Advanced Mud Logging: Key to Safe and Efficient Well Delivery

The high costs and high potential risks associated with drilling deepwater wells have prompted the development of an advanced computerized mud logging system. This paper highlights select technologies within the system and its application to three core areas of operation—circulating, making connections, and tripping—to provide early identification of fluid influxes and losses, thus helping ensure safe and efficient well delivery. The advanced mud logging system includes a kick-detection system, flowback monitoring, trip monitoring software, and mud accounting software based on a new methodology. The kick-detection system uses advanced flowmeters to enable stricter control of the drilling process; fluid influxes or losses are detected by integrating the variance for predicted and measured flow and alarming, with as little as a barrel gained or lost. Flowback monitoring uses sophisticated algorithms in conjunction with the same high-accuracy flowmeters to monitor influxes while making connections. These algorithms drive a complex alarm system tuned to trigger on minimal flow variance, pit volumes, and the rate of modification of each compared to a historical baseline. Additionally, trip-monitoring software automates the tracking of pipe displacements in real time to warn of a well control event, instead of relying on spreadsheets or handwritten calculations. Mud accounting software tracks drilling fluid balance across the entire pit system for redundant influx and loss detection and accounts for volume changes based on circulating rates. Application of the advanced mud logging system in the deepwater Gulf of Mexico (GOM) provided earlier detection of well control events—up to 10 minutes earlier than conventional well monitoring techniques. Flowback monitoring demonstrated the ability to identify minimal flow when making connections, which would be difficult to detect by visual inspection. The ability to trend flowback profiles consistently has allowed operators to reduce the pump's off time while making connections in less than 5 minutes, without jeopardizing the ability to confirm a static well. Additionally, the advanced system enables drilling operations to proceed without increasing mud weight and exacerbating wellbore damage during a ballooning event. This paper presents a case study in which the history of well control events documented in the literature was reviewed to help identify areas of improvement.