The Study On Technology And Hydraulic Parameters In The Constant Bottom Hole Managed Pressure Drilling

The control of precise bottom-hole pressure is the trend of drilling development and it's also an effective way to carry out the pore - fracture narrow pressure window, safety and fast drilling. Managed pressure drilling can achieve bottom-hole pressure precisely control, But as a new technology, there is not a wellbore pressure calculation model which can connect its technological feature well. So, it's important to study technology and hydraulic parameters in the constant bottom hole managed pressure drilling for exploiting oil and gas in the complicated formation.The paper analyzes the technological characteristics of managed pressure drilling, with connecting the field material given a detailed technological process of drilling, making a connection and tripping.And it also makes a detailed introduction in the use of equipment and precise pressure control system.The research established the multiphase flow equations in normal drilling, kick, drilling with back pressure, stop drilling and keep cycle with back pressure, shut-in, killing duration processes by considering the impacts of oil-gas phase transition, cuttings and formation output. This section also gives the back pressure calculation model and solved equations with numerical method.The experiment of annular multi-phase flow friction pressure drop was investigated by laboratory experimental set-up in different back pressure conditions. As the results: the same back pressure, fixed liquid displacement, the friction pressure drop increases with the growth of gas displacement, moderate increase in bubble flow region, large increase in churn flow region; fixed gas displacement, the friction pressure drop increases with the growth of liquid emissions; under the same liquid and gas emissions, the friction pressure drop increases with the growth of back pressure. The fiction coefficient of the bubble flow and churn flow is obtained by experiment data analysis and has a good matching after comparing. Programmed CBHP managed pressure drilling wellbore pressure and technical parameters calculation software on the base of control euqations and algorithms in this research,which is solved annular control equations of multiphase flow and temperature field equations in various operating conditions, to obtain the required back pressure under different conditions and through the graphical Real-time display of designed pressure and actual pressure.Based on software's calculations, author analysed the change of back pressure influenced by density and displacement for pure mud managed pressure drilling, the gas volume fraction and bottom hole pressure influenced by gas injection riser managed pressure drilling. This research also simulated managed pressure drilling of two wells by software.