The Optimization Of Process And Mechanism Study Of Polysaccharide Drilling Fluid System

With the development of green chemistry around the world, develop new kinds of drillingfluid additives has risen a wide concern to oilfield technology workers. This paper showschemical modification of natural polysaccharide (SJ) which has wide sources, non-toxiccharacteristics, determined the performance of the modified product as drilling fluid additives.This paper explored the application of polysaccharide drilling fluid system in the field and themechanism of action.In this paper, new kinds of modified products were developed by sulfonation, phosphoricesterification and cationization with plant polysaccharide derivatives (SJ) as raw material.Investigated the influences of modified agent dosage, reaction time, reaction temperature andpH on the modification by the orthogonal designed experiments and range analysis, and themodify reaction conditions were optimized. Explored the performance changes ofpolysaccharide before and after modification, evaluate the performance of the modifiedproduct in drilling fluid. The performances of modified products has been improved in normaltemperature drilling fluids, showing obviously thickening effect, filtration reduction property,and the lubrication effect. The results showed that, comparing to the raw agent, the modifiedproduct has higher water solubility. The viscosity of SJS drilling fluid system has beenenhanced by135.1%with the dosage at0.5%, and the filtration reduction is depressed by22.9%. The viscosity of SJP drilling fluid system has been enhanced by80.1%with the dosageat0.5%, and the filtration reduction is depressed by29.2%. Flocculation happened when thedosage of SJN is0.5%, the viscosity has been enhanced by472.1%with the dosage at0.5%,and the filtration reduction is depressed by14.9%. Drilling fluid ageing test showed that thetemperature resistance of modified product drilling fluid system has slightly decreased. Theviscosity of drilling fluid shows irregularity after aging, the filter loss increased sharply whenthe aging temperature over120℃. Linear bentonite expansion rate experiment and the mudball immersing experiment results show that the modified product has good inhibitive propertyand anti-sloughing effect comparing to the raw agent.This paper also explored the application of polysaccharide drilling fluid system whichuses KD-03as the main agent. The system maintains good viscosity, low filter loss, and showed good proppant carrying capacity during the drilling process. The flowback debris werecoated well. There is no obviously collapse spalling phenomenon. The CODCr/BOD5experiment results showed that polysaccharide drilling fluid system has good biodegradability,which means that it is good for environmental protection and there is no long-term harm to oiland gas reservoir.