Mirmorax

New Oil Era – New Challenges – Better Technology

MIRMORAX NOW HAS THE MOST ROBUST OIL IN WATER ANALYZER ON THE MARKET ACROSS ALL TYPES OF APPLICATIONS.

ROAD TO ROBUSTNESS

Whereas our Oil in water analyzers can be best described by evolution in technology our clients describe it as a revolution in results. So, why is that? Well, it starts and ends with making ourselves unaffected by the variables that the industry in general uses as excuses for not delivering results.

In 2010 Mirmorax started a journey through unknown territory with one single, ambitious goal set as the only known beacon: To create THE Oil in Water analyzer in the market, preferred across a variety of applications and by the vast majority of the market. At the time we had a technology that was developed to deliver accurate results under very stable condition and within a limited measurement range.

In contrast, our customers wanted to use the analyzers in more areas and different applications than before. This included a less stable environment, wider measurement range, changing process conditions, various chemicals and last but not least, measuring multiple oil types in the produced water.

FROM MEASURING DISCHARGE TO ENABLING REDUCTION

Through firstly a detailed technical analysis followed by a good soul searching exercise, we found that the path to making the most accurate Oil in Water analyzer on the market was less about measuring oil concentration more accurately and more about making sure we were unaffected by other factors. We already had the most accurate Oil in Water analyzer on the market for condensate applications and for low concentrations, we just needed to overcome the challenges other applications had.

We identified 5 challenges that we needed to overcome to get there:

• Measurement range increase from 0-1000 to 0-25 000 ppm
• Response time from measurement to data output from 15-30 min to 2 seconds
• Automatic compensation for changes in temperature, salinity and density
• Correct particle size measurements for high concentrations
• Automatic cleaning of the transducer

We managed to develop the expanded concentration range and the response and had several successful tests using this software. The way we did verification measurements also now enabled us to actually measure temperature, salinity and density of the water. And when we had these measurements, we could apply these to our models and maintain a stable concentration measurement regardless of changes in these three properties. Worth mentioning here was that chemicals such as MEG, corrosion inhibitors and other chemicals is only observed as a change in density of the water and therefore does not change oil concentration measurements.

AUTOMATIC CLEANING – MAINTENANCE FREE SYSTEM

Also, Mirmorax new automatic cleaning mechanism that ensures that the system can measure continuously across the whole measurement range and without any interruption in measurements. It is the only system that can provide uninterrupted measurement and clean sensor up to 400 bar operational pressure.

With these new features, an industrial software version was implemented offshore as a side-measurement and has proven to be a success. At a more challenging test, we found that an improvement needed to be made to get correct particle size at higher concentrations. What we had gained in faster response time, we had lost in particle size accuracy for the higher concentrations.

ACCURATE READINGS REGARDLESS OF PARTICLE SIZE OR API GRADE OR THE MIX OF THEM

By applying additional theoretical models that was developed in-house, we found a unique way to determine particle size, regardless of what concentration of oil that was in the water. This didn’t only solve the problem with reading correct concentrations and particle sizes, but also opened up a series of new opportunities. This testing, the iterative improvement and verification process was done closely with one of Mirmorax key customers who had very specific requirements on both ranges and accuracy.

As Mirmorax uses acoustics, the dominant property relevant for the acoustic response is the density of the oil. The density and corresponding viscosity of the oil will determine what particle size an oil concentration will have in a given part of the separation system. So, given that there are two different oil types with individual density in the same produced water, they will have different particle sizes.

For other measurement principles, such as fluorescence this represents a big problem since the ppm measurements is not a direct measurement, but a measurement of the aromatic oils, the dissolved oil and not the actual oil droplets. The aromatic response, fluorescence, is basically the surface area of the accumulated droplets as well as the density of the oil. So, if you have 4 particles, 1 with heavy oil and 3 with condensate they will measure about 150% wrong compared to if you had 2 particles with heavy oil and 2 with condensate. These are significant numbers, especially considering these numbers may be a bottleneck for production rates.

LAB PROVEN – FIELD PROVEN – RELEVANT

Mirmorax Oil in Water analyzer has been thorough testing with mixes of heavy oil and condensate now for about 18 months onshore and offshore.

