A method for staged fracturing with cryogenic fluid in horizontal wells

Abstract

The invention discloses a method for grading fracturing with low-temperature fluid in a horizontal well. Firstly, three fracture areas are prefabricated by using a perforating gun, and then a water pressure plugging device is filled by injecting water through a water pipe, thereby forming three sealed fracturing chambers; The three sealed fracturing chambers are filled with supercooled water, and finally the low-temperature fluid flows through the internally threaded heat exchange tubes and externally threaded heat exchange tubes in the three sealed fracturing chambers in sequence. When the low temperature fluid flows through each sealed fracturing chamber, each The supercooled water in the sealed fracturing chamber exchanges heat with the low-temperature fluid. At this time, the temperature of the supercooled water drops rapidly, turning the water phase into ice and increasing its volume, so that each sealed fracturing chamber is fractured by using its ice swelling force, and the continuous After a certain period of time, stop and cycle for many times to complete the process of supercooled water ice expansion fracturing; not only can effectively ensure the fracturing effect of coal and rock mass and reduce the high pressure required for hydraulic fracturing, but also because the supercooled water has no chemical agents added, so It will not pollute the surrounding environment after leakage.

Description

technical field [0001] The invention relates to a method for grading fracturing by low-temperature fluid in a horizontal well, and belongs to the technical field of coal and rock mass anti-permeability. Background technique [0002] China is rich in unconventional natural gas resources and has great potential for development, among which the recoverable resources of coalbed methane are about 10.87×10 12 m 3 , the recoverable resources of shale gas are 15×10 12 ~25×10 12 m 3 In the next 10 to 20 years, China's unconventional natural gas production will increase significantly, and it will play an increasingly important role in making up for the shortage of conventional oil and gas production. Although the reserves of unconventional natural gas resources in my country are large, the reservoirs are complex and dense, and the main part of the reservoir space is a nanoscale pore-throat system, with micron-millimeter-scale pores locally developed. Therefore, enhanced anti-refl...

AI Technical Summary

Problems solved by technology

The success of large-scale development of shale gas in foreign countries is inseparable from hydraulic fracturing anti-permeability technology, but at the same time, problems have also emerged, such as: adding special chemical reagents to fracturing fluid, once leaked, it will pollute the groundwater body, and hydraulic fracturing is difficult. High start-up pressure in the formation, a lot of waste of water resources, etc.

[0003] In addition, the existing hydraulic fracturing is to use high-pressure water to fracture the coal rock formation, so a relatively high pressure is required to ensure the continuous fracturing of the water on the coal rock formation, which leads to a large energy consumption; therefore, how to effectively reduce the hydraulic pressure The energy consumption in the cracking process and the prevention of groundwater pollution after leakage make the research direction of this industry

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