Low Molecular Weight Zwitterionic Polymer Synthesis And In The Research And Application Of Drilling Fluid System

Because low molecular weight zwitter-ion polymer have excellent zwitter-iongroups with thermal stability and salt resistance properties, so the polymer not onlycan adsorb and flocculate clay particle reasonably, but also have good dispersibility,so that can make the clay particle being symmetrical and stable status of suspendedgranule, keeping moderate size in the drilling fluid. Synthesizing and using thepolymer in the drilling fluid, it can not just improve the coordination and stability ofdrilling fluid system, but can reduce filtration, have good thermal stability and saltresistance properties, and can control swelled clay reasonably.By the special construction and excellent properties, the zwitter-ion polymerhave been used in the drilling fluid more and more widely, and have improved theproperties of the drilling fluid systems obviously. This paper has discussed speciallythe synthesizing of the low molecular weight zwitter-ion polymer and the using in thedrilling fluid systems, from the basic of the related theory and applied research of thezwitter-ion polymer and drilling fluid systems.This paper chose the ox red system of K₂S₂O₈and NaHSO₃as initiator, becausethis initiator has decomposable activation energy, so it often has been used to initiatepolymerization at not high temperature. We chose AMPS as anion monomer, DMCand DMDAAC as cation monomer and AM for the ternary copolymerization byradical in aqueous solution. We synthesized low molecular weight zwitter-ion polymer:AM-DMC-AMPS （LADA） and AM-DMDAAC-AMPS.This paper has discussed specially the effects of the reaction temperature, theratio and concentration of monomer, and the dosage of initiator and chain transferagent on molecular weight, and we also chose the best reaction condition forsynthesizing LADA. The molecular structures of LADA were characterized and themaps were analyzed through FTIR. Under a similar reaction conditions, we havebegun the work to synthesize polymer AM-DMDAAC-AMPS.After the work of synthesizing polymer LADA, the key of our work is that we discussed rheological properties and filtration of the drilling fluid with LADA underdifferent temperatures and densities. The related dates can be assayed by six-speedviscosimeter and API and high temperature high pressure filtration instrument. Wehad directly observed the dispersity of clay particle through GE-5.Experiments show that LADA can obviously optimize drilling fluid’s rheologicalproperties and reduce its filtration, and improve the stability of drilling fluid systemunder different temperatures and densities.At last, we discussed the mechanism of action of LADA in drilling fluid system,through the low molecular weight and the special construction of LADA.