The results can only be described as fantastic, and with the full range with variety of oil types and percentage of each oil, we are within +/-15% relative. The key for maintaining the accuracy is the measurement principle being insensitive to oil density changes and the accurate particle size measurement regardless of concentration. This means that Mirmorax can handle an unlimited number of different oil types and changing fractions of these in the same produced water stream.

This is in particular important in a market where production from various fields is done through tie-backs and share topside processing facilities, often build for one oil and having to separate a mix of several. On top of this, regulations and environmental awareness is higher than ever and as brown fields are producing more and more water, managing produced water becomes key for utilizing the existing capacity.

PRODUCED WATER – BOTTLENECK REDUCED

Mirmorax Oil in water analyzers are due to its measurement robustness an excellent and cost effective choice when trying to get more out of the existing processing capacity. By installing Mirmorax OiW, not only at the discharge for final verification, but further upstream, the operators has the opportunity to get capacity out of their produced water separation system. Based on case studies done by our clients, we have seen increases in an existing separation systems of more than 35% without other modifications than installing Mirmorax OiW to optimize each separation process.  Mirmorax today has the expertise to deliver enabling technology from 1 stage separator to discharge and will be a knowledgeable partner.

~ TIE IN FIELDS – MIXES OF OIL – PRODUCED WATER CHALLENGES – SOLUTION DELIVERED ~

by Mirmorax

Technology Advances in Subsea Sampling

BY EIVIND GRANSAETHER, CEO, MIRMORAX

While the last few years has seen a host of new subsea technology innovations, few technologies have developed quite as fast as that of subsea sampling.

Originally characterised as a manual-focused process with little consideration for flow dynamics and fluctuating reservoir conditions, today subsea sampling is providing operators with real-time information on oil, gas and water fractions as well as fluid properties and PVT data from closer to the wellhead than ever before.

The Importance of Subsea Sampling

There’s no doubt as to the importance of subsea sampling today. As operators look to generate a more complete picture of the reservoir, increase recovery rates and extend field life, subsea sampling is playing a crucial role – particularly in supporting multiphase meters.

Such meters can only operate to their full potential if they are precisely calibrated and sensitively aligned with the changing fluid, process conditions and flow rates of the reservoir. Such changing conditions might include an increased amount of liquid and water in the gas flow, growing water cuts, or varying well characteristics. And such calibration can only be achieved through the true volumetric sampling of oil, gas and water in the well.

Accurate PVT (Pressure, Volume, and Temperature) data is also vital. If operators can generate an accurate understanding of the PVT properties of their reservoir fluids and changes in fluid properties, such as density and viscosity (often as the reservoir is depleted), the more they will be able to predict reservoir behavior, ensure production optimisation and calibrate multiphase meters for maximum performance.

Such data is also particularly important as fields start to age, as is the case in many North Sea fields. In such cases, as figure 1 illustrates, the uncertainty of metering systems tend to increase and up to date volumetric sampling information is required to put the meters back on track. With the cost of purchasing and integrating just one multiphase or wet gas meter approximately US$400,000, subsea sampling can have a significant impact on the field’s economics as well.

Figure 1

Overcoming Technology Limitations

So given the importance of subsea sampling, what are the technology limitations preventing accurate and volumetric sampling?

The limitations of previous and even current sampling technologies include samples being taken randomly and topside; little consideration for flow dynamics; an inability to track and react to fluctuating reservoir conditions, such as high Gas Volume Fractions (GVF) and increased salinity; and a failure to maintain original pressure conditions in the laboratory.

The latter point is particularly important when it comes to water conductivity. While oil is relatively stable, water conductivity may change significantly during the time between the sample being taken and the results received by the laboratory. An inabilty to maintain the exact conditions subsea can jeopardise the validity of these results.

Furthermore, there are also the dangers of fluid contamination in cases where samples are exposed to oil-based drillling or other reservoir production fluids, for example, and the inevitable cost implications and risks surrounding subsea intervention.

The result is no volumetric representation in the samples, low repeatability and an incomplete and potentially inaccurate sample with a lack of PVT data and other information the operators require.

New Subsea Sampling Developments

It’s with these restrictions in mind that Norwegian-based Miromorax has committed to developing a subsea sampling system that delivers true volumetric sampling on oil, gas and water in the well - below the flowline, in controlled conditions and without interrupting production. In this way, the operator can accurately capture fluid properties, calibrate multiphase and wet gas meters, and ensure that the wells are performing at the peak of their production limits to deliver flow assurance

Mirmorax is delivering on this through a new Subsea Multiphase Sampling System (SMSS) that delivers accurate sampling through phase representative samples and in-situ analysis capabilities that are integrated to allow both fractional and salinity data.

