Supramolecular polymer clean fracturing fluid resistant to high temperature of 170 DEG C

Abstract

The invention discloses supramolecular polymer clean fracturing fluid resistant to high temperature of 170 DEG C. The fracturing fluid is prepared from the following components in percentage by weight: 0.2 to 0.5 percent of thickening agent for the clean fracturing fluid, 0.1 to 0.5 percent of viscosity synergist, 0.2 to 0.4 percent of structural intensifier, 0.05 to 0.2 percent of deoxidant, 0.1 to 0.3 percent of metal ion chelating agent, 1 to 2 percent of clay stabilizer and the balance of fresh water. According to the clean fracturing fluid, a reversible supramolecular network structure is formed through the intermolecular interaction, and the thickening agent is low in use concentration and can be used for effectively controlling the viscosity of a base solution of the fracturing fluid and improving the pumping performance of the fluid; viscoelastic sand-carrying of the fracturing fluid is realized by low viscosity and high viscoelasticity; the temperature resistance can reach 170 DEG C under a long-term shear condition; the shear resistance is excellent, and the fluid viscosity and the structure after high shear can be effectively recovered; the construction friction is low, and the equipment load and the fracturing construction risk are reduced; the residue content is low, so that the damages to a reservoir stratum and prop fractures are greatly reduced, and the fracturing stimulation effect is greatly improved.

Description

technical field [0001] The invention relates to a high-temperature-resistant supramolecular polymer clean fracturing fluid applicable to reservoir reconstruction below 170°C and a preparation method thereof, belonging to the field of oil and gas field development. Background technique [0002] In the fracturing construction of high-temperature wells, the temperature resistance of fracturing fluid is one of the key factors that determine the success of the construction. From the experience of fracturing reconstruction at home and abroad, fracturing fluids with poor temperature resistance are difficult to maintain the ability to create fractures and suspend sand after being subjected to long-term shearing in the high-temperature environment of the reservoir, which leads to failure of fracturing, and severe cases even It will cause a fracturing accident. [0003] Guar gum is an important part of fracturing fluid thickener. Due to its unique molecular structure and good viscosi...

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Problems solved by technology

From the experience of fracturing reconstruction at home and abroad, fracturing fluids with poor temperature resistance are difficult to maintain the ability to create fractures and suspend sand after being subjected to long-term shearing in the high-temperature environment of the reservoir, which leads to failure of fracturing, and severe cases even cause a fracturing accident

[0003] Guar gum is an important part of fracturing fluid thickener. Due to its unique molecular structure and good viscosity-increasing performance, it is known as the "King of Vegetable Gum". It has the advantages of excellent temperature resistance and sand-carrying performance. The fracturing fluid thickener has always been in a monopoly position, especially in high-temperature deep well fracturing, the guar gum fracturing fluid system must be used, but due to the insoluble matter produced by the guar gum under the action of cross-linking, it has great influence on the reservoir. severe debris blockage injury

Since the 1970s, in order to reduce the damage of the polymer to the formation, the newly developed guar gum modified polymer has reduced its residue content to 1% to 2%, greatly reducing the damage to the formation, and has been widely used , but the effect of reservoir stimulation is still unsatisfactory

[0004] In the past 20 years, VES viscoelastic surfactant fracturing fluid has solved the problem of fracturing fluid residue well, but its temperature resistance is poor, coupled with the large amount of thickening agent and high cost, this system cannot be widely used

In order to give full play to the characteristics of cleanness and viscoelasticity of VES fracturing fluids and solve the problem of poor temperature resistance, high-temperature resistant clean fracturing fluids have always been the focus of research by many scholars, especially polyacrylamide produced with acrylamide as raw material. , methylene polyacrylamide, carboxymethyl polyacrylamide and other polymers have been widely used as thickeners for fracturing fluids. This type of fracturing fluid has good viscoelasticity, good temperature resistance, and friction However, there are still many unresolved problems, such as cumbersome on-site preparation, poor shear resistance, and difficulty in gel breaking. The most important point is that the polymer fracturing fluids reported in the literature have excellent The temperature resistance ability must be achieved by greatly increasing the concentration of the thickener (the dosage can reach 1% or even higher). Although the indoor research shows that its temperature resistance can reach 160°C or higher, it can reach 160°C or higher in actual use. Without this effect, it cannot be applied to high temperature reservoir fracturing at all

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