Composite acid fracturing method for supporting front edge of fracture by utilizing phase change material

Abstract

The invention discloses a composite acid fracturing method for supporting the front edge of a fracture by utilizing a phase change material. The method includes the following steps that a prepad fracturing fluid is injected, a reservoir is fractured to form the hydraulic fracture, and meanwhile, the temperature of the reservoir is reduced to be the phase change temperature T of the reversed phasechange material or below; a mixed fluid of the liquid reversed phase change material and the fracturing fluid is injected, and part of the hydraulic fracture space is filled with the mixed fluid; an acid fluid is injected, the hydraulic fracture is etched, and the acid fluid further continues to flow into the deeper part of the reservoir; a displacement fluid is injected, so that all the acid fluid enters the hydraulic fracture; a well is continuously closed until the temperature of the reservoir is restored to be the phase change temperature T or above, the phase change material is changed into a solid state, and the front edge of the hydraulic fracture is supported; the well is opened, pressure relief is carried out, and the injected prepad fracturing fluid, a fracturing fluid, the acidfluid and the displacement fluid flow back. The injected fluids do not contain solid-phase particles, so that equipment abrasion is reduced; the reversed phase change material becomes liquid when injected, and after the reversed phase change material is heated and cured, the front edge of the fracture is effectively supported.

Description

technical field [0001] The invention relates to an acid fracturing method for oil and gas wells, in particular to a composite acid fracturing method using a phase change material to support the front edge of a fracture. Background technique [0002] In recent years, with the rapid development of industry and economy, our demand for energy is increasing. Among them, oil and natural gas, as the two most important energy sources, have played a key role in the process of economic and social development. In this context, the oil and gas exploration and development industry is developing rapidly. At present, oil and gas development is gradually developing from shallow and low-temperature reservoirs to deep and high-temperature reservoirs with richer oil and gas resources. big challenge. In the deep and high-temperature environment, the reaction speed between the acid liquid and the reservoir rock is accelerated, the length of acid-etched fractures is limited, and it is difficult ...

AI Technical Summary

Problems solved by technology

[0006] The existing method can increase the remote conductivity of acid fracturing fractures to a certain extent and increase the effective action distance of acid liquid, but there are still the following problems: the injected sand-carrying fluid contains solid particle proppant, which causes great wear and tear on equipment; The fluid must meet the requirements of sand-carrying, high viscosity, high injection pressure, and difficult injection; the proppant has a certain size, and the fracture front is small in width, so it is difficult for the proppant to enter and cannot fully cover the fracture front; The effective action distance of the acid liquid with improved liquid performance is limited, and the effect is not obvious in high temperature oil and gas reservoirs

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