At the centre of the new system is a permanently installed Analyzer system module that, mounted to the multiphase sampler, provides online, on-demand fractions of oil, gas, water, salinity and density without the need for subsea intervention.

The Analyzer uses a unique acoustic-based technology where online quantitative values can be obtained by just a push of a button and then made available through standard communications. Based on the functionalities of the in-line multiphase sampling system, the operator can then read the oil, gas and water fractions directly from the sampling bottles taken at a specific time window, providing a phase fractional set of data that can be directly compared to the metering data for the same time period.

By calibrating this fixed point at given pressure, temperature and volumetric fractions, the operator can provide the multiphase meter with a fixed point and increase the meter’s accuracy significantly in relation to the pressure and temperature conditions the sample was taken under.

Figure 2, for example, illustrates the correlation between variables in a multiphase meter. The landscape 3D plot illustrates the correlation curve between two core data inputs and the output value. The red point places the 3D plot of the meter in reference at a fixed point, with PVT data then needed to ensure that all values correlate.

Figure 2

The online fractional data generated through the Analyzer also provides crucial, high-value information to the operator when quality checking samples before they are extracted and transported to surface and can also help determine when a full PVT compositional analysis is required. Knowledge of the sample quality and representation before extracting and transporting for laboratory analysis also removes any risk of faulty samples and reduces transport and analysis costs.

Sometimes the knowledge generated through the system prior to extraction may even be enough to support EOR and other multiphase meter activities without the need for further laboratory analysis.

The System has also undergone rigorous testing at the Christian Michelsen Research Multiphase Flow Loop in Bergen.Here, the subsea sampling system delivered excellent Water Liquid Ratio (WLR) results with an absolute error of less than 1% within a 90% confidence interval; and GVF results that more than met expectations.

In addition, the system was able to accurately quantify the salinity of water. With salinity affecting water conductivity and adding uncertainty to the fraction measurements of the flow, such information is crucial to the operator in calibrating multiphase meters and optimising production.

It is the Miromorax Subsea Multiphase Sampling System’s ability to take measurements directly from the flowline under measurable and controlled conditions with fluid properties and PVT data taken closer to real-time and closer to the wellhead that is revolutionising subsea sampling today. For the first time, operators, through just a push of a button, can generate online, on-demand fractions of oil, gas, water, salinity and density without subsea intervention.

Other Technology Innovations

Yet, it is not just in subsea sampling that Miromorax is making an impact subsea. The Mirmorax oil in water monitoring solution has also been taken subsea.

With increased water production and discharges in the North Sea, the growth in brownfields, and stricter environmental regulations, the detailed information on the size and amount of sand and oil in produced water – whether it be reinjection or discharged – is crucial for operators today. And it is with these issues in mind that Mirmorax has developed a highly effective, and robust oil in water monitoring solution.

The system is based on an ultrasonic measurement technique in which individual acoustic echoes from both solids and oil droplets are analysed. Recent new developments also include new temperature and salinity measurements; an auto calibration feature to compensate for scale build-up and that allows for several millimeters of scale and oil to grow on the ultrasound transducer without affecting accuracy; and self-cleaning mechanisms that prevent the danger of thick oil clogging the system.

Through developments such as this, the monitor can cover a wider measurement range and compensate for layers of scaling and possible contamination. Salinity measurement is also a valuable source of data when determining the origin of water coming from multiple wells. Information about the salinity and density mix also provides the operator with verification of how much of the separation capacity is being used for each of the fields.

Rising to the Challenge

With operators needing greater control and insight into their subsea operations than ever before, the spotlight has fallen on subsea technology development.

It is encouraging to see that companies, such as Mirmorax, are rising to the challenge.

Eivind Gransaether is CEO of Mirmorax AS, an industry leader in sampling, monitoring and processing solutions to the oil & gas industry which he founded in 2009. Prior to founding Mirmorax, Eivind had a number of roles at Roxar (now Emerson Process Management) including Commercialisaton Manager and Global Subsea Sales Manager. Eivind is a graduate of the Norwegian University of Science & Technology (NTNU)

by Mirmorax

Monitoring production

ACCURATE MEASUREMENT OF OIL IN WATER IS A CRITICAL ELEMENT OF OIL AND GAS OPERATIONS TODAY BECAUSE OF THE INCREASE IN PRODUCED WATER AS A BY-PRODUCT OF PRODUCTION.

