Publications

Drillstring connections in a high pressure high temperature (HPHT) deepwater operation with narrow mud weight restrictions can be a difficult and high risk operation when using conventional drilling methods. Reduced bottom hole pressure caused by drilling fluid in the drillstring may cause a ‘kick’ due to influx into the well. Using Managed Pressure Drilling (MPD) techniques when making drillstring connections can reduce the drilling hazards of narrow mud weight tolerances with the application of surface backpressure to compensate for the reduction in annular friction. The application of the Constant Bottom Hole Pressure (CBHP) variant of MPD in a recent project in Indonesia has been successful in providing timely and accurate exertion and relief of surface backpressure. Data gathered on the CBHP connections enabled the analysis of bottom hole pressure management performance and the highlighting of variables that made the operation successful. Change of flow behavior in relation to choke position and movement and surface backpressure throughout the annulus are graphed for comparison and analysis. With the proper use of MPD equipment, particularly a Rotating Control Device (RCD) and an Automated MPD Choke Manifold, backpressure fluctuations can be prevented and the stability of bottomhole pressure is maintained. This can be seen in the constant bottomhole pressure reading, which shows that annular pressure losses are properly compensated. With applications and actual operations on location, as discussed in detail in this paper, drilling hazards involved with making drillstring connections were significantly reduced.