10 replies to this topic

[Megalith]

Dear friends,
I'm a recently graduated process control engineer working for an oil company on an offshore platform and i'm trying to catch up with everything that's going around me realizing that industry has a little to do with college, or so i have seen so far. Anyways...

On our offshore platform we're bringing on a new well and our concern is, and has been in recent months, that we are operating over the capacity limits of our HP and LP separators, based on information provided on SOG (System Operating Guide).

Currently we are doing around 110mbd - oil and 160 mmscfd - gas

I would appreciate if you can help me to prove numbers stated in SOG right or wrong and point me in the right direction. So far i've been struggling to find a starting point to resolve this problem.

Attached are the specs provided in SOG.

Regards,
Megalith

Attached Files

•  Seps_Specs.doc   40.5KB   134 downloads

[JoeWong]

As quick start for offshore separators, refer to API 12J.

[asade abiodun]

As JoeWong said, read API 12J and try to lay your hand on a book called Oil and Gas Processing Vol.2.

Regards

[Megalith]

As JoeWong said, read API 12J and try to lay your hand on a book called Oil and Gas Processing Vol.2.

Regards

Thanks a lot for you advices. Can you please also tell who the author of the book is?

Regeards

[djack77494]

Megalith,
Let me try to help you by immediately clearing up what may be some confusion on your part (or mine?). Separators do not have capacities. A separator is a mechanical peice of equipment that has characteristics such as volume, weight, etc., but it does not have a capacity. Under certain processing conditions, it is able to separate certain flowrates of predefined mixtures of multiple phases to meet predefined specifications as to the degree of separation that will be achieved. I'm sorry to be such a stickler on this, but I am trying to make the point that accuracy and clarity are absolute requirements in engineering.

[Megalith]

Megalith,
Let me try to help you by immediately clearing up what may be some confusion on your part (or mine?). Separators do not have capacities. A separator is a mechanical peice of equipment that has characteristics such as volume, weight, etc., but it does not have a capacity. Under certain processing conditions, it is able to separate certain flowrates of predefined mixtures of multiple phases to meet predefined specifications as to the degree of separation that will be achieved. I'm sorry to be such a stickler on this, but I am trying to make the point that accuracy and clarity are absolute requirements in engineering.

Dear friend,
have nothing against you correcting me and have no doubts that you are right. I'm still on my learning curve and value every input. Thank you for that

[Qalander (Chem)]

Megalith,
Let me try to help you by immediately clearing up what may be some confusion on your part (or mine?). Separators do not have capacities. A separator is a mechanical peice of equipment that has characteristics such as volume, weight, etc., but it does not have a capacity. Under certain processing conditions, it is able to separate certain flowrates of predefined mixtures of multiple phases to meet predefined specifications as to the degree of separation that will be achieved. I'm sorry to be such a stickler on this, but I am trying to make the point that accuracy and clarity are absolute requirements in engineering.

Dear friend,
have nothing against you correcting me and have no doubts that you are right. I'm still on my learning curve and value every input. Thank you for that

Dear Megalith Hello/Good Evening, I appreciate your positive attitude to respond Doug.
I am confident if you keep this up lot of learning and kmowlege is to come your way.
Regards
Qalander

Hi Megalith,

Please provide the product specification of gas, oil and water in order to rate the separator. Also provide type of separator (i.e. 3 phase, 2 phase, boot, bucket or weir type), maximum, minimum, normal allowable levels etc. Does separator has any internals (i.e. mesh or vane pack)?? Any vendor supplied data sheet???Any P&ID??? if you want detailed analysis.

However I calculated the gas side separation assuming some gas, oil and water properties and considering knock out drum at specified temperature, pressure and level.

HP separator gas can separate minimum 27 micron particle for case 1 and case 2 and 37 micron for case 3. If separator is running currently at 160 MMSCFD then it can separate 55 micron particle and above. If any internal is present then it can have better efficiency then calculated.

I have attached the spreadsheet so that you can start thinking. spreadsheet is without formula and based on GPSA and Ken Arnold book. Ignore the liq separation part as I haven't optimized oil and water levels.

Thanks,

suren

Attached Files

•  HP_separator_rating.xls   80.5KB   144 downloads

[Megalith]

Hi Suren,
Thanks for helping me out.
Some of our wells are routed in HP separator and some into LP. Both separators are weir type separators (500 mm).

HP Separator: 2-phase separator
Inlet from wells: 57 mbd liquid; 116 mmscf gas
Product Specs:
Gas - max 0.1 USG/MMscf carryover
Liquid - max 1% vol/val carryunder

Levels:
Max: 58%
Min: 23%
Normal: 45%

LP Separator: 3-phase separator

Levels:
Max: 55%
Min: 26%
Normal: 48%

Also attached is a data sheet for HP Separator. Thank you, i appreciate your help.

Would like to thank Qalander, as well, for the compliment and support.

Regards,
Megalith

Attached Files

•  HP_Sep_datasheet.doc   1003.5KB   93 downloads

[Qalander (Chem)]

Hi Suren,
Thanks for helping me out.
Some of our wells are routed in HP separator and some into LP. Both separators are weir type separators (500 mm).

HP Separator: 2-phase separator
Inlet from wells: 57 mbd liquid; 116 mmscf gas
Product Specs:
Gas - max 0.1 USG/MMscf carryover
Liquid - max 1% vol/val carryunder

Levels:
Max: 58%
Min: 23%
Normal: 45%

LP Separator: 3-phase separator

Levels:
Max: 55%
Min: 26%
Normal: 48%

Also attached is a data sheet for HP Separator. Thank you, i appreciate your help.

Would like to thank Qalander, as well, for the compliment and support.

Regards,
Megalith

Dear Megalith Hello/Good Evening and congratulations

I am reaally happy that, with patience and positive approach you finally achieved your goal to your satisfaction.
We all have to be considerate and sympathetic to others helping/ guiding and supporting us.
Through their hard earned knowledge/skills/expertise almost free of charge.

An Ideal way to help them is to show maximum self reteraint and be specific without missing important data of queries.

Best regards
Qalander

[Megalith]

Dear Friends,

Would like to thank you all, again, for showing support and giving me an encouragement to carry out my work.

I have done some calculations based on "Surface Production Operations" vol. 1, 2nd edition by K. Arnold and M. Stewart. And I seem to get pretty reasonable number for liquid capacity of 2-phase HP Separator but the gas capacity is off by the factor of 10.

Would really appreciate if you can help to see my mistake.

Thanks in advance
Megalith

Attached Files

•  Saparator_Capacity.xls   60.5KB   116 downloads