What is the difference between ActiveSONAR™ flow meters and PassiveSONAR™ flow meters? How do I choose which one is right for my application?

The PassiveSONAR flow meter and ActiveSONAR flow meter serve distinct and sometimes overlapping applications. Having both in our portfolio allows us to serve most oil and gas applications. Application screening by our expert team determines the best solution for the client’s needs, based on their goals and the flow conditions. The client does not need to “choose” between the two – we will recommend the best option (sometimes we mobilise both types to determine the best fit in the field). The cost is generally comparable between the two technologies. Click here for an application screening sheet.

Does Expro sell or rent their sonar meters? Does Expro provide services with their meters?

Expro offers both permanent installations for well flow monitoring and portable services for well flow testing.

Our SonarMonitor™ is for permanent wellhead monitoring for continuous flow measurement. This flow meter is an easily installed, cost-effective solution for high value, downstream applications. The customer owns this piece of equipment. SonarTest™ is a portable clamp-on flow testing service that provides the client with a well test report. This testing meter is a quick, safe, reliable, and cost-effective solution for applications requiring periodic wellhead surveillance. A certified Expro technician installs the temporary flow meter, provides a comprehensive well test report, and then leaves with the piece of equipment.

How accurate are sonar meters?

a) ActiveSONAR flow meters accuracy specifications
Accuracy: +/- 2% of reading

Calibrated gas flow range: 3 to 27 m/sec (10 to 90 ft/sec)
Calibrated liquid flow range: 0.8 to 6 m/sec (2.7 to 20 ft/sec)

b) PassiveSONAR flow meters accuracy specifications
Accuracy: +/-2% of reading

Calibrated gas flow range: 6 to 50 m/sec (20 to 150 ft/sec)
Calibrated liquid flow range: 1 to 10 m/sec (3 to 30 ft/sec)

Note: clamp-on meter accuracy can be a function of upstream/downstream piping geometry.

Is the sonar meter another ultrasonic meter?

No, Expro’s sonar-based technology provides effective well test measurements where ultrasonic meters fail. Our clamp-on flow meters have the capablility to measure multiphase conditions.

How are sonar meters different from ultrasonic meters?

Ultrasonic meters measure flow velocity based on the time-of-flight for an ultrasonic signal to travel from a transmitter to receiver. PassiveSONAR flow meters contain no ultrasonic components, and operate at low (subsonic to audible) frequencies. ActiveSONAR flow meters operate at higher (ultrasonic) frequencies, but utilise sonar processing techniques, not time-flight for flow velocity determination. Sonar meters are very multiphase tolerant, meaning the meters typically measure the dominant phase velocity within our operating range. Clamp-on ultrasonic meters are, in many cases, not multiphase tolerant, meaning they are typically specified only for use in single phase applications.

Are sonar meters completely non-intrusive?

Yes, our sonar meters clamp onto the outside of the existing pipework. There are no parts of the meter that are in contact with the flow. Therefore, sonar meters can be installed during normal flowing operations; there is no need to shut-in the well or shut down the process. There are no parts that would wear out as a result of being in contact with the flow.

Are sonar meters multiphase meters?

Sonar meters are multiphase tolerant, meaning they are generally robust to multiphase flow conditions. They measure the velocity of the dominant phase of the flow in the pipe. We leverage the sonar velocity reading, pressure and temperature at or around the meter location (instrumentation which is typically already available or can be installed in existing taps) and our equation of state software called TPS to calculate inferred liquid rates.

What is the operating envelope of your meters?

a) ActiveSONAR flow meter

For liquid flows, the flow velocity range is 0.5 to 50 m/sec (1.5 to 150 ft/sec)
For gas flows, the flow velocity range is 0.5 to 50 m/sec (1.5 to 150 ft/sec)
Actual measured velocities have been lower and higher than the above stated limits; the operating envelope is dependent on pressure, pipe wall thickness, liquid loading and other factors

b) PassiveSONAR flow meter

For liquid flows, the flow velocity range is 1 to 10 m/sec (3 to 30 ft/sec) 
The minimum flow velocity can be higher for very thick pipe walls or high noise/vibration environments
For gas flows, the flow velocity range is 6 m/sec to 50m/sec (20 to150ft/sec)

How does your multiphase interpretation work?

