Reliable Mud-Pulse Telemetry System for High-Resolution Real-Time Logs

Abstract

Abstract For drilling directional wells and exact reservoir navigation, a broad spectrum of measurement-while-drilling (MWD) and logging-while-drilling (LWD) measurements, as well as drilling optimization-related measurements, are available. The data they generate are used for accurate characterization of the formation while drilling and for steering within the reservoir. Additional data is needed for a safe drilling process, and for achieving a high rate of penetration (ROP) while drilling the reservoir. The oil and gas industry has developed many technologies that enable real-time transmission of this data from downhole to surface. For decades, mud-pulse telemetry (MPT) has been the most common transmission system for MWD and LWD data. Depending on the geology and the complexity of the well, a multitude of MWD and LWD measurements are required simultaneously on surface. The number of desired logs increases as applications become more challenging and performance is pushed to maximize penetration rates. The additional data required from new and existing measurement technologies pushes the envelope of reliable and fast transmission of data via MPT. To achieve real-time data rates that can accommodate all measurements, deliver the required resolution, and simultaneously achieve the planned ROP, a highly sophisticated and flexible telemetry system is required. This paper describes an MPT system that delivers high data rates and high reliability. The system includes a robust mud pulser and an improved, self-adjusting surface system. To overcome decoding challenges, the system has flexible options like diverse signaling types, various modulation schemes, and adjustable signal frequencies. With this system it is possible to drill wells that have a very high real-time data demand without limiting the ROP or reducing the amount of transmitted information. This MPT system helps achieve the desired data density in MWD and LWD logs, and in borehole images. This paper shows how the system enables data transmission from some of the most complicated instrumented bottom hole assemblies (BHAs), how it improves real-time logs and images, and how it lifts ROP ceilings while simultaneously increasing reliability.