Nano Composite Fluid Solid Coupling In Collapse Formation Model Research And Calculation

The research work of borehole instability has been carried out since 1940 s,until today,the problem of borehole instability is still a very important and difficult problem in the petroleum industry.with the gradual improvement of the development of science and technology and the various theories,people began to attention with a variety of disciplines to solve wellbore instability problem.The general evolution process is from the pure mechanical research,to the study of drilling fluid's chemical,coupling with mechanics and chemistry research to study coupling of multiple.But the coupling theory of mechanics and chemistry has always existed defects: model parameters are difficult to measure;second considering solely the mechanical problems cannot use mechanical calculation results and conclusions to guide the laboratory of materials synthesis and development.Although materials prepared in experiment based on anti collapse principle have good performance on maintaining good wellbore stability,whether they can meet the on-site application and the mechanical conclusion can only rely on in the field practice.This makes the materials properties of application lack of support of the mechanical theory.Therefore,combination of the mechanical factors and chemical factors from the theory and the macroscopic view,is of great significance to study and solve the problem of borehole stability.The research contents and the corresponding conclusions of this paper are as follows:(1)Using the rock mechanics formula to express the relationship between the mechanism of anti collapse and the properties of the nano composite system;(2)According to the fluid solid coupling theory,the change of pore pressure is calculated by using the performance data of the nano composite system in the laboratory;(3)The formation of the three pressure model is used to quantitatively verify the effect of the nano composite system on the stability of the borehole wall,and strengthen the combination of theory and practice;(4)To realize the combination of the properties of the nano composite system and rock mechanics to discuss the stability of the borehole wall in macroscopic view,and try to establish the mechanics and chemistry research methods.