Why foam fracturing is less popular in enhanced geothermal system compared with shale gas/oil production systems? Since foams possess high apparent viscosity which is good for suspending proppants. In addition, foams also limit the water use, fracturing fluid leak-off, and lead to faster fracture clean-up due to gas expansion. Also, compared with shale gas/oil production system, foam fracturing enhanced geothermal system (EGS) would not induced clay swelling because the mineral of EGS are mainly crystalline rocks, say granite or diorite.
Thanks for your interest, Hamit
However, it seems that your recommended website do not refer to foam fracturing.
However, I found something interesting and helpful for this question.
FYI:
Article Economic assessment and review of waterless fracturing techn...
" CO2/N2 foams do require a higher surface pressure than slickwater, and for some very deep wells, surface pressure requirements exceed 10 000 psi. As this may require an equipment upgrade, it is one of the reasons why foams are rarely applied in very deep wells. However, foam fractures have been reported in the Woodford shale at deeper than 12 000 ft. Thus the limitation to shallower wells is dictated by general practice and equipment availability rather than by any fundamental consideration. True “foam” behavior arises when bubble-bubble interactions become important, i.e., at 50%–60% and higher. Foam behavior is quite different from the behavior or the liquid or gas components taken separately. For example, foams typically have a viscosity that is much higher than that of either component. In practice, volume fractions in the 75%– 80% range are typically used. Improved proppant transport is one of the key advantages of foam fractures. The average loading in the slickwater case is 1.9 lbs/gallon. The downhole loading in the foam cases is similar to the slickwater case. The loading in the liquid fraction (at the surface) is 6.3 lbs/gallon, which is diluted on combination with N2 or CO2. The liquids used are capable of carrying these proppant loadings. "
Hence, according to this paper, it seems possible to adopt foam fracturing in EGS, although some potential determinant factors may not given in this article. Anyway, I will keep looking at this question.
Regards
The main disadvantage of using foam fluid for fracturing is its stability and controlled rheology over time beyond a particular temperature. Due to increase in temperature, the foam present in the HF fluid system undergoes expansion and finally bursts, leading to unstable system, in addition to those mentioned by Ma Zhaoyang . For this, application of foam fracturing fluid is mostly limited to low temperature and water sensitive reservoirs.
- Badges
- Science topic
- Similar topics
- Engineering
- Petroleum Engineering
- Oil