Synthesis and evaluation of new slickwater fracturing fluid for drag reduction

This paper examines the damage caused by slickwater fracturing fluid to the microscopic pore structure of tight sandstone in the Chang 7 member in the Ordos Basin. A submicron CT in situ displacement system was used to analyze and graphically represent changes in pores in core samples following fracturing fluid damage. The results show the following: (1) the damage caused by slickwater fracturing fluid to tight sandstone fractures mainly occurs in the early stage of fluid incursion. The damage is characterized by a decrease in the effective pore volume, increase in the number of pores, and insignificant subsequent damage. The main causes of pore damage by slickwater fracturing fluid are retention of slickwater in the liquid phase and hydration swelling of clay minerals in the pores. (2) After the high pressure intrusion of slickwater fluid, the pore size of large-size intergranular pores increases, and there is no obvious damage after water flooding. However, fractures and small dissolution pores in the cores are the main areas of fluid retention after fracturing fluid invasion due to their small flowing radius and complex structure. These are the locations where damage mostly occurs.

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Drag Reduction Mechanism of Viscoelastic Slick-Water Fracturing Fluid in Tortuous and Rough Fractures

Geofluids ◽

10.1155/2021/5827114 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Zhiyu Liu ◽

Fan Fan ◽

Donghang Zhang ◽

Yang Li ◽

Yuan Li ◽

...

Keyword(s):

Molecular Weight ◽

Drag Reduction ◽

Flow Rate ◽

Three Dimensional ◽

Flow Characteristics ◽

Flow Rule ◽

Mechanism Analysis ◽

Reduction Mechanism ◽

Fracturing Fluid ◽

Factors Affecting

Slick-water can effectively reduce the flow drag of fracturing fluid. Many studies have focused on the drag reduction performance of slick-water in wellbore and perforation, but there has been little research on drag reduction characteristics in fracture flow. In this paper, a new visualization experiment system is used to simulate real fracture. The fracture surface is produced through actual triaxial hydraulic fracturing and is copied by a three-dimensional printer using resin material to maintain its shape feature. In comparing the experimental results, it was found that the main factors affecting drag reduction in a fracture are the relative molecular weight and the added concentration. Unlike the flow rule of the drag reducer in a pipeline, when the concentration is greater than 0.10%, a negative DR effect begins to appear. The influence of molecular weight is related to the flow stage; the increasing of molecular weight causes a reduction in DR effect when the flow rate is 0.24 m/s. However, the flow rate exceeds 0.5 m/s; drag reducers with higher molecular weight demonstrate better drag reduction performance. The drag reduction mechanism analysis in fractures was obtained from visualization observations, and the flow characteristics of fluid were characterized by using tracking particles. Drag reduction effect occurs mainly on the surface of the fractures in contrast to near the centre of the flow channel. This research can provide a reference for the experimental study on drag reduction in fractures and is of great significance to the optimization and improvement of drag reducing agent.

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Experimental Study on the Drag Reduction Performance of Clear Fracturing Fluid Using Wormlike Surfactant Micelles and Magnetic Nanoparticles under a Magnetic Field

Nanomaterials ◽

10.3390/nano11040885 ◽

2021 ◽

Vol 11 (4) ◽

pp. 885

Author(s):

Ming-Liang Luo ◽

Xiao-Dong Si ◽

Ming-Zhong Li ◽

Xiao-Han Jia ◽

Yu-Ling Yang ◽

...

Keyword(s):

Magnetic Field ◽

Magnetic Nanoparticles ◽

Drag Reduction ◽

Particle System ◽

Flow Direction ◽

Reduction Rate ◽

Wormlike Micelles ◽

Fracturing Fluid ◽

Fracturing Fluids ◽

Viscoelastic Surfactant

This paper examines a new study on the synergistic effect of magnetic nanoparticles and wormlike micelles (WLMs) on drag reduction. Fe3O4 magnetic nanoparticles (FE-NPs) are utilized to improve the performance of viscoelastic surfactant (VES) solutions used as fracturing fluids. The chemical composition and micromorphology of the FE-NPs were analyzed with FT-IR and an electron microscope. The stability and interaction of the WLM-particle system were studied by zeta potential and cryo-TEM measurements. More importantly, the influences of the temperature, FE-NP concentration, magnetic field intensity, and direction on the drag reduction rate of WLMs were systematically investigated in a circuit pipe flow system with an electromagnetic unit. The experimental results show that a suitable content of magnetic nanoparticles can enhance the settlement stability and temperature resistance of WLMs. A magnetic field along the flow direction of the fracturing fluid can improve the drag reduction performance of the magnetic WLM system. However, under a magnetic field perpendicular to the direction of fluid flow, an additional flow resistance is generated by the vertical chaining behavior of FE-NPs, which is unfavorable for the drag reduction performance of magnetic VES fracturing fluids. This study may shed light on the mechanism of the synergistic drag reduction effects of magnetic nanoparticles and wormlike micelles.

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Study on the Mechanism of Sand-Carrying and Comprehensive Performance of Viscous Slickwater

10.1115/omae2021-61868 ◽

2021 ◽

Author(s):

Hao Bai ◽

Fujian Zhou ◽

Jie Wang ◽

Mengchuan Zhang

Keyword(s):

Molecular Structure ◽

Elastic Modulus ◽

Drag Reduction ◽

Oil And Gas ◽

Guar Gum ◽

Reduction Rate ◽

Space Structure ◽

Fracturing Fluid ◽

Unconventional Oil ◽

Comprehensive Performance

Abstract From the using history, we can see that conventional slickwater and guar fracturing fluid will be widely replaced by viscous slickwater in unconventional oil/gas fracturing. The viscous slickwater combines the advantages of slickwater and guar fracturing fluid but avoids the disadvantages of both, that includes drag reduction and good sand carrying capacity. This paper will analyze the viscous reducer’s molecular structure and viscoelasticity to find out the sand carrying mechanism. Using Haake RS6000 rheometer to test the elastic modulus and viscous modulus of conventional slickwater and viscous slickwater, reveal the sand-carrying performance from the perspective of viscoelasticity; using JEM 2100 LaB6 transmission electron microscope to test the molecular structure of two polymers, from the molecular space structure to analysis of its drag reduction performance. Finally, systematically evaluated the viscosity, drag reduction rate, sand-carrying, and gel-breaking properties of the viscous slickwater. The polymer enhances the viscous slickwater’s sand carrying performance by increasing the elastic modulus of fluid and reduces the drag in the flow through the intermolecular framework structure. The comprehensive performance evaluation results show that: 1) The apparent viscosity of the 0.6 wt% viscous slickwater is 80 mPa.s, which is close to conventional guar gum fracturing fluid; 2) When the linear flow rate reaches 5 m/s, the viscous slickwater drag reduction rate is greater than 75 %; 3) The viscous slickwater fluid static and dynamic sand carrying performance is better than conventional slickwater, which is close to guar gum fracturing fluid; 4) When the breaker concentration is equal to 50 ppm, the gel breaking time of viscous slickwater is about 35 mins and the residue content is less than 45 ppm. The conventional fracturing fluid will be more and more replaced by viscous slickwater during the fracturing of unconventional oil and gas reservoirs. This article provides a reference for researchers to understand its drag reduction and sand carrying performance.

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