Design considerations for a new high data rate LWD acoustic telemetry system

The first commercial acoustic telemetry system was successfully introduced in 2000 as part of a drill stem testing system. However, environmentally challenging LWD offshore applications and a need for higher throughput required a complete redesign of that system. Thus, the new system incorporates a new high power acoustic transmitter driven by an advanced signal processor that maximizes input energy into particular frequencies and therefore minimizes dispersion and distortion effects. Low-frequency acoustic attenuators were specifically designed to attenuate in-band noise entering the communication system. In addition, two other features were introduced as a part of the complete communication system. They were (1) an in-line wireless link to pickup, digitize, and transmit signals off the pipe while rotating and (2) a high data rate acquisition and telemetry processing system. The system is designed to work solo or in conjunction with a mud pulse telemetry system. This paper will discuss the system design considerations and the data rates associated with different modes of operation as well as results of initial field tests.