water, he drank a glass of the nutri-ent mix at a public meeting.The first goal is a well producing

30 Mcf/D, which Cavnar saidcould be profitable even when gassells for just under USD 4/Mcf.The economics reflect the desire ofwell owners to shed wells for littleto avoid the liabilities associatedwith abandonment.

We think of ourselves as thephoto negative of the big shaleplayers that drill huge well and havehuge capital and high production

costs, but high declines in produc-tion, Cavnar said.


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ing his theory that he has submitted fordelivery at a future SPE meeting.

Page of Glori said the challenge ofproving how enhanced oil recoveryworks is shared by other methods, suchas low-salinity waterflooding.

MEOR requires expanding the popu-lations of oil-eating bacteria native tooil formations. The population explo-sion, which uses up a small amount ofoil, is thought to encourage oil produc-tion in a variety of ways.

Molasses can also encourage growth,but the microbes that thrive on sugarare not thought to provide any benefitfor oil production. The exact formulaof the mix added to the water used in

flooding is a trade secret for companiesin the field. The mixes, based on theconditions in each field, commonlyinclude ingredients found in fertilizers,such as nitrates and phosphates, whichare in short supply in oil reservoirs.

Lab tests have found that the bacteriacan affect everything from the wet-tability by loosening the bond of theoil on the rock, to the interfacial ten-sion separating the water and the oil,thereby allowing the water to sweep itaway. Much of the attention has been

on how the growth of the bacteria canchange the relative permeability in theformation, directing more of the waterthrough zones holding oil for betterprofile control.

Ganesh Thakur, a vice president atChevron Energy Technology Companyand an expert on waterflooding, saidmicrobial techniques show promise forprofile control. But it needs to be dem-onstrated on a large field scale to con-vince the industry of the technologysviability, he added.

A Field Test

Glori has seen a significant rise ininterest since it reported on a test of

the technology at SPEs Enhanced OilRecovery Conference in July. The paper(SPE 144205) shows production gainsafter its MEOR treatment, called theAero System, was tried in a field ownedby Merit Energy.

Statoil also was involved in the testinvolving eight wells in the Stirrupfield in southwest Kansas. About 90%of the output from that part of the26-year-old field was water. Over oneyear, the company reported a net gainof 750,000 gallons of oil (17,900 bbl).

The company recently reportedthe treatment has added more than250,000 gallons (6,000 bbl) of outputthrough September.

Most of the gain came in a singlewell, 12-2, where the oil output settledat 60% higher. The water produceddid not rise as much, resulting in areduced percentage of water produced.The gains reduced the water cut from91% to 88% for the wells studied.

While the test was ongoing, the fieldswaterflood system injecting the nutri-ent mix into the field was modified.One well used to inject water was takenout. Analysis of the field suggested afault prevented water from that well

from pushing oil out of the productionwells. One production well was con-verted to an injection well to serve twoproducers apparently not served by theremaining injection well.

Page said the results since then havebeen encouraging. He added that theanalysis showed the gains could onlybe explained by microbial EOR. Hepointed to the reduced water cut as asign that the treatment had an effect.

Merits exploitation manager at thefield, Brad Bauer, said they saw good

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Tanks like this one are used by Glori Energy to pump its nutrient mix into an oil field. The blend is customizedto encourage the growth of certain bacteria said to promote production in older fields.


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Microbes in the Oil Field

Bacteria that have an impact on the oil and gas businessfall into two columnshelping and hurting. On the badside, bacteria cause corrosion and sour wells with hydrogensulfide. On the good side, they have been used to find oil,

mitigate the problems other bacteria cause, and quite pos-sibly produce more oil and gas.

Finding Oil and GasThe use of microbes in oil exploration goes back to the daysbefore seismic imaging became the dominant explorationtool. Soil samples are still tested by some for hydrocarbons,such as trace amounts of methane seeping to the surface,or the bacteria that dine on it.

This practice, which has some of its oldest roots in Russiaand eastern Europe, was studied by investor-owned oil com-panies in the 1950s. Where the geology is relatively uncom-plicated, it can point to the presence of oil or gas under-

ground. It must be used in conjunction with other methodsbecause it cannot predict how far down the hydrocarbon is.

One such method is used by Geo-Microbial Technologies,one of about 20 consulting firms looking for oil usingmicroseepage. Dietmar Deet Schumacher, director ofgeochemistry, said the companys study of nearly 2,800wells using the method in conjunction with traditionaltools including seismic, concluded that it is 89% accurate inpredicting dry holes and right 82% of the time in predictingwhere to drill.

