| dc.description.abstract | Managed Pressure Drilling (MPD) methods are used to drill wells with narrow pressure margins in a safe, efficient, and economical way. Controlled Mud Level (CML) is a dual-gradient MPD technique which is found effective in fractured reservoirs. Mud level in the riser is manipulated to reduce annular pressure in the well and to control Bottom Hole Pressure (BHP) to avoid severe mud losses. Real-time communication between downhole and MPD surface system is important for some MPD operations to manage the drilling process through precise control of well pressure and to achieve a high level of MPD automation.
Wired Drill Pipe (WDP) telemetry was implemented in 210 wells since 2015 and it has the potential to be the standard way of communication with downhole tools. It allows for high-speed data transmission of 57,600 bits per second. It offers substantial benefits for MPD operations due to its independence from fluid flow and type. WDP enables the use of Along-String Measurement (ASM) tools that provide downhole measurements along the well path. These measurements improve the understanding of the downhole environment and enhance well control in MPD operations.
The objective of this thesis is to study the interaction between EC-Drill CML system and WDP telemetry in drilling through karstified and naturally fractured carbonates. An overview of both CML and WDP technology is provided. Sensors data from both EC-Drill and ASM pressure tools were then studied and analyzed in conjunction. The dataset showed fast and accurate detection of losses. Mud level in the drilling riser was manipulated to reduce the severity of losses to allow safe drilling without the need to implement mud cap drilling. WDP offered continuous, real-time downhole data flow from Measurement and Logging While Drilling tools. Annular pressure measurements from ASMs confirmed that overbalance is achieved at all time. The drilling fluid as a primary barrier was maintained to prevent influxes despite severe losses. ASMs annular pressure measurements were fed to the CML control system in real-time to obtain a constant BHP in a step to achieve MPD automation. | |