THERMAL SCIENCE

International Scientific Journal

Thermal Science - Online First

online first only

Numerical analysis on the transient cavity flow field during liquid nitrogen jet fracturing

ABSTRACT
Liquid nitrogen jet fracturing (LNJF) is expected to provide a novel treatment for reservoir stimulation. To verify its feasibility, the flow fields in cavity at different times are simulated by computation fluid dynamic method. Then the transient temperature and pressure distributions are analyzed. Based on the cavity pressure distributions, the pressure boosting effect is evaluated. The results show that the nitrogen gas close to the cavity entrance is easily pushed out and the temperature in this region decreases quickly during LNJF. However, the temperature at the cavity bottom increases firstly at the squeezing action of LNJ and then decreases due to the heat transfer induced by the low-temperature LNJ. Compared with water jet, the LNJ can generate equivalent pressure boosting effect in the cavity. Due to the compressibility of nitrogen gas, the pressure boosting process of LNJF falls behind the HJF. This study identifies the pressure boosting capability of LNJ and can further provide theoretical basis for the researches of this fracturing treatment.
KEYWORDS
PAPER SUBMITTED: 2018-05-20
PAPER REVISED: 2018-10-09
PAPER ACCEPTED: 2018-11-12
PUBLISHED ONLINE: 2019-04-14
DOI REFERENCE: https://doi.org/10.2298/TSCI180520137C
REFERENCES
  1. Wang, L., et al., Waterless fracturing technologies for unconventional reservoirs- opportunities for liquid nitrogen, Journal of Natural Gas Science and Engineering, 35(2016), pp. 160-174.
  2. Cai, C., et al., The effect of liquid nitrogen cooling on coal cracking and mechanical properties, Energy Exploration & Exploitation, 36(2018), 6, pp. 1609-1628.
  3. Zhang, S., et al., Numerical and experimental analysis of hot dry rock fracturing stimulation with high-pressure abrasive liquid nitrogen jet, Journal of Petroleum Science and Engineering, 163(2018), pp. 156-165.
  4. Cai, C., et al., Feasibility of reservoir fracturing stimulation with liquid nitrogen jet, Journal of Petroleum Science and Engineering, 144(2016), pp. 59-65.
  5. Qu, H., et al., The boosting mechanism and effects in cavity during hydrajet fracturing process, Petroleum Science and Technology, 28(2010), 13, pp. 1345-1350.
  6. Cai, C., et al., Downhole transient flow field and heat transfer characteristics during drilling with liquid nitrogen jet, Journal of Energy Resources Technology-Transactions of The ASME, 140(2018), 12, pp. 122902.
  7. Cheng, Y., et al., Flow field character in cavity during supercritical carbon dioxide jet fracturing (in Chinese), Journal of China University of Petroleum (Edition of natural Science), 38(2014), 4, pp. 81-86.
  8. Span, R., et al., A reference equation of state for the thermodynamic properties of nitrogen for temperatures from 63.151 to 1000 K and pressures to 2200 MPa, Journal of Physical and Chemical Reference Data, 29(2000), 6, pp. 1361-1433.
  9. Lemmon, E.W., Jacobsen, R.T., Viscosity and thermal conductivity equations for nitrogen, oxygen, argon, and air, International Journal of Thermophysics, 25(2004), 1, pp. 21-69.
  10. Batchelor, G. K., An Introduction to Fluid Dynamics, Cambridge University Press, Cambridge, UK, 2000.