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45 comments on The Denver gas situation

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Gets IT on February 22, 2006 - 6:39am Permalink | Subthread | Parent | Comments top
The gathering field lines freeze between the wellheads and the first glycol dehydrator, which in many cases can be up to 50 miles away from a well.  In the gathering lines there can be a mixture of oil, water, salts, condensates, paraffins, waxes, NG, CO2, N2 maybe H2S.  Hydrates are crystals where water is embedded in gas molecules.  Any significant quantity of hydrates can plug the gathering lines.  Hydrates can form at temperatures above 32ºF.  If temperatures drop below 32ºF, then ice plugs can also form.  A lot of wellhead treater installations have heaters to keep the flow into the gathering lines above the temperatures where hydrates form.  Normally the well heaters are off unless hydrate formation temperatures are expected, in which case an operator will go out to the field and light up the heaters.  Even if the heaters are lit, they can still go off if hydrates form upstream, as this can shut down their fuel supply which also comes from the well.  In my experience it sometimes not possible to reach the wellheads in time to light the heaters and keep them from freezing, because of downed trees, and snow/ice on the roads and access trails.  It is also not uncommon for somebody to  get sick on those cold nights either.  Of course extremely cold weather usually happens on the weekends when there is only one person on call.
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Leanan on February 22, 2006 - 7:35am Permalink | Subthread | Parent | Comments top
Someone who claims to have worked directly for this particular company says they have hundreds of dehydrators per wellhead.  He didn't think it was likely that anything would freeze, even with equipment failure.
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Gets IT on February 22, 2006 - 8:44am Permalink | Subthread | Parent | Comments top
If he worked for the local distribution company, or the intrastate or interstate company, he is probably correct. In those systems the gas would not be subject to freezing. If he/she says they h/s worked at the company operating the gas fields, do a detailed check his/her credentials. The company I worked for was one of the largest independent drilling and gathering operators in the US at that time (we had more gas wells and gas flow volumes than Exxon produced by themselves) at the time. The only other thing that could possibly have happened (within my reasoning) is that the Denver local distribution company (LDC) had thier peak gas diverted by their intra/interstate supplier to other customers that were experiencing greater hardships or had contracted for more firm transport capacity than Denver. Normally, as was suggested by other posts, various customers will request a firm volume that the intra/interstate transmission company must guarantee to transport and another peak volume that the intra/interstate transmission company will transport only if he can reasonably do so. They will follow that SOP unless an emergency is declared, in which case they will revert to making special volume assignments according to priority level of the services that are affected. Could have been one of those things. I've said all about I can say without having been sitting in the control room myself, so ... I'll definitely leave any further details for the LDC to explain away.
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Leanan on February 22, 2006 - 9:39am Permalink | Subthread | Parent | Comments top
He says he worked for CIG, before it was acquired by  El Paso.

He also said all of CIG's wells are in steep decline, except the Jonah field in Wyoming.  And their plants are not in great shape, either.  

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Gets IT on February 22, 2006 - 11:44am Permalink | Subthread | Parent | Comments top
He's right then.  I never heard of Xcel. I left the USA in 1990 and there's been a lot of takeovers since then, but I do remember Colorado Interstate Gas and most of their immediate supply wells were in the Tx-Ok panhandles and SW Kansas.  Those were the old gathering systems in which I was trying to turn one around to supply a proposed peak generator in Larime Co.  They were some producing wells still left around that particular area, but they were on their last breath 16 years ago and were running at about 30-40% N2, so even then they wern't what you would call star performers.
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Gets IT on February 22, 2006 - 1:08pm Permalink | Subthread | Parent | Comments top
But he's still wrong about having hundreds of glycol treaters.  There's only a couple of those per field.
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kkinder on February 22, 2006 - 1:19pm Permalink | Subthread | Parent | Comments top
Xcel used to be called Public Service Company.
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Gets IT on February 22, 2006 - 1:25pm Permalink | Subthread | Parent | Comments top
The only XL that I heard about before was Microsoft's.  I'm surprized they don't sue Excel for some name infrigement violations.-)
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45 comments on The Denver gas situation

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