ABSTRACT
Cryogenic fracturing is a relatively new stimulation technology that looks to expand and improve the traditional hydraulic fracturing technology. Cryogenic fracturing rests on the idea that a sharp thermal gradient caused by contacting with and vaporization of a cryogen, can induce fractures when brought into contact with a much warmer rock under downhole conditions. Cryogen exists in the gaseous phase at standard conditions but takes a liquid form at low temperatures, such as liquid nitrogen and liquid carbon dioxide. Specifically, when liquid nitrogen is injected into a borehole, heat from the rock near the borehole will quickly transfer to the liquid nitrogen at boiling point (−195.8◦C or −320.4◦F at atmospheric pressure), resulting in rapid cooling of the near-borehole area, which will cause the surface of the rock or borehole wall to contract. Once the tension due to contraction is sufficiently increased, fractures orthogonal
the interface of cryogen and rock can These newly induced fractures can be further extended by high pressure gas from LN vaporization. Note that nitrogen has a liquid-to-gas expansion ratio of 1:694 at 20◦C (68◦F) and atmospheric pressure.
