International Scientific Journal

Thermal Science - Online First

online first only

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

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.
PAPER REVISED: 2018-10-09
PAPER ACCEPTED: 2018-11-12
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