Or is it geography. I was asleep that day at school. No. I was right the first time, although most people on this board probably concentrate more on the latter. I'm not sure how many geologists (other than Kirk) follow this board but I'll ask my question anyway, even though the very geologists who could answer my question are probably sworn to secrecy for obvious reasons.
One of the head guys at Devon recently said that Devon was going to concentrate more on the northern end of their acreage because of the "higher carbonates" up there. From what I can tell he is referring to the type of rock that fractures and stays open, as opposed to the more southern acreage, where there were rumors that the higher clay content was gumming up the fractures. (I'm assuming he is basing that opinion on the Soterra Fluker well and the southern wells in East Feliciana). So the obvious disadvantage of clay is that it limits the oil output. Since most things have a downside and an upside, what would be the advantage to the higher clay content, or do we even know it yet? (Even if you don't know, if anyone knows any good oil geology blog boards I would appreciate your posting them as I haven't had much luck finding any. Oil geologists are apparently really quiet guys).
Devon has a considerable amount of it's acreage in what I would call "that southern end" and what I assume is the "northern part" is just a stone's throw from the Mississippi line which, rumor has it, Devon refused to cross. This means that in several of the parishes where they leased heavily they have a huge "clay" problem looking them in the face. Furthermore, if the depth of the play at any geographic location determines the high clay content (and I'm not saying it necessarily does), then they have an even bigger problem, since the play in Kentwood is at about the 11,500 foot mark. That zone quickly goes northwest into Mississippi and if you move strictly west from Kentwood into St. Helena parish and the Felicianas the play gets deeper pretty fast. If what I say is at least partially true, it would appear that they have their backs against the wall of the state line of Mississippi in just Tangipahoa and St. Helena for their best acreage, or at least what I will call their best acreage depending on the results of the Kentwood well. Even the northern most parts of the Felicianas might be too soft to work.
If anyone knows how to turn "clay" into "brittle rock", I would suggest you call Devon. You might have a job waiting with RREEEAALLLLYYY good pay and benefits.
I hope Devon sells their interest in the TMS.
I would not be upset if Devon sold its interest to EOG.
Let them make room for interested parties.
Devon's public position right now is that their Initial Production numbers are inadequate, their costs are way too high, and most recently that the decline curve is horrible.(See my post above). They sure do have a funny way of marketing.
That is ok. Just not the right time for the TMS.
I am no geologist. But at the depths we are dealing with, I would not be concerned with clay as a soft mineral. At those depths clay would be rock like, perhaps even shale. Some shales are pretty damn hard. Just as some chalks are damn hard too, in fact so hard it is full of fractures. There is a tremendous amount of pressure at those depths and the clay would morf into rock. It would be sedimentary material, limestones, agregates and shales. Shales are so hard as in the Barnett Shale here in Texas that it takes severe fracture process to open up the wells to production. Same thing in the Marsellas in Penn. And I am pretty sure the Haynesville Shale is pretty hard too.
Production companies like Devon hold their cards close and do not reveal much outside of their company. And they have a lot of siesmic data and improved analysis processes. They are going to drill where they think the have the best opportunity to get a high production well.
But as a land man said, "They are looking for the bonanzas, not the everyday production well. They want their money back this year not over a number of years."
It is still a crap shoot.
The major limiting factor in Haynesville Shale fracture stimulation is clay content. In the northern reaches of the play (generally north of I-20) higher clay content has rendered wells non-economic. The True Vertical Depth of these wells is ~ 10,500' and the clay content makes the shale more ductile, more plastic. It is insufficiently brittle to frac properly or to maintain artificially stimulated fracture networks.
I understand your logic in your coments, but even at extreme depths where "hard" shales are present due to compaction and pressure, reservoirs with high clay content can be very ductile and very difficent to fracture stimulate.
Many formations that are called "shales" are not shales. Examples of this are the Barnett (silica rich / clays less than 30% +/-) and Eagle Ford (carbonate rich with less than 30% +/- clay minerals). It is the sliica and carbonate that make these formations brittle and easy to frac.