Jacques Jundt

Electromagnetic Propagation Logging While Drilling: Theory and Experiment

Presentation of the Compensated Dual Resistivity (CDR) tool, electromagnetic propagation tool for measurement while drilling. The CDR provides two resistivity measurements with several novel features that are verified with theoritical modeling, test-tank experiments, and log examples.

A microfluidic vibrating wire viscometer for operation at high pressure and high temperature

This article discusses a microfluidic vibrating wire viscometer with an internal volume of a few microliters. Accuracy of order ±10% for viscosities ranging from 0.1 to 100 cP is demonstrated for temperatures (10 °C-175 °C) and pressures (10-24,000 psi) suitable for oilfield use by prior calibration in air and toluene. Comparison between multiple data sets indicates that a large fraction of the discrepancy between literature values is systematic, indicating that future refinements may be possible with better interpretation. Confinement effects are evaluated and are not found to play a significant role, which is surprising since the ratio (6.6) of the fluid channel width to the wire diameter is very low.

Highly integrated microfluidic sensors

We have developed fabrication techniques for creating suspended electrically addressable MEMS structures in microfluidic channels, as well as monolithic integration of sensors within microfluidic devices. As we will demonstrate, creative use of state-of-the-art MEMS fabrication techniques allows the integrated manufacturing of a number of sensors, for simultaneous measurement of, for example, flow velocity, thermal conductivity and normal stress. We will demonstrate the versatility of these techniques with an example of capillary viscosity sensor integrating independent flowrate, temperature, and pressure drop sensors.

Stochastic time of flight flow rate measurement for microfluidic applications

We describe a thermal time of flight liquid flow rate measurement based on injection of a pseudo-random sequence of thermal tracers in a microfluidic flow stream, followed by downstream detection of the temperature variation. The cross correlation function between the injected sequence and the detected signal displays a peak corresponding to the time of flight, which in turn provides a sensitive measure of flow rate. We demonstrate the technique by using integrated MEMS silicon structures suspended across a microfluidic channel for both heating and detection. The encapsulation technique we use involves 3-layer glass-silicon-glass bonding. We are capable of measuring flow rate over more than three decades with an accuracy of a few percent (the exact measurement range scales with geometry, in our case corresponding to 5 - 10,000 µl/min). Our technique shows excellent agreement between measurement, theory and numerical simulation results; by comparison with other existing methods for microfluidic flow metering (anemometric, coriolis), ours has the advantage of being largely independent of physical fluid properties. In addition, the suspended MEMS heaters we fabricate can also be used as regular anemometer probes, extending the measurement possibilities to gas flow metering and phase detection.

A simple microfluidic Coriolis effect flowmeter for operation at high pressure and high temperature

We describe a microfluidic Coriolis effect flowmeter that is simple to assemble, operates at elevated temperature and pressure, and can be operated with a lock-in amplifier. The sensor has a flow rate sensitivity greater than 2° of phase shift per 1 g/min of mass flow and is benchmarked with flow rates ranging from 0.05 to 2.0 g/min. The internal volume is 15 μl and uses off-the-shelf optical components to measure the tube motion. We demonstrate that fluid density can be calculated from the frequency of the resonating element with proper calibration.