Establishment And Analysis Of The Mechanical Model Of Loose Sand On Wellbore Stability

With the development in field drilling and operation technology,some wellbore instability problems in loose sand reservoir after drilling operations have been gradually solved through some advanced completion methods,at the same time,the precise control of wellbore stability during drilling operations remains a much-needed in-depth study.Based on the summarizing of relevant researches on the mechanical stability of unconsolidated sandstone borehole,this paper firstly discusses the macroscopic and microscopic characteristics of unconsolidated sandstone,studies the mechanics properties of unconsolidated sandstone,and analyzes the influence of confining pressure on rock mechanics parameters of unconsolidated sandstone through the laboratory rock uniaxial compression test and the triaxial compression experiment.Then,using the FEM analysis software analyzes the parameters obtained in the laboratory experiments of rock mechanics and studies the effects of horizontal stress,vertical stress,caliper,the well fluid column pressure on wellbore stability of unconsolidated sandstone in general geological straight well.Besides,it is also analyzed that the influence of deviated inclination,azimuth deviation,the well fluid column pressure on the wellbore stability of unconsolidated sandstone.Finally,the simulations of unconsolidated sandstone and general sandstone are compared respectively in the conditions of horizontal stress of vertical well and Shai I angle.