Establishment And Performance Evaluation Of Silicate Anti-Collapse Drilling Fluid

Although the oil and gas resources of the Paleogene strata in the Pearl River Mouth Basin have achieved good economic benefits,they still face many difficulties during the drilling process,such as the collapse of the wellbore,the instability such as the reduction of diameter,etc.The poor results in low ROP,etc.These problems not only make the drilling cost of the area high,but also slow down the development progress of oil and gas resources in the area.In order to reduce the complexity of the drilling process of the Paleogene formation and reduce the operating cost,this paper has developed a method for the development of micro-fractures in the Paleogene formation,combined with the increase in the drilling fluid density,which will cause pressure differential stuck and low ROP A silicate anti-collapse drilling fluid system that meets the requirements of Paleogene formation drilling and has a temperature resistance of170℃ is successfully applied to the site.In this paper,the problems of Paleogene strata,the causes of wellbore instability and the commonly used anti collapse drilling fluid system at home and abroad are analyzed.The research status of silicate system,especially the mechanism of action,is analyzed.Based on the drilling conditions,clay mineral analysis,rolling recovery rate,expansion rate and scanning electron microscope technology,the paper analyzes the problems existing in the Paleogene formation and the causes of borehole wall instability,and summarizes that the main reason of borehole wall instability in the drilling process is the development of microfractures.To solve the problem of borehole wall instability in The formation,it is necessary to seal the microfractures and reduce the filtrate of drilling fluid,at the same time,it can improve the strength of formation rock and ensure the rapid and smooth drilling under the condition of low drilling fluid density.Carry out indoor experiments on the basis of preliminary investigations,through immersion and compatibility experiments,select high-performance inhibitors with good performance and good compatibility with silicate systems;through compatibility comparison experiments,with good performance and silicate High-performance rheology modifier,fluid loss agent and other treatment agents with good system compatibility.On this basis,the dosage experiment of each additive was carried out to determine the dosage range of each additive,and finally the formula of the silicate anti-collapse drilling fluid was finally determined The comprehensive performance evaluation results of the system show that the developed silicate drilling fluid system has good sealing performance,strong inhibition and pollution resistance,and achieves the expected goal.Based on a large number of laboratory experiments,the system was applied to two wells in the Pearl River Mouth Basin,and the drilling was successfully completed.Field application results show that the silicate anti-collapse drilling fluid system suitable for Paleogene formations-Bor STAB anti-collapse drilling fluid system is simple in formula,has good plugging ability,anti-pollution ability,excellent lubrication performance,andgood Improve the stability of the shaft wall,strong suppression ability and simple maintenance.The successful application of the system on site not only played a role in promoting the application of the silicate system,but also provided a reference for subsequent drilling in the area.