| 摘要 |
A method and apparatus for introducing refrigerant into a wellbore, for freeze-fracturing a selected region of a subsurface formation, uses refrigerant diffuser pipe having multiple orifices in a selected pattern along a designated section of its length. The orificed supply tubing is disposed within a refrigerant return conduit, thereby forming a tubing annulus. A flow of liquid refrigerant is introduced into the diffuser pipe and flows through the orifices into the tubing annulus, with the orifices acting as expander means creating a pressure drop and causing vaporization of the refrigerant as it passes into the annulus. To facilitate use of the same diffuser pipe in different wells having different requirements, a helical orifice-isolation wrap may be disposed around the diffuser pipe, with the orifice-isolation wrap having orifice-plugging elements arrayed to effectively block fluid flow through selected orifices, while leaving other orifices open as required. In this way, it is possible to design diffuser pipes with particular orifice arrangements that will accommodate two or more different isolation wraps, with each different wrap plugging different patterns of orifices.
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