Design and implementation of NMR system in downhole extreme conditions

Key words:  nuclear magnetic resonance(NMR)  oil and gas prospecting  extreme condition  complex reservoir

Abstract:

The design of nuclear magnetic resonance (NMR) system in downhole extreme conditions was briefly summarized. The extreme conditions here include environments with high temperature (up to 175℃) and high pressure (up to 68.95MPa) in a well bore, very restricted space for system size, measurements done in moving conditions, sample outside of the probe with low magnetic field and low signal-to-noise ratio (SNR). NMR systems in downhole extreme conditions are very different from the conventional ones, so the probe and control systems require special consideration. Noise reduction, data processing and interpretation are equally important. The key issues of design and implementation of downhole NMR systems, including design of components of the NMR system and signal flow, design and implementation of probe, monitoring and control system, noise reduction methods and design and implementation of data acquisition and processing software, were discussed. The NMR system proposed and designed was delivered to engineering and application stage, and improved high end instrumentation and technology for China petroleum industry.