Turbulent Drag Reduction with an Ultra-High-Molecular-Weight Water-Soluble Polymer in Slick-Water Hydrofracking

Abstract

Water-soluble polymers as drag reducers have been widely utilized in slick-water for fracturing shale oil and gas reservoirs. However, the low viscosity characteristics, high operating costs, and freshwater consumption of conventional friction reducers limit their practical use in deeper oil and gas reservoirs. Therefore, a high viscosity water-soluble friction reducer (HVFR), poly-(acrylamide-co-acrylic acid-co-2-acrylamido-2-methylpropanesulphonic acid), was synthesized via free radical polymerization in aqueous solution. The molecular weight, solubility, rheological behavior, and drag reduction performance of HVFR were thoroughly investigated. The results showed that the viscosity-average molecular weight of HVFR is 23.2 × 106 g⋅mol−1. The HVFR powder could be quickly dissolved in water within 240 s under 700 rpm. The storage modulus (G′) and loss modulus (G″) as well as viscosity of the solutions increased with an increase in polymer concentration. At a concentration of 1700 mg⋅L−1, HVFR solution shows 67% viscosity retention rate after heating from 30 to 90 °C, and the viscosity retention rate of HVFR solution when increasing CNaCl to 21,000 mg⋅L−1 is 66%. HVFR exhibits significant drag reduction performance for both low viscosity and high viscosity. A maximum drag reduction of 80.2% is attained from HVFR at 400 mg⋅L−1 with 5.0 mPa⋅s, and drag reduction of HVFR is 75.1% at 1700 mg⋅L−1 with 30.2 mPa⋅s. These findings not only indicate the prospective use of HVFR in slick-water hydrofracking, but also shed light on the design of novel friction reducers utilized in the oil and gas industry.

Preparation and evaluation of acryloyl morpholine modified emulsion fracturing fluid thickener with high temperature resistance and salt resistance

“…The six-membered heterocycle expanded the hydrodynamic volume of ASC, and the macromolecules were intertwined to form a threedimensional network structure, which made the ASC solution viscosity increase greatly with the increase of the mass fraction of thickener. 30 It indicated that ASC had good viscosity-increasing and thickening ability in high salinity brine and satisfied the requirements of continuous fluid preparation on the fracturing process. mass ratio of 5:1 with concentrations of 0, 5000, 10,000, 20,000, 50,000, 100,000, and 150,000 mg/L, respectively.…”

“…As the mass fraction of ASC increased, the hydrophilic groups on the molecular chain were ionized in the brine after the thickener diffused into brine, the higher thickener concentration, the more hydrophilic groups, which increasing the interaction force between the thickener and facilitating the diffusion of the thickener molecules into brine, so the dissolution rate was faster. The six‐membered heterocycle expanded the hydrodynamic volume of ASC, and the macromolecules were intertwined to form a three‐dimensional network structure, which made the ASC solution viscosity increase greatly with the increase of the mass fraction of thickener 30 . It indicated that ASC had good viscosity‐increasing and thickening ability in high salinity brine and satisfied the requirements of continuous fluid preparation on the fracturing process.…”

“…In this paper, a new type of temperature resistance and salt resistance monomer acryloyl morpholine was was should be further improved [30] of fatty alcohol poly(oxyethylene ether), [industrial grade, 99%]) and mineral oil (industrial grade, 99%) were bought from Jiangsu Haian Petroleum Chemistry Factory, China. Dry powder thickener (DPT) was a kind of temperature resistance and salt resistance thickener, which was made of polyacrylamide copolymers with the molecular weight of 6 Â 10 6 g/mol and provided by the Shengli oilfield.…”

Comparative Studies on Thickeners as Hydraulic Fracturing Fluids: Suspension versus Powder

“…Additionally, they usually suffer from shear degradation under turbulent-flow conditions [ 28 ]. To overcome these shortcomings, researchers can enhance the temperature, salinity, and shear resistance of the polymer by introducing monomers with a ring structure, betaine, strong electrolyte group, and hydrophobic structure into the backbone of acrylamide [ 29 , 30 , 31 ]. Mao et al [ 29 ] reported a quaternary thickener P (acrylamide/acrylic acid/2-acrylamide-2-methylpropanesulfonic acid/hydrophobic monomer) and found that the thickener solution had a salt resistance of 30 × 10 4 mg/L and temperature resistance of 120 °C.…”

“…Zhang et al [ 30 ] developed a terpolymer with acrylamide, acrylic acid, and 4-isopropenylcarbamoyl-benzene sulfonic acid with high temperature and shear resistance using the aqueous solution polymerization method; the viscosity of the fracturing fluid was about 135 mPa s after 120 min at 150 °C and it had a shear rate of 170 s −1 . Wei et al [ 31 ] synthesized a W/O emulsion thickener by using acrylamide, acrylic acid, acrylamide-2-methylpropanesulfonic acid, and dimethyldiallyl ammonium chloride and realized the continuous mixing of slick water fracturing fluids; the drag reduction rate of the thickener was greater than 70% at a salinity of 2.5 × 10 4 mg/L.…”