Oil in Water Monitoring – A Key Element of Production Separation Technology Today

                                                    By Erlend Blanchard, Mirmorax

The accurate measurement of oil in water is a critical element of operations today for one main reason - the continued increase in produced water as a by-product of oil & gas operations.

With 70% of the world’s production coming from mature fields and with a renewed focus on enhanced recovery techniques, such as Produced Water Re-Injection (PWRI) and water flooding, the oil & gas industry today is producing more water than oil. The growing increase in water cuts, for example, is a direct result of water flooding techniques as injected water eventually reaches the production wells.

The total discharge of produced water on the Norwegian continental shelf during 2011, for example, was 131 million m³ with the Norwegian Petroleum Directorate (NPD) predicting that this number will increase in the period up until 2015. Looking worldwide and in 2010, produced water rates exceeded hydrocarbon globally by as much as 50% and on the UK Continental Shelf this figure reached over 130% between 2011 and 2012 (Source: Genesis).

So what does this mean for oil & gas operators and oil in water monitoring?

There are two key arguments for the case for accurate oil in water monitoring today – one economic and one environmental.

The Economic Case for Oil in Water Monitoring

From an economic perspective, accurate information on the size and amount of sand and oil in produced water – whether it is reinjection, discharged or processed water – means more optimal operations, particularly during the water and oil separation and treatment processes.

The greater the detail on the specific components, concentrations and respective size distributions, for example, the more likely there will be optimum production through the enhanced design and use of separators and filters throughout the separation process.

Having accurate information and being able to control water/oil content also improves oil recovery and oil quality as well as ensuring reliable oil production estimates and the long-term economic future of the field. Such information can also negate lost revenues through produced water discharge.

There also remains a real danger to production if produced water is not carefully monitored – not just during the separation phase but throughout production. Typical problems might include the plugging of disposal wells by solid particles and suspended oil droplets, and the plugging of lines, pumps and valves due to inorganic scales.

To this end, information on sand and oil size distributions and concentrations will minimize effects such as plugging and decline in formation permeability that can have a highly negative economic effect on the field, reducing reservoir pressure and injectivity in water flooding operations and negating PWRI’s effectiveness as a secondary recovery technique.

The Environmental Case

The environmental case for oil in water monitoring is strong today also. Today, there are a number of regulators and bodies ensuring minimal oil discharge.

These include the OSPAR (Oslo/Paris) Convention, the main legal instrument overseeing international cooperation on the protection of the marine environment of the North-East Atlantic through to federal regulations in the Gulf of Mexico and bodies, such as the Norwegian State Pollution Control Authority (SFT) and US Environmental Protection Agency (EPA).

OSPAR, for example, has already set a target of ‘zero harmful discharge’ from produced water by 2020 and today, the current OSPAR limit is 30 mg of dispersed oil per litre of produced water. In the United States, according to the Environmental Protection Agency (EPA), produced water discharges must not exceed an oil daily maximum limitation of 35 mg per litre of produced water (40 CFR 435.52(b)).

In addition, OSPAR has also recently set out a new risk-based approach for operators as a means of integrating the assessments of all substances in produced water and identifying those posing the greatest unacceptable risk.

According to OSPAR, “where unacceptable environmental risks have been identified, contracting parties should review management options, evaluate measures and develop and implement site-specific actions to reduce the risks to an acceptable level.” In such circumstances, oil in water monitoring will be even more important.

From international regulations through to a company’s reputation and the importance of protecting the marine environment, the environmental argument for oil in water monitoring and reducing the liability of environmental discharges is every bit as strong as the economic one.

Oil in Water Monitoring Technologies Today

So are today’s oil in water monitoring technologies providing operators with all the information they need to meet both the economic and environmental criteria?

Traditionally, oil in water monitoring was manual, with samples taken from the produced water discharge, acidified to a low PH and then extracted through chemicals. Infrared quantification would then take place with oil content determined by the infrared absorbance of the sample extract and the total methylene (CH₂) present.

