Numerical Simulation For Casing Deformation In Weiyuan Shale Gas Well

The casing deformation problem has always plagued the development of shale gas in Weiyuan,Sichuan.Scholars have done a lot of research on the formation mechanism and prevention of casing deformation,but the casing deformation problem has not been solved well.Based on previous work,this paper studies the main control factors of casing deformation from the analysis of field data;compiling the numerical simulation software module;calculating the displacement of the casing deformation and proposing specific suggestions for reducing the casing deformation problem in Weiyuan,Sichuan.Through a comprehensive investigation of the casing deformation in the Weiyuan,the main mechanism of casing deformation of shale gas wells is obtained by statistical analysis of the characteristics of multiple casing deformation wells in this block.The study shows that the uneven shear stress field generated by the shale formation under the action of hydraulic fracturing makes the formation along the natural weak surface slips,and the shear deformation occurred in the casing after the formation slips.The main controlling factors affecting casing deformation in the Weiyuan are divided into internal and external causes.The internal cause is that there are lots of natural fractures in the area,and the external cause is the accumulation of strata stress caused by large-scale fracturing construction.In order to study casing deformation quantitatively,a numerical simulation model is established to simulate the formation slip along natural fractures caused by hydraulic fracturing--Case Damage.It utilizes the core calculation on the Cohesive unit of ABAQUS software..The operation interface is more concise.Just enter the relevant parameters to complete one-click modeling,which can simulate the process of casing deformation caused by formation slip after multi-level hydraulic fracturing.The displacement of casing deformation calculated by Case Damage are basically in line with the real situation in Weiyuan.The different factors of casing deformation were simulated by using the Case Damage software and the method of controlling single variable.According to the result,the fracturing construction parameters are optimized.It is recommended to select 10m~3/min as the volume of fracturing fluid in work to reduce the casing deformation while maintaining high shale gas production;at the same time,it is recommended to appropriately increase the spacing between each stage.