PVT Analysis Discussion

Hey guys,
I'm working a project using prosper, now. I have several basic questions regarding the PVT data. I've read the manual, yet I couldn't find any information.
What I'd like to discuss with you is about PVT. I still confuse about using the data from PVT analysis data (not analyzed by software yet), which sample we should use? From separator or wellhead sample, or any other reference?

And, if we have several PVT data which is taken on the same spot, how do we compile them all? Can we take the average mole% of the components?
How do we get the salinity of water?

If you guys have the reference books or papers, I hope you can share them here.
Thanks.


Regards
[email]e4s_air@yahoo.com[/email]

Can anybody share or discuss this topic?

Dear Bang Gaol :

The type of the reservoir fluid mainly effects on the samples should be taken for analysis, for example for gas condensate reservoirs it is highly recommended to take separator oil and gas samples and then doing physical recombination in the Lab. and that also the same for high GOR fluid on contrarily for low GOR fluid the choice of mono phasic sample (Wellhead , Bottomhole) is recommended

Hoping this contribution will be useful for you but wait another replies from the experts in reservoir engineering which they are a lot here in our great forum

Hey Bang Gaol,

Is it an oil reservoir or a gas condensate reservoir.?

@ tiger842002
not complusory to take sample samples at the separator. it depend of the sampling philosopy of the company.Sampling at the seperator is the cheapest method but it is more prone to errors when recombining. Most companies take downhole samples they are more representative of the fluid.
@BangGoal
dont use prosper 2 much so cant help.im better with Pvtsim. You should have a detailed pvt report which states the best fluid to use.(most of the pvt reports are downhole samples). Basically wit PVT software you input the fluid into the software package and tune the properties in the software to get a best representation of the pvt report.

@tiger842002: Thank you for the share. I know it depends on the result (the best one).

@ELgharib: it's gas condensate (let's say dry and wet gas) reservoir.

@ibro: Is it true if it depends on the company policy, since I haven't seen any statement like that in the report? I already discussed with other REs if there ain't no such statement. Can you share more?
And can you share the reference about the PVTSim? I never use it, although I have it installed in my computer.

Thanks all, look forward for another reply.

Regards

you might use the winprop in CMG to analyze your PVT based on the composition



thanks

[URL="http://www.4shared.com/dir/11988956/a3a543a2/sharing.html"]Whitson Lectures[/URL]

It will take a bit of time, but this series of lectures on PVT will be well worth the time taken to listen to. Do It :)

McCain said in Rapid “Tuning”of Equations of State for Compositional Simulation

THE TUNING STRATEGY

Step 1.Extend measured plus fraction to SCN45+, match saturation pressure by adjusting molecular weight of plus fraction.

Step 2.Group to eight pseudocomponents, rematch saturation pressure by adjusting the acentricfactor of heaviestpseudocomponent.

Step 3.Match PVT data by adjusting the Penelouxmolar volume translation parameters.

Whitson proposed in … I do not remember

Step 1.Extend measured composition into single carbon number groups, SCN, to SCN 45+, assign properties to the SCNs, calculate coefficients of the equation of state, match the saturation pressure by changing the molecular weight of the plus fraction.

Step 2. Group the extended composition into pseudocomponents, group the properties of the pseudocomponents, rematch the saturation pressure by altering a correction factor to the ratio of the critical temperature to the critical pressure of the heaviest pseudocomponent.

Step 3.Match the PVT properties by adjusting the Peneloux et al, molar volume translation parameters of the grouped composition.

The most important thing “I say”, in gas condensate PVT data, is to take CCE (Vapor Z factor, Vapor density, Liquid saturation, Relative volume), CVD (Vapor z factor, Vapor visc. Liquid saturation, Moles recovery, 2 phase Z factor) and Separator Data (GOR, liquid density) to EOS tuning.

The most important variables:

1. Ps
2. GOR
3. Liquid density
4. Liquid saturation.

Do not make any regression with Vapor viscosity data before you finish with those 4 variables.

