Mud Pulse Telemetry systems in drilling operations have enabled the industry to gather valuable directional and formation data while drilling the well, and to optimize the drilling process. This makes drilling operations more cost efficient and allows the drilling of complex wells. In recent years, new LWD technologies have dramatically increased the amount of information collected downhole. This increasing demand for realtime bandwidth is a major challenge for conventional Mud Pulse Telemetry, which has data rates that are normally below 3 bits per second. This paper describes a system for downhole-to-surface Mud Pulse Telemetry that uses baseband or carrier modulated pressure signals generated by a novel mud pulser design and a surface data acquisition unit with advanced signal processing capabilities. The new system is able of handling the complex and continuously varying properties of the transmission channel (the pipe bore filled with flowing drilling mud) by optimizing the transmission signal and the surface processing algorithms in realtime. Under a given scenario, higher data rates can be achieved that, from a log-quality standpoint, result in high log-densities for improved realtime decision making. Surface processing algorithms include active pump noise cancellation, dual pressure transducer processing, signal filtering and signal decoding. In addition, the system contains an automated calibration routine that after turning pumps-on measures the characteristics of the transmission channel. This novel feature assures that the latest knowledge about the transmission channel is available in the processing algorithms. The new system has been successfully run in field-trials in the United States, North Sea, South America and the Middle East. During these deployments, data rates could be substantially increased compared to previous offset runs. The focus in this paper will be on a description of the system and its impact on both MWD and LWD realtime services. Introduction Mud Pulse Telemetry (MPT) has been the global standard for real time data delivery from Measurement While Drilling (MWD)/Logging While Drilling (LWD) systems for the past thirty years. This is largely due to the robustness of the downhole system, the simple concept of a single down hole transmitter and a single surface receiver, proven performance under various conditions and the possibility to adjust various down hole Bottom Hole Assembly (BHA) parameters while drilling the well. With the introduction of more complex MWD/LWD tools and services, most of which produce large amounts of real-time data, it has become crucial to use the available mud channel more efficiently to ensure that there is sufficient information to make informed decisions whilst drilling. This is a complex task given the uncertainty and continuous fluctuations of the various system properties in the mud channel, most of which are outside the control of the MWD/LWD service company, these include:mud pumpspulsation dampenerssurface pipingpressure transducer locationsdrill string componentsmud propertieswell depth In addition, MWD/LWD companies have to deal with a limited amount of down hole power which adds to the restrictions in optimizing the entire system. This paper introduces a new telemetry system, including a novel, advanced, mud pulser design which has been in development since 2001 and a new surface data acquisition unit with improved signal processing capabilities. The overall system is able to automatically adjust its decoding parameters during data transmission. Since measurements are made continuously, fluctuations of channel properties are captured and accounted for. Field-trials have been carried out that proved the new concept. Data rates of up to 20 bits per second (bps) have been achieved in commercial drilling situations. Compared to earlier offset runs this is an increase of more than 200%. Those optimized, high data rates are essential to support present and enable future MWD/LWD services.
Mud Pulse Telemetry (MPT) systems enable the MWD/LWD companies to transmit to surface valuable directional and formation data during the drilling process. This data is used to optimize the drilling process, making drilling operations more cost efficient and allowing the drilling of more complex wells. The major factors limiting MPT data rates include maximum downhole signal strength, signal attenuation, surface induced noise and surface piping induced signal reflections. Most of these are not predictable, not arbitrarily adjustable and potentially change their properties during the course of data transmission. To achieve maximum possible data rates under those challenges, telemetry systems must be highly flexible, both downhole and at the surface receiver. Downhole, the transmission tool should be able to support different signal types and different signal frequencies to optimally use the transmission channel (the mud filled pipe bore).These signaling parameters should be changeable during operation. On surface, sophisticated noise processing should be employed to increase the overall system Signal-to-Noise Ratio (SNR). This paper describes a new system for mud pulse telemetry that supports two signaling types, different signal modulations and various signal frequencies. The new system comprises a novel mud pulser and a digitally controlled, automatically adjusted surface system. With the downhole mud pulser in the borehole, the new system allows the optimization of the mud pulse telemetry process for maximum MWD/LWD information at surface while drilling the well. This paper introduces the system and gives details on how the achieved high speed data rates of the new telemetry system have helped to deliver real time answers while drilling. Introduction Mud Pulse Telemetry (MPT) systems share a common communication principle (Figure 1). Downhole, drilling fluid passes a moving valve that in some fashion restricts flow and in turn generates pressure waves which travel to surface at varying speeds depending on the drilling fluid properties. The mud channel (the pipe bore filled with flowing drilling mud) causes the transmitted signal to be attenuated and further distorted. Depending on the severity of the channel conditions, signal reception can be a difficult task. Major components affecting signal properties include mud pumps, pulsation dampeners, surface piping, pressure transducer locations, drill string components, mud properties, well depth and others. Due to the complexity of the involved parameters and their often varying properties, reliable high speed telemetry requires a system that adapts its downhole and surface settings during drilling. In this paper we discuss a new telemetry system comprising a novel, advanced and reliable mud pulser design and a new surface data acquisition unit with enhanced signal processing capabilities. The system can automatically adjust its decoding parameters during data transmission by making continuous measurements of the transmission channel conditions during drilling. This assures high speed mud pulse telemetry even under highly varying mud channel conditions. The entire system has been extensively tested and improved since 2001 and data rates of up to 20 bits per second (bps) have been achieved in commercial drilling situations. Using this data rate increase of more than 200% compared to previous offset runs, higher quality decision making was attained in various applications. Those optimized, high data rates are essential to support present services and to enable future MWD/LWD services, including reservoir navigation service (RNS), wellbore stability and drilling optimization. In the next sections we introduce the downhole mud pulser and the new surface system with a focus on how to optimize the quality of the signal received at surface. We explain the implemented features and highlight a case that showed higher data rates to be the enabling technology for efficient Reservoir Navigation Service (RNS) operations.
