Modelling and Simulation of Oil Production Tubing Dynamic and Static Characteristics due to Fluid Dynamic Loading

This report outlines the modelling and simulation of oil production tubing to investigate the dynamic and static characteristics of the tubing due to fluid dynamic loading with respect to different production rates. The fluid-structure interaction between the tubing and the contained oil are modeled and simulated using Ansys. Pressure difference between the wellhead choke and bottomhole forces the oil to move upwards in the tubing, thus exert fluid dynamic loading onto the tubing, which in turn creates the static and dynamic characteristics of the tubing due to fluid loading. At different production rate, different pressure difference between wellhead choke and bottomhole is generated, which produces variation in the static and dynamic characteristics of the tubing due to fluid loading. Therefore, there is a need to investigate the static and dynamic characteristics of the tubing with respect to different production rates. Due to confidentiality, the name of the oil company that provides the data is kept secret and the company will be referred as “the oil company” throughout the report. The scope for the tubing length is resized to 50m only, which is the depth for one oil production zone, focusing on the region from bottomhole to the subsequent upward 50m depth, which is critical in oil production system, since the location of the oil production zone is the critical region where the production tubing receives the highest fluid loading from the oil production. The simulation focuses on single phase incompressible oil flow with constant viscosity in an isothermal environment. Experimental validation is excluded, instead, simulation validation is needed to verify that the model case built is acceptable and produces results in agreement with the data from the oil company. Literature review is conducted at the early stage of this project, followed by validation of the model case through modelling and simulation. Upon validation, the settings of the model case are applied for different production rates, followed by the simulation of the dynamic and static characteristics of the tubing due to fluid loading, whereby the results are analysed and interpreted. The results show that the pressure, stress and deformation occurring on the tubing increases as the production rate increases. For lower modes of vibration, the natural frequencies also increase with increasing production rates.