The Preparation And Properties Of Multi-Branched Humic Acid

Humic acid as drilling fluid additives is widely used in the oil drilling industry because of its good viscosity and dilution properties.Nevertheless its performance of fluid loss controlling needs to be further improved.In this paper,a natural polymeric substance of humic acid which is extremely abundant,inexpensive and environmentally harmless is taken as the raw material,and it is modified by grafting method to improve the fluid loss performance and temperature resistance ability.The main research contents focus on grafting humic acid with sulfonated phenolic resin and hydrolyzed polyacrylonitrile.The results of Infrared Spectroscopy and Gel Permeation Chromatography confirm that humic acid can be effectively grafted by sulfonated phenolic resin by means of a condensation reaction.The fluid loss properties,rheological properties,temperature resistance of graft modified samples were tested.The results showed that the grafted sample can significantly increase fluid loss performance and temperature resistance,meanwhile keep the original viscosity and dilution properties of humic acid.The reasons behind the good performance of grafted humic acid was discussed according to the morphological characterization of filter cake,filter cake permeability,the adsorption properties of grafted sample on the clay particles and ζ-potential of the slurry system.The grafted humic acid can more easily adsorb on the clay surface and result in a better protection to the stability of clay-water dispersion system.In addition,the humic acid grafted by hydrolysis polyacrylonitrile also showed excellent fluid loss performance and temperature resistance,and the the property of salt tolerance is effectively improved as well.(1)The preparation of alkalized humic acids and their properties as a drilling fluid additiveThe humic acid was alkalized with Na OH solution,the as-prepared sample is characterized by the Infrared Spectroscopy and properties test which include fluid loss,rheology and temperature resistance.The obtained results will be compared to the grafted samples.(2)Grafting humic acid with sulfonated phenolic resin and their properties as a drilling fluid additiveThe sulfonated phenolic resin was grafted onto the humic acid scaffold successfully to achieve a copolymer.A series of properties such as the fluid loss,rheology,and adsorption of the grafted sample were tested.The results showed that the grafted sample has better fluid loss and rheological properties;furthermore the grafted sample achieve the high temperature resistance ability.(3)The preparation of the humic acid grafted by hydrolysis polyacrylonitrile and their properties as a drilling fluid additiveIn the experiment,a low viscosity fluid loss additive that hydrolyzed polyacrylonitrile sodium was prepared,and their properties of temperature resistance,salt tolerance and rheological properties were tested.The results showed that the grafted sample could overcome the shortcoming of traditional hydrolysis polyacrylonitrile,which is excessive viscosifying effect.The grafted sample has high temperature resistance over 150℃ and has a better salt tolerance;In addition,the performance of the humic acid grafted by hydrolysis polyacrylonitrile;under high temperature and pressure were tested,the results showed that the grafted sample has better temperature resistance and high pressure fluid loss.