Bionic lubricating mechanism of water-based drilling fluid with hyperbranched polymer
With the advancement of directional drilling technologies,the lubricity of water-based drilling fluids has gradually become the key factor to ensure the smooth implementation of directional drilling.Thus,designing novel drilling fluid lubricant has been taken as the research hotspot and focus in the field of oilfield chemistry.To explore the lubricating mechanisms of the water-based drilling fluid with hyperbranched polymer,this paper synthesizes the 1.5th generation of ethylenediamine-methyl acrylate-octadecyl acrylate hyperbranched polymer G1.5 P(EDA-MA-OA),in reference to the bionic lubrication theories.Then,its synthesized product structure,microscopic morphology and thermal stability are tested,and its ability to enhance the lubricity of water-based drilling fluid is evaluated.Finally,the adsorption behaviors of hyperbranched polymer and bentonite particle are analyzed systematically.And the following research results are obtained.First,G1.5 P is a kind of dispersed particle with a size of tens of nanometers and has good thermal stability with pyrolysis temperature concentrating at 214℃.Second,the water-based drilling fluid with G1.5 P as lubricating additive has the lubricity coefficient of 0.068,exhibiting prominent friction reduction and wear resistance.Third,G1.5 P is adsorbed on the surface of hydrophilic material in the form of"molecular brush",which not only changes the surface wettability,but also promotes the aggregation of bentonite particles to form compact and flexible mud cakes.Fourth,based on the lubrication enhanced structure-activity relationship of hyperbranched polymer drilling fluid,a boundary-solid lubrication model of water-based drilling fluid is newly proposed.It reveals that hyperbranched polymer promotes the formation of low shear strength mud cake between drill tool and borehole wall friction pairs,and the internal friction of mud cake replaces the rigid external friction of drill tool,thus achieving friction reduction and wear resistance of drilling fluid.In conclusion,the research results further improve the design idea of the lubricating additive of water-based drilling fluid,and can provide theoretical and technological supports for the design of novel high-performance lubricant treatment agent and the development of superlubrication water-based drilling fluid.
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维普
