Abstract
Research on using nanotechnology to solve shale instability problems in drilling engineering has been increasing. The combination of amphiphilic polymer and silica nanoparticles may be a new way to improve shale stability. Herein, an amphiphilic polymer/nano-silica composite (poly(styrene-methyl methacrylate-acrylamide)/nano-SiO2) was introduced as a novel shale stabilizer SMA/SiO2 for water-based muds, which possessed the advantages of both physical plugging and chemical inhibition during the drilling operations. The SMA/SiO2 was prepared and characterized by Fourier transform infrared spectra (FT-IR), nuclear magnetic resonance (1H-NMR), transmission electron microscope (TEM), particle size distribution (PSD) and thermogravimetric analysis (TGA) experiments, which confirmed that SMA/SiO2 was regularly spherical with nano-scale and showed good high-temperature resistance. To evaluate the plugging capacity of SMA/SiO2, the pressure transmission test and BET analysis were applied. The results indicated SMA/SiO2 was capable of effectively plugging the pores and fractures in shale. To evaluate the hydration inhibition capacity of SMA/SiO2, the rolling dispersion experiment and contact angle test were adopted. The results demonstrated that SMA/SiO2 could reduce the tendency of shale hydration, which was better than potassium chloride (KCl) and polymeric alcohol (JHC). In addition, SMA/SiO2 only created slight variations on the rheological parameters of the water-based muds (WBMs) and showed a significant filtration control performance. Due to the outstanding performance of physical plugging and chemical inhibition, SMA/SiO2 was expected to be a novel shale stabilizer to solve shale instability problems.
Highlights
Drilling fluids are considered as circulating fluids in the drilling operations, which provide multiple functions
Drilling fluids are usually grouped into three types: water-based muds (WBMs), oil-based muds, and synthetic-based muds
The following conclusions can be drawn from the current work: (1) An amphiphilic polymer/nano-silica composite (SMA/SiO2 ) was prepared and characterized as a novel shale stabilizer for water-based muds
Summary
Drilling fluids are considered as circulating fluids in the drilling operations, which provide multiple functions. Their major functions consist of suspending/transporting drill cuttings, cooling and lubricating the drilling bits, maintaining borehole stability and reducing the formation damage [1,2,3]. Drilling fluids are usually grouped into three types: water-based muds (WBMs), oil-based muds, and synthetic-based muds. Due to their lower cost and lesser impact on environment, WBMs have become the most widely used drilling fluids in the world [4,5].
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