Flowmeter Sensor Research Articles

Test study on rupture process and permeability properties of coal-rock in simulating mining stress effect

A test system was designed by using a set of self-made experimental devices of coupled coal-gas in simulating mining stress effect, combining the equipment with RMT-150B rock mechanical experimental system, monitoring the rupture process of coal-rock with an acoustic emission (AE) device and collecting gas-flow rate and gas-stress data in real-time automatically with a gas flow-meter and gas pressure sensor. The fracture process and permeability properties test of the coal-rock in mining stress effect was carried out. Test results indicate that AE events and variation of stresses have the same variance tendency and the rupture process of coal-rock can be monitored by AE. The relation curves among stresses, parameters of AE and permeability properties demonstrate that the permeability of coal-rock decreases gradually at quasi-elastic stage, increases gradually at plastic damage micro-fracture stage, rises suddenly near the peak point and has multi-variation at post-peak slip stage. From the results, such conclusion can be drawn that the variation of permeability can be monitored by AE parameters or stress change.

Optical flowmeter using a modal interferometer based on a single nonadiabatic fiber taper

A novel in-fiber modal interferometer is presented that is based on a nonadiabatic biconical fused taper that couples light between the cladding and the core, combined with the Fresnel reflection at the fiber end. It is observed that the returned light from this fiber structure shows a channeled spectrum similar to that of a two-wave Michelson interferometer. The application of this device as a fiber optic flowmeter sensor is demonstrated.

Assessing the Influence of Antivibration Glove on Digital Vascular Responses to Acute Hand‐arm Vibration

This study was designed to assess the influence of an antivibration glove on digital vascular responses in healthy subjects exposed to short-term grasping of a vibrating handle. To measure finger blood flow (FBF) and finger skin temperature (FST) once at the end of every min, a blood flowmeter sensor was attached to the dorsum and a thermistor sensor was attached to the medial surface of the subject's middle phalanx of the third finger of the right hand. After 5 min of baseline measurements without or with an antivibration glove meeting ISO standard 10819, worn on the right hand, subjects gripped a vibrating handle with the same hand for a period of 5 min. Vibration was generated at two frequencies of 31.5 Hz and 250 Hz with a frequency weighted rms acceleration of 5.5 m/s(2). FBF and FST continued to be recorded for a further 5 min after release of the vibrating handle. Statistical analysis showed no significant change after vibration exposure in either FST or FBF at 250 Hz, compared to baseline (control) measurements while using the antivibration glove. At 31.5 Hz, FBF data exhibited a significant difference between before and after grasping of vibrating handle, which was less under the condition of wearing the antivibration glove than under the condition of bare hand. The results provide evidence that the antivibration glove considerably influenced finger vascular changes in healthy subjects induced by vibration exposure, especially against high frequency vibration. Further studies are required to assess finger vascular responses to hand-transmitted vibration with antivibration gloves of different manufacturers.

Ultrasonic flowmeters: temperature gradients and transducer geometry effects

Ultrasonic flowmeter performance is addressed for the case of cylindrically shaped flowmeters employing two reciprocal ultrasonic transducers A and B so as to measure time-of-flight differences between signals transmitted from (1) transducer A towards B followed by (2) an equivalent signal transmitted from transducer B towards A. In the case where a liquid flows through the flowmeter’s measuring section (“spoolpiece”), the arrival times of the two signals differ by an amount related to the flow passing between the two transducers. Firstly, a detailed study of flow measurement errors with mean flow in the laminar flow regime is carried out as a function of the mode index and the transducer diameter/cylinder diameter ratio in the case where no temperature gradients are present in the flowmeter sensor. It is shown that all modes except the fundamental mode overestimate the mean flow by a factor of 33.33% while excitation of the fundamental mode solely give error-free measurements. The immediate consequences are that the flowmeter error decreases as the transducer diameter/cylinder diameter ratio approaches 1 from 0 reflecting the fact that the excitation level of the fundamental mode increases from almost 0 to 1 as this ratio approaches 1 from 0. Secondly, the effect on flowmeter performance due to flow-induced temperature gradients is examined. It is shown that the presence of temperature gradients leads to flowmeter errors at the higher-flow values even in the case where the fundamental mode is the only mode excited. It is also deduced that flowmeter errors in general depend on the distance between transducers A and B whether temperature gradients exist or not. This conclusion is not reflected in the usual definition of flowmeter errors given by the so-called mode-dependent deviation of measurement introduced in earlier works [J. Acoust. Soc. Am. 109 (2001) 102].

