Experimental study of the effect of liquid nitrogen penetration on damage and fracture characteristics in dry and saturated coals

Advances in Liquid Nitrogen Fracturing for Unconventional Oil and Gas Development: A Review

“…In the 1970s, Tenneco Oil Company proposed injecting cryogenic fluid into coal and rock fractures to increase natural gas production. − Industrial field tests were successfully conducted by B. W. McDaniel in 1997 and Steve R. Grundman in 1998 and proved that repeated fracturing using LN 2 can increase the production of unconventional oil and gas. − Between the late 1990s and the early 21st century, unconventional oil and gas production met demand from the energy market, and research on LN 2 fracturing stagnated. − In recent years, the share of unconventional oil and gas in global oil and gas production has continued to increase. As a result, LN 2 technology, fracturing mechanism, and influencing factors have once again become the focus of many research studies. − Liquid nitrogen fracturing has many advantages over traditional fracturing technologies. They include the following: As a fracturing fluid, LN 2 greatly reduces the expansion of reservoir clay and the water lock effect.…”

“…Saturation of rocks has an important effect on the efficiency of LN 2 fracturing at low temperatures. Failure modes and mechanisms of dry rock samples are different from those of saturated samples that have been frozen using LN 2 . The LN 2 causes pore water to turn to ice; pore water volume expands, increases pore pressure, and destroys the cementation between rock particles.…”

“…Failure modes and mechanisms of dry rock samples are different from those of saturated samples that have been frozen using LN 2 . 157 The LN 2 causes pore water to turn to ice; pore water volume expands, increases pore pressure, and destroys the cementation between rock particles. In saturated sandstone, macroscopic cracks visible to the naked eye appear on the surface; the internal pore structure is severely damaged, and is considerably different from that in dry samples.…”

Investigation of Fracture Evolution and Failure Characteristics of Rocks under High-Temperature Liquid Nitrogen Interaction

“…Shao et al examined the impact of nitrogen cooling on the acoustic propagation characteristics of coal. The study revealed a substantial reduction in both velocity and amplitude, indicating notable alterations in the internal structure and mechanical strength of coal rock induced by nitrogen cooling [25]. Li et al and other researchers explored the influence of cyclic nitrogen freeze-thaw processes on the expansion of preexisting fractures and compressive strength in coal rock.…”