A study on creep analytical solution and creep parameters of granite drilling in steady state under high temperature and high pressure

Abstract

Rock creep is one of the important reasons for large deformation and instability while drilling, so the study on creep characteristics has great significance. However, it is difficult to determine creep parameters, and much harder when it is under high temperature and high pressure. Reasonable determination of the parameter is the key to make accurate calculations. Experiments show that drilling deformation of rock is part of deformation stage of steady state creep with the temperature below 500°C and hydrostatic stress below 150 MPa. Generalised Kelvin model can be a very good reflection of its characteristics. In this paper, through the detailed deduction, the analytical solution of the drilling creep deformation is obtained. Based on the above analytic solution, the physical equation of creep parameters k₁, k₂ and η in generalised Kelvin model vary as a function of temperature and stress is obtained through the inversion of experimental data of drilling deformation. The equation above has certain guiding significance on rock drilling construction with high temperature and stability prediction.

Keywords:

• Granite
• Drill
• High temperature and high pressure
• Generalised Kelvin model
• Creep parameter