Field Test Results of An Acoustic Telemetry MWD System

Abstract

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. Introduction The goal of Extreme Engineering's acoustic program is to develop and commercialize a viable acoustic telemetry system for use in drilling applications. Starting with a proof of concept device, initial field trials progressed through a preliminary development program and led to its present commercial viability. This program began over five years ago, not long after Extreme Engineering completed a successful project for Sandia National Laboratories with the goal of ruggedizing a proof of concept acoustic telemetry tool (Oracle) such that it could be run in a downhole environment. Extreme's current engineering prototype system has evolved from those fundamental roots into high-speed telemetry devices that are completely independent of drilling fluid properties, rig hydraulics and formation properties. These systems are also capable of being operated solely by the rig crew while providing limited commercial MWD services in shallow wells. Remote real-time access is provided by a satellite or cellular radio link. In this paper we cover in detail the field trial results, lessons learned, commercial requirements and conclude with anticipated future developments. Due to the success of our field trials it is expected that the commercial AT system will offer a reliable, cost effective alternative to mud pulse, EM and wired drill pipe telemetry systems. Acoustic Telemetry Technology Overview The acoustic telemetry system comprises four main components as illustrated in Fig. 1 below. The system components are: The ATT and AIT are installed in the BHA, the EAR is installed on the kelly or top-drive quill, and the DDU is installed inside the doghouse with remote antennas located on the roof to support wireless communications between the EAR and the DDU as well as remote wireless communications between the DDU and any authorized remote user with access to the internet.