[Scrub Puller]

Yair . . . Do coal seam gas wells exhibit the same depletion characteristics as shale and are the Australian frakked shale wells at (say) Moomba similar to (say) Bakken wells in the US in their production curves.

Anyone with insights or maybe point me in the right direction to find some info?

Cheers

[Tanada]

Yair . . . Do coal seam gas wells exhibit the same depletion characteristics as shale and are the Australian frakked shale wells at (say) Moomba similar to (say) Bakken wells in the US in their production curves.

Anyone with insights or maybe point me in the right direction to find some info?

Cheers

I am an outsider looking in but my impression of coal seam natural gas is that is it dissolved in ground water that permeates the deep underground coal seams. They pump the water out and separate the natural gas from the water. It is entirely possible that is not the case everywhere, but IIRC that is how they proposed doing it in Michigan where there are many layers of thin bed coal that is not competitive to mine as coal.

Shale is a very different situation from coal beds.

[ROCKMAN]

CBM production characteristics vary a good bit. Here are some generalities: In most CBM-producing basins in North America, water production is normally greatest immediately after the well is brought on line. This is just the opositeThis pattern occurs because CBM is sorbed on the surfaces of the coal itself and is held in place by the hydrostatic pressure of the water that fills the fractures (known as cleats) of the coal. As water is pumped out of the coal-bearing formation and the pressure in the formation drops, the gas desorbs from the coal into the cleats and migrates into the well where it is captured at the ground surface. As a rule CBM depletion is much slower than fractured shale wells. But the daily production rate from a CBM well is very low by comparison. A nice shale well might initially flow 6 million mcf per day. A nice CBM well might flow 300 mcf per day.

Here’s a good bit of detail about Aussie CBM:
http://www.deakin.edu.au/research/stori ... -australia

[Scrub Puller]

Yair . . . thanks for link ROCKMAN. I must say I mostly understand and enjoy reading your posts.

I take it from what you say that "they" are going to have to drill many more CSG wells to fill those two 42"(?) pipes going onto Gladstone than if the project was based on a "conventional" frakked shale recourse?

Cheers.

[ROCKMAN]

SP - Exactly. That's why CBM fields tend to be very shallow...often just a few hundred ft to 1,500'. Way too many wells to drill in order to deliver a total meaningful amount. There is on good potential upside: sometimes that water production is also very needed in the area. That was the situation in some parts of Wyoming.

[John_A]

Yair . . . Do coal seam gas wells exhibit the same depletion characteristics as shale and are the Australian frakked shale wells at (say) Moomba similar to (say) Bakken wells in the US in their production curves.

No.

Anyone with insights or maybe point me in the right direction to find some info?

Cheers

Figure 5 would seem to show the difference between normal pressure depletion decline versus the very different sorbed gas and dewatering effect explained by Rockman.

http://www.sciencedirect.com/science/ar ... 6203000740

His estimate of what constitutes a "good" coalbed methane well appears to be off a little though, I would refer you to an EUR analysis done by the USGS related to exactly this topic except as the government is currently shut down, it is not available.

Consistently, the "sweet spot" of the Fruitland Coal formation kicks ass in terms of ultimate recovery over nearly all the shale gas plays in the US to date. Other coalbed methane plays tend to have much lower well level productivity, and the scientists have some nice comparisons of just this.