Reliable High-speed Mud Pulse Telemetry

Abstract

Abstract Mud pulse telemetry (MPT) has been the dominant measurement-while-drilling (MWD) data transmission technology for more than three decades. Continuous development has enabled the oil and gas industry to drill deep and complex well paths and deliver valuable real-time measurements. With the advent of recent logging-while-drilling (LWD) technologies, the amount of information collected downhole has considerably increased the demand for real-time transmission bandwidth. Driven by this demand, new developments in downhole and surface equipment have made higher data rates available. In addition, reliable high-speed MPT (HSMPT) is needed when utilizing a complex LWD bottom hole assembly (BHA) to deliver answers while drilling. Transmitting data at high rates introduces new challenges for MPT due to the higher signal attenuation and distortion that occurs when drilling very deep wells with high-density, high-viscosity oil-based muds. This paper describes improvements to the MPT system to overcome these challenges. Optimized surface signal processing and enhanced telemetry sequences are used to automatically tune adjustable filters at the receiver. These adaptive filters respond to new drilling conditions, adjust for changes in the MPT channel, and test their performance automatically, thereby enabling field personnel to easily make decisions when optimizing decoding quality. Advanced manual options complement these automated processes. The new system has been successfully run in challenging fields in the North Sea. Compared to offset runs, the automated system has significantly increased reliability. Examples of the improved decoding capability and operational performance are provided. This paper will highlight the necessary changes to further improve reliability for high-speed telemetry to enable real-time log density measurements. The MPT system can enable answers while drilling without having to limit the drill rate in critical sections.