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Separator

01/11/2017 3:16 AM

Hi Friends

We do have 15 oil producing wells coming to our facility . We do have a test separator to test each well and production separator in common for wells .

While testing each well we are getting average of 250 SCF gas so total will be around

3750 SCF

But diverting to production separator we are getting 50% more Gas Around 5625 SCF . The meters are coriolis and calibrated . and base density are same .

The test separator capacity is 700BBL/D and production separator 3500 BBL/D

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#1

Re: SEPERATOR

01/11/2017 3:46 AM

...and the problem is?

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#2
In reply to #1

Re: SEPERATOR

01/11/2017 3:55 AM

It should be almost same how it comes 50%more

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#3
In reply to #2

Re: SEPERATOR

01/11/2017 4:35 AM

Possibilities:

  • A selection error
  • An installation error.
  • A set-up error.
  • A measurement error.
  • An arithmetic error.
  • Some combination of the above.

Coriolis meters require setting up upon installation and their set-up depends upon the substances flowing through them, their temperature and pressure. If the set-up has been done incorrectly, then any of the above could occur. Furthermore, if liquid/gaseous material separation is inadequate, the instrument will give the wrong reading.

The process description documents, P&IDs and instrument set-up record sheets cannot be seen from here.

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#5
In reply to #2

Re: SEPERATOR

01/11/2017 7:23 AM

Bear in mind that coriolis instruments measure volumetric flowrate.

  • One cannot do a mass balance on the basis of volume. Although the principle of Conservation of Mass is used to determine the mass balance, there is no such thing as a volume balance as, for the same mass, volume depends upon pressure.
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#7
In reply to #5

Re: SEPERATOR

01/11/2017 8:24 AM

Basically coriolis measure mass flow only and I have divided it with the base density which is same with both production sep and test sep.

I just encountered the difference in flow .

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#8
In reply to #7

Re: SEPERATOR

01/11/2017 8:36 AM

Consider the possibility of two-phase flow occurring in any one of the flowmeters in question.

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#12
In reply to #2

Re: SEPERATOR

01/11/2017 12:12 PM

Are you producing a light crude with "white gas" in it? Maybe by one measurement, you are seeing a warmer product at the separator and getting more of the light ends to come out of solution from the oil.

The conditions between field testing, common separator, etc. need to be the same, or have a way of standardizing.

Count your blessings, the "white oil" part is very valuable commodity. Don't waste it!

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#4

Re: Seperator

01/11/2017 7:23 AM

Hold the docs a little closer, please.

Sorry, this is all we've got.

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#6

Re: Seperator

01/11/2017 7:56 AM

I guess it all depends on how these wells are coming to your facility. If they are driven then maybe ask the driver. If there is a narrow path way for single entrance and a big road when you let them all in at the same time then that might be a reason.

If in doubt choke the man man the choke to find out where the extra gas comes from. My guess is the Seperator man hides the extra gas for his personal use. The best place is maybe the oil. Check the oil. Its always the oil.

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#14
In reply to #6

Re: Seperator

01/11/2017 6:08 PM

Fair chance a large gas pocket or pockets/veins in one or several wells opened up between the time the initial well test were done and the main system went on yielding a now far higher gas production from one or more wells than had previously been measured earlier.

I worked for a well fracking company and it was not uncommon to have all sorts of odd down hole events happen that could only be attributed to formation shift and or gas void/pockets getting opened up.

A 100+ Barrel a minute flow at 9000 PSI surface pressure while cracking hard shale formation open doesn't just drop to a such a low down hole pressure it almost creates a surface vacuum then slowly come back up without having opened up into some sort of substantial cavity.

Our experienced guys and lead engineers always attributed that to being gas voids being broken into and the gas being displaced into the formations with far less pressure (standing column pressure) than the fracking fluids normally did.

Just a guess.

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#9

Re: Seperator

01/11/2017 10:04 AM

What pressure the crude oil coming out of the well and arriving at your separator at?

You may very well be seeing the effects of outgassing of of the oil like CO2 coming out of soda when the pressure is dropped once it enters into your separator systems.

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#10
In reply to #9

Re: Seperator

01/11/2017 10:06 AM

...which makes it an arithmetic error in the mass balance calculation.

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#13
In reply to #10

Re: Seperator

01/11/2017 5:57 PM

I don't know about you but I see way too many knowledgeable and experienced professionals make basic mathematical errors that result in large theory Vs real world discrepancies all the time.

Then you got those goons who are convinced they can do math using the alphabet provided they use enough letters and if they run out start using symbols and squiggles too. There's no way in hell I trust them to do any form of basic math and be right.

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#15
In reply to #13

Re: Seperator

01/12/2017 5:17 AM

Quite.

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#24
In reply to #13

Re: Seperator

01/12/2017 6:00 PM

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#21
In reply to #9

Re: Seperator

01/12/2017 9:14 AM

I agree with this, can you measure the SG of the oil coming out of the test separator and production separator(s)? Is the pressure and temperature in each separator the same? Are the residence times the same?

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#23
In reply to #9

Re: Seperator

01/12/2017 1:45 PM

A second on that one. That is why, even after the gas separator on the tank batteries around here, there is still a vent on each storage tank that flows most of the time. On a foggy day like today, some of the valleys around here smell like they could explode.

Guess that is going to change in the near future according to EPA.

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#11

Re: Separator

01/11/2017 11:38 AM

Your oil has gas.....

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#16

Re: Separator

01/12/2017 5:45 AM

Hi All both the production seperator and test seprator are in the facility . The wells are 1.5 km apart with fixed lines to the sepera tors . NO choke used . If there is moisture more in gas we can get in the drive gain of the coriolis ,which is also in range .

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#19
In reply to #16

Re: Separator

01/12/2017 8:41 AM

Then you should be discussing the matter with the meter suppliers. I do not agree that Coriolis flow meters are mass flow for a two phase system.

You need a true mass flow meter that can cover two phase flow? Go buy one. You have money coming out of the ground. Be realistic. Do not ask the instruments to do something they were never designed for.

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#17

Re: Separator

01/12/2017 8:08 AM

First, the gas at the well and production separator must be at the same temperature so as the pressure, then you can say a correct mass balance.

Ideal gas equation is

PV=mRT; m=PV/RT or in rate, we have dm/dt=dV/dt(P/RT)--> mass rate=flow rate*(P/RT). The readings should be corrected by this, otherwise it can become erroneous.

Here is a a good read http://www.tuvnel.com/_x90lbm/Emerson_-_Temperature_Effects_on_Coriolis.pdf

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#18
In reply to #17

Re: Separator

01/12/2017 8:39 AM

You applied the ideal gas equation improperly. The OP is not dealing strictly with single phase gas flow anyway. Gas and oil are produced concurrently, and there are situation where it is two phase, sometimes even three phase flow (depending on what all comes up out of the well, LOL).

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#20
In reply to #18

Re: Separator

01/12/2017 8:56 AM

No, you got the wrong concept of what I meant. One way of eliminating the two-phase gas is pre-heat and pressure regulate it, so that it will have a homogeneous state before flow measurement. And, that is exactly what is implicated by my post. PV=mRT.

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#22
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Re: Separator

01/12/2017 10:25 AM

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#25
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Re: Separator

01/13/2017 12:43 AM

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Re: Separator

01/13/2017 9:33 AM

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Re: Separator

01/13/2017 3:32 PM

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Re: Separator

01/13/2017 3:47 PM

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#29

Re: Separator

01/14/2017 7:30 AM

That is a good new. Congratulations

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