Minimum distance from a new facility to an abandoned oil well 3

[vargaslu]

Greetings to all.
I'm in a new project to install five natural gas compressor 120 mmscfd each.
In two of the possible installation sites, there are oil wells constructed in the 50s and nearly 30 years of being abandoned.
My question to you is: Is there a code or standard that indicates the criteria for determining the minimum separation distance from a new facility to an abandoned oil well?
Do you know any criteria established by any oil company for a similar case?
Do you know of a similar thread on this site?
Thanks in advance.
LV

 

[zdas04]

I think due-diligence requires you to pull the plugging report from the government and making sure that they did a workmanlike job, but beyond that you only have to make sure that if the P&A marker is in the middle of a road or the skid for a piece of equipment that you relocate the road or equipment rather than bearing the cost of moving the marker below grade (which is often a big expense and can create some liabilities). I saw a house in West Texas that the homeowner had bolted a cross bar on a P&A marker as one end of a clothesline.

A properly plugged well is just about the most inert thing on the planet.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[vargaslu]

Thanks you David.
my question arises because our people here, are having a discussion about how near an abandoned well can be built the foundation of a compressor. Civil engineers say that could be compromised the integrity of the foundation if it is built very close to the abandoned well. I am not expert on the subject, so, and I wanted to ask some questions to have better information.

 

[BigInch]

Normally I would think there would be no real worries about the surrounding soil strength. The soil may even be better near the well, because of well pad construction and previous compaction. My only concerns would be that the well becomes damaged due to some future event, flood washout, corrosion, seismic event, faulting, whatever and there is no longer any space to get whatever rig or equipment in to repair it, replug it etc. Another possibililty is that you can often find a lot of buried trash nearby an old well. I've found wire cables, electrical cables, drill pad timbers, junk pipe bits, sacks of cement, or simply too much residual crude oil in the soil. Does the site need a clean up? Is there any hazardous waste around?

 

[zdas04]

The buried junk issue that BigInch brings up is important. The standards for P&A require removing all the buried pipe and cable, but it does not always happen.

The soil strength issue is nonsense. When the well was drilled, the surface casing was encased in cement. When it was plugged, the production casing was filled with cement. Is there anywhere else on the site that has hundreds of meters of steel and cement as a support? Probably not. We have a lot of trouble getting crops to grow in the compacted soil around a wellhead after abandonment so I'm not sure that the issue about surrounding soil strength is more than just spit-balling what-if garbage.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[LittleInch]

Vargaslu,

Excellent advice from two highly experienced engineers above.

The key for me is in zdas04's sentence "A properly plugged well is just about the most inert thing on the planet."

The converse is also true - An improperly plugged well....

I have seen some very dodgy plugged wells which still had some crude and little bubbles of gas on the surface (it was the FSU...)

Personally I would go for a 5m or 15ft radius as an exclusion zone and avoid anything in that area. Basically engineering judgment on the basis that the well itself is well plugged. The contaminated soil bit is something to investigate - what was common practice back in the 50's and 60's was a lot different to todays practice and burying things accepted. If you find contaminated soil, the clean-up and disposal costs will be many times any savings you make by getting close to this item.

I'm struggling to think why you are so space limited that you're even getting to this point, but I guess that's the hand you're dealing with.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[georgeverghese]

What discharge pressure do you have for these compressors? The higher the Pd, the greater will be the impact on surrounding equipment if you had an explosion in this compression facility. Talk to a safety engineer who does blast studies.

Guess other things that may affect the outcome of this study may be :

a) Are each of these machines fitted with auto emergency depressurisation / blowdown valves?
b) What is the separation distance between each compression train ?
c) Will you auto blowdown all trains when one train is being blowdown ?
d) Asuming this abandoned oil well may still be pressurised, was this well in sour service?
e) Any vessels with volatile liquids / H2S in this compression facility ?
f) Do you want to allow for any maintenance (hot) work at this abandoned well when this compression facility is running?

 

[georgeverghese]

If this compression facility has an elevated flare, the process safety / technical safety engineer would also recommend a minimum separation distance to this well to meet max permissible radiation loads and ground level pollutant concentration limits at operational or peak flare / vent loads, whichever is applicable, depending also on the potential for any maintenance activity at this well in the future.

 

[vargaslu]

georgeverghese:
What discharge pressure do you have for these compressors?
1200psig

a) Are each of these machines fitted with auto emergency depressurisation / blowdown valves?
Yes
b) What is the separation distance between each compression train ?
25m
c) Will you auto blowdown all trains when one train is being blowdown ?
No.
d) Asuming this abandoned oil well may still be pressurised, was this well in sour service?
No
e) Any vessels with volatile liquids / H2S in this compression facility ?
No
f) Do you want to allow for any maintenance (hot) work at this abandoned well when this compression facility is running?
No

 

[vargaslu]

thank you guys for your answers and coments. It was really helpfull

 

[0707]

Soil studies will be required after that you can decide safely