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.
Regardless of whether you look at consumer or industrial applications, whenever a technical breakthrough in available communication bandwidth is achieved, the affected en vironment and feasible applications change significantly. One recent example was the introduction of the digital subscriber line (DSL) to replace modems for Internet access.With high-speed telemetry systems becoming economically viable in an increasing number of drilling applications, our industry is in a situation similar to that seen at the introduction of DSL. Following the parallel of Internet access via DSL vs. modem, the relevant questions are: How has high-speed telemetry changed the drilling process, and what further changes will we see in the near future?This article first intends to explain why oilfield service companies continually strive for higher telemetry data rates. It then identifies and exemplifies fields of application for both available technologies-high-speed mud-pulse telemetry and wired drillstring telemetry-with two case histories. The conclusion provides an outlook on possible future opportunities and technological developments.
The potential operator cost efficiencies of acquiring valid formation pressure data while drilling are becoming more influential in deciding the value proposition of a wireline reservoir characterization program. Cost efficiencies may indeed be pivotal but importantly, the benefit of acquiring pressure data in real time needs equal consideration, as a number of novel applications now exist. The paper will use case histories and lessons learned from experience with 300 logging while drilling (LWD) formation pressure runs in different operating areas including Asia Pacific to demonstrate the applicability to conventional formation pressure applications, traditionally acquired with wireline formation testers upon reaching section or well total depth (TD). These are the determination of formation pressure, fluid contacts, reservoir connectivity, and near-wellbore mobility. We discuss novel real-time applications and benefits for drilling and subsurface teams, such as mud weight management, safe selection of casing points, calibration of pore pressure predictions, selection of wireline sampling points, reservoir monitoring, geosteering, and obtaining data in high-risk wells. Incorporating formation pressure testing into the drilling process presents challenges to perform measurements in a timely manner, as well as the need for continuous circulation while testing to ensure wellbore safety. Providing this type of while-drilling formation evaluation data with an LWD tool allows a continuous approach to data evaluation and decision-making. The ability to measure accurate LWD formation pressure data in a variety of hole sizes represents a significant opportunity for safe and cost-efficient wellbore construction, especially in challenging environments. Introduction With the introduction of LWD formation pressure testers, it has become possible to acquire formation pressure and mobility data during short breaks in the drilling process. Formation pore pressure and near-wellbore mobility are key parameters for reservoir description. Traditionally, these data are acquired with wireline formation testers upon reaching section or well TD. In high-angle wells, this is a time-consuming operation, as the tools must be conveyed by drillpipe. Providing this type of formation evaluation data with an LWD tool allows for a continuous approach to data evaluation and decision-making and represents a significant opportunity for safe and cost-efficient wellbore construction. Smart Technology - Reliable Performance The success of the discussed LWD formation tester is in particular based on smart, self-learning operating processes, which improve the accuracy of the pressure and mobility data as well as the sealing success rate. In addition to mobility-dependent test times, this smart test function reduces shock effects while drawing down on tight formations and also avoids sanding in highly unconsolidated formations. The precise control of the drawdown pump allows the optimization of the individual pressure test sequence. The drawdown process is governed by the drawdown rate and volume being applied to the formation by the pump system in the tool. In order to achieve valid pressure tests quickly, both parameters need to be optimized for the mobility and pore pressure encountered in the formation being tested. However, pressure may differ from expectations and mobility may vary over several orders of magnitude, which requires that drawdown rate and volume parameters be adjusted between individual pressure tests. Intelligent pad control allows individual and continuous control of the test cycle and the drawdown pump. A closed-loop control of the pad contact force enables optimum sealing efficiency, saving significant time for "lost seal" retesting and avoids formation damage. Initial LWD formation pressure test results have been good. However, the drive has been to decrease test times and improve seal success and accuracy. Fig. 1 shows the improvement (global basis) in seal success since the introduction of the discussed smart technologies1.
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