GB2481831A

GB2481831A - Ultrasonic material property measurement

Info

Publication number: GB2481831A
Application number: GB201011473A
Authority: GB
Inventors: Laurie Linnett
Original assignee: BIOS TECHNOLOGIES LLP
Current assignee: BIOS TECHNOLOGIES LLP
Priority date: 2010-07-08
Filing date: 2010-07-08
Publication date: 2012-01-11
Also published as: GB201011473D0

Abstract

Determining properties of samples are described, in which a reference member, such as a pipeline 20, is in contact with a particular sample, such as oil or rock strata, and then a signal is applied to the reference member with a first transducer 10. The reflection of the signal from an interface between the reference member and the sample and/or a transmitted signal that has been transmitted at least partially through the sample can then be measured, using both transducers 10, 15, in order to determine a property of the sample, such as the viscosity, impedance or density. The signal may be an ultrasonic seismic signal.

Description

MEASUREMENT DEVICE

Field of the Invention

The present invention relates to a device and method for measuring a property of a material, particularly, though not exclusively, the density and/or viscosity and/or impedance of materials.

Background to the Invention

The determination of properties of materials, such as viscosity and density, is useful in a wide range of applications. For example, determination of material properties may be used in the control of process parameters, in quality control to ensure a material matches a specification or in characterisation of materials, wherein the determined properties can be used to characterize or differentiate between materials.

Various methods and devices for measuring parameters of liquids are available, such as hydrometers, pycnometers and oscillating u-tube based methods for measuring density. Rotational or vibrational viscometers, for example, may be used to determine viscosity.

Sensors that are operable in-situ and/or substantially in real time may be highly advantageous in permitting more responsive process control and monitoring of materials without interrupting a process. Devices capable of in-situ calibration may also allow regular calibration checks without having to remove or replace the device.

Sensor arrangements may be particularly useful in analysing a material flowing within a pipeline. For example, sensors such as pH sensors or Attenuated Total Reflection (ATR) optical sensors may be used to determine properties of, and optionally characterise, a material flowing in a pipeline.

In the field of drilling, including oil field exploration or geological probing, seismic measurements are particularly useful in providing data to operators for use in altering and optimising drilling parameters and/or assessing and analysing features of surrounding geological structure, such as characterising hydrocarbon containing formations.

For example, reflection seismology is commonly used to probe the structure of geological formations in order to determine subsurface structure of rock formations, including the type or density of rock strata. This method typically involves providing a suitable vibration signal, for example by using an explosion or a vibrating or impacting source, and measuring the reflections from geological features.

Summary of Invention

According to a first aspect of the present invention there is provided a method for determining a property of a sample, comprising: providing a reference member in contact with a sample; applying a signal to the reference member; measuring a reflection of the signal from an interface between the reference member and the sample and/or a transmitted signal that has been transmitted at least partially through the sample; and determining a property of the sample using the measurement of the reflection of the signal and/or the transmitted signal.

The property may comprise density.

The property may comprise viscosity, which may comprise kinematic viscosity and/or dynamic viscosity.

The property may comprise impedance.

The method may comprise providing a transducer arrangement. The transducer arrangement may comprise at least one transducer.

The transducer arrangement may comprise at least one transducer for applying or transmitting the signal to the reference member.

The transducer arrangement may comprise at least one transmitter for receiving the reflection of the signal. Optionally, separate transducers may be operable to apply or transmit the signal to the reference member and collect the reflection of the signal.

Optionally, the same transducer may be operable to apply or transmit the signal to the reference member and collect the reflection of the signal.

The transducer arrangement may comprise at least one transducer for measuring the transmitted signal. The transmitted signal may be a signal transmitted through at least a portion of the reference member and sample.

The transducer arrangement may comprise an ultrasonic transducer and/or the signal may comprise sound.

The transducer arrangement may comprise a seismic signal generator, which may comprise an air gun, a plasma sound source, an impact device, a vibration source, a boomer or the like. The transducer arrangement may comprise a seismic signal receiver, such as a geophone, a hydrophone or the like.

The method may comprise determining the properties of the reference member, which may comprise impedance and/or speed of signal in the reference member and/or density of the reference member.

The reference member may have known properties. The impedance of and/or density of and/or speed of sound in the reference member may be known. The reference member may comprise stainless steel.

The method may comprise estimating properties of the reference member.

The reference member may define a coupling member. The transducer arrangement may be coupled with the reference member The reference member may define a receptacle, such as a container or conduit, for

example, a pipe.

