Present logging-while-drilling (LWD) technologies have substantially increased the amount of information collected downhole. Mud pulse telemetry (MPT) is the core real-time data transmission technology in the oil industry, and it must deliver answers while drilling with equal log densities despite the increased number of services. Ultimately, faster real-time data rates are required when a compromise between rate of penetration (ROP) and log density is not an option. In particular, when using high-density and high-plastic viscosity oil-based muds in deep wells, transmitting data at high rates presents challenges due to the harsh transmission channel conditions. We describe improvements to the MPT system, enabling reliable data transmission with physical data rates of 10bits/s and higher. Special signal sequences are used to automatically adjust adaptive filters. The pulser sends out the sequences regularly, enabling the surface system to tune the adaptive filters for changing channel conditions. The filter performance is tested and saved into a data base with quality indicators, empowering field personnel to optimize decoding quality through better decision making. Enhanced signal processing algorithms on the surface significantly increase the success rate of this automated system, as well as improve the decoding quality and reliability. This improved MPT system has been effectively run in challenging fields in different regions. The system has achieved improved operational performance and higher system reliability compared to offset runs. Complex bottomhole assemblies (BHA) with many LWD services can be deployed with outstanding data density and no ROP reduction. Its ease of use enables the increase of real-time data rates and timely decisions when decoding quality indicators start to decrease. Furthermore, the new system introduces higher automation level, which allows the field service engineer to concentrate on delivering more answers to the operator. By enabling high-speed data rates in a wider variety of environments as well as higher data rates in standard settings, the improvements in MPT increase the safety while drilling and lower the overall cost of drilling wells.
Mud pulse telemetry (MPT) has been the dominant measurement-while-drilling (MWD) data transmission technology for more than three decades. Continuous development has enabled the oil and gas industry to drill deep and complex well paths and deliver valuable real-time measurements. With the advent of recent logging-while-drilling (LWD) technologies, the amount of information collected downhole has considerably increased the demand for real-time transmission bandwidth. Driven by this demand, new developments in downhole and surface equipment have made higher data rates available. In addition, reliable high-speed MPT (HSMPT) is needed when utilizing a complex LWD bottom hole assembly (BHA) to deliver answers while drilling. Transmitting data at high rates introduces new challenges for MPT due to the higher signal attenuation and distortion that occurs when drilling very deep wells with high-density, high-viscosity oil-based muds. This paper describes improvements to the MPT system to overcome these challenges. Optimized surface signal processing and enhanced telemetry sequences are used to automatically tune adjustable filters at the receiver. These adaptive filters respond to new drilling conditions, adjust for changes in the MPT channel, and test their performance automatically, thereby enabling field personnel to easily make decisions when optimizing decoding quality. Advanced manual options complement these automated processes. The new system has been successfully run in challenging fields in the North Sea. Compared to offset runs, the automated system has significantly increased reliability. Examples of the improved decoding capability and operational performance are provided. This paper will highlight the necessary changes to further improve reliability for high-speed telemetry to enable real-time log density measurements. The MPT system can enable answers while drilling without having to limit the drill rate in critical sections.
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.
Mud pulse telemetry (MPT) is the leading real-time data transmission technology in the oil industry to deliver answers while drilling. New logging-while-drilling (LWD) tools produce increasing amounts of data that has to be transmitted to the surface. To avoid a compromise between rate of penetration (ROP) and log density, the real-time data rate has to increase. This is particularly true when demanding mud environments create demanding transmission conditions for MPT. As the well depth increases, it affects the mud density and mud plastic viscosity, making the situation even more challenging. This paper describes evolutionary changes to a MPT system. The system uses a special training sequence (TS) that is regularly sent by a shear valve pulser. Surface controls detect the TS and use it to tune, automatically, adaptive filters. These filters respond to the current channel conditions, enabling reliable physical data rates of 10bit/s and greater. To avoid decreasing the decoding quality due to non-optimal filters that have been calculated during pressure/flow disturbed transmission, the system automatically tests the performance of all filter sets. Afterwards, the coefficients are saved into a database with additional information. This empowers the field service engineer to perform a quick look at the database and maintain high decoding quality. Sophisticated changes to the TS and to the surface algorithms have significantly improved the automated detection rate of the TS search. Compared to offset runs in challenging fields, decoding quality and reliability have improved. The introduction of higher automation levels enables field personnel to deliver more answers to the operator, and provide multifaceted bottomhole assemblies with many LWD services. By eliminating the tradeoff between ROP and log density through higher data rates in MPT, the overall cost of drilling wells decreases without compromising safety.
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.
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