AnAlysis of sCAle squeeze residuAls in Co-Mingled subseA And deepwATer environMenTs

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The requirement for accurate and specific analysis of scale squeeze inhibitors is often driven by the

complexity of the operational considerations. Furthermore, where polymeric scale inhibitors are being

deployed this can require a suite of possible methodologies from which the most suitable methodology

for a specific application can be chosen. Often the standard industry tests struggle for both resolution

and specificity. This is a particularly significant issue in subsea and deepwater applications of co-mingled

wells where there may be a primary inhibitor in the presence of secondary and tertiary inhibitors of either

squeeze, subsea or topside application.

Improved analytical serviceThrough on-going research and development of our polymeric inhibitor detection methods, Champion Technologies

has created a new advanced “toolbox” of state-of-the-art analytical methods and techniques. Based upon four

generations of analytical methods, including LCMS, this toolbox allows the analyst an unparalleled ability to lower

detection limits of scale inhibitor, and generate accurate, specific and robust data from even the most complex and

demanding of applications.

When used in conjunction with Champion Technologies’ comprehensive range of scale inhibitor product packages,

our unique analysis service allows for individual monitoring of scale inhibitors from multiple co-mingled wells.

Improved detection limits can allow for longer treatment production periods to be confirmed through the polymer

specific analysis.

scale squeeze analysis in co-mingled subsea and deepwater environments

Polymer 1

Polymer 2

Channel 1

Channel 1

Residuals from produced water

2ppm

Polymer 2

Polymer 1

Channel 2

Channel 2

No Signal

4ppm

2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7

RETENTION TIME (minutes)2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7

Sig

nal (

Cou

nts)

Champion Technologies’ analytical service “toolbox” quantifies two polymers in the presence of each other. Proof of this

concept was also established and fully validated in field brine in a co-mingled well scenario for two families of scale

squeeze inhibitors in the presence of the third topside polymer scale inhibitor.

• Validation in North Sea brines has demonstrated high accuracy, precision and sensitivity for a range of patented polymers with detection limits down to < 0.5ppm.

• Test work has determined the method has no interference from other production chemicals, so there is no need to turn off topside scale inhibitor during wellhead sampling for squeeze residuals.  

• The ability to monitor with improved confidence to low MIC

(Minimum Inhibitor Concentration) levels allows squeeze treatments to run to longer lifetimes.

• Discrete and accurate analysis of two polymeric scale inhibitors in one sample allows the use of scale inhibitor tracers for placement information and optimum squeeze design.

• Potential for “squeezing” blends of scale inhibitors to optimize treatment lifetimes in harsh scaling environments.

• Potential for “squeezing” co-mingled and multilateral wells.

Advantages:

Our on-going commitment to research and development has led to a ground-breaking

development in the chemical management of co-mingled wells. Champion Technologies

can offer customers both a product package and a unique analysis service which allows the

individual monitoring of scale inhibitors from multiple co-mingled wells.

Co-mingled scale squeeze residual analysis

Chemical A

Inhibitor A

WELL 1MIC reached at 270 days. Will need re-squeezed.

90 days 180 days 270 days 360 days 90 days 180 days 270 days 360 days

MIC reached at 360 days. Will need re-squeezed.

MIC LevelMIC Level

MICMIC

Inhi

bito

r C

once

ntra

tion

Inhibitor B

WELL 2

Inhi

bito

r C

once

ntra

tion

Co-mingled scale squeeze residual analysis

Chemical A + b co-mingled at the sample point

Chemical b

Inhibitor A

WELL 1MIC reached at 270 days. Will need re-squeezed.

90 days 180 days 270 days 360 days 90 days 180 days 270 days 360 days

MIC reached at 360 days. Will need re-squeezed.

MIC LevelMIC Level

MICMIC

Inhi

bito

r C

once

ntra

tion

Inhibitor B

WELL 2

Inhi

bito

r C

once

ntra

tion

Problem:A subsea field had complex scaling issues and scale squeezes were needed in several of the wells, as well as, continuous subsea scale inhibitor injection.

Challenges:Champion Technologies was asked to determine the residual levels of a scale squeeze polymer in the presence of other interfering scale inhibitors. In addition to scale squeezing, it was necessary to protect the subsea frame with a continuously applied scale inhibitor. Only environmentally-acceptable products were accepted, so polymeric products were needed, and this often meant applying one polymer-based chemical for scale squeeze and another polymer-based chemical for the continuous injection application. While sampling the produced water, both scale inhibitors were present in the samples collected and interference between the polymers was often observed in the analysis of the samples, even using a variety of both standard and more novel techniques. Since both products contained some phosphorus, it was also impossible to distinguish scale squeeze inhibitor by phosphorus analysis by ICP. To avoid this, the continuously applied subsea scale inhibitor was often turned off before sampling, but this did not prove to be a very practical and successful solution. The interference and analysis issue had become so problematic that the operator had even considered

not squeezing the wells due to the cost of treating the wells and the lack of confidence and uncertainty in the scale inhibitor return profiles.  

