Abstract
Currently, the wellbore strengthening mechanism has not been fully understood, especially for the fracture network loss of the drilling fluid. In view of this, a new analytical model was established to discover the wellbore strengthening mechanism, considering the fracture network loss of the drilling fluid. In this model, the additional stress induced by the natural fracture network was calculated based on the fracture mechanics, and the fluid pressure distribution within the fracture network during the drilling fluid loss was investigated considering the fracture roughness. Especially, the wellbore strengthening mechanism was revealed, by comparing the stress intensity factors before and after the wellbore strengthening. The proposed analytical model was verified by comparing its results to those one of the numerical model. The comparison was focused on four aspects, namely, the fracture pressure, the fracture width, the stress acting on the fracture and the stress intensity factor. The maximum difference between the analytical and numerical results is within 5.45%. Additionally, the results show that the stress intensity factor obviously decreases after the wellbore strengthening. More importantly, the effect of the fracture roughness (JRC) on the fracture network loss was discussed. The results show that the fracture has a lower fracture pressure, a smaller fracture width and a smaller stress intensity factor with the increasing of JRC, which means that the fracture network with a higher JRC has a lower drilling fluid loss. Meanwhile, the effect of JRC on the wellbore strengthening was investigated, and the results show that the fracture with a higher JRC has the larger reduction for the fracture pressure, the fracture width and the stress intensity factor through operating the wellbore strengthening. This means that the fracture network with a larger JRC is better to operate the wellbore strengthening.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
