Parametric study of fracture interference effects on fracture geometry for wellbore strengthening

ABSTRACT

As one of the most widely used preventive treatment of lost circulation, wellbore strengthening techniques need to be further investigated to improve its efficiency. It is crucial to accurately predict the dynamic propagation of fractures for wellbore strengthening, while most of the numerical simulations neglect the distortion of fracture trajectory affected by fracture interference. Thus, a fully coupled poroelastic model is established by using the extended finite element method (XFEM) – based cohesive zone method (CZM) to investigate the effect of fracture interference. The rock deformation, seepage flow of pore fluid, fluid flow of fracture and leak-off of drilling fluid are coupled by the model. The sensitivity analysis is studied by capturing the change of fracture length, width and deviation angle. The results show that the distortion of the fracture trajectory and the closure extent of fracture surface after bridging can be controlled more easily with lower injection rate and larger spacing. A proper viscosity can balance between the distortion of the fracture trajectory and the tendency of fracture reopening after bridging. The anisotropic stress mainly affects the wellbore strengthening by influencing the propagation direction. Adjusting the inclination and azimuth of the wellbore to increase the effect of stress anisotropy can reduce the effect of stress shadow.

KEYWORDS:

• Wellbore strengthening
• XFEM-based CZM
• fracture interference
• fracture trajectory
• fracture width

Highlights

A fully coupled wellbore strengthening model is developed by using XFEM-based CZM.

The effect of fracture interference on wellbore strengthening is investigated.

The suggestions for treatment of wellbore strengthening are proposed.

Acknowledgments

This work was supported by the 13th Five-year Plan National Key Project (No. 2017ZX05005005-006, 2017ZX05032-004-005), the National Natural Science Foundation of China (No. 51704322), and the Natural Science Foundation of Shandong Province (No. ZR2017QEE011).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51704322];Natural Science Foundation of Shandong Province [ZR2017QEE011];13th Five-year Plan National Key Project [2017ZX05005005-006,2017ZX05032-004-005]