The reference member may comprise a layer or stratum of a layered structure. The reference member may comprise a geological structure, which may comprise a geological stratum, rock, or the like. The reference member may comprise a liquid, such as oil or water, which may comprise at least a portion of a body of liquid, such as a sea, lake, river, or the like.

The sample may comprise a layer or stratum of a layered structure. The sample may comprise or form at least part of a geological structure, which may comprise a geological stratum, rock, or the like, which may be a different geological stratum, rock, or the like from that of the reference member. The sample may comprise a liquid, such as oil or water. The sample may comprise one or more layers of liquid, which may be comprised in or disposed between geological strata.

The first and samples may comprise different layers of the same geological structure.

The method may comprise performing a calibration.

The sample may comprise, form or be comprised in a reference sample.

The calibration may comprise providing the reference sample in contact with the reference member.

The calibration may comprise applying a signal to the reference member whilst the reference member is in contact with the reference sample.

The calibration may comprise measuring the amplitude of a reflection of the signal whilst the reference member is in contact with the reference sample, which may be a signal reflected from an interface between the reference member and the reference sample.

The impedance and/or density and speed of sound in the reference sample may be known, previously determined and/or estimated. The reference sample may comprise water.

The calibration may comprise determining the impedance of the reference member and/or the reference sample using the density and speed of sound in the reference member or reference sample respectively. The impedance may be determined using the relation: Z=p v where Z is the impedance, p is the density and v is the speed of sound in that material.

The calibration may comprise determining the amplitude of the signal at a surface of the reference member, which may be a surface of the reference member opposite the transducer for transmitting the signal. In embodiments where the reference member is a receptacle, the surface may be an inner surface of the receptacle. The surface may be an interface between the reference member and the sample.

The calibration may comprise determining the signal amplitude at the surface of the reference member using the impedance of the reference member, the impedance of the reference sample and the amplitude of the reflected signal. The calibration may comprise determining the signal amplitude at the surface of the reference member using the relation: A1 (Z2+Z1)A (Z2 -Z1) where A1 is the amplitude of the signal at the surface, A2 is the measured amplitude of the reflected signal, Z1 is the impedance of the reference member and Z2 is the impedance of the reference sample.

The reference sample may comprise one or more layers of a layered structure, such as strata of a geological formation and/or liquid, such as oil or water, which may be disposed between strata of the geological formation.

The calibration may comprise providing a plurality of reference samples and/or reference members. The calibration may comprise collecting reflections from a plurality of interfaces between reference members and reference samples. The reflections may be reflections from interfaces between a plurality of layers or strata of a layered structure.

The device may be arranged such that the signals reflected from the plurality of interfaces are received at different times. The calibration may comprise applying a signal to the reference member and collecting temporally separated reflections of the signal.

The calibration may comprise determining the impedances of the plurality of reference members and/or reference samples.

The calibration may comprise determining the amplitude of the signal at one or more of the plurality of interfaces, which may comprise using a measured amplitude of a reflected signal associated with the interface and/or the impedance of a reference member and/or reference sample forming the interface.

The method may comprise determining the density of a measurement sample.

The sample may comprise, form and/or be comprised in a measurement sample.

The method may comprise providing the measurement sample in contact with the reference member.

The method may comprise applying a signal to the reference member whilst the reference member is in contact with the measurement sample. The method may comprise measuring the amplitude of a reflected signal, which may be a signal reflected from an interface between the reference member and measurement sample.

The method may comprise determining the impedance of the measurement sample.

Determining the impedance of the measurement sample may comprise determining the impedance (Z2) of the measurement sample using the amplitude (A1) of the signal at the surface of the reference member and/or the amplitude (A2) of the reflected signal obtained when the reference member is in contact with the reference sample and/or the amplitude (A2) of the reflected signal obtained when reference member is in contact with the measurement sample and/or the impedance (Z1) of the reference member. The amplitude (A1) of the signal at the surface of the reference member may be determined using the above calibration method.

The measurement may comprise determining the impedance of the measurement sample using the relation: z; = (A1 -A2) The measurement may comprise determining the impedance of the measurement sample using the relation: z' A(Z2+Zi)+A;(Z2_Zi)z 2 A2(Z2+Z1)-A(Z2-Z1) 1 The measurement may comprise determining the speed of sound in the measurement sample.

Determining the speed of sound in the measurement sample may comprise 1 0 measuring the time taken for a signal to travel from a transducer for transmitting the signal, via at least part of the sample to a transducer for receiving the signal.

