Study On Casing Deformation In Fracturing Of Shale Gas Horizontal Well

In the development of shale gas reservoirs,the multi-stage fracturing technology is one of the key technologies to improve single-well production of shale gas horizontal well,which can fracture the shale layer by hydraulic pressure to form artificial fractures,which allows the artificial fractures to communicate with the natural fractures to form a seam mesh body,thereby improving the fluidity of the reservoir fluid and achieving the purpose of increasing production.But the casing deformation often appears in the process of multi-stage fracturing,which influences the fracturing effect of shale gas reservoirs seriously.Therefore,the mechanism of casing deformation and its main influencing factors in multi-stage segmented fracturing process are studied,which is of great significance for the efficient development of shale gas in China.Based on the conclusion of previous research and combined with laboratory experiments and numerical simulation,this paper studies the casing stress in multi-stage fracturing.Firstly,after analyzing the cementing quality and casing wear of horizontal shale horizontal wells in the field,finite element models with different cementing sheath missing forms and different casing wear patterns were established to study cementing quality and casing uneven wear depth on casing stress.Secondly,the relationship between the elastic parameters of cement stone and the number of heat-exchange cycles under different displacements is studied by the experiments of heat exchange cycle on cement stones.Then the finite element software is used to study the relationship between the number of heat exchange cycle and casing stress.The paper comprehensively considers factors such as cementing quality,casing wear,thermal stress and other factors,and studies the stress conditions of casing under multi-factor coupling conditions.The theoretical analysis results are compared with the actual site conditions,and the casing deformation mechanism is clarified.And its main influencing factors can provide reference for control of casing deformation during horizontal fracturing of shale gas horizontal wells.