A Temperature-Sensitive Polymeric Rheology Modifier Used in Water-Based Drilling Fluid for Deepwater Drilling

Abstract

Rheology modifiers are essential for the flat rheology of water-based drilling fluids in deepwater. The low temperature thickening of deepwater water-based drilling fluids results in dramatic rheological changes in the 20–30 °C range. To address such problems, NIPAM with a self-polymerized product LCST of 32–35 °C was selected as the main body for synthesis. While introducing the hydrophilic monomer AM to enhance the thickening properties, the hydrophobic monomer BA was selected to reduce the LCST of the product. In this paper, a temperature-sensitive polymeric rheology modifier (PNBAM) was synthesized by emulsion polymerization using N-isopropyl acrylamide, acrylamide, and butyl acrylate as monomers. The PNBAM was characterized using infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and nuclear magnetic resonance hydrogen spectroscopy (NMR). The rheological properties, temperature resistance, and salt resistance of PNBAM in the base fluid (BF) were tested. The performance of PNBAM in the drilling fluid system was also evaluated, and a water-based drilling fluid system of flat rheology for deepwater was formulated. The rheological modification mechanism of PNBAM was analyzed by turbidity analysis, particle size analysis, and zeta analysis. Experimental results show that PNBAM has good rheological properties. PNBAM is temperature resistant to 150 °C, salt-resistant to 30 wt%, and calcium resistant to 1.0 wt%. PNBAM also has good flat rheology characteristics in drilling fluid systems: AV4°C:AV25°C = 1.27, PV4°C:PV25°C = 1.19. Mechanistic analysis showed that the LCST (Lower Critical Solution Temperature) of 0.2 wt% PNBAM in an aqueous solution was 31 °C. Through changes in hydrogen bonding forces with water, PNBAM can regulate its hydrophilic and hydrophobic properties before and after LCST, which thus assists BF to achieve a flat rheological effect. In summary, the temperature-sensitive effect of PNBAM has the property of enhancing with increasing temperature. While the tackifying effect of conventional rheology modifiers diminishes with increasing temperature, the temperature-sensitive effect of PNBAM gives it an enhanced thickening effect with increasing temperature, making it a more novel rheology modifier compared to conventional treatment additives. After LCST, compared to conventional rheology modifiers (XC), PNBAM has a more pronounced thermo-thickening effect, improving the main rheological parameters of BF by more than 100% or even up to 200% (XC less than 50%). This contributes to the flat rheology of drilling fluids. PNBAM has good application prospects and serves as a good reference for the development of other rheology modifiers.

Development and Characterization of Thermoresponsive Smart Self-Adaptive Chitosan-Based Polymer for Wellbore Plugging

“…Bai et al [21] developed a temperature-responsive plugging agent composed of NIPAM-grafted silica nanoparticles. These studies demonstrate the effectiveness of temperature-responsive plugging agents [22]. Lei et al [23] grafted MAOEM with carboxymethyl chitosan (CMCS) to preliminarily prepare an environmentally friendly temperature-responsive polymer, which can reduce the filtration loss of drilling fluids and inhibit clay swelling properties.…”

Application of High-Density Brines in Drilling and Completion Fluids: Current Insights and Future Perspectives

“…Rather, it serves as a parameter solely dedicated to quantifying the suitability of the brine for its designated role as a completion fluid. The turbidity levels present in brines can have substantial ramifications for many industries that depend on brines, including but not limited to the oil and gas, mining, and food processing sectors . An instance of elevated turbidity in brine solutions employed in oil and gas extraction might result in diminished production rates and augmented operational expenses, as it necessitates more frequent stimulation procedures.…”

Development of Multiple Crosslinked Polymers and Its Application in Synthetic-Based Drilling Fluids

“…That is because the polymer structure contains many hydrogen-bonded crosslinked networks and rigid particles, which improves the capacities of resist oil-water segregation and structural destabilization at elevated temperatures. On the other hand, because the polymer is a deformable flexible particle and nanoparticle doped aggregate, the particle deformation and PSD distribution are wider under differential pressure, compared with the formation of a denser filter cake after deposition, which prevents the further intrusion of solid-phase particles and liquid-phase, which is conducive to the stabilization of the well wall and the control of reservoir damage [25,26].…”