Field Experience Level Instruments and Water Cut Meters for Crude Oil 1

[compo]

We are seeking operational feedback on level instrument and water cut meter manufacturers and specific technology that has been applied successfully in the field for crude oil water emulsion interface detection and outlet oil water cut metering for 3 phase production and test separators. The application is for heavy crude primary and test separators, 22API with potential stable emulsions forming, no foaming issues. FPSO installation and ships movements considered.

On level instruments for interface detection with emulsion band etc. we would appreciate feedback on any experience and recommendations on potential instruments that have been used or retrofitted successfully in similar heavy crude FPSO applications.

We are putting in a 3 phase test separator with a water cut meter in the oil outlet and are expecting to get emulsion carryover and expect accuracy issues with the meter. We would appreciate any feedback on instrument selection that you may have or could recommend.

I am aware of some of the technologies available in the market place and the reputed vendor claims however the crux of the matter is what actually works in practice and has been proven. I would appreciate any feedback and or contacts you may have.

Many thanks

 

[KernOily]

Here is what works in the onshore 13° California heavy crude oil patch at high temperature. These are time-proven.

* Endress-Hauser "tuning fork" for point-level detection, i.e. level switches
* Drexelbrook vertical capacitance probe for continuous interface or point interface, e.g. tank or vessel interface level monitoring
* Robertshaw for wet oil cut probe in your test separator

I guarantee you _will_ have accuracy issues with your cut probe. You can only minimize the problems. Best to set up a rigorous calibration schedule, make sure you have representative samples in the test line, i.e. no oil slugging, and make sure there is no gas in the test line. Also, the physical configuration of the oil-out leg on the test separator has a huge effect on the accuracy and repeatibility of the cut probe.




Thanks!
Pete

 

[toffy42]

I can only answer on the Watercut meter issue. My experience with Roxar Watercut meter has been well above our initial expectation. This meter is amazing and will give you entire satisfaction. It is also very accurate and stable with time.

Chris

 

[compo]

Appreciate the feedback. Chris can you provide more information on your water cut meter application i.e. is it dealing with a heavy crude or emulsions?

 

[par5fore]

Am looking for contact rep for the robertshaw cut probe. have been asked about calibration here in california. i would like to provide some answers. am having difficulty finding the rep. a name and number wouild be appreciated.

what is thought of as the best cut probe currently available? varying conditions 15 gravity to 34. steam conditions, gas.

thanks,
terry

 

[UMIST]

The Watercut meter has no problems with emulsions or heavy crude. The meter is available in different versions, low cut (0-15%), medium cut (0-50% and full cut (0-100%). A good mix (emulsion) is required, so it's recommended to install it dwonstream of a T with flow vertically upwards. It will have trouble if the gas content is higher than 5%.

 

[KazakhJeff]

Please allow me to "piggy-back" onto this thread. We are installing a custody transfer facility in a line with varying water cut from 3 to 30% water, with avg 20%, but there should be no gas. There is a straight 3 kms upstream, so I anticipate the flow to be stratified. Mass metering will be made by Coriolis, a side stream taken off for water cut with "phase dynamics" (as a check), and a continuous sample catcher which will give us oil and water densities to balance up the water cut with the Coriolis. My question concerns the mixing requirements, as I believe that the flow should be pretty homogeneous before the sampler, requiring an in line mixer. My colleagues however believe a 3 hole sampler will give a representative sample. Does anyone out there have practical experience, and advice? Can anyone also comment on using the Coriolis to determine water cut?
Thank you.

 

[khan101]

We are using Roxar water cut meter on very heavy hydrocarbon froth service and it is very reliable. It has been in service for the last 10+ years and still performs superbly. It is a full-bore, in-line field mounted instrument for accurate measurements of water in oil. We find it reliable and easy to use. We installed these meters at the discharge of pumps so the stream is mixed homogeneously.

For interface detection we have used several technologies and the best has been Tracerco by Synetix. It is very expensive though. Other things we have tried are optical feed back by using submursible cameras.

 

[KernOily]

For oil-water interface in tanks and vessels in 13° API crude and 150-200F temperatures, the capacitance probes by Drexelbrook or Endress Hauser are bulletproof for interface level. Accurate and repeatable.

Thanks!
Pete