Surface modification of polyethylene glycol-nano silica using SDS to improve rheological and filtration properties of water-based mud

Abstract

In this study, 5 concentrations of SDS are used to surface-modify nanocomposite of polyethylene glycol-based silica (PEG-SiO2-SDS NC). The objectives of the study are to evaluate the influence of SDS concentration in the surface modification of PEG-SiO2-SDS on the rheological properties (plastic viscosity (PV), yield point (YP), and gel strength) and filtration properties of water-based drilling fluid. The experiment was conducted into two stages. The first part is the synthesis of PEG-SiO2 NC then surface modifying it with 5 SDS concentrations of 1.5, 2.5, 3.5, 4.5, 5.5 vol%. The synthesized PEG-SiO2-SDS NCs undergo characterizations such as FESEM, EDX and TEM in order to confirm the synthesis and modification processes are successful. The second part is to study the effect of the 5 NCs on rheological properties and filtration properties as an additive to water-based mud (WBM). PEG-SiO2 NC was synthesized from Tetraethyl orthosilicate (TEOS), polyethylene glycol (PEG), Ethanol (EtOH), ammonium hydroxide (NH4OH), and deionized water. The sodium dodecyl sulfonate (SDS) surfactant was used to functionalize the synthesized PEG-SiO2 NC via surface modification. The WBM materials are freshwater (320 ml), caustic soda (NaOH) (0.15 gm), and bentonite (25 gm). All the materials were used as obtained without purification. The experimental results revealed that after modifying SDS, the low pressure-low temperature (LPLT) and high pressure-high temperature (HPHT) filtration loss of PEG-SiO2 additives was improved before and after hot rolling of mud samples at 250 °F for 16 h. When compared to base mud, the modified 0.1 g of PEG-SiO2 with 3.5 vol% of SDS reduced the LPLT and HPHT filtration loss of drilling fluid by 46.3% and 45.5%, respectively. Drilling fluid rheological parameters such as AV, PV, YP, and gelation were also improved by modifying PEG-SiO2 with SDS. The optimal SDS concentration for the best rheological properties is 3.5 vol%. As a result, the use of PEG-SiO2 with 3.5% SDS in water-based mud produced favourable results, reaffirming the feasibility of using them in successful drilling operations.