Normal-pressure sand mixing quasi-dry fracturing method, and used fracturing fluid, preparation method and application thereof

Abstract

The invention discloses a normal-pressure sand mixing quasi-dry fracturing method, and a fracturing fluid used in the method, a preparation method and application thereof. According to the normal-pressure sand mixing quasi-dry fracturing method, a water-based fracturing fluid thickened by a water-based fracturing fluid thickening agent system material is used, a carbon dioxide dry fracturing fluidthickening agent system material is carried, normal-pressure sand mixing is performed, combining with liquid carbon dioxide in a carbon dioxide dry fracturing fluid according to a designed proportionis performed, two-phase synergistic effect is performed to form a mixed liquid phase with enough viscosity and structure after liquid carbon dioxide thickening, the mixed liquid phase is a normal-pressure sand mixing quasi-dry fracturing fluid, and drag-reducing and sand-carrying integrated fracturing construction is performed. According to the normal-pressure sand mixing quasi-dry fracturing method and the normal-pressure sand mixing quasi-dry fracturing fluid, special closed sand mixing equipment is not needed, normal-pressure sand mixing is achieved, and preparation is convenient; drag reduction and sand carrying are integrally applied, and drag reduction liquid and sand carrying liquid are prepared at the same time; damage is low or even avoided, and reservoir protection is facilitated; and the yield-increasing effect is excellent and the cost performance is high.

Description

technical field [0001] The invention belongs to the technical field of fracturing stimulation, and in particular relates to a fracturing method that organically combines water-based fracturing and carbon dioxide dry fracturing, that is, an atmospheric pressure sand mixing quasi-dry fracturing method, an atmospheric pressure sand mixing quasi-dry fracturing fluid , its preparation method and its application in oil and gas fields. Background technique [0002] The purpose of fracturing is to form fractures with conductivity in the reservoir, and the fracturing fluid used largely determines the fracturing effect. At the same time, there are certain requirements for the viscosity of the fracturing fluid, so that it can become a low-viscosity fluid after fracturing and is easy to flow back, so as to avoid damage to the oil and gas layers in the reservoir. [0003] Conventional fracturing methods currently used mainly include oil-based fracturing, water-based fracturing, and carb...

AI Technical Summary

Problems solved by technology

However, in unconventional oil and gas reservoirs such as shale oil and gas, tight oil and gas, and coalbed methane, they all exhibit the characteristics of "three lows" of low porosity, low pressure, and low permeability, and the reservoirs are highly sensitive, such as water sensitivity, water lock, etc. , stress sensitivity and temperature sensitivity, etc., water-based fracturing fluid will inevitably cause different degrees of damage to the reservoir after entering the reservoir, resulting in a significant decline in oil and gas production, and the final production stimulation effect is not satisfactory

On the other hand, in dry fracturing, conventional dry fracturing equipment cannot be used together, and special airtight sand mixing equipment is required, but its research, development, use and maintenance all require high costs. At present, there are very few domestic and foreign Large-scale equipment manufacturers have the ability to design and manufacture related professional equipment

Due to the ineffective thickening of dry fracturing fluid, liquid carbon dioxide (hereinafter referred to as “liquid CO 2 ") with low viscosity, low sand ratio, and small amount of sand, it is difficult to carry sufficient sand, and at the same time, the pumping friction is large, and it is difficult to form effective fractures in the reservoir

Therefore, various factors such as equipment, materials, and cost also limit the development of dry fracturing. Even if dry fracturing has performance advantages, it cannot be widely promoted and applied.

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