Study On Synthesis And Properties Of Drilling Fluid Filtrate Reducer Acrylic Acid-acrylamide-acryloxyethyl Trimethylammonium Chloride

Poly cationic and zwitterionic filtrate reducer have some incomparable advantages over the anionic type drilling fluid filtrate reducer in improve the rheological behavior, reduce the bit nozzle viscosity, control well bore stability and mud yield, especially they have great resistance ability to high valence metal ion pollution, they can satisfy the high pressure jet drilling and the optimal-fast drilling program. From the mid 1990s to today, the research about zwitterionic copolymer filtrate reducer made gratifying progress and new products emerge in endlessly. But the A shortcoming of zwitterionic copolymer filtrate reducer is the low temperature resistance. All of this brings out the higher requirements for the researchers to develop higher temperature resistance products which adapt to the need of super deep drilling.This article attempts to use acrylic acid (AA), acrylic amide (AM) and acryloxyethyl trimethylammonium chloride (DAC) as comonomers, deionized water as solvent, ammonium persulfate as the redox initiator to synthesize water soluble copolymers of AA-AM-DAC as drilling fluids filtrate reducer.The properties of AA-AM-DAC drilling fluid as apparent viscosity, plastic viscosity, the filtration, yield point and the AA-AM-DAC water solution properties as reduced viscosity are discussed; the optimum polymerization parameters as initiator consumption, AA/AM mass ratio, DAC consumption, and reaction temperature are established. The effect of the salt concentration, calcium content and temperature to zwitterionic polymer drilling fluid properties was analysed.The molecular structure and the thermal stability of the synthesized water soluble polymers were characterized by fourier transform infrared spectroscopy (FTIR) Analysis and the thermal gravimetric analysis (TGA). The AA-AM-DAC drilling fluid temperature resistance was validated by hot rolling test. The inhibition and preventing collapse capability of the copolymer was verified by the shale rolling recovery test. The termerature resistant, salt resistant, calcium resistant and polymer drilling fluids filtrate reducer which can be used for various drilling fluids system was obtained. The main research achievements are as follows:(1)To achieve the objectives of a stable and rapid polymerization and copolymers with high molecular weight, the polymerization technique was optimized and the optimal polymerization parameters are as follows: AA/AM mass ratio of 4:6; DAC amount of 20%; initiator amount of 1%; polymerization temperature of 55℃.(2)The synthesized AA-AM-DAC polymers has good salt-resistance and high valence metal ion pollution resistance.The ability of resistance to Ca²⁺ was higher than Na⁺.(3) The hot rolling test showed: the filtration of the AA-AM-DAC polymer drilling fluid increased slightly with increase temperature at 25-160℃, an indicative of good temperature-resistance of the polymer drilling fluids, temperature- resistance amounted to 160℃.(4) Inhibitory evaluation showed: the copolymer has great inhibited shale hydration dispersed capacity, and the inhibition increased with the copolymer dosage increased. Not only the first recovery rate is high but also the second recovery is high. Strong adsorption capacity of the copolymer on the shale surface was showed.(5) FTIR spectra showed the water soluble polymer was AA/AM/DAC copolymers. TGA showed the onset decomposition temperature of the copolymer was 210℃, the starting decomposition rate at 6.15% and 14.76% residual quality at 501.4℃.So the terpolymer has high thermal stability.