High-temperature and high-salt resistant hyperbranched lubricant for water-based drilling fluid, and preparation and application thereof

A preparation method of a high-temperature and high-salt resistant hyperbranched lubricant for a water-based drilling fluid, comprising the steps of:

• (1) synthesis of highly reactive hyperbranched polysiloxane
• mixing tetraethyl orthosilicate (TEOS), diethanolamine (DEA), and triethanolamine (TEA), and stirring uniformly for a transesterification and polycondensation reaction;
• and after the reaction is completed, performing dialysis and freeze-drying to obtain highly reactive hyperbranched polysiloxane, wherein a mass ratio of TEOS, DEA, and TEA is 1-5:3:2;
• the transesterification and polycondensation reaction is performed at a temperature of 60-100° C. for 3-7 h;
• and
• (2) preparation of high-temperature and high-salt resistant hyperbranched lubricant
• adding an acrylamide (AM) monomer, an anionic monomer, and a polar ester monomer into deionized water to obtain a monomer solution;
• adjusting the pH of the monomer solution to 5-9, and then adding highly reactive hyperbranched polysiloxane prepared in step (1) to obtain a mixed reaction solution;
• introducing nitrogen to remove oxygen, raising the temperature to a reaction temperature, adding an initiator, and thermally initiating a polymerization reaction;
• and after the reaction is completed, vacuum-drying and crushing an obtained product to obtain the high-temperature and high-salt resistant hyperbranched lubricant for a water-based drilling fluid,
• wherein the AM monomer is one of or a combination of two or more of AM, methacrylamide (MAM), and N,N-dimethylacrylamide (DMAA);
• the anionic monomer is one of or a combination of two or more of 2-acrylamido-2-methylpropane sulfonic acid (AMPS), sodium styrene sulfonate (SSS), and vinyl sulfonate (VS);
• the polar ester monomer is one of or a combination of hydroxyethyl acrylate (HEA) and butyl acrylate (BA);
• a mass ratio of the AM monomer, the anionic monomer, and the polar ester monomer is 1-7:1-2:1-2;
• a ratio of the mass of highly reactive hyperbranched polysiloxane to the total mass of the AM monomer, the anionic monomer, and the polar ester monomer is 0.05-0.15:1;
• the initiator is cerium ammonium nitrate (CAN);
• the polymerization reaction is performed at a temperature of 30-80° C. for 2-6 h.