Manual sampling has its limitations, however. As well as the fact that it is a highly labour-intensive process, there can be inconsistencies in the results. For example, spot samples rather than continuous samples over time are taken at just one moment in time with operators not getting the full real-time picture.

There is also potential confusion as to what constitutes ‘dissolved’ and ‘dispersed’ oil with both extracted by the extracting solvent. The result is that dissolved oil is often included in the dispersed oil content, making it more difficult for operators to effectively and accurately meet environmental requirements.

The recent emergence of online, inline oil in water monitoring technologies, however, has negated many of these limitations.

Online, inline monitoring can provide direct measurements at the dispersed and suspended phase and generate more detailed information on the size distribution and concentration of oil and sand in water. The fact that the monitoring is able to take place in real-time also provides a highly effective early warning system in terms of any production threats.

Real-time monitoring also optimizes the ongoing separation process. With any deviation, one can quickly step in so that production can continue. Separators, hydro cyclones and the type and regularity of chemical injection can all be run seamlessly with significant benefits to production.

Yet, even these technologies have their drawbacks – particularly in remote, offshore environments where there are often complex mixtures of produced water and dangers of scaling and possible contamination. In such circumstances, the accuracy and robustness of oil in water monitoring technologies are pushed to the limit.

The Rise in Acoustic-based Monitoring

It’s with these issues in mind that Mirmorax has developed an oil in water monitoring solution based on an ultrasonic measurement technique in which individual acoustic echoes from both solids and oil droplets are analyzed.

This is achieved through advanced signal processing that provides accurate information on size distribution and concentration. The amplitude of the scattered signals from each passing particle is used to characterize the produced water.

The way the system works is that a highly focused ultrasonic transducer is inserted directly into the produced water flow, enabling direct measurements on the suspended particles and dispersed oil phase. In the transducer focus, particles passing through the measurement volume will scatter the transducer beam and generate reflected waves or acoustic echoes. These acoustic signatures contain particle specific information. A large number of measurements are then performed to generate a distribution and from the distribution of these amplitudes, the particle size distribution and particle concentration can be calculated from accurate acoustic scattering models.

Furthermore, by being an ‘inline’ instrument, the monitor can provide direct measurements at the dispersed and suspended phase with more detailed information on the size distribution and concentration of oil and sand in water. The monitor caters for concentrations of 0 – 1000 + parts per million (ppm) and can provide complete size distributions ranging from two to three micrometers.

Meeting Scaling and Contamination Challenges

Many monitors, however, struggle to generate accurate measurements when there is scaling. To counteract this, the Mirmorax monitor is able to ‘sound penetrate’ material as opposed to optical based monitoring solutions that can’t. If there is an issue of oil film or scaling, the ultrasonic technology can work just as effectively and accurately because the ultrasonic energy will penetrate the layer and still transmit a signal into the produced water flow.

In addition, we have also introduced a new auto calibration feature to compensate for scale build-up and that allows for several millimeters of scale and oil to grow on the ultrasound transducer without affecting accuracy

Other recent developments include self-cleaning mechanisms that prevent the danger of thick oil clogging the system, and enhanced salinity detection, where salinity can be compensated for in the final measurements. Salinity measurement is a valuable source of data when determining the origin of water coming from multiple wells. Information about the salinity and density mix also provides the operator with verification of how much of the separation capacity is being used for each of the fields.

It is through developments such as these that the monitor can cover a wider measurement range and compensate for layers of scaling, possible contamination and salinity – issues that are particularly prevalent in offshore fields.

North Sea Installations

Last year, Mirmorax provided three of its oil-in-water monitoring units to Statoil’s Kristin Platform, where the ultrasonic pulse echo technology provides Statoil with highly accurate oil ppm measurements allowing them to monitor and optimize their produced water treatment process.

A number of other North Sea orders have also been recently signed and a trial is currently taking place in the Orkney Islands in partnership with leading operators. In another North Sea oil field, where three Oil in Water monitors were installed, the monitors managed to reduce the overall oil content in discharge water by more than 30%.

A ‘Must’ for Operators

With increased water production and discharges in the North Sea, the growth in brownfields, and stricter environmental regulations, the detailed information on the size and amount of sand and oil in produced water is an absolute ‘must’ for operators today. It’s encouraging to see that the latest in oil in water monitoring technologies are rising to the challenge.

by Mirmorax

Oil in water monitoring is a key to production seperation

ACCURATE MEASUREMENT OF OIL IN WATER IS A CRITICAL ELEMENT OF OIL AND GAS OPERATIONS TODAY BECAUSE OF THE INCREASE IN PRODUCED WATER AS A BY-PRODUCT OF PRODUCTION.

