Challenges with allocation measurement -- solved

A consistent challenge in upstream oil and gas is accurate allocation measurement.  Often times, meters are over-reporting the oil rate due to either contamination from water or from gas carry-under in the separator or flashing in the meter itself.  Use of a more accurate meter alone doesn't solve this challenge.  Working with customers who are already Coriolis users, we analyze the density measurement and drive gain diagnostics to first identify when these upsets occur.  Coriolis density measurements can indicate when the oil is contaminated with either water or gas, indicating, for example, poorly operating level control or heater.  Coriolis drive gain is a diagnostic that can indicate very quickly when two phases are present in the meter, ie liquid and gas.  This diagnostic can be a powerful indicator to incorrectly sized valves that draw gas into the oil line during a dump cycle or pressure drop through the meter that results in flashing.  

In all cases, the best solution to this challenge is to address the root cause in the process -- if the valves are too large, change it out for  a smaller size.  If a heater has failed, replace the heater.  However, in many cases, the process cannot be addressed without a significant CAPEX investment.  In this case, algorithms are available in the Micro Motion Coriolis meters to utilize diagnostics to identify contamination and report a remediated oil total and rate.  This has helped some operators identify erroneous over-measurements of oil by over 20%!   Micro Motion Advanced Phase Measurement has seen tremendous uptake in the upstream oil allocation off three phase separators.

If interested in learning more, drop me a note and I can direct you to resources on the Emerson website and Youtube!

Cheers-

Laura

4 Replies

  • Dear Laura,
     
    I came across your post on the topic “Challenges with allocation measurement – solved’’ and wish to inform you that I am interested. I will like to have detailed information on this. Thanks in advance for your assistance.
     
     Kind Regards,
     
    Chris Adaro | Metering Specialist | Maintenance Team | Sea Eagle FPSO Operations
    Shell Petroleum Development Company | Offshore Division | Lagos - Nigeria  
    T +234 807 025 3486|  Ext. 53486
     
     
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  • Chris—
     
    A great place to learn more about Coriolis and how it can be used to improve Allocation measurement is in our webinar available here on YouTube:
     
    A brief demonstration of the product in action is available on this video here: https://www.youtube.com/watch?v=mrRbHb5UsMA&t=8s
     
    Additionally, if you have a specific case or application you’d like to explore, please let us know – we have worked with a number of FPSO operators and onshore applications where we have helped identify poorly operating separators and provided solutions.
     
    Cheers-
    L
    Laura Schafer | VP, Oil & Gas | Flow Solutions
    Emerson Automation Solutions | 7070 Winchester Cir | Boulder | Colorado| 80301 | USA
    T/M +1 303 809 1008 | laura.schafer@emerson.com
     
    Learn how to improve your Terminal’s operation by joining Emerson's Terminals Automation Webinar Series
     
  • In reply to Laura Schafer:

    I am nt sue if I am at the right place to talk on this issue but
    we have a 10" micromotion Coriolis meter {built in core processor} for allocation which has been giving erratic flow readings/spikes for several months now. my first suspicion was from the core processor so it was decided to change it. however on a second thought, we replaced the unit with another new micromotion elite sensor {same size} but this time, with a stand alone core processor. After observation over a 1 week period of time, with this new installation, the erratic flow meter readings/spikes still persisted. kindly advice what could be the cause of these problems.
  • In reply to okpako:

    Okpako--

    I encourage you to check the 'drive gain' diagnostic output and density output on the meter -- often times, erratic volumetric measurement is caused by two phase flow in the meter which can be identified by monitoring these two variables. Erratic volumetric measurement will occur and the same time that density drops and drive gain increases.

    If you're able to confirm two phases with this approach, examine your separator operation and look for an opportunity to increase back pressure on the meter (increase downstream pressure) or otherwise improve separation or keep gas in solution.

    If you would like help reviewing data, you're welcome to email me a sample of data with volume, density and drive gain recorded that we can take a look at. We can also engage local service/support organization if you'd like Lifecycle Services to take a look.

    Cheers!