Casing Force Analysis During MPC Injection Considering the Coupling Effect of Temperature and Pressure

ABSTRACT The problem of casing force and deformation during MPC (managed pressure cementing) injection pose great challenges to cementing in deep and ultra-deep Wells. According to the combination structure size of casing, the properties of multi-density and variable volume fluid in casing and annulus, the calculation method of multi-density fluid position change with injection time in cementing process is presented. Combined with causes of casing force during MPC injection stage, a temperature-pressure coupled mathematical model was established to calculate the temperature and pressure of casing caused by injection fluid flow in cementing. The calculation formula of U-tube effect was used to correct the parameters in the model. The energy conservation equation of casing and annulus is given, and wellbore pressure is obtain based on the theory of fluid mechanics. Taking a well A as an example, the model has been well used in pressure prediction and casing force analysis during MPC injection stage. The results show that the casing force is complicated during the injection process. The optimization of displacement can effectively alleviate casing deformation and make the bottom hole pressure in a safe state. The research results provide a theoretical basis for the optimization of construction parameters during MPC injection stage. INTRODUCTION The exploitation of ultra-deep oil and gas resources has promoted the continuous breakthrough of drilling technology. At present, there are more than 30 Wells in the world with a depth of over 9000m, which is of great significance for improving self-sufficiency in natural gas, increasing energy supply, optimizing and adjusting the energy structure, and improving people's livelihood. However, increasing well depth has brought great challenges to cementing. Many new problems have emerged (Rostami et al.; Thibodeaux et al., 2018), such as high cement slurry density, high circulating resistance, high liquid column pressure, high surface pump pressure for cementing, and high temperature and pressure formation. These problems have a serious impact on casing deformation during MPC injection stage.