Small-molecular clean fracturing fluid and preparation method and application thereof

Abstract

The invention provides a small-molecular clean fracturing fluid and a preparation method and an application thereof. The fracturing fluid includes a thickening agent, an auxiliary agent, a co-solvent, an activator, an inorganic salt and water, wherein the thickening agent, the auxiliary agent, the co-solvent, the activator and the inorganic salt are each composed of a substance with the molecular weight of less than 500 and the molecular dynamics diameter of less than 60 nm, and the mass ratio of the thickening agent to the auxiliary agent to the co-solvent to the activator to the inorganic salt to water is (0.8-3.5) to (0.01-0.05) to (1.0-3.0) to (0.4-1.5) to (0.1-0.8) to 100. The invention also provides a preparation method for the fracturing fluid. The method comprises the steps: dissolving the inorganic salt in water; mixing the thickening agent, the auxiliary agent and the co-solvent; and adding the thickening agent solution into the salt solution, cooling the mixed solution to room temperature, adding the activator to the mixed solution, aging at room temperature, and thus obtaining the small-molecular clean fracturing fluid. The fracturing fluid provided by the invention has the advantages of wide range of temperature resistance, good shearing property, low cost and simple preparation.

Description

technical field [0001] The invention relates to a fracturing fluid, in particular to a small molecule clean fracturing fluid for fracturing tight oil formations. Background technique [0002] With the sharp increase in world energy demand, unconventional oil and gas resources are getting more and more attention. Tight oil reservoirs belong to unconventional oil reservoirs, which have a large area of ​​continuous distribution of oil and gas, porosity less than 10%, permeability generally less than 0.1mD, oil-bearing Area greater than 1×10 4 km 2 Tight oil is recognized as an important replacement resource for increasing oil and gas reserves and production in the future. It is for this reason that the development of tight oil has attracted widespread attention in recent years and has become the theme of oil and gas resource development in my country and the world. [0003] Although tight oil and gas resources are abundant, they have not been effectively developed and utilize...

AI Technical Summary

Problems solved by technology

[0003] Although tight oil and gas resources are abundant, they have not been effectively developed and utilized, mainly because the diameter of pore throats in tight sandstone is very small (nanoscale), and the use of conventional macromolecular guar gum fracturing fluids will often cause damage to the reservoir. It is manifested in three aspects: the adsorption and retention of macromolecular substances block the seepage channel of reservoir fluid, the fracturing fluid residue blocks the support fracture, and the filter cake will cause damage to the wall of the fracture.

[0004] At present, many types of clean fracturing fluids have been developed and applied, but they do not pay attention to the molecular size of fracturing fluids, and most of them are expensive, have a single selection of materials, and are not temperature-resistant (more than 80% of the tight oil reservoir temperature They are all in the range of 80-100°C, while the temperature resistance of conventional fracturing fluid systems cannot meet the temperature requirements of tight oil fields)

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