An electronically switched flowmeter and temperature sensor employing a single thermistor probe

The design of an electronically switched flowmeter and temperature sensor employing a single thermistor probe is described. Digital temperature compensation is incorporated in the design. The concept is applicable to geophysical flows; in this case, design criteria for a tidal channel were used. The flowmeter is designed for use in the 0.05 to 0.5 m s4-1 range with a fluid temperature variation of 2 degrees C. A frequency response of 0.25 Hz is obtained.

Testing and Interpretation in Layered Reservoirs

Introduction This paper summarizes recently developed techniques for testing layered reservoirs that field tests have shown to be successful. The effects of layering on. conventional pressure-transient tests have been studied by a number of investigators, starting with a model for the commingled reservoir system by Lefkovits et al. in 1961. An extensive list of publications on this subject is given in Ref. 2. In a multilayered reservoir, each layer may have distinct values for its thickness, porosity permeability, and formation skin factor. In gas -wells, each layer may be subject to an additional skin because of non-Darcy flow near the wellbore. Layers may communicate vertically in the reservoir by formation crossflow. For interpretive purposes, the reservoir system is organized into zones, which are groups of communicating layers. Between adjacent zones there are impermeable barriers. Interpretation procedures assume that each zone is either infinite-acting or confined by either a constant-pressure or no-flow outer boundary. Finally, single-phase flow is assumed in the formation. Each change in the surface rate causes downhole transients, which depend on the system properties. Under commingled flow, the bottomhole flowing pressure is affected by the total system. The fluid flow rate to or from each layer, however, is a function of the properties of the layer and the adjacent communicating layers. Often, there may be flow in the wellbore from one layer into another. Determination of the layer properties by these techniques is not prevented by the presence of wellbore crossflow and/or wellbore storage. Layered Reservoir Test Data Acquisition The layered reservoir test (LRT) relies on a combination of measurements, including production log surveys, and pressure and flow-rate transients acquired with the sensors maintained in a stationary position. The simplest LRT technique is called selective inflow performance (SIP). To perform the SIP test, it is necessary to achieve stabilized flow in the well for several surface injection or production rates. Under stabilized flow conditions, the wellbore pressures and flow rates are surveyed, and flow for each perforated interval is computed as the difference between the flow rates measured above and below the interval. To determine permeabilities and skin factors for each layer, it is necessary to perform a multilayer transient (MLT) test." A typical MLT test sequence is shown in Fig. 1. Following an initial pressure and flow-rate survey, the flowmeter sensor is positioned above one of the perforated intervals. The surface flow rate is changed, and the tool is left in the same position until nearly the end of the flow period. Then a pressure and flow-rate survey is taken, and the tool is relocated above another perforated interval for the next transient measurement. As shown in Fig. 1, this procedure is repeated for each interval to be tested. If the well reaches stabilized steady- or pseudosteady-state flow before the end of each flow period, then the pressure and flow-rate surveys can be used for SIP analysis. If the system has reached stabilized infinite-acting radial flow at the time of each vertical survey, then the SIP analysis is modified slightly by use of the transient SIP interpretation procedure. Because flow-rate measurements are required for the analysis, it is important to conduct the test at flow rates high enough to be measurable in the wellbore. It is useful, although not required, to run a conventional pressure buildup test at the end of the LRT sequence.. Hence, the simulated test sequence in Fig. 1 is terminated with a pressure buildup. JPT P. 1087^