Abstract:

The Jimsar Shale Oil Demonstration Area in Xinjiang, China’s first national-level lacustrine shale oil demonstration area, is in the middle to late stage of development. The concentrated placement of horizontal wells and large-scale fracturing have led to fracture activation, causing casing deformation and impeding the development progress. Considering that the conventional numerical simulation of casing deformation yields results with low accuracy of multiple types of faults in strike-slip fault zones, a strike-slip fault induced casing deformation model was established and then combined with engineering practices to reveal the factors controlling the casing deformation induced by strike-slip fault. The results show that the casing deformation is mainly controlled by fracture dip, applied fluid pressure, and angle between the fracture orientation and the maximum horizontal principal stress direction. For the section of casing deformation at the risk level 1, the injected liquid volume should be reduced to 65%-70% of the original level as designed, and the temporary plugging should be advanced to the time when the injected liquid volume reaches 300 m³, so that the risk of casing deformation can be effectively mitigated. The research breaks through the limitations of traditional fracturing design in the homogenization treatment of strike-slip fault zone, and provides a theoretical basis for the prevention of casing deformation and efficient development of shale oil in complex fault systems.

Key words: Jimsar sag, shale oil, strike-slip fault, casing deformation, numerical simulation, fracturing scheme