BTU Factor and gallons NGL per Mcf

Can someone explain the conversion of  gallons NGL/Mcf into a BTU factor?  Or estimate a BTU factor from gallons/Mcf?  What's the math?   I can estimate the ethane/propane/iso butane/normal butane and natural gasoline percentages in a barrel if required.   Thanks.

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Permalink Reply by deer spotter on March 19, 2014 at 5:54am

Phil: Hydrates is the term we used describe all the fluid from wells including water. Hard to break old habits after 40 years. Propane, butane, ethane, will drop out of the gas stream in a fluid form from pressure cuts. Gas will lose 7 degrees per 100# pressure cut. same principle as the cryogenic plant, smaller scale.

Permalink Reply by Philip Thackray on March 19, 2014 at 6:06am

Deer S,

Got it!  Thanks.

Phil

Permalink Reply by INVICTUS on March 19, 2014 at 6:57am

Deer Spotter: are these gases actually liquids below ground?

I was told some weeks ago the resting pressure was 3250psi.

And I thought I understood temps to be about 135-140 degrees down there.

Permalink Reply by INVICTUS on March 19, 2014 at 12:21am

Can a gathering pipeline rated at, say 1150 BTU, possibly be carrying any gas heavier than ethane?

I'm trying to determine what the cutoff point is to transport gases via truck or pipeline with that BTU limit.

Permalink Reply by Philip Thackray on March 19, 2014 at 1:20am

Invic,

Here in the wet Marcellus, EVERYTHING goes into the pipeline and on to the cryogenic plant.  Most of the condensate is removed by the separators at the well head along with the water but some of the condensate goes to the plant along with ALL of the C1 thru C4.  Deer Spotter mentioned something about corrosion with high BTU gas and that may have something to do with certain types of pipes but whatever modern pipe they put in the gathering systems today, they handle everything.  Now, wet gas gathering systems have to deal with the possibility that water and condensate will pool in low areas and block the flow of gas and liquids.  For this reason the wet gas gathering pipeline have provision for lots of "pig" launchers and receivers.  I can post a picture of the "pig" apparatus as there are several nearby.

I'm still confused about the "propane" tanks you pictured earlier.  If they are storage for C3,C4 how are these molecules removed from the gas stream on the well pad?

Phil

Permalink Reply by INVICTUS on March 19, 2014 at 1:50am

Thanks Philip.

That is exactly one of the questions I have. I was told by workers earlier it was holding tanks for Propane/Butane/Isobutane to be trucked out.

In, fact, I've seen propane trucks there so I am drawing a conclusion that these items never make it into the 8" gathering line.

I was also told over several visits that the onsite equipment that generates heat or the compressor is powered from the gas from the pad.

As far as the separation, that must involve some of the other equipment on the pad.

The working conclusions I am drawing at this point are:

C5 and heavier: The condensates, light oil, casing head gas, whatever, are stored in the large white tanks, then trucked out. volume meters of some kind (like the old Veeder-Root meters at gasoline stations) are used to determine volume removed from the tanks. I have 8 Large white tanks and was told three are for brine, 5 are for oil/condensate.

Methane and Ethane are piped out through the gathering line.

Propane/Butane/Isobutane must be in those "propane tanks", and are trucked out.

I also have a pig launcher just outside the fence. This is apparently called "the sales point"

As I indicated, that is my working theory. I'd sure like some of the Geo professors who watch this site to grade this little essay of mine!

Permalink Reply by Philip Thackray on March 19, 2014 at 2:10am

Invic,

I think you have it figured out!  I would like to learn more about the well site C3, C4 separating equipment. 

I do know that one of the reasons the local XTO and Markwest cryogenic plants are so complicated is that they can separate the ethane from the gas stream along with the propane and butane.  Right now there is not much market for the ethane so that is not being done.

Phil

Permalink Reply by Bluflame on March 19, 2014 at 1:54am

Philip,

 Another factor in the BTU limitation is the end usage of natural gas in residential and commercial heating equipment. Furnace burner orifices are sized to safely process natural gas at ~1000-1100 BTU. There is flexibility, but at some point there is risk of over-heating equipment or even explosion as the BTU content increases. When furnaces operate on propane, for instance,  the furnace requires a different (smaller) burner orifice to reduce flow of the higher-BTU content hydrocarbon into the burner and maintain a safe temperature in the heat exchanger unit.

 

BluFlame

Permalink Reply by INVICTUS on March 19, 2014 at 2:54am

That raises a question I've had for some time. Just how "pure" is the methane at an end use (residential) site?

Feedstock aside, I don't know why more folks don't have "ethane furnaces". Are those burners at this pad probably burning Ethane?

It seems like so much waste not to burn it if there is no local cracker plant.

Permalink Reply by Bluflame on March 19, 2014 at 5:04am

Invictus,

   Right now the midstream guys are in "ethane rejection" mode, meaning they are peppering the methane stream with as much ethane as possible, while remaining under the pipeline BTU limit. Short answer, "not very pure". And the ethane over-supply will only get worse over the next few years. There is talk of shipping ethane to Europe, but most of the European crackers are configured for mideast naptha.

 

BluFlame

 

Permalink Reply by Philip Thackray on March 19, 2014 at 5:44am

Blu,

You have been reading RBN Energy posts!!!

Phil

Permalink Reply by Bluflame on March 19, 2014 at 6:37am

Hi Phil,

 I start every weekday with the RBN blog and a cup of coffee. Rusty provides an invaluable service to us shale junkies.

 

BluFlame

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