Study On The Damage Of Mud Shale Wall Under Seepage

Avoid engineering accidents caused by the borehole instability is a serious challenge of oil and gas fields in industrial production,and the shale is often a well section of the accident prone,so grasp and understand the mechanism of instability of elements can have objective and targeted prevention and remedy.Based on the basic research of shale flow solid coupling,chemo-mechanical coupling and other aspects of the consideration on the fluid acting on the shale rock mass caused by the damage,and the equivalent stress principle of fluid solid coupling model in the shale in the chemical field,with the rock physical property equation of state and the fluid quality equation and the momentum and energy equations of the shale flow curing coupling model.Analysis and research:(1)The shale rock will be affected by the initial defects caused by the micro fluid invasion defect damage in the near wellbore by affecting the distribution of stress,the stress strain constitutive relation of rock damage in mudstone given state equation of elastic-plastic region.(2)Using numerical simulation to solve the model equations,the distribution effect of using finite element simulation software of ANSYS drilling shale formation with stress.The results show that the formation drilling moment,affected by the body wall surrounding the maximum and minimum stress deformation displacement,the displacement magnitude and direction of influence of stress.(3)Consider fluid effect in mud shale rock caused by the injury,on the basis of FLUENT software simulation fluid invasion of mudstone rock,the results show that the fluid near the borehole formation should be more serious damage smaller damage to the mudstone,the severity of impact pressure and flow stress.(4)Characterize the damage of the mudstone damage to the mudstone,respectively with different fluid saturated specimens after mudstone mechanics analysis of the experimental results,the experimental results that the tensile properties of the compressive strength of mudstone are weaker,cohesion is reduced with different mechanical parameters the degree of.In this experiment,the effect of drilling fluid weakens the strength of mudstone.