Blake T. Sturtevant

An acoustic resonance measurement cell for liquid property determinations up to 250 °C

This paper reports on the development of a compact, rugged, and portable measurement cell design for the determination of liquid sound speed at temperatures up to 250 °C and pressures up to 3000 psi. Although a significant amount of work exists in the literature on the characterization of fluids, primarily pure water, over a wide range of pressures and temperatures, the availability of experimentally determined sound speed in water between 100 °C and 250 °C is very limited. The need to measure sound speed in liquids up to 250 °C is of both fundamental interest, as in the case of basic equations of state, and applied interest, such as for characterizing geothermal or petroleum downhole environments. The measurement cell reported here represents an advancement in the established room temperature swept frequency acoustic interferometry measurement for liquid sound speed determinations. The paper details the selection of materials suitable for high temperature operation and the construction of the measurement apparatus. Representative sound speeds as a function of temperature and pressure are presented and are shown to be in very good agreement with an internationally accepted standard for water sound speed.

Measured sound speeds and acoustic nonlinearity parameter in liquid water up to 523 K and 14 MPa

Sound speed in liquid water at temperatures between 275 and 523 K and pressures up to 14 MPa were experimentally determined using a high temperature/high pressure capable acoustic resonance cell. The measurements enabled the determination of the temperature and pressure dependence of sound speed and thus the parameter of acoustic nonlinearly, B/A, over this entire P-T space. Most of the sound speeds measured in this work were found to be within 0.4% of the IAPWS-IF97 formulation, an international standard for calculating sound speed in water as a function of temperature and pressure. The values for B/A determined at laboratory ambient pressure and at temperatures up to 356 K, were found to be in general agreement with values calculated from the IAPWS-IF97 formulation. Additionally, B/A at 293 K was found to be 4.6, in agreement with established literature values.

The acoustic nonlinearity parameter in Fluorinert up to 381 K and 13.8 MPa

This work reports on the determination of the acoustic nonlinearity parameter, B/A, from measured sound speed data, in Fluorinert FC-43 at temperatures up to 381 K and pressures up to 13.8 MPa using the thermodynamic method. Sound speed was measured using Swept Frequency Acoustic Interferometry at 11 pressures between ambient and 13.8 MPa along 6 isotherms between ambient and 381 K. Second-order least-squares polynomial fits of measured sound speeds were used to determine temperature and pressure dependence. A room temperature B/A = 11.7 was determined and this parameter was found to increase by a factor of 2.5 over the temperature/pressure range investigated.

Determination of the acoustic nonlinearity parameter in liquid water up to 250°C and 14 MPa

This work reports, for the first time, the direct measurement of sound speed in liquid water at temperatures up to 250°C and pressures up to 14 MPa. These measurements enabled the determination of the acoustic nonlinearity parameter, B/A, an important property of liquids. From an applications perspective, B/A determines the efficiency of devices that are based on acoustic nonlinear mixing. The objective of the present work was to use a specialized measurement cell for sound speed measurements and the determination of B/A in liquid water as a function of temperature and pressure. Sound speed was measured using Swept Frequency Acoustic Interferometry, while B/A was determined from the derivatives of the sound speed with respect to pressure and temperature. B/A at ambient pressure and temperature was determined to be 4.8, in good agreement with literature values. At 250°C and 14 MPa, B/A was found to be roughly twice its ambient temperature value.

An ultrafast broadband digital signal processing approach to pulse echo measurements

Pulse-Echo (PE) measurements are commonly used to determine the sound velocity in a sample of known length. In PE measurements, the interface between the transducer and buffer rod, and that between the buffer rod and sample, introduces a total phase shift, Φ, to the acoustic wave that must be accounted for if high accuracy in the velocity is desired. The appropriate time correction, τ=Φ/ω, is traditionally determined by measuring the time-of-flight of multiple acoustic waves with different angular frequencies, ω. A single PE measurement can take several minutes, depending on experimental details such as the number of frequencies measured and the amount of signal averaging performed. Several minutes of data acquisition is tolerable for static experiments, but it is too long for many dynamic processes of interest in biology, pulsed magnetic fields, or any other rapidly changing system. This work describes an approach to PE in which a single broadband signal is collected and later processed offline using sta...

