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.

Drilling liner technology has become a standard for entering depleted reservoirs in areas of the North Sea and Southeast Asia and interest continues to increase for use of drilling liners to overcome other drilling problems. Marketing analyses have shown that further development of drilling liner technology and application has been rated with high priority. Based on experience gathered during the last five years, this paper covers possible further Drilling Liner applications, new challenges, and requirements for new systems. "Drill and Case" systems will be introduced and benefits shown by means of case histories of jobs carried out in Norway and Indonesia. Introduction Drilling Liner technology seeks to drill and case the well in one run. Over the last five years, typical Drilling Liner runs were carried out in applications where the target depth was just a few meters away, but could not safely be reached with standard drilling bottom hole assemblies (BHA's). Drilling ahead with standard BHA's risked loss circulation, hole collapse and potentially losing the BHA, drill string and hole section. The success of the entire well was dependent on drilling just a few meters ahead. Drilling Liner technology has helped solve these problems in Norway and Indonesia—enabling savings of over 1.0 mm US$ per well. A typical Drilling Liner application occurs when drilling into depleted reservoirs—a situation, which will become more evident and critical in the future. Former drilling technology has required the use of intermediate casing strings and/or set cement plugs as a means to achieve this. Using Drilling Liners, it often takes only a few hours to drill the liner to target depth and overcome existing drilling problems. The Drilling Liner was standardized to enter depleted reservoirs, but questions challenging the use of this system in other applications continue to arise. These new applications include long distance (ERD) drilling, deep water/shallow water flows, unconsolidated sands or time critical unstable formations. Market analysis has shown that further development of "Case and Drill" systems are rated within the top level of desired drilling technologies industry-wide. On the other hand, although existing systems have been on the market for some years, they are sometimes not fully recognized as potential cost savers or problem solvers. Case and Drill Simultaneously. Various liner drilling systems and casing drilling systems are on the market. Figure 1 refers to liner and casing drilling concepts. Using casing drill systems, the operator can change the drilling BHA several times, whilst the casing stays in the hole. Due to the fact that the casing reaches to surface, the BHA can be retrieved with jointed pipe or wire line. Under-reamers or extendible bits enlarge the hole to allow the casing to follow. The casing must be designed to withstand all drilling loads from the bottom of the well up to surface.