Successful Deep Water Drilling MPD, Early Kick Detection and Performing Managed Pressure Cementing With CML Controlled Mud Level System in GOM and North Sea

摘要

Control mud level (CML) technology is a method to manipulate the mud level in the riser in order to control bottom hole pressure (BHP) and Equivalent Circulating Density (ECD). It is also a Dual Gradient Drilling (DGD) technology, designed for drilling post-BOP sections. The system uses a subsea pump installed on a modified riser joint (MRJ) to control mud level in the riser's annular space. CML eliminates the effect of ECD and enables drilling with a close-to-constant BHP. This may impact well design by allowing more optimal placement of casing points. By eliminating circulating friction, flow rate can be increased in the horizontal section and in unstable formations, to clean the wellbore from cuttings. CML is a valuable tool while drilling into formations with a high probability of losses, or the layers with a high risk of influx. This paper will show that a CML system detected kicks earlier than the rig crew and geoservice company sensors both in GOM and the North Sea. In addition, how quickly was the kick detected and the driller informed will also be examined. With the CML system, the sensitivity for kick detection was greatly improved as the effect of rig motion on surface volumes was eliminated.