ultrasonic meters in unstabilised crude ?? 1

[jae3806]

Anybody had experience with ultrasonic liquid meters on crude oil ?.
Interested in the thought of using the VOS (Velocity of sound) to interperate the oil water cut in the meter..

 

[ICman]

I've used ultrasonic meters on crude oil very successfully. They are going to measure the fluid flow in the line, but I doubt you are going to be able to determine the water cut.

If your "mixture" changes a lot, ultrasonic may not provide the accuracy you desire. You can try a clamp-on type meter as a trial.

I would suggest an Agar probe for determining the amount of water/oil. They use microwave technology and are designed for this application.

 

[jae3806]

Are you willing to mention brand names for the ultrasonic meters ?. Two path or three path ?.

 

[brianslater]

Hi jae
The established way to determine water cut is to use and bypass sampler with a capacitance meter, this is quite accurate and is used for custody xfer and fiscal duty.
There's a lot of gen out there on pipeline sampling and determination of water cut (BS&W). Have a look out there. btw dont forget that at low flow conditions in a pipeline, water starts to slug flow or just run along the bottom. I could quote volumes on this topic, having been a specialist in this area.

Ultrasonic flowmeters have always been something full of eastern promise, rarely reaching expectations. At best they will give you an idea that you have some fluid flow, but you need to calibrate in situ by some means, maybe you have a tank, can measure level and have a stop watch - this may give you some quantitave info, but dont be too sure - expect +/-20%. This applies to many of the flow gizmos. O course the attraction is the non invasive concept, no hot tapping

 

[shobi]

How much water cut in % are we talking about? Check with Phasedynamics, they have high and low water cut devices and are reliable.

 

[jae3806]

I'm hopeing to run a trial with a 3 path ultrasonic on unstabized crude, with a 2% water cut and after a separator so most of the gas should be cut out. Meter will be run in series with a turbine meter to benchmark the meter.

 

[mabor10]

I am using Controlotron clamp on ultrasonic flow meter with good results. I know this people also have an ultrasonic mass meter.

Another solution would be to try a coriolis meter (Micromotion) that is excelent for this use because it measures mass, density an temperature and doesn't depend on flow profile ass volumetric flowmeters.

 

[jsummerfield]

Both the Coriolis meter and transit time ultrasonic meter will have problem if the unstabilized crude contains vapor bubbles. Transit time and doppler are mutually exclusive applications so doppler should work if you have vapor bubbles. I doubt that doppler has any hope for water cut.

Check with Agar for the water cut or perhaps to eliminate the need for a test separator.

John

 

[mbrooksuk]

To get turbine meter accuracy with an ultrasonic meter you need a multipath time of flight meter. Khrone have a meter that is now accepted for custody transfer of crude oil in at least some of the European countries. There may be others as well. Strap ons are great for general purpose metering of crude but are not to custody transfer accuracy.

Do not even think of using Doppler. This technique in my experience only works for flow/no flow applications.

In all cases, be wary of ultrasonic meters if line pressure is not well above the vapour pressure of the crude oil.

 

[shobi]

We have tried ultrasonic meters on more than one streams including crude and were not satisfied with thier performance.

 

[ICman]

I've used Panametrics, Controlatron, Daniel, and Flow Dynamics ultrasonic meters, with mixed results. Clamp-ons are great for water, and can be used for homogeneous fluids with good repeatability.

Panametrics says they can measure 2-phase flow. I haven't ever tried it, though.

I doubt you could detect water cut with an ultrasonic meter.

 

[jae3806]

Appreciate all the input re the ultrasonic meter. I think the Phase that sums it up is "Full of Eastern promise".I am still keen to run a test, but although it might be the answer on one of the platforms. Due to changes in composition, don't think it will work on all platforms (15). Hight GOR etc.

Coriolis are certainly the way to go, but when you talk about a vibrating piece of pipe in 1500# service, design engineers run a mile.

 

[jmw]

Vibrating element sensors have a long history of use in arduous conditions. Density measurement for fiscal applications uses instruments like Solartron and PEEK (ONYX). Micromotion have also spent some serious effort on the Elite both as a fiscal meter and as a "coriolis" density meter. However, when it comes to an slipstream measurement why use coriolis? the complex tube shapes can present some problems, the higher the presure the more the "straightening out" effect and this can also require care when there are pressure pulsations.
As always, talk to the manufacturers before deciding.
However, when it comes to water cut, check out the other thread in this forum.
You may also care to consider the various multi-phase meters which are begining to emerge and which are reported to be very vluable as they do away with separators, as i understand it.

 

[alexpln]

I'm been working with ultrasonic flow meter... don't think there is a way to determine the water cut...
You can only measure 2-phase fluids but the volumetric or mass flow would be calculated as one.