Frequently Asked Questions

Questions:

1. Is scaling a problem for the monitor and how will you solve this problem?
2. Is a bypass loop needed? Is there a need for connection to drain?
3. What are the manual maintenance requirements?
4. Is the oil in water monitor equipped with a self-cleaning technology?
5. What is the expected up-time of the instrument?
6. What measurement principle is used? What are the advantages / disadvantages?
7. How much temperature and pressure can the oil in water monitor handle?
8. How can the monitor be used for reporting of discharges to the governmental authorities?
9. What certifications does the oil in water analyzer have?
10. Can several measurement points be connected to the same measurement unit?
11. What is the optimal location for the monitor? How big is the monitor? Requirements to the measurement point?
12. Is local (process) or platform shutdown needed to install the oil in water monitor?
13. How is measurement data reported and presented?
14. Is the monitor sensitive to flow characteristics (turbulent or laminar flow)
15. Is the monitor accessible onshore? What can be done without travelling to the site with respect to service an upgrades?
16. How is personnel safety requirements satisfied?

1. Scaling

Question: Is scaling a problem for the monitor and how will you solve this problem?

Answer:
No, scaling is not a problem for the Argus oil in water monitor.

However, scaling has always been a significant challenge for all oil in water monitors. At fields with high level of scaling (iron-salts, asphaltenes, calcium-carbonate or barium/strontium sulphate and similar), online oil in water measurements will normally go down within hours / days. Especially monitors that are bypass based have challenges, as scaling leads to the blocking of bypass lines, the measurements become unreliable and the level of manual maintenance too high. The Argus technology is the first solving this problem, with its in-line probe design (no bypass) with ultrasound cleaning, which is powerful enough to remove scale. This has been thoroughly tested and documented at several fields.

2. Bypass

Question: Is a bypass loop needed? Is there a need for connection to drain?

Answer:
No bypass is needed, the Argus oil in water monitor measures in-line. There is no need for connection to drain.

3-5. Maintenance and User Friendliness

Question: What are the manual maintenance requirements?

Answer:
Condition based maintenance (expected interval for inspection of the probe, which is a 15 minutes operation) is once per 3-6 months, dependent on the installation and whether ProAnalysis has remote access to the instrument for diagnostics.

Question: Is the oil in water monitor equipped with a self-cleaning technology?

Answer:
Yes. Ultrasound-based cleaning of the measurement probe is highly recommended for most applications in produced water from oil production.

Question: What is the expected up-time of the instrument?

Answer: > 99%

6. Measurement principle

Question: What measurement principle is used? What are the advantages / disadvantages?

Answer:
Argus uses (laser-induced) UV fluorescence.

Advantages:

• High sensitivity (accurate measurements at ppb level)
• High selectivity (eliminating sources of error / noise)
• No or little interference from particles (gas and sand), salt, chemicals etc.
• Not affected by pressure or temperature
• Mainly not affected by droplet size

Disadvantages:

• Need to keep the optical interface (window towards the process) clean, which is common for all optical measurement technologies. This is solved for Argus through the ultrasonic cleaning.
• Need to recalibrate if the oil composition (PAH composition) is significantly changed, e.g. if new fields are put on stream or similar.

7. Pressure and temperature

Question: How much temperature and pressure can the oil in water monitor handle?

Answer:
Argus is today specified for pressure up to 100 barg (pressure class 600#) and 120 °C. ProAnalysis is presently working on the design for a system handling up to 200 barg (pressure class 1500#) and 250 °C. In principle, this is only a matter of mechanical engineering and design of the in-line probe.

8. Reporting

Question: How can the monitor be used for reporting of discharges to the governmental authorities?

Answer:
Argus will most probably be the first online oil in water monitor ever to be qualified and used for reporting to governmental authorities. Using British authorities" guidelines, Statoil is presently qualifying Argus for reporting to the Norwegian Pollution Control Authorities.

The oil in water monitor provides ppm values directly to the control system, and reporting to authorities can easily be done weighting these ppm values with flow. Ppm values are also logged in the monitor, and can easily be read with the Argus Manager user software.

9. Certification

Question: What certifications has the oil in water monitor?

Answer:
The Argus oil in water monitor is ATEX certified, and satisfies relevant CE-requirements. A program for CSA certification has been initiated.

10. Multipoint monitoring

Question: Can several measurement points be connected to the same measurement unit?

