Mud pulse telemetry (MPT) is the main real-time data transmission technology in oilfield drilling. Constant advances in technology have permitted the oil and gas industry to drill complex well paths and deliver valuable real-time formation measurements. New logging-while-drilling technologies have considerably increased the amount of information collected downhole and therefore the demand for real-time transmission bandwidth.
Reliable high-speed MPT with increased data rates is needed when utilizing complex bottomhole assemblies (BHAs) to deliver information without compromising the rate of penetration. When drilling deep wells with high-density and high-viscosity oil-based mud, transmitting data at high rates introduces challenges for MPT because of the higher signal attenuation and signal distortion. This paper describes enhancements to an MPT system. Improved signal processing at the surface and adjusted signal sequences are used to tune adaptive filters on the receiver side, enabling data transmission with physical data rates of 10 bits/sec and higher in these challenging conditions.
These adaptive filters adjust to new drilling conditions and changes in the MPT signal channel. A test sequence is sent regularly during operation of the system to improve adaptive filters. Improved noise cancellation techniques assist with automation of signal search functions. Filter performance is tested and saved into a database, enabling field personnel to optimize decoding quality at the rigsite. Challenging fields in different regions have successfully run this MPT system and improved decoding capabilities and increased performance compared to offset runs. In addition, the system provided overall higher reliability.
The improvements in MPT enable high-speed data rates in a wider variety of environments, as well as higher data rates in standard settings, lowering the overall cost of drilling wells.