Research on the Mechanism and Prevention Technology of Casing Deformation Fracturing of Shale Oil

In order to effectively utilize GuLong shale oil, it requires large-scale fracturing. However, the problems caused by casing deformation, such as section loss, severely restrict the efficiency and effectiveness of its development. To clarify the casing deformation mechanism in GuLong shale oil, a comprehensive analysis of various factors that may affect casing deformation is conducted. The analysis shows that factors such as casing strength, wellbore curvature, and cementing quality are not the main controlling factors of casing deformation in GuLong shale oil wells. The deformation mechanism is induced by fracturing, which activates the fracture and causes the formation to slip along the fracture, leading to shear deformation of the casing. Based on the understanding of the casing deformation mechanism, targeted risk prediction and control measures for casing deformation are proposed. Firstly, multiple seismic attributes are used for detailed interpretation and prediction of fracture activation to assess the risk of casing deformation. Secondly, temporary plugging and reduction of construction displacement during the fracturing process, as well as optimization of cementing systems to improve the compacting effect of cement sheath, are employed to control the risk of casing deformation. The research findings can provide important guidance for the prevention and control of casing deformation in GuLong shale oil and similar shale reservoirs during fracturing operations.