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Case Study: CH-0037

SITUATIONConventional plays throughout the US often experience

iron sulfide deposition issues throughout the production

fluid stream. Iron sulfide species are especially prevalent in

downhole equipment and fluids, which can lead to problems

with wells utilizing rod pumps. Historically, remediation

methods were often large scale acid or cleanup treatments,

which were costly and increased asset integrity concerns.

CHALLENGEWhen iron sulfide deposition occurred, producers often

witnessed a vast decrease in well performance through

pumping conditions and dynamometer scans. Residing

within the annular working fluid column, iron sulfide

would fraction from the oil/water interface into the

hydrocarbon phase and become oil-wet. This viscous, solids-

laden emulsion would stick to critical pump components

resulting in restriction of pump fillage, delayed standing

valve closures, increase or erratic pump friction, increased

restriction of fluid flow-through, pump sticking, and delayed

traveling valve closures.

WELLBORE SOLIDS AND FLUID QUALITY IMPROVED BY RenewIQ™ SOLUTION ANNULAR CLEANUPS

CH-0037-V2

INSIGHTDuring field evaluations with Nalco Champion BIOC16734A

biocide, a peracetic acid-based RenewIQ™ solution

chemistry, the chemistry oxidized the emulsifying iron

solids and broke the surface tension enough to resolve the

emulsion. Nalco Champion utilized this knowledge to design

downhole treatments that performed this same task in

annular fluids feeding the pump.

SOLUTIONWells exhibiting pump performance issues were first base-

lined via wellhead fluid grindouts and dynamometer scans.

From this information, candidates were selected for trial

annular cleanups. Treatments utilizing BIOC16734A biocide

and FESD11088A combination surfactant/iron chelant

product, were designed to focus on removing iron solids

from the near wellbore fluids, resolving the associated

emulsions, and moving the negative fluids through the

pump. This approach was implemented to restore pump

performance and reduce the risk of failure.

RESULTSBaseline dynamometer scans and wellhead grindouts

performed on a trial well indicated significant downhole

pump issues. Grindouts indicated approximately 1.0% oil-wet

iron sulfide within the production fluids, while pump and

surface dynamometer cards indicated poor pump fillage

along with subsequent rod stacking. The data highlighted

the likely cause of the decreased pump performance to

be solids-laden emulsions residing within the annular fluid

column. To assist in cleaning this fluid column, consecutive

annular batch treatments utilizing 1 gallon of BIOC16734A

biocide and 1 gallon of FESD11088A surfactant/chelant were

performed. Follow up wellhead grindouts were completed and

data showed a shift from oil-wet to water-wet iron sulfide,

indicating a positive effect from the treatment. Additional

samples were gathered in the subsequent days, and they

showed a continual reduction in the amount of oil-wet and

total iron sulfide. (See Figure 1 below).

Figure 1 – Wellhead Grindouts Before/After Treatment

0.0% 0.2%

1.2%

0.4%

0.2%

1.0% 1.0%

0.8%

0.6%

0.0% 0.0%

0.2%

0.4%

0.6%

0.8%

1.0%

1.2%

1.4%

7/8/14 7/9/14 7/10/14 7/11/14 7/21/14

Per

cen

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eS/B

S

Date Sampled

Wellhead Grindouts Before/After Treatment

Water-Wet FeS

Oil-Wet FeS

Treatment

Date Water-Wet FeS Oil-Wet FeS

7/8/14 0.0% 1.0%

7/9/14 0.2% 1.0%

7/10/14 1.2% 0.8%

7/11/14 0.4% 0.6%

7/12/14 0.2% 0.0%

Wellhead Grindouts Before/After Treatment

After the second treatment, dynamometer scan results

were again positive, with a noticeable improvement in both

surface and pump dynamometer cards. A pump fillage of

100% was noted, improving 64% from the baseline level.

(See Figures 2 and 3 below). The Nalco Champion RenewIQ

solution, which focused on improving the quality of fluids

entering the pump, improved the overall pump efficiency of

the well and cost much less than conventional remedies.

This solution is a breakthrough in mitigating stress-related

failures, which tanslates into reductions in equipment

replacement and workover costs.

Figure 2 – Trial Well Before Treatments and SPM Change

Trial Well Before Treatments and SPM Change

Position (inches)

Dynamometer Cards May 28th 2014Card #2

Rod Stacking

NormalOperation

56-61% PumpFillage

Unacceptable Load Variances to Peak Load

16000.00

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Compression

Trial Well Before Treatments and SPM Change

Figure 3 – Trial Well After Treatments and SPM Change

Improved LoadTransitions

Position (inches)

Dynamometer Cards

Trial Well After Treatments and SPM Change

July 17th 2014Card #2

100% PumpFillage/Fluid

Pound Position

15000.00

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0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60

Trial Well After Treatments and SPM Change

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