Study On Casing Damage In Horizontal Wells Of Steam Injection

Because of the economic effectiveness and efficiencies, steam injection with horizontal wells is applied more broadly now. However, due to the complexity of horizontal wellbore trajectory and the influence of high temperature, there are a large number of casing damages in the process of steam injection, which has seriously affected the normal oil field operation. So, it is of great significance for the completion designing and production method chosen to find out the main reasons for casing damage, and propose effective preventive measures.Firstly, based on the common structure of completion strings and the project horizontal well trajectory data, the paper set up the friction drag model, with which we calculate the frictional drags and the axial forces of the horizontal completion strings in the tripping process. In the analysis, abnormal wellbore trajectory and dogleg both are also involved. Secondly, analyze the heat transfer characteristics of the wellbore and then carry out numerical simulations of the wellbore by using the finite element analysis software ANSYS. To the vertical section, this paper analyzes the influence of different apparent heat conductivities of insulated tubing and the thermal recovery packer failure. To the horizontal section, time of the steam injection cycle is considered to find its influence on the wellbore temperature field. Finally, based on the calculated results of the vertical section temperature field, we can get thermal stresses and check the vertical casings. And we also check the horizontal casings by calculating the stresses and deformations in many conditions to find out the main cause of casing damage, such as in the general condition, shale collapse and wellbore trajectory suffered depressions.etc.On basis of the above theoretical analysis and combined with the requirements from oilfield actual operations, this paper proposes many preventive measures and protection methods for horizontal steam injection wells casing damages, which is expected to provide some guidance in oilfield practice.