Synthesis and Crosslinking Mechanism of Colloidal Graphene Oxide Crosslinker for Crosslinking Low-Concentration Hydroxypropyl Guar Gum Fracturing Fluids

Abstract

Guar gum fracturing fluid is widely used in hydraulic fracturing due to its excellent viscoelastic and proppant-carrying properties. With the increasing burial depth of oil and gas resources, strengthening the temperature and shear resistance of guar gum fracturing fluid is a significant engineering issue. Although graphene oxide is known to be effective in enhancing the structural strength of materials, few studies reported its ability to enhance guar gum fracturing fluid properties. To address this issue, herein, we prepared a boron-functionalized colloidal graphene oxide crosslinker (GOB) to enhance the temperature and shear resistance of guar gum fracturing fluid. Colloidal graphene oxide crosslinkers have a larger size and more crosslinking sites, reducing the amount of self and guar gum. Compared with organoboron crosslinkers under the same conditions, GOB can improve the temperature resistance of fracturing fluid by 8.9 °C and viscosity by 20−50 mPa•s. It was observed by vacuum freeze-drying combined with scanning electron microscopy that guar gum exists as irregular linear structures when dissolved in water. The addition of crosslinkers makes the irregular linear structures bind to each other and form a continuous membrane structure. Meanwhile, the distribution of graphene oxide crosslinker on the surface of the continuum film enhances the membrane's tensile strength, resulting in the enhanced water retention capacity of the fracturing fluid gel at high temperatures. Thereby, the temperature and shear resistance of the gel is enhanced. In addition, this work reveals in detail the effects of pH and crosslinker dosage on the gel properties of fracturing fluid formed by graphene oxide crosslinker. It has significant significance for further improving the GOB's properties and developing other types of nanomaterials in guar gum fracturing fluids.

A Supramolecular Reinforced Gel Fracturing Fluid with Low Permeability Damage Applied in Deep Reservoir Hydraulic Fracturing

“…The G' and G'' of SRG fracturing fluid are shown in Figure 3. Both the G' (Figure 3a) and G'' (Figure 3b) increased with the increase in the oscillation frequency, except that the G'' increased at low frequencies when the concentration of Zr-crosslinker was 0.2 wt% and 0.3 wt% [24,25]. Unlike SNG fracturing fluid, SRG fracturing fluid could form highstrength gels at lower Zr-crosslinker concentrations.…”

“…High temperatures, some of which can be higher than 180 • C, are common in deep reservoirs. Neither the glucoside bond of the guar gum nor the boron crosslinker can be stabilized at such high temperatures [23,24]. Currently, polyacrylamide-based gels are mainly used to replace guar gum to solve the problem of high-temperature resistance (>180 • C) of gel fracturing fluid.…”

Review on High-Temperature-Resistant Viscoelastic Surfactant Fracturing Fluids: State-of-the-Art and Perspectives

“…285 The nanoparticle (NP) surfaces can be modified to obtain different physical and chemical properties, which enables them to cope with different environmental and technical requirements of oilfields. 286,287 Quantities of studies concerning nanomaterials and WLMs have brought about some extremely interesting and promising applications. A summary of surfactants and nanomaterials used for high-temperature-resistant nano-enhanced VES fracturing fluid systems is presented in Table 6.…”

“…So they have a very high specific surface area, leaving enough space for interaction with other materials . The nanoparticle (NP) surfaces can be modified to obtain different physical and chemical properties, which enables them to cope with different environmental and technical requirements of oilfields. , …”