Geology of the Piceance Basin — An Ursa Presentation

Ursa well pad in Battlement Mesa -- March 2015 [Photo by Amy Hadden Marsh/KDNK]

Ursa well pad in Battlement Mesa — March 2015 [Photo by Amy Hadden Marsh/KDNK]

Guest post by Fiona Lloyd*

Ursa’s informational meeting was held on Monday night in response to Battlement Mesa residents concerns about the impacts of increased drilling in their community. The attendance was good, about 70 people along with just 4 Ursa representatives. The main question seemed to be: Given the current technology, why are you drilling from inside the PUD when you could be drilling from outside it?

The answer is twofold. Firstly, Ursa “is” drilling from outside. From a starting point of 14 well pads originally planned, Antero whittled that down to 11. Ursa has reduced that even further to 5 active well pads plus one other “in reserve” for Niobrara well development. They have moved many of their planned wells outside the PUD. Secondly, the geology of the Williams Fork formation does not lend itself to horizontal drilling whereas the Niobrara does.

Ursa geologist, the fabulously named Duke Cooley, used the analogy of a bowl of chips to describe the gas-bearing sandstone lenses in the formation, with air spaces in between the chips being the friable muds between the lenses. If you insert a straw vertically into your bowl of chips, you pass through a bunch of chips, if you insert a straw horizontally, you run the risk of not hitting any chips at all. Conversely, the Niobrara formation is a continuous layer about 200’ thick spread like jam in a cake. A horizontal well can stay in the jam for a couple of thousand feet.

The presentation also touched on seismic activity, injection wells, drilling methods, casing, and spacing. Spacing is confusing. Apparently you need 64 vertical wells to drain a section (one square mile of Williams Fork) plus only another 4 horizontal wells to drain a section of Niobrara. If my math is correct and you can put on average 20 wells on one pad, then you only need 4 well pads in a section, one in each quarter. Which begs the question how come Battlement Mesa PUD gets 5 well pads plus being ring-fenced by goodness only knows how many more?

Monday’s crowd was, on the whole, hostile in an extremely well-mannered and well-educated way. Perhaps sensing this, Ursa made no attempt to win them over. It was made very clear that another 80 wells were planned. They would be inside the PUD and, once the Williams Fork formation was drilled, Ursa will be coming back for the Niobrara. No ifs, no buts. Interestingly, Ursa turns up to its meetings in Silt mob-handed and bearing snacks. In Battlement, they fielded a skeleton crew and not even water was on offer. “Let them eat chips” presumably being the take home message.

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Fiona thumb*Fiona Lloyd is an RSPN organizer and Silt Mesa resident.

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One Comment on “Geology of the Piceance Basin — An Ursa Presentation”

  1. Barb Coddington Says:

    I think this is also about the injection well. One of these days, on of these injection wells will cause an earthquake that fractures all the casings for the production wells and we will see just how bad it can be.

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