Field-Test Results of an Acoustic MWD System

Abstract Acoustic telemetry (AT) MWD systems are finally coming of age as a commercially viable alternative to mud pulse and electro-magnetic propagation systems. Building upon our theoretical and experimental knowledge and understanding of communicating through the steel walls of drill pipe we have developed a practical, high data rate, acoustic telemetry system for use in drilling assemblies. We utilize one of the passbands that allow acoustic signals to propagate through the periodic structure of typical drill pipe. In this paper we describe the field test program used to evaluate our through-bore AT system performance and demonstrate its practical and commercial applications. The program was limited to shallow, vertical and directional land wells (<2,500m) drilled with jointed pipe using both kelly and top drive systems. The AT tool was placed in a number of different locations in both rotary and steerable BHAs. A variety of operational modes and configurations were tested. The system performance was evaluated for various carrier frequencies and baud rates (5, 10 and 20bps) while signal, battery, decoding and reliability data were recorded and evaluated. The AT system performance was found to be acceptable for commercial applications. Significant time savings and improved drilling efficiency were demonstrated. Test results, including the present AT system limitations, are presented. As far as the authors are aware, the AT system has achieved the highest wireless data rates in a drilling environment compared to mud pulse and EM telemetry. The system as it exists today is suitable for use as a rig-operated, automated, survey-on-connection tool in shallow wells. Several technical innovations have enabled the successful development of our system including advanced digital signal processing techniques and novel signal-to-noise enhancement techniques, as confirmed by field trials.