The transducer used to transmit the signal may be spaced apart from the transducer used to receive the signal.

The same transducer may be operable to transmit and receive the signal.

The method may comprise providing a reflecting member, wherein the reference member and at least part of the sample are locatable between the transducer for transmitting the signal and the reflecting member. The method may comprise determining the time elapsed between providing the signal and detecting a reflection of the signal from the reflecting member.

The method may comprise providing two or more transducers, each separated by a specified distance (d) apart. Determining the speed of sound in the measurement sample (v2) may comprise determining the two way travel times (t1, t2) of the signal to each of the transducers through the measurement sample. Determining the speed of sound in the measurement sample may comprise applying the relation: 2d (t2 -t1) The method may comprise determining the density of the measurement sample (p2) using the impedance of the measurement sample and the speed of sound in the measurement sample. The density of the measurement sample may be determined using: z2 P2 V2 The method may comprise providing a plurality of measurement samples.

The or each measurement sample may comprise at least one layer or stratum of a layered structure.

Each layer or stratum may comprise a material having at least one physically distinct property.

The layered structure may comprise or form at least part of a geological structure, which may comprise geological strata, rock, or the like, which may be a different geological stratum, rock, or the like of the same geological structure to that of the reference member. The measurement sample may comprise a liquid, such as oil or water. The measurement sample may comprise one or more layers of liquid, which may be comprised in or disposed between geological strata.

The method may comprise collecting a plurality of reflected signals. The reflected signals may comprise signals reflected from a plurality of interfaces between strata or layers.

The reflected signals may be temporally separated.

The method may comprise determining a property of the plurality of measurement samples using the plurality of reflected signals.

The method may comprise sequentially determining the property of layers or strata.

The method may comprise sequentially determining the properties of adjacent layers or strata, starting from the layer or strata adjacent to the reference member, and determining the property of a layer or strata using the determined property of at least the preceding strata or layer.

The method may comprise determining attenuation of the transmitted signal. The method may comprise determining the property of the sample using the attenuation of the transmitted signal by the sample.

The sample may comprise, form, or be comprised in the measurement sample.

Determining the viscosity of the measurement sample may comprise using properties of the reference member.

The transducer arrangement may comprise at least one transducer for receiving a transmitted signal that has passed though at least a portion of the sample.

The method may comprise determining the attenuation of the signal using the signal amplitude at the surface of the reference member and the amplitude of the signal after the signal has passed though at least a portion of the measurement sample.

The method may comprise taking the log or natural log of the ratio of the amplitude of the signal at the surface of the reference member and the amplitude of the signal after the signal has passed though at least a portion of the reference member and at least a portion of the measurement sample. The attenuation may be determined using: a=2o1oio9 where a is the attenuation in dB.m1, A1 is the amplitude of the signal at the interface between the reference member and the sample and A is the amplitude of the signal measured by the transducer arrangement after passing through at least a portion of the measurement sample.

The signal may comprise a signal having a specified frequency.

The method may comprise determining the kinematic viscosity of the measurement sample using the speed of the signal in the measurement sample, the attenuation of the signal by the measurement sample and the frequency of the signal. The speed of the signal in the measurement sample may be determined as described above.

The kinematic viscosity may be determined using the relation: = 5.79 la.2 where v is the kinematic viscosity of the sample in Stokes, a is the attenuation of the signal by the sample in dB.m1, is the frequency of the signal in Hz and v2' is the speed of the signal in the sample in m.s1.

The method may comprise determining the dynamic viscosity of the measurement sample, which may comprise determining the kinematic viscosity of the measurement sample, determining the density of the measurement sample and determining the dynamic viscosity of the measurement sample from the kinematic viscosity and density of the measurement sample. The density may be determined as detailed above.

The method may comprise providing an array of transducers for applying or transmitting the signal and/or an array of transducers for receiving the reflected and/or transmitted signal.

The method may comprise producing a property map, which may comprise properties of material located on pathways between the transducers for applying the signal and transducers for receiving the reflected and/or transmitted signals. The property may comprise a 2D and/or 3D property map.

According to a second aspect of the present invention, there is provided a measurement device, comprising a reference member and a transducer arrangement for applying a signal to the reference member such that the signal is transmitted through at least a portion of the reference member to a sample contact surface of the reference member, the transducer arrangement being adapted to measure a reflection or transmission of the signal.

The device may be adapted to implement a method according to the first aspect.

The device may be operable to determine a property of a sample, which may be contactable by the sample contact surface of the reference member.

