Research And Application Of High Temperature Resistant Starch In Drilling Fluid

Starch and its derivatives,homologues and other substances are a kind of natural resources in nature,which have wide sources,low cost,easy degradation and good environmental adaptability.However,the application of starch in industry is very limited,mainly because of its poor stability and water solubility after heating,and it will ferment at a certain temperature.This paper introduces the action principle,research direction and application of high temperature resistant modified starch for drilling fluid.The research status of modified starch used as fluid loss reducer at home and abroad was reviewed,and the field application of modified starch was discussed.High temperature resistant modified starch for environmental protection drilling fluid with better performance was selected to meet the requirements of field drilling and production process.Based on the investigation of the development and research status of starch modified by environmentally friendly drilling fluid at home and abroad,and on the basis of the performance indexes of starch modified by gelatinized in water-based drilling fluid,this paper carried out the research on starch system modified by gelatinized drilling fluid for environmental protection.The performance of different types of modifiers in drilling fluid was compared and studied.Combined with the linear expansion rate test of bentonite and mud ball test,the selection of modifiers as drilling fluid modified starch was completed.The system mainly studied the temperature resistance of the compound system,and also discussed the inhibition,filtration loss and other properties,from which the best temperature resistance of2.0% corn starch + starch quality of 5% modifier formula was selected.The results show that the formula has good temperature resistance,fluid loss reduction and inhibition.Among them,the system with 2% corn and 5% plant phenol co-gelatinization showed the best performance.At 150°C,the system still maintained good temperature resistance and filtration loss,and the filtration loss was only 5.6m L,while at 110℃,the filtration loss of corn starch gelatinized slurry was 5.2 m L,indicating that the temperature resistance of the modified 5% plant phenol gelatinized slurry increased by about 40 ℃.At the same time,the system also has good inhibition performance and thermal stability.After aging at 140℃,filtration loss,apparent viscosity and plastic viscosity increased slightly.The inhibition,fluid loss reduction and lubricity of the environmental protection drilling fluid modified starch system meet the requirements of field drilling and production process,and can effectively overcome the shortcomings of high cost and large consumption of the current environmental protection drilling fluid.In this paper,potato,cassava and corn starch were gelatinized to improve the temperature resistance,salt resistance and fluid loss reduction performance of modified starch as drilling fluid additives;At the same time,it can reduce the cost of drilling fluid modifier.