Oil in Water Monitoring – A Key Element of Production Separation Technology Today

                                                    By Erlend Blanchard, Mirmorax

The accurate measurement of oil in water is a critical element of operations today for one main reason - the continued increase in produced water as a by-product of oil & gas operations.

With 70% of the world’s production coming from mature fields and with a renewed focus on enhanced recovery techniques, such as Produced Water Re-Injection (PWRI) and water flooding, the oil & gas industry today is producing more water than oil. The growing increase in water cuts, for example, is a direct result of water flooding techniques as injected water eventually reaches the production wells.

The total discharge of produced water on the Norwegian continental shelf during 2011, for example, was 131 million m³ with the Norwegian Petroleum Directorate (NPD) predicting that this number will increase in the period up until 2015. Looking worldwide and in 2010, produced water rates exceeded hydrocarbon globally by as much as 50% and on the UK Continental Shelf this figure reached over 130% between 2011 and 2012 (Source: Genesis).

So what does this mean for oil & gas operators and oil in water monitoring?

There are two key arguments for the case for accurate oil in water monitoring today – one economic and one environmental.

The Economic Case for Oil in Water Monitoring

From an economic perspective, accurate information on the size and amount of sand and oil in produced water – whether it is reinjection, discharged or processed water – means more optimal operations, particularly during the water and oil separation and treatment processes.

The greater the detail on the specific components, concentrations and respective size distributions, for example, the more likely there will be optimum production through the enhanced design and use of separators and filters throughout the separation process.

Having accurate information and being able to control water/oil content also improves oil recovery and oil quality as well as ensuring reliable oil production estimates and the long-term economic future of the field. Such information can also negate lost revenues through produced water discharge.

There also remains a real danger to production if produced water is not carefully monitored – not just during the separation phase but throughout production. Typical problems might include the plugging of disposal wells by solid particles and suspended oil droplets, and the plugging of lines, pumps and valves due to inorganic scales.

To this end, information on sand and oil size distributions and concentrations will minimize effects such as plugging and decline in formation permeability that can have a highly negative economic effect on the field, reducing reservoir pressure and injectivity in water flooding operations and negating PWRI’s effectiveness as a secondary recovery technique.

The Environmental Case

The environmental case for oil in water monitoring is strong today also. Today, there are a number of regulators and bodies ensuring minimal oil discharge.

These include the OSPAR (Oslo/Paris) Convention, the main legal instrument overseeing international cooperation on the protection of the marine environment of the North-East Atlantic through to federal regulations in the Gulf of Mexico and bodies, such as the Norwegian State Pollution Control Authority (SFT) and US Environmental Protection Agency (EPA).

OSPAR, for example, has already set a target of ‘zero harmful discharge’ from produced water by 2020 and today, the current OSPAR limit is 30 mg of dispersed oil per litre of produced water. In the United States, according to the Environmental Protection Agency (EPA), produced water discharges must not exceed an oil daily maximum limitation of 35 mg per litre of produced water (40 CFR 435.52(b)).

In addition, OSPAR has also recently set out a new risk-based approach for operators as a means of integrating the assessments of all substances in produced water and identifying those posing the greatest unacceptable risk.

According to OSPAR, “where unacceptable environmental risks have been identified, contracting parties should review management options, evaluate measures and develop and implement site-specific actions to reduce the risks to an acceptable level.” In such circumstances, oil in water monitoring will be even more important.

From international regulations through to a company’s reputation and the importance of protecting the marine environment, the environmental argument for oil in water monitoring and reducing the liability of environmental discharges is every bit as strong as the economic one.

Oil in Water Monitoring Technologies Today

So are today’s oil in water monitoring technologies providing operators with all the information they need to meet both the economic and environmental criteria?

Traditionally, oil in water monitoring was manual, with samples taken from the produced water discharge, acidified to a low PH and then extracted through chemicals. Infrared quantification would then take place with oil content determined by the infrared absorbance of the sample extract and the total methylene (CH₂) present.

