Study On Synthesis And Properties Of Temperature-resistant And Salt-resistant Fluid Loss Reducer In Water-based Drilling Fluids

As one of the important treatment agents for drilling fluid,fluid loss reducer can maintain effective filtration loss performance under high temperature and high salt conditions,which is the basis for determining the normal operation of drilling fluid.A fluid loss additive was obtained by quaternary copolymerization,and the characterization experiments were carried out by infrared spectroscopy,molecular weight analysis and thermogravimetric analysis.At the same time,rheology and high temperature and high pressure filtration evaluation experiments were carried out.Finally,the mechanism of action was studied by SEM analysis of filter cake,Zeta potential and particle size analysis.In this paper,based on the performance requirements of high temperature and salt resistance fluid loss reducer,the molecular structure of polymer fluid loss additive was designed.The four monomers of sodium styrene sulfonate(SSS),acrylamide(DMAM),dimethyldiallylammonium chloride(DMDAAC)and N-vinylpyrrolidone(NVP)are used as raw materials,and an aqueous solution polymerization method is employed.And then the polymerization product was dehydrated and dried.A new type of high temperature resistant anti-saturated salt fluid loss additive was named FLA-1.By optimizing the synthesis reaction conditions,such as the total monomer concentration,the monomer ratio,the synthesis temperature,the amount of the initiator,etc.,it is finally confirmed that the optimum reaction conditions are: total monomer concentration of 30 wt%,monomer molar ratio SSS: DMAM : DMAAC: NVP = 7:5:3:1,the reaction temperature was 80 °C,the amount of the initiator was 0.08 wt%,the p H was 5.1,and the synthesis reaction time was 1.5 h.Characterization and analysis of the polymer product by infrared spectroscopy,molecular weight,thermogravimetric experiments,etc.,showed that FLA-1 contain all the selected monomers,and has excellent thermal stability.The experimental results of FLA-1 performance evaluation showed that FLA-1 has good rheology and fluid loss,and has excellent resistance to high temperature and salt resistance.The saturated brine base slurry containing 3% FLA-1 is aged at 200 °C for 16 h.After that,the base slurry is thickened and the high temperature and high pressure filtration loss is 15.0 m L.The mechanism of action of FLA-1 fluid loss additive was analyzed by SEM analysis of filter cake,zeta potential of drilling fluid and particle size analysis.The results show that FLA-1 is beneficial to the formation of a dense filter cake in saturated brine-based pulp,reducing fluid loss.