Effect Of Lignite Composition On The Properties Of Drilling Fluid And Their Modified Method

The compose of different regions lignite was detailedly analyzed in this paper,and the lignite characteristics of different regions were combined, the relationshipbetween various components and the drilling fluid viscosity reduction performance,fluid loss performance, heat and salinity tolerance performance was defined. On thebasis of this, a variety of lignite drilling fluid was prepared, so as to adapt to the needsof different drilling fluid system and geological mining conditions.The content of lignite total humic acid, free humic acid，fulvic acid, ulmic acid,black humic acid, wax, asphaltene and ash were obtained by different methods. Theresults show that the lignite components concentration of different regions has verybig difference. These differences have a significant impact on reducing viscosity andfluid loss when as drilling fluid additives.Those lignite were treated by the right amount of sodium hydroxide, as the basisof drilling fluid additives raw materials, the viscosity reduction performance test, fluidloss performance test, heat and salinity tolerance performance test were conducted,the relationship between various lignite components and all kind of performance weredefined.According to the characteristics of the lignite composition, it was modified byoxidation, sulfonation and grafting, get the regularity that a variety of modifiedmethod influence on the mud filtration and viscosity.