Simulation And Study Of Pressure-bearing Leakage Stoppage Based On ABAQUS

The formation pressure system of long open hole section is complex,and it is easy to fracturing the upper low pressure weak formation while drilling the lower formation,thus destroying the stress balance of the wellbore and causing serious leakage.In order to solve the leakage accident,we can put down the technical casing,but from the economic point of view,the cost is too high.Therefore,in order to drill to the design depth smoothly,we can carry out pressure sealing operation in low pressure weak formation,improve the formation pressure bearing capacity,so that drilling deeper can withstand greater drilling fluid density.In this paper,the method of combining theoretical analysis with numerical simulation is used to study the pressure-bearing plugging of wellbore.Firstly,the stress state of wellbore is analyzed,and the mechanism of leak plugging under confined pressure is summarized.Then,based on the principle of stress cage,the model of leak plugging under confined pressure in wellbore is simplified briefly.Using Cohesive viscous element in ABAQUS finite element software,two-dimensional models of leak plugging under confined pressure and single and double cracks in wellbore are built respectively,and the difference of ground stress,the position of bridge erection and the length of bridge erection are discussed.The influence of leakage velocity,formation permeability and filtration coefficient on fracture opening and well stress.It is pointed out that after bridging and plugging the fractures produced in the formation with the LEAK-PLUGGING material,the fracture will compress the surrounding strata after maintaining a certain opening,and ultimately the formation pressure-bearing capacity will be significantly improved;different in-situ stress difference,leak rate,formation permeability and filtration coefficient will have a significant impact on the opening of the fractures and the ultimate pressure-bearing effect;and in-situ stress difference,leak rate,formation permeability and filtration coefficient will have a significant impact on the fracture opening and ultimate pressure Choosing reasonable bridge-erecting position and bridge-erecting length in the process of pressure plugging also determines the magnitude of formation pressure-bearing capacity improvement;after the first pressure plugging for the wellbore,the weakest point of pressure-bearing capacity on the wellbore shifts from the direction of maximum horizontal principal stress to the direction of minimum horizontal principal stress.Through the study of several interaction factors near the wellbore,it can provide necessary theoretical basis for the field confined plugging operation,and make the formation confined effect better.