A gel-breaking degradation method of polyacrylamide polymer fracturing fluid

Abstract

The invention belongs to the technical field of oilfield production, in particular to a polyacrylamide class polymer fracturing fluid gel breaking degradation method. The polyacrylamide class polymerfracturing fluid gel breaking degradation method comprises four steps of adding an energized agent, adding an additive, adding CO2 and open flow and depressurization, so that the polymer flowback liquid viscosity is reduced below 2mPa.s, the molecular weight degrades below 20000, the molecular particle size is within 80nm, the stratum damage rate is less than 5%, the flowback rate is increased more than 10%, the reservoir reformation requirement of low-permeability oil and gas fields is met, and thus, the fracturing construction effect is ensured.

Description

technical field [0001] The invention belongs to the technical field of oilfield production, and in particular relates to a gel breaking and degradation method for polyacrylamide polymer fracturing fluid. Background technique [0002] Fracturing has been developed rapidly and widely used as the main production and injection measures of oil and gas reservoirs. Fracturing is the use of pressure to open formations to form fractures and support them with proppant to reduce fluid flow resistance and increase production and injection measures. The purpose of fracturing is to form fractures with conductivity in the formation. The fracturing fluid used determines the fracturing effect to a large extent. At the same time, there are certain requirements for the viscosity of the fracturing fluid so that it can Fluids known as low viscosity flow back easily to avoid damage to hydrocarbon layers in the formation. [0003] The most commonly used fracturing fluids at home and abroad are m...

AI Technical Summary

Problems solved by technology

However, guar gum and its modified products have the inherent disadvantages of easy corruption of vegetable gum, and the composition of the fracturing fluid system is complex. The formation of jelly depends on chemical cross-linking. After the gel is broken, the flowback fluid is difficult to treat, the cost is high, and reuse is feasible. Therefore, the plant gum fracturing fluid such as guar gum can neither alleviate the pressure of environmental protection nor meet the above-mentioned on-site construction requirements.

[0004] At present, there are many kinds of acrylamide polymer thickeners, which generally have problems such as incomplete gel breaking, easy gel return, and high residue content of gel breaking fluid, which are easy to cause blockage damage, resulting in a decrease in matrix permeability and fracture conductivity. , thus affecting the effect of fracturing stimulation. Therefore, it is necessary to form a degradation method for this type of polymer, so that the polymer can be quickly degraded into small molecules, and then flow back quickly to reduce the damage to the formation, so as to meet the requirements of current tight oil and gas reservoirs. The need for layer transformation

[0005] Patent CN105967306A describes a water-soluble polymer solution degradation agent and its preparation method and application. This patent only considers the apparent viscosity of the polymer solution and the frequency of replacing the filter element during recovery and treatment, and improves the recovery and utilization of its produced water as much as possible. rate, the molecular weight of the polymer itself, the damage of the particle size to the radius of the formation, and no further analysis and research on the degradation degree of the main chain and branch chain of the polymer molecule. At the same time, the degradation time is longer, fundamentally Does not address formation damage from polymer retention

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