2023, 44(12): 1463-1472.
doi: 10.21656/1000-0887.440171
Abstract:
To study the mutual law between the vertical shaft wall fracture and the internal strain, a physical model for the shaft wall was built to simulate the process and state of the shaft wall stress fracture. The distributed optical fiber technology was used to monitor the internal strain of the shaft wall, and the in-depth analysis was conducted from multiple perspectives of stress and strain. The results show that, for the strain state, the wellbore strain degree will increase with the applied stress. In the wellbore position corresponding to the maximum strain value, the strain degree will reach the maximum value within the range, and the risk of fracture will be the highest. For the stress effect, the larger the deviation between the maximum and minimum strain values of the wellbore under different stresses is, the poorer the wellbore stability will be, and the more likely it will rupture. The analysis of the correlation between stress and strain, and the fitting of the linear equation of strain change at the wellbore position corresponding to each direction angle indicate that, the larger the change rate value is, the bigger the growth rate of wellbore strain will be. For the strain value exceeding the allowable limit, the wellbore is more prone to fracture. Through monitoring of the wellbore strain data and analysis of the strain difference, deviation and strain change rate, and combined with the Lame formula, a wellbore strain rupture relationship model was established. The study provides a new scheme for wellbore rupture warning.