Probing dynamic response to temperature changes in Berea Sandstone using acoustic time-of-flight and resonant ultrasound spectroscopy

In this study, through-transmission acoustic time-of-flight experiments and bulk resonance tracking were used to study the anomalous elastic behavior in Berea Sandstone with temperature cycling. Previously published results (Davis et al., 2016) using Resonant Ultrasound Spectroscopy (RUS) indicated that Berea Sandstone softens by as much as 10% when cooled from 205°C to 110°C. This result is in contrast to the behavior of most materials, which stiffen when cooled. The time-of-flight experiments confirmed the RUS results and revealed the need for additional analysis of this phenomenon. By tracking the location of resonant frequencies at each temperature step, the qualitative behavior of the sample was obtained without the need for a rigorous RUS analysis. The results from this analysis showed that Berea Sandstone has significant hysteretic behavior under temperature cycling. It was also revealed that the qualitative elastic behavior of Berea Sandstone is unchanged with increasing relaxation time from the thermal shock induced by rapid cooling of the sample.In this study, through-transmission acoustic time-of-flight experiments and bulk resonance tracking were used to study the anomalous elastic behavior in Berea Sandstone with temperature cycling. Previously published results (Davis et al., 2016) using Resonant Ultrasound Spectroscopy (RUS) indicated that Berea Sandstone softens by as much as 10% when cooled from 205°C to 110°C. This result is in contrast to the behavior of most materials, which stiffen when cooled. The time-of-flight experiments confirmed the RUS results and revealed the need for additional analysis of this phenomenon. By tracking the location of resonant frequencies at each temperature step, the qualitative behavior of the sample was obtained without the need for a rigorous RUS analysis. The results from this analysis showed that Berea Sandstone has significant hysteretic behavior under temperature cycling. It was also revealed that the qualitative elastic behavior of Berea Sandstone is unchanged with increasing relaxation time from the t...

Ultrasonic Sensing for Non-invasive Characterization of Oil-Water-Gas Flow in a Pipe

A technique for noninvasive ultrasonic characterization of multiphase crude oil-water-gas flow is discussed. The proposed method relies on determining the sound speed in the mixture. First, important issues associated with making real-time noninvasive measurements are discussed. Then, signal processing approach adopted to determine the sound speed in the multiphase mixture is presented. Finally, results from controlled experiments on crude oil-water mixture in both the presence and absence of gas are presented.

High frequency sound speed measurements in liquids and solids using a smartphone

Much has been written in recent years on the use of smartphones and other personal electronic devices (PED) in the high school and college teaching laboratories. Due to the bandwidth limitations (< 20 kHz) of these devices, experiments proposed to date have focused almost exclusively on measurements of phenomena in air and in the audible range. This talk will focus on a simple way to extend the use of these devices to measure sound speed in liquid and solids which have significantly higher sound speeds than air. High frequency acoustic standing waves in these media can be generated using standard teaching laboratory instrumentation (e.g., signal generators providing white noise, chirp signals, CW signals with manually adjusted frequency, etc.) and two opposing piezoelectric disks. By down-converting the high frequencies with an inexpensive diode mixer and measuring the difference frequency spectrum with a PED, it is possible to determine multiple successive standing wave frequencies in the medium. The mea...

High frequency signal acquisition using a smartphone in an undergraduate teaching laboratory: Applications in ultrasonic resonance spectra

A simple and inexpensive approach to acquiring signals in the megahertz frequency range using a smartphone is described. The approach is general, applicable to electromagnetic as well as acoustic measurements, and makes available to undergraduate teaching laboratories experiments that are traditionally inaccessible due to the expensive equipment that are required. This paper focuses on megahertz range ultrasonic resonance spectra in liquids and solids, although there is virtually no upper limit on frequencies measurable using this technique. Acoustic resonance measurements in water and Fluorinert in a one dimensional (1D) resonant cavity were conducted and used to calculate sound speed. The technique is shown to have a precision and accuracy significantly better than one percent in liquid sound speed. Measurements of 3D resonances in an isotropic solid sphere were also made and used to determine the bulk and shear moduli of the sample. The elastic moduli determined from the solid resonance measurements agreed with those determined using a research grade vector network analyzer to better than 0.5%. The apparatus and measurement technique described can thus make research grade measurements using standardly available laboratory equipment for a cost that is two-to-three orders of magnitude less than the traditional measurement equipment used for these measurements.

Resonant Ultrasound Spectroscopy studies of Berea sandstone at high temperature

Resonant Ultrasound Spectroscopy was used to determine the elastic moduli of Berea sandstone from room temperature to 478 K. Sandstone is a common component of oil reservoirs, and the temperature range was chosen to be representative of typical downhole conditions, down to about 8 km. In agreement with previous works, Berea sandstone was found to be relatively soft with a bulk modulus of approximately 6 GPa as compared to 37.5 GPa for α-quartz at room temperature and pressure. It was found that Berea sandstone undergoes a ~17% softening in bulk modulus between room temperature and 385 K, followed by an abnormal behavior of similar stiffening between 385 K and 478 K.