Mud Pulse Telemetry (MPT) is the most common down hole-to-surface communication technology utilized by MWD/LWD systems. Compared to alternative technologies, MPT systems are characterized by a proven record of high reliability in a wide range of operating environments. Reliable data delivery is feasible in a variety of scenarios ranging from shallow vertical to complex, deep water wells in all types of drilling fluid media.Recent years have seen the introduction of many new LWD technologies which are providing unparalleled amounts of wireline quality evaluation data in realtime. Access to high quality, complete, evaluation data sets whilst drilling is enabling geologists and engineers to make decisions with higher confidence based on more and higher quality datasets, consequently enabling wells to become more complex and fulfill multiple objectives. The ever increasing volume of information generated by these new technologies has begun to exceed the bandwidth transmission capacity that traditional MPT technology can deliver. To fully capitalize on the LWD technological advances being implemented, an increase in data transmission speeds is required. This paper discusses a new telemetry system that delivers data rates in excess of 6 bits per second (bps). The system has been deployed in a number of complex 3D extended reach offshore wells in Norway. During operations, the system reliably delivered high data rates of up to 20 bps, resulting in improved drilling efficiency, and reduced operational risk due to enhanced realtime decision quality based on the improved quality of FE and downhole diagnostics data.
For almost two decades, coiled tubing drilling (CTD) has proved to be a successful method to reach the un-swept portions of Alaska’s North Slope reservoirs. This method of drilling has evolved over the years with new technologies and efforts from contractors and operators striving to improve performance from lessons learned. Despite these improvements in equipment and processes, operators and contractors must still deal with certain inherent deficiencies of this drilling method when compared to conventional rotary drilling – suboptimal weight transfer, sometimes troublesome hole cleaning — due mainly to lack of string rotation and low flow rate range, etc. These shortcomings have the potential to induce other drilling performance problems that affect the smoothness of coiled tubing drilling operations. Severe lateral vibration and severe stalling have become acceptable evils over the years, resulting in undesirable trips for failure and unacceptable non- productive time (NPT), both undermining one of the key benefits of coiled tubing drilling – rapid pace operations compared to rotary drilling. This paper introduces a new lower-speed downhole positive displacement motor (PDM). The technology is equipped with high-performance elastomer and was engineered to improve drilling and drill-bit performance in CTD applications. Recent field deployments in Alaska’s North Slope CTD operations proved this design by eliminating earlier performance problems for improved CTD project economics. For example, the technology’s ability to allow for about 10gal/min higher flow rates (compared to other motor designs) significantly improves hole cleaning; a key aspect in CTD operations. Up to today, this downhole mud motor design has been utilized on 13 wells, accumulating 1,303 circulating hours, 577 drilling hours and over 20,700 ft drilled. Performance improvements in depth of cut, reduced lateral vibration, reduced amount of stalls, and other benefits were achieved. There was no trip for PDM failure in all of the 34 runs, traversing different formation zones. The corresponding paper will provide additional information on application benefits by investigating two recent field deployments.
A simulation method has been developed to predict the sound emission of the railway wheelsets due to the excitation of wheelset vibrations by surface roughness of wheel and rail. This model treats the contact in a linearized manner and is therefore not capable of modelling the local effects of the roughness in the wheel-rail contact zone. These effects are very important since the contact acts as a low pass filter which is calculated within a contact simulation.
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