Study On Casing Damage Mechanism Caused By Reservoir Compaction

Casing damage is a common phenomenon in the development of oil and gas fields,and has a serious impact on the normal production of oil and gas fields.Research on casing damage mechanism has very important significance for casing protection.In this paper,the numerical simulation method is used to solve the reservoir compaction and ground subsidence caused by the reduction of formation pressure after oil production in different reservoirs of a sandstone oil field.The ABAQUS software is used to establish a two-dimensional surface model of the surface to the reservoir;the reservoir section is analyzed.Without sanding and casing-cement ring-synthetically bonded formation,the surface deformation of the casing caused by compaction of the formation is studied;the critical voids in which the casing is destabilized and destroyed after compaction and formation of voids are studied.Height;discusses the axial tensile load generated by the casing in the overlying strata under compaction;establishes a finite element model of the reservoir casing and simulates the effect of perforation parameters on the stress concentration distribution of the casing under compaction.Plastic deformation of different grades of casing.The results show that the depth,radius,thickness,elastic modulus,Poisson's ratio and compressibility of the reservoir directly affect the compaction of the reservoir.The settlement of the overlying rock caused by reservoir compaction is not uniform and the surface settlement is less than that of the reservoir.For layer compaction,the simulation results of ABAQUS software and the numerical solution have little error;when the reservoir section is not sanded and the casing-cement ring-layer cementation is in good condition,the compaction results in the yield deformation of the casing surface,and the plastic deformation of the casing is The perforation is the largest,the rest of the area is small,and the deformation of the high-grade casing and the low-grade casing has little effect,and the plastic deformation occurs.After the cavity around the reservoir section is hollow,the compaction results in the formation of the casing.The tube is unstable and the plastic deformation is concentrated in the local area.Increasing the outer diameter and wall thickness of the casing or using a high-grade steel casing can effectively improve the stability of the casing after the compaction in the formation of voids in the reservoir;compaction produces axial tensile loads in the casing that have little effect on the casing strength;the perforation phase has a significant effect on the stress concentration of the perforations,and the pore size and pore density are close to the perforation and the entire tubular body.Distribution little effect.The results of the study can provide a theoretical basis for the calculation and design of the casing strength when considering the effect of reservoir compaction,so as to reduce the casing damage and protect the casing.