Liquid nitrogen fracturing process

Abstract

The invention discloses a liquid nitrogen fracturing process method. The method comprises the steps that replacing accumulated fluid in a well to the ground from a fracturing pipe column; at the position higher than a reservoir to be fractured by the reserved distance, packing an annulus into an upper annulus and a lower annulus; blocking the bottom of the fracturing pipe column and the well bottom, and meanwhile enabling the fracturing pipe column to communicate with the lower annulus; opening the upper annulus for pressure relief, obtaining pressure in the fracturing pipe column, and after confirming that the upper annulus and the lower annulus are packed, opening the fracturing pipe column for pressure relief; blocking the bottom of the fracturing pipe column; under the condition of opening the pressuring pipe column, lowering a flow guide pipe from the fracturing pipe column, and pumping and injecting liquid nitrogen into the fracturing pipe column through the flow guide pipe untilthe interior of the fracturing pipe column is full of the liquid nitrogen, and achieving precooling of the fracturing pipe column; communicating a liquid nitrogen injection device with the fracturingpipe column, and pumping and injecting the liquid nitrogen; and when the fracturing pipe column communicates with a perforation segment, increasing the displacement to carry out fracturing. It can beensured that the low-temperature liquid nitrogen has the higher conveying efficiency and better heat preservation effect.

Description

technical field [0001] The invention relates to the technical field of fracturing reconstruction of oil and gas reservoirs, in particular to a liquid nitrogen fracturing process. Background technique [0002] The statements in this section only provide background information related to the present disclosure and may not constitute prior art. [0003] China's unconventional oil and gas resources are huge, among which the recoverable tight gas resources exceed 7×8 12 m 3 , the recoverable resources of shale gas reached 2.5×8 13 m 3 , the total amount of tight oil resources is 124.5×8 7 T. Unconventional oil and gas reservoirs generally have the characteristics of tight lithology, high fracture initiation pressure, and difficult stimulation. Most of the reservoirs need large-scale fracturing to be effectively put into production. On the basis of traditional hydraulic fracturing technology, developing a new reservoir fracturing technology system to reduce the degree of res...

AI Technical Summary

Problems solved by technology

After research, it was found that during the fracturing process, the pressure in the well is very high, and nitrogen injection at normal temperature in the annular space will increase the heat exchange rate between the annular fluid and the outer wall of the fracturing string and the inner wall of the casing, which will not only fail to maintain the temperature of the casing, but also cause The fracturing string continuously provides heat, so that the liquid nitrogen continues to absorb heat, and the temperature is very high after being transported to the bottom of the well

Therefore, it can be said that the previously used fracturing method, the delivery efficiency of low-temperature liquid nitrogen is low, and the temperature of liquid nitrogen after delivery to the bottom of the well is too high to produce low-temperature fracturing

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