Replies to This Discussion

Permalink Reply by Jack Straw on August 8, 2012 at 4:05pm

RE: "Obviously totally off topic, but i thought that the "k" was perfectly acceptable in the vernacular use?"

Engineers and Scientists tend to be sticklers for detail - to the point of being "anal retentive".

It was fracing for about 60 years, so for those of us who have an industry history, there is no "k' in frac.

In the O&G industry, a mistake can cost a life (lives) or a great deal of money (or both). Mistakes (accidents) do happen, but people in the engineering and technical end of the business do not tend to "double check", they "triple check". In a very complex and quite dangerous environment, accidents are surprisingly uncommon. When accidents do occur, there is no one more surprised than someone in the industry.

Being a stickler for detail is part of my nature, I will stick with frac.

 

All IMHO,

                  JS

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Permalink Reply by Dan on August 2, 2012 at 3:17am

Monroe,

I have followed a few very slow moving dry ice tanker trucks through the hills of WV.  I up until today have been one of the uneducated "k" users.  I am curious if the dry ice is used in frac'ing.  If so, is it injected to increase frac'ing preasure as it sublimates in the water? 

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Permalink Reply by monroe on August 2, 2012 at 7:12am

I have never heard of such things being used or can I think of why it would be used (I am not positive on this however). With the shale we are at depths of ~7000' so the pressures and temperatures I'm sure would change the form of the dry ice. So pretty sure it is not for frac'ing however I can't tell you 100% sure, companies are trying all kinds of new stuff especially in low populated areas to find what works best and most environmental. If your testing something new your going to do it where not many people know if something goes wrong, not testing it in canton or something of the sort. Maybe someone else can confirm 100%.

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Permalink Reply by Dan on August 2, 2012 at 9:45am

I am no chemist but I would think since dry ice as it melts goes from solid to gas skipping the liquid state, it would increase frac'ing preasure by expanding rapidly as it hits the water and heat.  The CO2 gas is fairly harmless and cheap.

I finally found this below at wikipedia but they are talking about liquefied CO2,  Not dry ice (solid CO2)  I may have incorrectly assumed with my arm chair science that the Liquid CO2 was going to be coverted to solid at the well sites.   

                

                                                     Oil recovery

Carbon dioxide is used in enhanced oil recovery where it is injected into or adjacent to producing oil wells, usually under supercritical conditions. This kind of production may increase original oil recovery by 7 per cent to 23 per cent further from primary extraction.^[25] It acts as both a pressurizing agent and, when dissolved into the underground crude oil, significantly reduces its viscosity, enabling the oil to flow more rapidly through the earth to the removal well.^[26] In mature oil fields, extensive pipe networks are used to carry the carbon dioxide to the injection points.

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Permalink Reply by monroe on August 2, 2012 at 12:22pm

Dan, you are looking at enhanced oil recovery or EOR. EOR covers all the methods to extract more oil out of the ground once the field has reached its economic limit. Other popular methods is water flooding, steam flooding (used with heavy oils in california and canada), and even things such as in-situ combustion, (in-situ is uneconomic and heavily frowned upon especially by environmentalists but it's pretty cool) but EOR does not include frac'ing, frac'ing is part of the initial development. EOR will be done many many years later and with current technology EOR is not useful in shale, (almost anything that needs frac'ed does not respond well due to low porosity and low permeability), but technology will improve as demand improves. With CO2 injection you will inject CO2 into "injector" wells (not what most of you hear about these injectors are at the same depth as your producing formation and you do not dump waste water here) and as you pump more CO2 in theory it pushes your remaining residual oil in the formation out to nearby producers in the same formation. This is done frequently with water and steam but is being researched and tested a lot right now to kill two birds with one stone and inject CO2 pollution for power plants (imagine that, big oil is trying to help save the environment from pollution, who woulda thunk it!).

Although your "arm chair science" makes sense in theory it doesn't really work to that degree. As I explained earlier you need high pressures to reach the fracture pressure of your rock, water helps this with the hydrostatic pressure you get from the weight of your fluid column, now you still need to use a good amount of surface pressure but not as much as you would without hydrostatic pressure. Also when you would inject this as dry ice you wouldn't be able to contain it in that form to the formation because you have almost 8000' to go mainly costing you a lot of money to pump plain CO2 that won't carry your proppant.

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Permalink Reply by Jack Straw on August 2, 2012 at 5:17pm

I agree with Monroe that dry ice would not likely have any potential use in a deep frac.
Fracing depends upon an incompressible medium, dry ice sublimating to CO2 gas does not meet that criteria.

A possibility is that the dry-ice was for Dry-ice blasting.
Dry-ice blasting (under certain circumstances) is a preferable alternative to sand-blasting.
http://en.wikipedia.org/wiki/Dry-ice_blasting

It is possible that Dry-ice blasting is being used to clean out tanks that might contain a residue of a combustible substance; thus potentially useful in an oil field environment. The resultant CO2 is not flammable (and also would not produce a spark – as sand against steel might). CO2 displacing atmospheric gas could be a safety issue in cleaning tanks that contain hydrocarbon residue.

Just a thought.

JS

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