| With the increasing number of special wells, super-deep wells and complicated wells, the increasing depth of drilling along with more and more complicated formation, how to reduce the viscosity and shear matters much during the oil exploration, especially drilling in mud-making formation. The recycle of calcium lignosulphonate from pulped waste liquor in pulp industry has a dual significance whether from the perspective of energy use or environmental protection. In the paper, first of all, the copolymer LSGC is prepared by the graft copolymerization reaction between polyanionic (Ca-Ls) and nonionic monomer (AM). Then, ALSGC is finally prepared by Mannich cationic reaction of LSGC which is a kind of amphoteric lignin thinner. The optimum reaction conditions of preparing LSGC and ALSGC are determined on the basis of orthogonal design and single factor optimal experiments. The products, LSGC and ALSGC, are characterized by determining intrinsic viscosity, infrared spectroscopy and pyrolysis gas chromatography-mass spectromety. The viscosity reduction effect of ALSGC is evaluated in various drilling fluids by lab experiments. The law and mechanism of viscosity reduction are analyzed and discussed in various base mud of drilling fluid. Lab experiments show that ALSGC has a good resistant performance to temperature, salt and calcium which can resist temperature of 180℃and above, be used in saturation salt solution and is stable in 2% calcareous base mud. By compared with similar products, it shows that ALSGC is a kind of multifunction thinner which has the property of scattered thinner while has inhibitive ability, so it can be used in high density drilling fluid and nondispered polymer drilling fluid. Field applied test confirmed that ALSGC has a good compatibility with other agents in drilling fluid, has a long length of maintenance cycle and can dramatically reduce viscosity and shear of drilling fluids under the condition of high salinity and high temperature.
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