Answer: The unique Argus design enables the connection of several measurement probes to the same control and measurement unit. ProAnalysis is the first supplier worldwide to deliver such a system (to ConocoPhillips), integrating 7 measurement probes in one sensor system, located in safe (non-hazardous) area. Up to 12 measurement points can be connected to one sensor system, and the distance from measurement point to sensor can be up to 100 meters. This enable the localization of the sensor system in safe area, avoiding the EX.

A standard instrument with EX field enclosure can operate 2 measurement probes.

A multipoint system will reduce the cost per measurement point.

11. Placement of monitor

Question: What is the optimal location for the monitor? How big is the monitor? Requirements to the measurement point?

Answer:
The monitor can be located any place where there is a connection (flange) to the water pipe. The measurement probe itself (150 x 1106 mm [w x h], see GA drawing) is normally inserted into the water pipe through a 1,5" or 2" flange, and requires only 1,5 m space in front of connection point to retract and insert the probe. The probe can be inserted both vertically and horizontally, at high and low pressure rates. A fibreoptic cable connects the probe to the field enclosure (490 x 785 x 355 mm [w x h x d]), which can be located up to 100 m away from the measurement probe. In that way the localization of the measurement point should not be a limitation.

12. Shutdown

Question: Is local (process) or platform shutdown needed to install the oil in water monitor?

Answer:
No (provided that insertion point (flange and ball valve) is in place)

13. Presentation of measurement data

Question: How is measurement data reported and presented?

Answer: There are several alternatives. Normally the operator want a signal (often Modbus, but analogue signal 4-20 mA can also be provided) to the control room, where the ppm values are integrated in and reported from the control system. In addition an analogue display can be mounted where the oil in water monitor is located, providing ppm values at the site.

An advantage with Argus is that the instrument is equipped with a unique IP address, enabling communication with the instrument through TCP/IP network (Ethernet). This facilitates access to and operation of the instrument from a remote location, offshore or onshore. A user software is developed (Argus Manager) for the presentation of data and statistics, control and diagnostics functions, as well as the setting of important parameters (measurement and cleaning intervals, cleaning parameters, calibration etc.)

14. Sensitivity to Produced Water characteristics

Question: Is the monitor sensitive to flow characteristics (turbulent or laminar flow)

Answer:
Argus is in principle not sensitive to various flow characteristic (turbulent / laminar).

Generally for both in-line probe and bypass based monitors:

In cases with low flow rate, high oil concentrations and laminar flow, there may be a separation of the oil/water phase, and it is recommended to install the monitor in a vertical part of the pipe to measure on a representative segment.

If the oil is not homogenously distributed in the pipe, this will be a challenge for all oil in water analyzers without exception, as all monitors measures on a small segment of the total pipe volume. However, bypass monitors are especially vulnerable, as they take out a sample of the water pipe through a fixated probe. Argus on the other hand, measuring directly through an in-line probe, will have far better flexibility. In addition to having a larger measurement volume, the adjustable insertion length of the probe may be used to measure at different "depths", to examine whether the oil/water is segregated or homogenously distributed in the cross-section of the pipe.

15. Online diagnostics of the instrument

Question: Is the monitor accessible onshore? What can be done without travelling to the site with respect to service an upgrades?

Answer:
Yes, the monitor is accessible onshore, through TCP/IP connection (the monitor has a unique IP address). Using the user software Argus Manager, one can:

• See historical and real-time (live) ppm values, compare with manual samples and get simple statistics.
• Have control with and get diagnostics on central components (relevant parameters for laser, optics, sensor etc.)
• See system status, including status if manual maintenance is required.
• Control and set all important parameters as cleaning intervals, intensity, length of measurement/cleaning, measurement intervals etc.
• Change calibration.
• Upgrade software.

In general the accessibility onshore will reduce the need for manual maintenance, as maintenance can be done on condition basis, based on remote diagnostics.

16. Personnel safety

Question: How is personnel safety requirements satisfied?

Answer:
Personnel is protected using a mechanical interlock-system, prohibiting personnel exposure to laser light. The probe can not be retracted until the instrument power is turned off.

Also, the interlock-system prohibits personnel exposure to the process and process water. Partially retracted, the probe can not be fully retracted until the ball valve is closed.

For high-pressure applications, a special high-pressure retraction tool is used to ensure safe insertion and retraction of the probe.