Polyacrylamide polymer viscosity reducer

Abstract

The invention relates to a polyacrylamide polymer viscosity reducer. The polyacrylamide polymer viscosity reducer comprises the following components by mass part: 2.2-30% of a mineralization degree conditioning agent, 0.1-0.5% of a viscosity conditioning agent, 0.1-0.5% of a surfactant, 0.5-2% of a corrosion inhibitor, 0.1-1% of a cleaning compound and the balance of water; wherein a sum of the mass percentages of the components is 100%. The provided viscosity reducer can rapidly reduce viscosity of the polyacrylamide polymer and reduces the viscosity of polyacrylamide polymer fracturing fluid, the viscosity of the liquid after viscosity reduction tends to the viscosity of water, and flowback of the liquid is easily carried out.

Description

technical field [0001] The invention belongs to the field of exploration and development of oil and gas fields, and in particular relates to a viscosity reducer for polyacrylamide polymers. Background technique [0002] The world's conventional natural gas resources are 436 trillion cubic meters, while shale gas is as high as 456 trillion cubic meters (according to EIA), which is one of the important development directions of clean energy in the future. China's shale gas reserves are extremely rich, mainly distributed in the Sichuan Basin, Ordos Basin, Bohai Bay Basin, Songliao Basin, Tarim Basin, and Junggar Basin. The technically recoverable resources estimated by relevant domestic units exceed 10 trillion cubic meters. According to the EIA assessment, among the major shale gas resource distribution countries in the world, China ranks first in the world with recoverable resources of 36.1 trillion cubic meters. At present, domestic shale gas exploitation often adopts large...

AI Technical Summary

Problems solved by technology

At present, domestic shale gas exploitation often adopts large-scale "drag reducing water + glue" staged sand fracturing technology in horizontal wells, and polyacrylamide polymers and derivatives will adhere to the wellbore string during the fracturing process In the formation, the wellbore or the formation is blocked, which affects the construction process and single well production

[0003] Moreover, for polyacrylamide polymers and derivative fracturing fluids, ammonium persulfate is usually used as a gel-breaking system to reduce the viscosity of the polymer in the subsequent treatment process. The ammonium persulfate gel-breaking system has the following deficiencies Disadvantages: (1) Ammonium persulfate takes a long time to break the gel

(2) Incomplete glue breaking

During the fracturing construction process, under the premise of ensuring smooth sand carrying, optimize the concentration of the gel breaker to break the gel quickly and completely. However, when the fracturing fluid is pumped and the fracture is closed, the polymer concentration will increase by 5- 7 times, the concentration of the polymer brings great difficulties to the gel breaking

[0004] Chinese patent CN101104844B discloses a sulfate-reducing bacterium with polyacrylamide viscosity-reducing function and its application. The sulfate-reducing bacterium is used to reduce the viscosity of polyacrylamide, but the sulfate-reducing bacterium is an anaerobic bacterium, and it needs The key to a suitable growth and reproduction environment is that high-concentration sulfate-reducing bacteria have limited viscosity-reducing effects on high-concentration polymers.

Chinese patent CN103043830A discloses a method for reducing the viscosity of polyacrylamide by chlorine dioxide under an acidic activator. Adhesive polyacrylamide, but strong acids such as hydrochloric acid are added during the activation process, which will cause different degrees of corrosion to the production string; moreover, the viscosity reduction is carried out by releasing free radicals through chlorine dioxide, and the viscosity reduction time is long depending on the temperature of the oil

[0005] In addition, "Research on the Viscosity Reduction Mechanism of Polyacrylamide in Oilfield Sewage", Petrochemical Application; "Research on Chemical Viscosity Reduction of Polyacrylamide", Journal of Daqing Petroleum Institute; "Research on Chemical Viscosity Reduction of Polyacrylamide", Oil and Gas Field Environmental Protection, Introduce different methods of polyacrylamide viscosity reduction respectively. Oxidative viscosity reduction is commonly used in oilfields. In the literature, the addition of reducing substances and strong oxidants undergo oxidation-reduction reactions to release free radicals for viscosity reduction of polyacrylamide. However, these methods are not Depends on temperature, and the rate of viscosity reduction is slow

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