For Coop As He Is Probably Grafting31 Jan 2018 16:27
I just wanted to clarify a few things I've read on this and various boards about the Dempsey Frac.
1. The Frac does not increase the porosity of the rock, the porosity is the porosity - this is where your hydrocarbons are stored.
2. The Dempsey we has poor permeability - this is a measure of how well the pore space (i.e. porosity) of the rock is connected. The Frac will increase effective permeability by an order of magnitude (above 10 but below 1000) - depends if it connects to natural fractures which may be present.
3. A vertical well is the easiest and cheapest to Fracture stimulate - we don't need to worry about the magnitude of minimum and maximum horizontal stresses as we would in a highly deviated well.
4. The frac will grow vertically until it reaches a bounding stress - a stress plot can be obtained from the gamma ray which is representative.
5. The frac will also grow radially (or tangential) to the wellbore.
6. What limits frac growth is pressure and rate - hence with a frac spread which will consist of multiple high pressure pump units all connected in parrallel to a single high pressure manifold.
7. The frac could potentally grow 200 - 500ft vertically and 300 - 500 ft radially or more - a hell of a lot better that a few perforations that will only go 6 to 8 inches into the formation - we don't know what perforation skin is present and what damage zone is present from the drilling - we're currently having to produce through these - the stimulation removes all these barriers to flow.
Risks:
1. A CBL (cement bond log) will be required if it hasn't already been conducted to ensure the integrity of the cement bond and prevent the frac propagating parallel to the casing / liner - this is one of the reasons that water tables can become contaminated
2. Because this is a sandstone, they'll need to use a proppant to ensure that once they create the fracture, they can keep it open. Screen out is the big risk here - this is when you don't get all the proppant into the formation and you leave some in the casing / tubing - They would need to rig up coil tubing to go in and clean out the proppant prior to flowing the well - adds additional time and cost
The extended flow test will provide a lot of quantitative information with regards volumes. Don't be too surprised that after the fracture stimulation that the connected volumes increase as well as the permeability (flow rates); remember we'll be fraccing vertically as well as radially.
Coop
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