The surface of the reference member may define an interface with the sample. The reflected signal may comprise a signal reflected from the interface between the reference member and the sample.

The transmitted signal may be a signal transmitted at least partially through the sample. The transmitted signal may be a signal transmitted though at least a portion of the reference member and sample.

The transducer arrangement may comprise at least one transducer.

The transducer arrangement may comprise at least one transducer for applying or transmitting the signal to the reference member. The transducer arrangement may comprise at least one transmitter for receiving the reflected signal.

Separate transducers may be operable to apply or transmit the signal to the reference member and collect the reflected signal.

The same transducer may be operable to apply or transmit the signal to the reference member and collect the reflected signal.

The transducer arrangement may comprise at least one transducer for measuring the transmitted signal.

The transducer for receiving the transmitted signal may be spaced apart from the transducer for applying the signal and/or the transducer for receiving the reflected signal.

The transducer arrangement may comprise a seismic signal generator, which may be an air gun, a plasma sound source, an impact device, a vibration source, a boomer, a piezoelectric vibration source or the like. The transducer arrangement may comprise a seismic signal receiver, such as a geophone, a hydrophone, a piezoelectric transducer or the like.

The reference member may define a coupling member. The transducer arrangement may be coupled with the reference member. The transducer arrangement may comprise the reference member. The reference member may be adapted to couple with the sample.

At least one transducer of the transducer arrangement may be spaced apart from at least one other transducer and/or the reference member.

The reference member may comprise a wall of a receptacle, such as a conduit or container, for receiving a sample. The receptacle may be a cylinder. The receptacle may be a pipeline.

The transducer for transmitting the signal and/or the transducer for receiving the reflected signal may be located outwith the receptacle, for example, on an exterior wall of the receptacle. The transducer for receiving the transmitted signal may be located within the receptacle.

The reference member may be formed from a material of known properties. The reference member may comprise stainless steel.

The reference member may be formed from a material of known impedance. The reference member may be formed from a material of known density and/or speed of sound.

The sample may comprise a layered structure. The sample may comprise or form at least part of a geological structure, which may comprise a geological stratum, rock, or the like, and or a liquid, such as oil and/or water.

The device may be arranged to determine one or more properties of the sample.

The device may comprise a processing module, which may be operable for generating and/or processing signals and/or determining one or more properties of the sample.

The device may be arranged to determine impedance and/or density and/or viscosity, which may be kinematic viscosity and/or dynamic viscosity. The device may be arranged to determine impedance and/or density and/or viscosity using the reflected signal and/or a transmitted signal.

The device may be arranged to determine the impedance of the sample using the signal applied or transmitted to the reference member and the reflected signal.

The device may be arranged to determine the speed of the signal in the sample. The device may be arranged to determine the speed of the signal in the sample using the transmitted signal.

The device may be arranged to perform a calibration.

The sample may comprise, form or be comprised in a reference sample.

In use, the transducer arrangement may be operable to provide a signal and measure amplitude of a reflected signal when the reference member is in contact with the reference sample.

The impedance and/or density and speed of sound in the reference sample may be known. The reference sample may be water. The reference sample may be oil.

The device may be arranged to determine the impedance of the reference member and/or the reference sample using the density and speed of sound in the reference member and/or reference sample respectively.

The device may be adapted to determine amplitude of the signal at a surface of the reference member, which may be a surface of the reference member opposite the transducer for transmitting the signal. In embodiments where the reference member is a receptacle, the surface may be an interior surface of the receptacle. The surface may be an interface between the reference member and the sample.

The device may be adapted to determine amplitude of the signal at a surface of the reference member using the interface of the reflected signal obtained when the reference member is in contact with the reference sample and the impedances of the reference member and the reference sample.

The sample may comprise, form or be comprised in a measurement sample.

The device may be adapted to provide a signal and to measure amplitude of a reflected signal when the reference member is in contact with the measurement sample using the first transducer.

The device may be adapted to determine the impedance of the measurement sample using the impedance of the reference member and/or the impedance of the reference sample and/or the amplitude of the reflected signal obtained when the reference member is in contact with the measurement sample and/or the amplitude of the signal at the surface of the reference member and/or the amplitude of the reflected signal obtained when the reference member is in contact with the reference sample.

The device may be operable to determine the speed of the signal in the measurement sample.

The device may be adapted to determine the speed of sound in the sample using a measurement of the time taken for a signal to propagate from the transducer for transmitting the signal to the transducer for receiving the reflected and/or transmitted signal.

Determining the speed of sound in the sample may comprise determining the time taken for the signal to propagate through the reference member.

