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 Philip Thackray on March 13, 2014 at 2:09am

Here is a list of BTU content for methane (C1) and the C2-4 NGL's

Here in Southern Butler County PA, the ethane is being rejected into the methane stream and the producers specify gallons of NGLs (C3 and C4) without any mention of the percent C3 and C4.

Hope this helps.

Phil

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Permalink Reply by Harry E. Rose on March 13, 2014 at 3:22am
The % of C3 and C4 would vary by location would it not?
Permalink Reply by Harry E. Rose on March 13, 2014 at 3:36am
Ignore my comment as I was still asleep.
Permalink Reply by The Hiker on March 13, 2014 at 4:40am

A friend asked me to take a look at his royalty "stub" that shows the amounts of gas and NGL's produced by the well.  So far, all the math is correct, but there is a "BTU FACTOR" listed that does not seem to enter into the calculations.  NGL gallons and gas Mcf are listed but I don't understand the connection of the two to the BTU factor.   If I take the ethane%, propane%, etc in a gallon NGL...and use a chart as Phillip provided, convert a gallon of NGL's into BTU's, I get something like 2300 BTU/gallon.  It sounds low, but that's what falls out.  I'd like to tie the NGL+gas to the BTU factor, but can't seem to get there.  Does anyone know how a BTU factor is calculated?  Any help appreciated.

Permalink Reply by Philip Thackray on March 13, 2014 at 5:14am

Hiker,

Without seeing your check stub this is my best answer:

The BTU factor refers to the BTU content of the residual gas (methane + ethane).  Natural gas is priced by the BTU not by cubic feet.  Let's say that a cubic foot of "normal" methane has 1000 BTU then a thousand cubic feet would have 1 million BTU (MmBTU) and lets say that the gas price today is 4.00 per MmBTU.  Under those conditions a thousand cubic feet of 1000 BTU/cubic foot product would sell for $4.00.  When other products are left in the natural gas stream (mostly ethane) the BTU content per cubic feet will be higher -  say for example 1100 BTU/cubic foot.  A thousand cubic feet of 1100 BTU/cubic foot product would sell for (1100/1000) x $4.00 / MmBTU = $4.40.  So the 1100/1000 is the BTU factor.

Phil

Permalink Reply by deer spotter on March 13, 2014 at 7:20am

The BTU of natural gas is determined after a gas sample is run through a gas chromatograph. This will give a breakdown of the % of carbon elements in the gas stream, such as methane,propane, butane,and so on. The total % of all carbons should add up to exactly 100.If these % of carbons plus BTUS and some other technical factors are entered into a electronic  measurement corrector on the well site this will provide an accurate amount of recoverable NCLS. Hope this helps.

Permalink Reply by Harry E. Rose on March 13, 2014 at 7:49am
Is this electronic measurement corrector built into the wellhead, so it does a contineous measurement of the well contents; or how often do they check the contents coming from the well? I assume thewell contents have some variation.
Permalink Reply by deer spotter on March 13, 2014 at 8:17am

The meter run is separate from the well head. The meter run should be the custody exchange point between the landowner and the production co. This is what the landowner should be paid on, But depends on contract language. Some large volume sites have a chromatograph on site that would update % once every hour, However most production co. only update once or twice a year. Newer wells seem to have more variation then older wells. Some well pads in central PA. make over 50 million per day. One BTU is huge amount of royalty at that flow rate.

Permalink Reply by Harry E. Rose on March 13, 2014 at 7:56am
Also how often do they check the BTUS with the chromatograph?
Permalink Reply by deer spotter on March 13, 2014 at 11:06am

Harry: It depends the instruments can be programed to any time interval, but not closer than 1 hour. The chromatograph is usually calibrated 1 time per 24 hours by a know cal. gas. These runs can take 45 min. to 1 hour

Permalink Reply by The Hiker on March 13, 2014 at 10:38am

Philip:  Thanks so much for clearing this up.  I get it.  Unfortunately, there is no connection between the NGL's in the gas stream and the BTU factor, so I was chasing something that doesn't exist.  The factor refers to the methane+ethane only.  Bummer.   The state only reports "gas" and "oil" volumes for each well, and not NGL's, so this volume cannot be verified (or can it?).   The shenanigans that Chesapeake has been caught playing makes us nervous about ALL the oil companies ....and numbers like this that cannot be easily verified.   Too bad.  I like the idea of a continuous measuring device at the wellhead (if it was made public).  Thanks again for the information.

Permalink Reply by Philip Thackray on March 13, 2014 at 11:47am

Hiker,

I'm in an XTO production unit in Southern Butler County PA.  In PA only "residual gas" (natural gas) and "oil" is reported to the State.  This is a "wet" area with NGLs and Condensate.  The condensate is considered oil so it is reported.   The royalty check stubs list residual gas, NGLs (as one number) and Condensate separately.

There is a "continuous measuring device at the wellhead" on EACH well that measures basically everything leaving the well.  This information is transmitted by a cell phone like radio wave system to the Mother Ship.  This information is also available at each well from a display behind a door on a medium sized box.  A friend of mine owns the well pad in another unit.  The well tender has shown him how to operate the readout from the electronics box.  When he returns from FLA he is going to show me how to operate the box.  Then I'll know for sure just how detailed the information is.  I believe that they can measure C1, C2, C3, C4 and condensate independently.  I get checks from two different wells (only two have been drilled on this unit so far).  The price for the NGLs is usually slightly different for each well which leads me to believe that they can measure propane and butane separately - at the well head.

Perhaps someone calibrates this measuring device using gas chromatography but I have had the sensor pointed out to me by a well tender and it is a rather simple looking thing attached to the side of the gas pipe leaving the well pad.  Of course there is a cable that goes to the box I described earlier.

So, to the extent that you believe the box’s information and to the extent that someone has access to the box, you can determine exactly what is coming out of the well.

In fact, when my friend returns we are going to compare his check stub information with the box information.

To me, an even bigger problem is the price and deductions that are listed.  How can these number be verified???

Phil

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