FightingCorrosionStudies that showed bacteria can cause corrosion in oil

fields and pipelines go back more than 25 years. Oil-eating microorganisms can damage steel by producingacids or iron sulfides as a byproduct. Some even eat iron,said Gary Jenneman, corrosion management supervisor atConocoPhillips.

The company has used the growing understanding of howbacteria form destructive biofilms to develop better focused,less toxic ways of preventing the damage. One methodcombines biocides and natural control approaches.

To gain a better understanding of the microbes causingthe problems and the traits that may be used in control strat-egies, ConocoPhillips and Total helped found the Universityof Oklahoma Biocorrosion Center, which is studying whatbacteria cause corrosion and how they can be controlled.

The goal is to use the knowledge for more targetedapproaches that use fewer toxic chemicals and cost lessthan biocides designed to kill all varieties of bacteria. Inour labs, we are testing biocides and how effective they areagainst biofilms and corrosion, said Jenneman. Were notinterested in killing bacteria; we are interested in control-ling corrosion.

Souring SolutionsAs injection wells using seawater have grown, so haveproblems associated with well souring. The problems stem

from injection water containing sulfates, which certain bac-teria in oxygen-free environments convert into hydrogensulfide, which is toxic, corrosive, and flammable.

Treatment options include investing in water treatment to

remove the sulfates or going after the sulfate-consumingbacteria underground. Biocides often do not work becausethey can be absorbed in the formation and are difficult todeliver throughout a field.

In the North Sea, Statoil turned to a biological option:Crowd out the sulfate-reducing bacteria by building up thepopulation of competitors. It did so initially by pumping airinto the formation, said Egil Sunde, a reservoir microbiol-ogy specialist at Statoil. A more common solution, whichhas also been used by companies such as Shell, BP, andMaersk, is mixing in nitrates into the injection water toencourage the compound to consume bacteria that crowdout the sulfate eaters.

Making and Eating MethaneIn ponds holding wastewater from oil sands production,bacteria show up on both sides of the ledger. They aid insettling these lake-sized bodies of water. In the process,some produce methane, while others living near the surfacecan consume the greenhouse gas.

The Hydrocarbon Metagenomics project, which is build-ing a database of the species found in a wide range ofhabitats, hopes to apply this knowledge to problems suchas methane emissions in the tailings ponds. The goal isto balance the bacterial populations so the methane pro-duced by one variety is consumed by another, said Sean

Caffrey, who manages the metagenomics project. They arealso seeking varieties capable of breaking down toxics,such as toluene.

The project is also studying how groups of methanogensare able to turn coal into methane. There are companiesout to prove that they can profitably speed the work onthese natural gas producers enough to revive old coal seamgas fields.

Using Microbes for More OilThe idea that promoting the growth of certain microbescan mean more oil production has been around for a longtime. But the science needed to understand why it works, ornot, is still developing. It is thought that MEOR can increase

production by rerouting the waterflood into areas where oilremains, loosening its hold from the rock, thus looseningthe bonds between the oil and the rock.

One advantage of MEOR is the costthe only equipmentneeded is a tank for the nutrients that are pumped in viathe existing waterflood system. Results have been reportedwithin weeks. Skeptics question the inconsistent results frompast tests. The science behind this field has advanced, butmore field testing is needed to show that it can consis-tently deliver, and research is needed to show how it can betweaked to deliver more.


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JPT NOVEMBER 2011 37

indications. To the best of our ability,through a very careful look at the cur-rent projections, and what it was doingwhen the project started up, we feel themost likely explanation for the impacton Well 12-2 is MEOR, he said.

Bauer said it is difficult to nail somethings down because production fromeach well is not continuously measuredin the Stirrup field. The cause andeffect relationship between MEOR andproduction changes is hard to establishin a field trial. Jack of the University ofCalgary said, EOR is problematic. It ishard to show it works in the lab and itis hard to show in the field.

A 5% production gain for a fieldwould be considered a good outcomeconsidering the relatively low cost ofMEOR. Proving that the bacteria were

the cause is complicated by the wayfields often are changed during testing.

The need to modify operations tomaximize daily production will nor-mally trump plans for a controlledfield experiment, said Sean Caffrey,project manager of the HydrocarbonMetagenomics project, a Canadianresearch consortium set up to broadenthe knowledge of microbes found inoil, gas, and coal formations. Formicrobiologists, it is hard to do testing.They are lucky to get a well.

In order to gain control, Glori boughtan old field in Kansas it calls the GreenField, which will be its proving groundto test the effectiveness of its micro-biology research and ways to improvethe technology.