Manual sampling has its limitations, however. As well as the fact that it is a highly labour-intensive process, there can be inconsistencies in the results. For example, spot samples rather than continuous samples over time are taken at just one moment in time with operators not getting the full real-time picture.

There is also potential confusion as to what constitutes ‘dissolved’ and ‘dispersed’ oil with both extracted by the extracting solvent. The result is that dissolved oil is often included in the dispersed oil content, making it more difficult for operators to effectively and accurately meet environmental requirements.

The recent emergence of online, inline oil in water monitoring technologies, however, has negated many of these limitations.

Online, inline monitoring can provide direct measurements at the dispersed and suspended phase and generate more detailed information on the size distribution and concentration of oil and sand in water. The fact that the monitoring is able to take place in real-time also provides a highly effective early warning system in terms of any production threats.

Real-time monitoring also optimizes the ongoing separation process. With any deviation, one can quickly step in so that production can continue. Separators, hydro cyclones and the type and regularity of chemical injection can all be run seamlessly with significant benefits to production.

Yet, even these technologies have their drawbacks – particularly in remote, offshore environments where there are often complex mixtures of produced water and dangers of scaling and possible contamination. In such circumstances, the accuracy and robustness of oil in water monitoring technologies are pushed to the limit.

The Rise in Acoustic-based Monitoring

It’s with these issues in mind that Mirmorax has developed an oil in water monitoring solution based on an ultrasonic measurement technique in which individual acoustic echoes from both solids and oil droplets are analyzed.

This is achieved through advanced signal processing that provides accurate information on size distribution and concentration. The amplitude of the scattered signals from each passing particle is used to characterize the produced water.

The way the system works is that a highly focused ultrasonic transducer is inserted directly into the produced water flow, enabling direct measurements on the suspended particles and dispersed oil phase. In the transducer focus, particles passing through the measurement volume will scatter the transducer beam and generate reflected waves or acoustic echoes. These acoustic signatures contain particle specific information. A large number of measurements are then performed to generate a distribution and from the distribution of these amplitudes, the particle size distribution and particle concentration can be calculated from accurate acoustic scattering models.

Furthermore, by being an ‘inline’ instrument, the monitor can provide direct measurements at the dispersed and suspended phase with more detailed information on the size distribution and concentration of oil and sand in water. The monitor caters for concentrations of 0 – 1000 + parts per million (ppm) and can provide complete size distributions ranging from two to three micrometers.

Meeting Scaling and Contamination Challenges

Many monitors, however, struggle to generate accurate measurements when there is scaling. To counteract this, the Mirmorax monitor is able to ‘sound penetrate’ material as opposed to optical based monitoring solutions that can’t. If there is an issue of oil film or scaling, the ultrasonic technology can work just as effectively and accurately because the ultrasonic energy will penetrate the layer and still transmit a signal into the produced water flow.

In addition, we have also introduced a new auto calibration feature to compensate for scale build-up and that allows for several millimeters of scale and oil to grow on the ultrasound transducer without affecting accuracy

Other recent developments include self-cleaning mechanisms that prevent the danger of thick oil clogging the system, and enhanced salinity detection, where salinity can be compensated for in the final measurements. Salinity measurement is a valuable source of data when determining the origin of water coming from multiple wells. Information about the salinity and density mix also provides the operator with verification of how much of the separation capacity is being used for each of the fields.

It is through developments such as these that the monitor can cover a wider measurement range and compensate for layers of scaling, possible contamination and salinity – issues that are particularly prevalent in offshore fields.

North Sea Installations

Last year, Mirmorax provided three of its oil-in-water monitoring units to Statoil’s Kristin Platform, where the ultrasonic pulse echo technology provides Statoil with highly accurate oil ppm measurements allowing them to monitor and optimize their produced water treatment process.

A number of other North Sea orders have also been recently signed and a trial is currently taking place in the Orkney Islands in partnership with leading operators. In another North Sea oil field, where three Oil in Water monitors were installed, the monitors managed to reduce the overall oil content in discharge water by more than 30%.

A ‘Must’ for Operators

With increased water production and discharges in the North Sea, the growth in brownfields, and stricter environmental regulations, the detailed information on the size and amount of sand and oil in produced water is an absolute ‘must’ for operators today. It’s encouraging to see that the latest in oil in water monitoring technologies are rising to the challenge.

by Mirmorax