Mike
Moderator
Registered: 01/09/09
Posts: 62
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| #1 |
I would like to see some good discussion on the topic of gas referencing. I know there is at least one person on this forum who has experience with this technique.
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Mike Cunningham Jr.
Geospect Instruments
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myra
Registered: 02/13/09
Posts: 20
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| #2 |
That was a sucker punch.
Gas referencing is an excellent technique if you can afford the initial setup and the royalty fees. This technique simplifies lag calculations, makes it easy to prove your instruments are working by providing a constant reference background of a non-native gas, and makes it easy to find small shows, By small shows I'm talking about the ten or twenty unit gas increase that you're not sure what caused it. Was it a change in the mud weight, was it an change in the pump rate, was it a fluctuation in the mud level in the possum belly, or some other engineering factor.
With the constant background provided by the non-native gas if both the non-native gas and the native gas readings increase, the increase is probably (95%) caused by a change in an engineering factor. This provides the logger with a way to determine which small gas fluctuations are shows. This part of the process is better suited to places where drilling breaks don't have a great increase in prate, think 10 fph to 20 or 30 fph.
On the Gulf Coast the benefit would be in simplifying lag calculations and by having to prove to the company rep that your instruments are working. With the proper setup you don't have to wait for a connection to 'drop a carbide' to check lag. You just activate a solenoid that increases the inflow of the non-native gas for a specified length of time to inject your lag check.
On the topic of proving your instruments are working, the constant background provided by the 'reference or non-native' gas eliminates the trap checks etc when you've got that railroad track look to your gas curves.
Another use for gas referencing is the ability to normalize your gas curves when some engineering factor changes.
Now about costs. Since this technique is patented you have to pay royalties to the man who holds the patent. He originally charged $25.00 per day while you were using gas referencing. Too many companies didn't keep good records and Randy lost a lot of money. The current scheme is $50.00 per trailer per month, or $3000.00 per year for per trailer. Last time I checked you had to pay for all your trailers whether you used it on all of them or not. The next cost is the equipment setup and programming. The solenoids need to be controlled by a computer so some extra programming is required plus the cost of solenoids, extra flow control equipment, extra lines to the pits, and the extra gas which is in constant use. If you use acetylene (the original reference gas), you have to deal with it's unstable nature. A newer gas used is propylene which is not as unstable as acetylene.
A company has to be committed to gas referencing to use it. You have to be committed to the up front costs then proving its use to the oil companies without expecting a day rate increase up front.
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Mike
Moderator
Registered: 01/09/09
Posts: 62
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| #3 |
I meant that as a compliment ....not a sucker punch. Ha Ha! Thanks for the post.
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Mike Cunningham Jr.
Geospect Instruments
http://www.geospect.com |
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Mike
Moderator
Registered: 01/09/09
Posts: 62
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| #4 |
By the way, if anyone needs help with the programming part for the solenoids and such, I may be able to help if Randy isn't already doing this.
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Mike Cunningham Jr.
Geospect Instruments
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KiwiKim
Registered: 02/25/09
Posts: 6
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| #5 |
This whole discussion has been very interesting. I'm going to set up a simple propane line that feeds gas into the rig's mud suction line. We will use this to do our lag tests on our next job. This means we can do away with carbide bombs (Carbide is very dificult to obtain these days even if you have the appropriate certificuits to handle and purchase it). Anyway I'll let let you know how it works out.
Cheers
Kim
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myra
Registered: 02/13/09
Posts: 20
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| #6 |
KiwiKim:
Although it will be a good test the problem with propane is that it is an indigenous gas. The reference gas should be something that is not normally found in a formation. That makes the retention time for the chromatograph column different from the formation gases used for evaluation.
I'm not sure how much info you already have, but will glad to provide you will all I have. Send me an email with your address and I'll get it to you.
Myra
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