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Data Fusion System Development
The data fusion receiver is a key element of the EM telemetry system, with much of the system development focused on perfecting this new technology. Development efforts consisted of two fundamental areas: the development and tuning of the data fusion computer algorithms, and the design and construction of the data fusion receiver hardware platform.
Downhole tool power amplifier and receiver assembly
The objective of the data fusion computer algorithm development was to generate and validate a set of innovative signal-processing algorithms that maximize the noise rejection capabilities of a high-sensitivity subterranean communications receiver.Within the context of the energy exploration market, developing a methodology that increases a subterranean telemetry receiver’s noise rejection capability works to improve the signalto- noise ratio resulting in a receiver capable of recovering the extremely weak electromagnetic field signals associated with deep drilling telemetry applications.
The data fusion receiver hardware platform was designed to maximize electronic signal sensitivity, employing techniques adopted from biomedical sensing devices. It also was critical the data fusion receiver be computationally efficient, rugged and compact to satisfy the requirements of the oil and gas market.
The receiver platform (Figure 1) developed during the Deep Trek project consists of two primary components: an ultra low-noise signal conditioning unit and a Windows-based notebook computer.
The ultra-low noise signal-conditioning unit accommodates up to four electric-field signal channels and up to 12 magnetic-field signal channels for a total of 16 real-time receive-input channels.
A Windows-based, personal computerarchitecture computer provides an industry standard platform for digitizing the incoming signal channel. It also provides the run-time processing platform for the data fusion and demodulation engines. The computer also hosts the data fusion receiver’s graphical user interface (GUI) application, the primary function of which is to provide the operatorinterface for display of the data received from the downhole tool. This data can be real-time information from the tool sensors, such as tool-face information for measurementwhile- drilling (MWD) applications; or diagnostic information about the “health” of the tool, such as battery voltages and gap antenna impedance. The GUI application also allows the operator to format downlink commands to the downhole tool to configure the tool for telemetry uplinks or query it for real-time health/diagnostic information. Additional GUI functionality includes the ability to display multiple incoming/receive antenna waveforms, allowing the operator to select any four of the 16 incoming waveforms for real-time display.
The data fusion receiver application also allows the user to save the incoming real-time waveform data to the hard drive to facilitate post-processing analysis of the raw temporalwaveform data. The receiver application also keeps an electronic log of all uplinks received from the tool and all downlinks sent to the tool. This log is time stamped and can be used to facilitate the post-processing of the raw waveform data archived to the hard drive.
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