Feasibility of reservoir fracturing stimulation with liquid nitrogen jet

In this paper, a new idea of fracturing with liquid nitrogen jet was proposed because the conventional liquid nitrogen fracturing treatment has difficulty in controlling the fracture initiation location and creating multi-separated fractures along the wellbore. To analyze the feasibility of this treatment, the flow field of liquid nitrogen jet was simulated using computational fluid dynamics method, and the cracking effect of liquid nitrogen on rock was tested by laboratory experiments. The results indicated that under the same nozzle pressure drop, the liquid nitrogen jet presented better performance in abrasive particles acceleration and pressure boosting in perforation cavity than water jet. In addition, the impact effect induced by liquid nitrogen jet was equivalent to that generated by water jet. Liquid nitrogen could bring about additional cracking effect on rock because of cryogenic cooling, water freeze and nitrogen vaporization, which were also beneficial for the improvement of stimulation reservoir volume and the formation of fracture network. What's more, the liquid nitrogen jet induced the pressure boosting effect in cavity and the hydrodynamic sealing effect in annulus, which could realize the control of fracture location and the isolation of wellbore respectively without any machinery packers or bridge plugs. In conclusion, the liquid nitrogen jet fracturing presented apparent superiorities not only in avoiding the problems in hydraulic fracturing but also in overcoming the technical shortcomings of conventional liquid nitrogen fracturing. This technique will play a significant role in oil and gas development with a promising future. (C) 2016 Elsevier B.V. All rights reserved.