What Shale qualities make for an economically viable dry gas well?

In an all dry gas area, what Shale quality is important to satisfying a gas companies need for economical success?   Is it carbon content?  Is it thickness to the Shale layer?  What specifically is a gas company looking for from well samples taken during the drilling phase?   Will these well samples provide an indication of the gas capacity/volume before the well is completed?  Does the Shale quality differ throughout the lateral or remain the same?

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0i7okn54zwbdoPermalink Reply by 0i7okn54zwbdo on April 15, 2014 at 5:50am

There are a lot of questions in there, farmgas. 

1. In an all dry gas area, what Shale quality is important to satisfying a gas companies need for economical success?  

The answer is remarkably simple, actually: production revenues have to exceed costs by a certain percentage in order for it to be deemed economical.

2.  Is it carbon content?  Is it thickness to the Shale layer?

Thickness isn't necessarily an indicator of productivity.  The Utica is much thicker in Carroll County than it is in Noble yet the numbers in Noble are better and more encouraging.  Why?  It has to do with a fairly technical issue and how the fracking interacts with the rock.

3. What specifically is a gas company looking for from well samples taken during the drilling phase? 

The makeup of the rock itself.  What the content is (interbedded limestone, sandstone, carbonate, clay, etc.) and what the porosity and permeability are.

4. Will these well samples provide an indication of the gas capacity/volume before the well is completed?

Yes.  Or no.  Depends on a ton of other factors.  DVN took a core in Ashland County that was full of fluorescents (which indicate hydrocarbons) and the thing was dry as a bone.  So samples are good for collecting data but there's no data set that compares to actually drilling. 

5. Does the Shale quality differ throughout the lateral or remain the same?

Usually in such a small area the rock will remain mostly consistent.  From one mile to another there isn't likely to be a huge difference.  However, from one mile to say 30 miles there could be an enormous difference.

Permalink Reply by farmgas on April 15, 2014 at 9:22am

Thanks, Marcus...so, will the make-up of the rock provide an indication of how successful  the fracking will be?   Will the rock analysis indicate how well the gas will flow into the fracked areas?  Are there various fracking techniques which might create different yield results? Thanks again!

Permalink Reply by farmgas on April 15, 2014 at 12:42pm

Another question(s), Marcus...what would occur with just a top hole drilling to require flaring, and is it a significant event and why?  Is it necessary to flame off gas from a top hole prior to drilling deeper?   Thanks again!

0i7okn54zwbdoPermalink Reply by 0i7okn54zwbdo on April 15, 2014 at 4:37pm

Flaring a top hole is not unusual but it isn't the norm, either.  They might have hit a small trap on the way down and wanted to get the gas out of the way before bringing in the horizontal team, but that's purely a guess.  

0i7okn54zwbdoPermalink Reply by 0i7okn54zwbdo on April 15, 2014 at 4:43pm

It's all about frac dispersal.  How far out does the frac go and how much more efficient is it based on the composition of the rock?  Thicker shale with less carbonate (and more clay) might contain the frac a little more and thus cause less dispersal.  

Permalink Reply by farmgas on April 22, 2014 at 11:59pm

Marcus...is there any difference between Marcellus vs. Utica regarding shale make-up?  Will each generally have fracking results that are similar?   Do you know if Utica Shale is economically feasible for drilling in central Pa in the Indiana, Jefferson & Armstrong counties?  If so, what makes it feasible... having the same qualities as MS...??

Thanks!

0i7okn54zwbdoPermalink Reply by 0i7okn54zwbdo on April 23, 2014 at 10:10am

Farmgas,

There is a measurable difference between the make up of any shales that come from different eras.  Fracking results may end up being similar but the method of each frac is dependent on the shale's composition.  One of the reasons that for decades wildcatters called shale, specifically the Barnett, the "driller's tombstone" was because it has a higher clay content and the thought was that a hydro frac would simply swell the rock rather than fracture it.  As far as what is economically feasible, that's a matter better suited for a price speculator.  At $3 gas most of the Marcellus--and every other dry gas shale--is uneconomical.  At $8 gas the field expands to a much, much greater area.  So the market conditions play a major role in how many wells get drilled, where they get drilled, and how much R&D is spent trying to tweak the frac formula and completion methodology in order to up production.  

Permalink Reply by stephen weiss on April 15, 2014 at 7:53am

A non-geologist's reply:

Three characteristics of shale that are associated with high yield of gas are thickness of the layer, depth of the layer, and maturity.

Greater depth and greater thickness are both associated with increased yield.

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