What is foam fracturing? is it an alternative to the conventional fracturing fluid and fracturing technique?
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Farooq Mohibuddin
Jun 22, 2017
Neil,
Thanks for this great question. Foam Fracturing have been around for a while, dating back to 90s (i think). However despite being a novel idea, foam fracturing have failed to provide extensive benefits over conventional fluid fracking and therefore unable to overtake conventional fluid in mainstream fracking industry.
Lets quickly evaluate few pros & cons to see why foam fracking isnt "the-nexxt-bing-thing" in fracking:
Pros:
1. Greatly helps in flowback. Gas in the fluid is compressible so it holds the energy of pumping and aids in flowback from the the tinniest pores in the reservoir. Flowback is almost 80-90% completed.
2. Doesn't create water blockage or doesnt alter relative permeability in the pores of near fracture face. Again as the medium in contact is gas (CO2 or N2), rel perms are altered very slight if at all
3. Proppant suspension is relatively better. This allows minimum proppant dropout in wellbore and in the fracture. (although the new ultra light proppant that is hitting the market eliminated the dropout problem from conventional fracs too)
4. Micro fissures in the reservoir that open upto fracture and result in fluid leakoff are isolated with gas bubbles therefore fluid leakoff is controlled.
Cons:
1. Horsepower requirement or surface pressure requirement for breakdown and fracture propagation is increased dramatically. As Foam is a mixture of gas and liquid, the density and weight is reduced, hence hydrostatic head in the wellbore is reduced. This calls for increased pumping pressure requirement (which sometimes makes the job impossible or uneconomical)
2.Creating & maintaining the foam at its prime quality is a real challenge on site. Degraded foam quality results in loss of purpose in using foam frac hence quality is a must. Unfortunately maintaining ideal quality is too costly.
3. Procuring CO2 & often N2 can be a concern for remote frac locations and often logistics of liquified gases kills the economics of the project
4. In unconventional reservoirs like shale or very tight sandstones, fluid leak off is not a concern. Often in shales, we want to target secondary fissures to create a large fracture network (or increased stimulated reservoir volume) therefore we dont need to isolate the small fissures.
These are just some general comments. Obviously, depending on case to case basis, sometimes foam fracturing is the most ideal solution and therefore there is no harm in conducting foam fracs.
Neil,
Thanks for this great question. Foam Fracturing have been around for a while, dating back to 90s (i think). However despite being a novel idea, foam fracturing have failed to provide extensive benefits over conventional fluid fracking and therefore unable to overtake conventional fluid in mainstream fracking industry.
Lets quickly evaluate few pros & cons to see why foam fracking isnt "the-nexxt-bing-thing" in fracking:
Pros:
1. Greatly helps in flowback. Gas in the fluid is compressible so it holds the energy of pumping and aids in flowback from the the tinniest pores in the reservoir. Flowback is almost 80-90% completed.
2. Doesn't create water blockage or doesnt alter relative permeability in the pores of near fracture face. Again as the medium in contact is gas (CO2 or N2), rel perms are altered very slight if at all
3. Proppant suspension is relatively better. This allows minimum proppant dropout in wellbore and in the fracture. (although the new ultra light proppant that is hitting the market eliminated the dropout problem from conventional fracs too)
4. Micro fissures in the reservoir that open upto fracture and result in fluid leakoff are isolated with gas bubbles therefore fluid leakoff is controlled.
Cons:
1. Horsepower requirement or surface pressure requirement for breakdown and fracture propagation is increased dramatically. As Foam is a mixture of gas and liquid, the density and weight is reduced, hence hydrostatic head in the wellbore is reduced. This calls for increased pumping pressure requirement (which sometimes makes the job impossible or uneconomical)
2.Creating & maintaining the foam at its prime quality is a real challenge on site. Degraded foam quality results in loss of purpose in using foam frac hence quality is a must. Unfortunately maintaining ideal quality is too costly.
3. Procuring CO2 & often N2 can be a concern for remote frac locations and often logistics of liquified gases kills the economics of the project
4. In unconventional reservoirs like shale or very tight sandstones, fluid leak off is not a concern. Often in shales, we want to target secondary fissures to create a large fracture network (or increased stimulated reservoir volume) therefore we dont need to isolate the small fissures.
These are just some general comments. Obviously, depending on case to case basis, sometimes foam fracturing is the most ideal solution and therefore there is no harm in conducting foam fracs.
Please let us know if we can elaborate more.
Best Regards
Farooq