Solution:Champion Technologies developed a unique technique for the scale squeeze polymers that had a very high specificity and no interference from the continuously applied subsea scale inhibitor. The limit of detection for the scale squeeze product was < 0.5 ppm. 

Results:The residual scale squeeze inhibitor concentration in the produced water was able to be easily monitored uniquely, even in the presence of the subsea scale inhibitor.  

Value:The operator gained confidence in the scale squeeze performance and the need to turn off the subsea scale inhibitor before sampling for scale squeeze residuals was removed. The improved analysis method led directly to improved scale control in the system.

Analytical improvements allow continued co-deployment of polymeric scale squeeze and subsea scale inhibitorsCase history:

Problem:  A subsea field had barium sulphate scaling issues and several of the wells required scale squeeze treatments.

Challenges:Environmentally-acceptable products were required so polymeric scale inhibitors were selected. Since well access was limited and a supply vessel was needed to perform the squeeze treatments, a long squeeze lifetime was desired to minimize the well intervention costs. The existing analytical techniques for polymer based scale inhibitor had a limit of detection of around 5-6 ppm. Champion Technologies had developed a new highly efficient polymer-based chemical, which had a MIC at 2.5 ppm.  However, due to the detection limit of the chemical during back production being 5-6 ppm, monitoring the wells to below this level gave uncertainties that meant the well was re-squeezed more frequently than necessary based only on chemical performance.  

Solution:Champion Technologies developed a unique Mass Spectometry technique with high-accuracy and high-specificity. Limit of detection was < 0.5 ppm for the polymeric scale inhibitor being used. 

Results:With the new detection method, the residual scale inhibitor concentration in the produced water was easily monitored to the value of the MIC with proven scope to determine even lower values. This gave confidence in the residual monitoring results and allowed squeeze life for the treatment (between interventions) to be doubled. Fig 1.

Value:Total savings for the customer – based on less frequent squeeze requirements - was in excess of $750,000/year.

scale squeeze monitoring to low MiC results in $750k savingsCase history:

Problem:Scaling issues in long-reach horizontal co-mingled wells – limited confirmation of placement.

Challenges:Champion Technologies was asked to monitor two distinct scale squeeze polymers (in the same sample) in the presence of a further continuously injected subsea scale inhibitor. Squeezing long-reach horizontal wells with permeability and pressure contrast can be very difficult and the placement of the scale inhibitor in the right zones can be problematic. Often viscous polymer treatments are required to overcome some of these issues, but it can still be difficult to understand what has happened during the various stages of a treatment operation, especially in co-mingled wells. Tracer technology was needed to mitigate the problem and a second scale squeeze polymer was included in the over flush of the main scale squeeze treatment to try and understand the distribution of the over flush along the production interval.

Solution:Champion Technologies developed a unique technique for the separate detection of two scale squeeze polymers in the same sample without any interference from the subsea scale inhibitor.

The limit of detection for the main scale squeeze product was < 0.5 ppm and for the secondary squeeze polymer used for tracer purposes was ~10-20 ppm. This was agreed to be fit-for-purpose for this application. 

Results:Residual scale inhibitor concentrations for the two polymers in the produced water were monitored separately within the same samples. This gave confidence in the use of secondary scale squeeze inhibitors as tracers and for the detection of two polymeric scale inhibitors (in one sample) in the presence of a third subsea scale inhibitor. The results from the separate scale inhibitor return profiles indicated that the over flush went into the same zones as the main scale inhibitor treatment. Fig 2.

Value:The operator gained a higher degree of confidence in the placement of scale squeeze inhibitors in long-reach horizontal wells through using secondary scale squeeze inhibitors as tracers. The trial also showed the potential for monitoring two co-mingled wells squeezed with different polymeric scale inhibitors. 

Monitoring placement in subsea horizontal wells squeezed with two polymeric scale inhibitorsCase history:

Fig 1 Fig 2

Cumulative produced water (m3)

% R

etur

n of

che

m a

nd W

HT

(˚C

)

Res

idua

l inh

ibit

or c

onc.

(m

g/l)

0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 400,000 450,000

100,0000

10,0000

1000

100

10

1

100

90

70

50

30

10

80

60

40

20

0

Calculated Cummulative Water (m3)Polymer 1

Polymer 2

% Return of Polymer 1

% Return of Polymer 2

Ret

urn

of c

hem

ical

(%

)

Res

idua

l inh

ibit

or c

onc.

(m

g/l)

1

10

100

1000

10,000

0

0 2,000 4,000 6,000 8,000 10,000 12,000

20

40

60

80

90

100

70

50

30

10

Reference technical paper, “Mixed Polymeric Scale Inhibitors in Co-Mingled Subsea and Deepwater Environments”, presented at the CORROSION

2012 Conference in Salt Lake City. For more information, please contact Alan Thompson at alan.thompson@champ-tech.com.

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