Managed Pressure Cementing

Abstract

Managed Pressure Cementing (MPC) is a method to cement deep offshore wells in a safer, more controlled and more efficient way. It will end up being less costly because by applying managed pressure drilling (MPD) first the sections drilled are less so there is less cement to spend which ends up being cheaper. As it is a relative new process the companies do not want to release the information about it to the outside world. Oil platforms normally belong to a company which hires several smaller companies to do different tasks but the rig owner always has someone of their staff to supervise the different operations. Statoil asked for this project thesis which can become a complement to the formation given to a supervisor who will follow future cementing processes. Through similar methods better known like MPD it is shown a simple model for the fluid movement inside the well during the process and a controller is applied to maintain the annular bottom hole pressure (BHP) constant. The model is implemented with MatLab code in order to retrieve simulations of estimates of the fluids behaviour and also of different pressures along the well. As an imperative component to fulfil the proposed objectives the controller is a proportional and integral one (PI) and it controls the BHP by actuating on an automatic choke at the rig that regulates the flow out of the well. The pressure reference at the bottom is 890 Bar which is a huge value that became a problem as the controller gains had to be really small. Despite having a slow response and the targeted value sometimes would not even be reached an approximated value was quickly overtaken and that can be enough as the most important thing is to maintain the BHP between pore and fracture pressures.