Please visit the multiphase solutions page for a full description of our multiphase approach.

Does the meter work on liquids and gas and multiphase mixtures? What about CO2?

Sonar meters work on single phase liquids, gasses and in most multiphase conditions. Generally gas continuous flows with less than 70% liquid by volume and liquid flows with less than 20% gas volume fraction are suitable conditions for sonar meters. The meters have been proven to work on CO2 applications, typically a difficult application space for other types of clamp-on meters.

Do your meters need calibration in field?

No, our clamp-on meters are tested against calibrated meters prior to leaving our manufacturing facilities. A small footprint and lack of moving parts mitigates the necessity of “in field” calibration.

Can I move the sonar meters around my field from well to well?

Our sonar meters are designed for permanent and semi-permanent installation or for use by our trained and certified field service technicians. Based on years of experience, we believe that our clients achieve the best results by leveraging our expertise in installing and commissioning the meters and for data interpretation. If the client requires the meter to be moved to a different well, we are happy to mobilise a technician to properly decommission and re-commission the meter in the new location.

Do you need to remove paint or coatings from the pipe?

Paint or coatings on the pipe surface are typically not a problem for sonar meters. Very rough pipe surfaces will sometimes require our field service technicians to lightly sand the pipe surface to a smooth condition, but we do not require the pipe to be cleaned to the steel surface.

What are the power requirements for the meters? What are the communications interfaces?

a) ActiveSONAR flow meter:

Power requirements:
19-35VDC at 12 watts
Communication interfaces:
(2) RS-485 Modbus serial communications ports

b) PassiveSONAR flow meter:

Power requirements:
i. DC unit: 18-36VDC at 25 watts
ii.AC unit: 100-240VAC at 25 watts

Communication Interfaces:
i. RS-485 Modbus Serial Interface
ii. (2) 4-20mA outputs
iii. Pulse output

a. Ethernet port (diagnostics only)
b. Foundation Fieldbus interface (optional)

Can you please advise me how you validate the flow readings from your meters during commissioning?

There are two basic validation steps that our field technicians go through when they install and commission a sonar meter. First, they look at internal electronic and software diagnostics to verify that the meter has been properly installed and the hardware and software are functioning properly. Second, the technician will examine sonar flow diagnostics which provide qualitative and quantitative analysis of the “quality” of the measurement – quality is defined as the flow signal-to-noise ratio. Based on the review of the diagnostics, certain meter settings may be adjusted to improve the quality of the measurement. The technician will obtain a ‘data snapshot’ from the meter, containing raw sensor data and configuration information, and send that to our base engineering team, where it is analysed and if certain settings can be further improved upon to enhance the data quality, those settings will be communicated to the technician, who will update the meter configuration settings appropriately.

Based on our experience in calibrated flow facilities and in our track record, we are confident that if the quality of the flow data is acceptable, the sonar meter will measure the flow accurately. If the piping geometry is not ideal (upstream and downstream disturbances such as elbows, expansions/contractions) there may be an offset to the actual flow rate (typically <10%), but the meter will still provide excellent repeatability even in these instances.

A precise “actual” flow rate is often not known, since there is typically no reliable reference measurement available in the field. If there is a reference measurement available in the field, however, we will review with the client the maintenance procedures, configuration and calibration of the reference measurement to ensure that it can be relied upon for comparison purposes. This reference can in some cases be used to provide an in-situ calibration of the meter to account for piping geometry and other flow effects.

Does Expro provide services with their meters?

Yes, Expro offers periodic well testing services thru SonarTest™ - we provide clients, around the world, with non-intrusive production well testing services utilising our proprietary sonar meters, operated by trained and experienced field engineers and supported by our multi-disciplinary base engineering team. Our production testing solutions complement a program of conventional well testing by offering a quick, safe, reliable and cost-effective solution for applications requiring periodic well test and wellhead surveillance. A certified engineer installs meter, provides a comprehensive well test report then leaves with the piece of equipment.

What is your track record?

Sonar meters have been successfully deployed in a very wide range of applications for many of the leading IOCs and NOCs around the world. Please see our case studies for examples of our work.

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