Microbial EnhancedLab TestingLab testing offers multiple reasons whymicrobes may matter. Statoil reportedthat it has found that bacteria were ableto create a significant reduction in theinterfacial tension normally separat-ing the water and oil. Oil-consumingbacteria live in water near oil. Statoilsaid the microorganisms are able tostraddle that boundary by creating anatural biosurfactant called tenside. Alaser light scattering technique is used

to measure the change in the interfacialtension, which the company describedas notoriously difficult to do.

DuPonts lab testing found littlechange in that measure. In a paper(SPE 129657), the company reportedthat some drop in interfacial tensionis possible, but not enough to causethe emulsification that would facilitatesignificantly higher production. Thetests did indicate the microbes can alterthe wettability of the rock. The lab testsobserved that growing populations of

microbes reduced the flow in channelswhere water had been bypassing theoil. This change in the relative per-meabilty redirects the waterflood intopassages with oil.

The lab test supports a widely heldtheory of why MEOR can increase

production. Others are studying condi-tions in formations to see if what goeson there resembles the lab setup.

Testing to see what happens on amicroscopic level and then scaling thatup to what goes on in a field is a chal-lenge. Creating more realistic tests ofwhat goes on in a reservoir is a long-term project for the Energy BiosciencesInstitute, which is funded by BP.

The group has spent three yearsworking on a variety of projects, rang-ing from new lab testing methods to

more accurately simulate what goes onbelow to comparative studies of the bac-terial life in mature oil fields with placesthat have never been drilled before, saidSusan Jenkins, managing director of theinstitute, who said the work could takeanother decade or more.

Making MEOR work will require agreater understanding of the conditionsneeded to control both the popula-tions of select bacteria and changes inthe waterflood likely to produce moreoil, said Li Li, an assistant professor atPennsylvania State University who isworking on computer models of theseprocesses. It is a complicated problem.We are dealing with bacteria, and deal-ing with reservoir propertiesporosityand permeabilitythat vary.

A Hybrid ApproachDeveloping improved microbial recov-ery methods starts with bringing arange of talents often not found in anoil companymicrobiologists, reser-voir engineers, chemical engineers, andgeophysicists. To work effectively, the

specialists need to learn how to com-municate in each others language.

The point is in the past, these ideason microbiology were proposed byengineers who didnt understand muchabout microbiology, or a microbiologistwho didnt know anything about res-ervoir engineering, said Bart Lomans,principal researcher at Shell. When hejoined Shell, he embarked on a pro-gram to learn reservoir engineering.

These sorts of collaborations havepaid off for the industry. A better under-

A magnified image of bacteria from an oil field suggests the chal-lenge of identifying the varieties and behavior of microorganisms in anextreme environment.


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standing of the bacteria at work in oilfields is changing the methods used forcorrosion control and well souring.

When Sunde joined Statoil in themid-1980s, the company was begin-ning to deal with well souring causedby bacteria that eat sulfates, produc-

ing hydrogen sulfide. More precisely,these anaerobic sulfate-reducing bac-teria are using the chemical as an elec-tron acceptor, just as aerobic creaturesuse oxygen.

The goal of microbial souring tech-niques is to promote the growth ofother bacteria that crowd out the sul-fate-reducing ones. Statoil did it byinjecting air from the surface, addingoxygen to the microbes environment.More often calcium nitrate is added tothe waterflood.

Gary Jenneman, corrosion manage-ment supervisor at ConocoPhillips,said a greater understanding of themicrobial life in reservoirs has helpeddeal with souring, which often cannotbe effectively treated using biocides.

He sees the research work into thebiological origins of oilfield problemscreating more options based on a bet-ter understanding of what works. Forinstance, ConocoPhillips in collabora-tion with the University of Calgary hascreated combinations of biocides and

chemicals such as nitrites that havebeen found to inhibit the activity ofcorrosion-causing bacteria that are less

toxic to the environment, cost less, andare as effective.

We cant eliminate biocides. We canlessen the amount of chemicals usedwith a combination of these strate-gies, said Jenneman. Microbiologyhas been an area that is sometimes

overlooked. It does impact corrosionand souring and potentially, therecould be other opportunities. JPT

For further reading:

SPE 144205 Field Experience From a Biotechnology Approach to WaterFlood Improvement by B.G. Bauer, Merit Energy, et al.

SPE 129657 Microbial EOR: Critical Aspects Learned From the Lab byScott C. Jackson, DuPont, et al.

NACE 04760 H2S Inhibition by Nitrate Injection on the Gullfaks Fieldby Egil Sunde, Statoil, et al.

SPE 129657 Biogenic Gas Generation From Shallow Organic-Matter-Rich Shales by M. Cokar, University of Calgary, et al.

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From Bacteria to Barrels: Microbiology Having an Impact on Oil Fields

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