Phase-change hydraulic fracturing technology

Abstract

The invention discloses a phase-change hydraulic fracturing technology. The technology includes the steps that firstly, clean water or conventional fracturing fluid is injected to a stratum, so that the stratum cracks; secondly, non-phase-change liquid M and phase-change liquid N are placed in different liquid mixing tanks and injected into a shaft at the same time, wherein the injection volume ratio of the liquid M to the liquid N is (0-0.7):(0.3-1); thirdly, displacement fluid is injected into the shaft, so that the non-phase-change liquid M and the phase-change liquid N in the shaft completely enter a reservoir; fourthly, well shut-in and pressure building are conducted for 30-200 min, so that solid-phase matter generated by the phase-change liquid N is laid in cracks; fifthly, decompression is conducted, and construction is finished. The liquid M is conventional fracturing fluid, seawater, stratum water or ground fresh water, and the liquid N is composed of a super-molecular construction unit, surfactant, inorganic salt, oxidant and the like. Channels and ditches for underground oil gas seepage can be formed without solid supporting agents, flow guide capacity of hydraulic fracturing cracks is greatly improved, and the technology is simple, safe and efficient in construction operation.

Description

technical field [0001] The invention relates to a reservoir hydraulic fracturing stimulation technology in the oil development process, in particular to a phase change hydraulic fracturing technology. Background technique [0002] Hydraulic fracturing technology has been widely used in the development of low-permeability oil and gas fields as the main measure for oil and gas well stimulation and water well injection, and has made important contributions to the stable production of oil and gas fields. The process of hydraulic fracturing is to pump high-viscosity pre-fluid into the target reservoir to form fractures and extend them at high pressure, and then pump sand-carrying fluid mixed with proppant, which can continue to extend the fracture and carry proppant at the same time. Go deep into the fracture, and then degrade the fracturing fluid into a low-viscosity fluid and flow back to the bottom of the well, leaving a flow channel with high conductivity formed by the proppa...

AI Technical Summary

Problems solved by technology

[0007] (1) If the fracturing fluid is not completely broken and flowed back, it will seriously damage the conductivity of the formed artificial fractures and reduce the matrix permeability near the fractures;

[0008] (2) In the face of high-temperature deep wells, in order to maintain the sand-carrying ability of fracturing fluid at high temperature, the concentration of additives such as guar gum and cross-linking agent is increased, resulting in a further increase in residue content and frictional resistance, which further brings about fractures. Glue, flowback and other issues;

[0009] (3) For sand fracturing, in order to pursue high conductivity, high sand ratio is used to add sand, which may easily lead to sand plugging and other accidents;

[0010] (4) With the prolongation of production time after construction, problems such as embedment, deformation and backflow of conventional proppants such as ceramsite and quartz sand will cause a significant decline in the conductivity after compression, and the effective period of construction will be greatly shortened

[0011] The above-mentioned problems often lead to a great reduction in fracture conductivity, so the fracture permeability measured by the well test after fracturing often can only reach one-tenth, or even one-hundredth of that of the laboratory.

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