In this work, we use monocrystalline LaPO4:Eu nanorods as polarized luminescent probes. By distinguishing between emission peaks originating from magnetic and electric dipole transitions, we can derive the three-dimensional orientation of the nanorods through measurements of their polarized luminescence. This spectroscopy-based orientation analysis can furthermore be used to characterize microfluidic media, as the collective orientation of nanorods is directly related to flow conditions they are subjected to. Using a confocal microscope, we can locally determine their collective orientation which provides a direct measure of the shear stress. We demonstrate this method to map the shear stress profile in different microfluidic channel geometries and monitor the shear stress in an energy harvesting device.
A novel noise suppression method is proposed for the pressure surveillance of heavy oil thermal recovery well using
white light extrinsic Fabry-Perot interferometric (EFPI) fiber-optic sensor. The moving grey model GM(1, 1) algorithm
is applied to suppress the non-stationary noise and disturbance in downhole environment. Both theoretical analysis and
field test results show that there exists a threshold effect for the moving window length selection, the optimized value of
window length occurs at the threshold point which best removes the high frequency disturbance as well as retaining the
fast change of actual pressure signal. Field test results show that the proposed method can increase the signal to noise
ratio (SNR) of pressure profile with 10.4dB, and then can effectively suppress the large deviation in the forecasting result
of daily oil production by combining temperature information.
KEYWORDS: Wavelets, Signal to noise ratio, Autoregressive models, Optical fibers, Temperature sensors, Signal processing, Silica, Fiber optics sensors, Surveillance, Algorithm development
Pure silica core optical fiber is commonly used as the sensing fiber in Raman-backscatter distributed temperature sensors
(DTS) in heavy oil thermal well. However the sensing signal collected from this type of fiber statistically belongs to nonstationary
random process which cannot be effectively de-noised by simply applying conventional methods. To solve
this problem, we develop a novel noise suppression algorithm by combining wavelet multi-scale analysis and moving
grey model GM(1,1). The algorithm first applies wavelet de-noising in spatial domain of temperature profile to remove
the high frequency noise, then uses moving GM(1,1) method to remove both high frequency and low frequency nonstationary
noise in time domain. Autoregressive (AR) model and least square regression are used to optimize the
forecasting parameters of GM(1,1). Finally the results of both domains are reconstructed to obtain the de-noised profile.
Long-term field test was proposed on the Karamay oil field F11051 steam stimulation well, Xinjiang Province, China.
Field test result shows that signal to noise ratio (SNR) is improved by 11dB using the algorithm.
KEYWORDS: Fiber optics, Receivers, Digital signal processing, Telecommunications, Fiber optics sensors, Sensors, Signal processing, Michelson interferometers, Signal detection, Demodulation
We demonstrated a down-hole seismic survey system that can be applied in three dimensions vertical seismic profile (VSP) detection in petroleum exploration. The results of experiments show that the system has a dynamic measurement range of 80db (ratio of maximum to minimum value) and the total delay for signal collection, process and communication is less than 200ms @ 2k bit sample rates. An array consisting of six fiber-optic accelerometers (receivers) is applied in this system. Each receiver is comprised of three fiber-optic Michelson interferometers. In order to meet the requirements of high precision and real-time measurement, the high-speed DSP chips are employed to realize the algorithms of signal filters and Phase Generated Carrier (PGC) demodulation to obtain the seismic information. Multi-ARM CPUs are introduced into the system to design the fiber-optic accelerometer array controller and the receiver array local bus that are used for real-time data communication between the multi-level receivers and controller. The system interface for traditional ELIS Down-hole Instrument Bus (EDIB) is designed by the use of FPGA so that our system can attach to EDIB and cooperate with other instruments. The design and experiments of the system are given in this paper in detail.
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