Reversible physical crosslinking polymer fracturing fluid and preparation method thereof

Abstract

The invention relates to a reversible physical crosslinking polymer fracturing fluid and a preparation method thereof. The fracturing fluid is composed of 0.3% to 0.6% of a polymer thickening agent, 0.12% to 0.3% of a reversible physical crosslinking agent, 0.1% to 0.5% of a clay stabilizing agent and 0.001% to 0.05% of an ammonium persulfate gel breaking agent, with the balance being water. The reversible physical crosslinking polymer fracturing fluid can be applied in fracturing construction of a reservoir at 120 to 160 DEG C, and does not need addition of a temperature stabilizing agent, a cleanup agent, a defoaming agent and a bactericide, so the cost of the fracturing fluid is saved; meanwhile, the fracturing fluid has a gel breaking liquid viscosity less than 2 mPa-s, a gel breaking liquid surface tension lower than or equal to 28 mN / m, a residue content less than or equal to 100 mg / L, and a damage rate less than 10%.

Description

Technical field [0001] The invention belongs to the technical field of oil and gas field reservoir reconstruction, and specifically relates to a reversible physically crosslinked polymer fracturing fluid and a preparation method thereof. Background technique [0002] At present, the fracturing fluids used in oil fields at home and abroad mainly include natural vegetable gum and its derivatives, viscoelastic surfactant-based fracturing fluids and synthetic polymer-based fracturing fluids. The disadvantages of natural vegetable glue and its derivatives fracturing fluid are easy biodegradation, high water-insoluble content, incomplete gel breaking and great damage; viscoelastic surfactant-based fracturing fluid has low damage to cracks and no damage after gel breaking. Residue, but poor temperature resistance (generally no more than 110℃) and high cost; synthetic polymer fracturing fluid mainly includes chemically cross-linked polymer fracturing fluid and physical cross-linked polym...

AI Technical Summary

Problems solved by technology

Disadvantages of natural plant gum and its derivative fracturing fluids are easy biodegradation, high water-insoluble content, incomplete gel breaking, and large damage; Residue, but poor temperature resistance (generally no more than 110°C) and high cost; synthetic polymer fracturing fluid mainly includes chemical cross-linked polymer fracturing fluid and physical cross-linked polymer fracturing fluid, chemical cross-linked polymer fracturing fluid The fracturing fluid has good temperature resistance, but it takes a long time to completely break the gel, which will cause great damage to the reservoir; the physical cross-linked polymer fracturing fluid has good temperature resistance, salt resistance, shear resistance, and sand suspension performance. and gel breaking performance, etc., this type of fracturing fluid is currently a hot spot in the field of fracturing fluid research at home and abroad.

[0003] Chinese patent CN 103013487A discloses a multi-branched polymer fracturing fluid and its preparation method, which consists of 0.3-0.6 parts of thickener, 0.3-0.6 parts of crosslinking agent, 0.3-0.6 parts of 2 parts of anti-swelling agent, 0.01-0.05 parts of gel breaker, this invention uses chemical cross-linking to prepare polymer fracturing fluid, at 90°C, 170S -1 After shearing for 120 minutes under the same conditions, the tail stickiness is greater than 100mPa s, but no rheological data for temperatures above 90°C

Wang Siyu and others reported a chemically cross-linked polymer fracturing fluid system in the article "Study on the Formulation System of Organic Zirconium Jelly Fracturing Fluid" (Oilfield Chemistry, 2014, 31(2): 211-214), which consists of 0.5% thickener, 2.5% organic zirconium chemical cross-linking agent and other additives, the polymer fracturing fluid is at 90℃, 170S -1 After shearing for 120 minutes under the same conditions, the tail viscosity is about 50mPa·s, and this polymer fracturing fluid cannot meet the requirements of reservoirs above 90°C; Yibaoan et al. Research" (Oilfield Chemistry, 2012, 29(4): 407-410) reported a hydrophobic association polymer fracturing fluid, which consisted of 0.55% thickener, 0.32% acidic chemical cross-linking agent, 1% KCl, 1% demulsifier, 1% drainage aid, the polymer fracturing fluid system at 130°C, 170S -1 After shearing for 76 minutes under the same conditions, the tail viscosity was about 50 mPa·s, but the polymer fracturing fluid could not meet the requirements of reservoirs above 130 °C; Yang Zhenzhou et al. Drilling Fluid and Completion Fluid, 2011, 28(1): 49-51) reported a fracturing fluid that uses chemical cross-linking to form a polymer, and its composition is 0.25-0.8% thickener, 0.5-0.8% Chemical cross-linking agent, 0.2% drainage aid, at 180°C, 170S -1 Under the same conditions, after shearing for 180 minutes, the tail stickiness is 70mPa·s, but it takes 8 hours for the polymer fracturing fluid to break the gel, which cannot meet the requirements of on-site construction.

[0004] The main problems of existing chemically cross-linked polymer fracturing fluids are the wide variety of auxiliary agents required, high cost, long gel breaking time and low flowback efficiency. Therefore, it is necessary to research and develop a new type of fracturing fluid

Images