Do not use so many variables in the regression procedure.

I hope, those ideas can help you to start EOS tuning !!!!!

@shakespear: I can't download the book. Thanks anyway, I'll read it right after it's able to be downloaded.
@olmos: BIG help, thanks very much. Now I have slight understanding about the tuning process. Can you share more?

The Whitson lecture tell you some good things regarding Tuning the Eq. of State. IT IS NOT SIMPLE and can lead to errors. Which means that someone who does this for the first time or without the help of an experienced engineer is heading for trouble. ;)

I am no t sure, but I think Shakespeare proposed this information:

[url]http://www.4shared.com/dir/11988956/a3a543a2/sharing.html[/url]

Very good information !!!!!

Thanks olmos. Appreciate it.

[QUOTE=Shakespear;82178][URL="http://www.4shared.com/dir/11988956/a3a543a2/sharing.html"]Whitson Lectures[/URL]

It will take a bit of time, but this series of lectures on PVT will be well worth the time taken to listen to. Do It :)[/QUOTE]

Hello,

H mentions some course handouts and other supportive materials, is it possible to obtain them?

Thx.

Dev_r

there is a PVT analysis of an oil reservoir that i want to use for EOS regression.
when i split puls fraction into three seudo components the calculated saturation pressure
will be 1622 psi while the observed saturation pressure is 1618 psia.
there are some questions:
how could i know that this is a good splitting?
can i use phase diagram of new mixture(with 3 pseudoComponents) as a valid reference for regression?
or I should compare phase diagram of new mixture with phase diagram of mixture before splitting?

what is more acurate?
phase diagram of mixture before splitting with 1450 psi calculated saturation pressure OR
phase diagram of mixture after splitting with 1622 psi calculated saturation pressure?

thank you

When you are grouping some components, or in this case where you are splitting C7+, properties which will be calculated with your equaion of state have to change. There are some authors who have analyzed the best way to make this changes but finally they made different combinations and selected the one which reflects more accurate results with the laboratory data (not only pressure). Please analyze saturaton pressure, liquid density, GOR.

It is very important to tune your EOS with inforation from different test (CVD, CCE, Separatr, etc). You know, you can have the same saturation pressure but the shape of the envelope could be change because the quality lines.

In most cases with ag good control you can use this diagram as a valid references but as starting point, then you hae to elect some variables in the regression to adjust the bahivior of your EOS ith the laboratory data.

I always have control with the different envelopes during an EOS tuning to evaluate some inconsistences during the process specially if you are using BIC. The do not have to chanege so much.

Refering to your last question, heavy components properties are frequently unkown and for this reason you should use them during EOS tuning. You can have both cases, and both could be valids in terms of saturation pressure due to you can adjust during regression but as I told you before, it is necesary to evaluate other properties.

In a paper draw an envelope and then define your saturation pressure and then draw another envelope 2 times bigger than first one. you have to assure this one pass at the same saturation pressure. For this reason you have to analyze more variables.

thank u for your guidance.
the shape of envelope is the same as the shape of envelope before splitting but it is bigger due to saturation pressure.
please note that Psat(lab)= 1618 psia Psat(calculated before splitting)= 1450 psia and Psat(calculated after splitting)= 1622 psia
other calculated properties after splitting are much closer to laboratory data than calculated properties before splitting.
so i think that the phase envelope after splitting is much closer to real fluid phase envelope.?!!

i dont undrestand what do u mean? "In a paper draw an envelope and then define your saturation pressure and then draw another envelope 2 times bigger than first one. you have to assure this one pass at the same saturation pressure."

Yes, you are right.

The second one is to show you the importance to evaluate other laboratory properties. You can have two envelopes with the same saturation pressure but with different quality lines.

Unfortunately the 4share account (not mine) does not appear to have it :-(

This may be of interest to some of you

[url]http://www.ebookee.net/-quot-PVT-Analysis-for-Compositional-Simulation-quot-by-Steve-Furnival_343980.html[/url]