Determining the speed of sound in the sample may comprise subtracting the time taken for the signal to propagate through the reference member from the time taken for a signal to propagate from the transducer for transmitting the signal to the transducer for receiving the reflected and/or transmitted signal to thereby determine the time taken for the signal to propagate through the measurement sample and thereby the speed of sound in the measurement sample.

The device may comprise a reflection member, wherein the reference member and at least part of the measurement sample are located or locatable between the first transducer and the reflection member. The device may be adapted to determine the speed of sound in the sample using a measurement of the time between provision of the signal and detection of a reflection of the signal from the reflection member. The reflection member may comprise a surface of the reference member.

The device may comprise two or more transducers separated from each other by a specified distance. The device may be adapted to determine the time taken for the signal to travel to each of the two or more second transducers and thereby determine the speed of sound in the measurement sample.

The device may be arranged to determine the density of the measurement sample using the impedance of the sample and the speed of sound in the measurement sample.

The device may be arranged to determine viscosity using the signal at a surface of the reference member and the signal measured by the transducer for receiving the transmitted signal.

The device may be adapted to determine the attenuation of a signal by the measurement sample. The device may be adapted to determine the attenuation of a signal by the measurement sample from the amplitude of the signal at the surface of the reference member and the amplitude of the signal after passing through the measurement sample.

The device may be adapted to determine the kinematic viscosity of the measurement sample using the speed of sound in the measurement sample, the attenuation of the signal by the measurement sample and the frequency of the signal.

In embodiments where the measurement sample comprises or is part of a layered structure, the device may be adapted to determine the properties of a plurality of measurement samples, which may comprise or be part of the plurality of layers or strata. The device may be adapted to sequentially determine a property of a layer or stratum and use the determined property to determine a property of a subsequent stratum or layer.

The device may comprise an array of transducers for applying or transmitting the signal and/or an array of transducers for receiving the reflected and/or transmitted signal.

The device may be adapted to produce a property map, which may comprise properties of material located on pathways between transducers for applying the signal and transducers for receiving the reflected and/or transmitted signals. The property map may comprise a 2D and/or a 3D property map.

The device may be adapted to, or operable in, control of drilling apparatus and/or a process.

According to a third aspect of the present invention is a calibration method for calibrating a device according to the second aspect and/or a device for use in the method of the first aspect, the calibration method comprising providing a reference sample in contact with a reference member, applying a signal to the reference member, receiving a reflected signal and determining a property of the signal at an interface between the reference member and the sample using the reflected signal.

The property of the signal at an interface between the reference member and the sample may be amplitude.

The reference member may define a receptacle, such as a container or conduit, for example, a pipe. The reference member may comprise stainless steel.

The method may comprise providing a transducer arrangement for applying the signal and receiving the reflected signal. The transducer arrangement may comprise at least one transducer.

The transducer arrangement may comprise at least one transducer for applying the signal and receiving the reflected signal. The transducer arrangement may comprise at least one transmitter for receiving the reflected signal.

The transducer arrangement may comprise at least one transducer for measuring a transmitted signal. The transmitted signal may be a signal transmitted through at least a portion of the sample. The transmitted signal may be a signal transmitted through at least a portion of the reference member and reference sample.

The reference member may comprise a layer of a layered structure. The reference member may comprise a geological structure, such as a geological stratum, rock, or the like. The reference member may comprise a liquid, such as oil or water, which may comprise at least at least a portion of body of water such as a sea, lake, river, or the like.

The reference sample may comprise or form at least part of a layered structure. The reference sample may comprise or be part of a geological structure, such as a geological stratum, rock, or the like, which may be a different geological stratum, rock, or the like from that of the reference member. The reference sample may comprise a liquid, such as oil or water, which may comprise one or more layers of liquid comprised in or disposed between geological strata.

The reflected signal may be a signal reflected from the interface between the reference member and the reference sample.

The impedance and/or density and speed of sound in the reference sample may be known, determined or estimated.

The method may comprise determining the impedance of the reference member and/or the reference sample using the density and speed of sound in the reference member or reference sample respectively. The impedance may be determined using the relation: Z=pv where Z is the impedance, p is the density and v is the speed of sound in the reference member.

The method may comprise determining the signal amplitude at a surface of the reference member, which may be a surface of the reference member opposite the transducer for transmitting the signal. In embodiments where the reference member is a receptacle, the surface may be an interior surface of the receptacle. The surface may be an interface between the reference member and the sample.

The method may comprise determining the signal amplitude at the surface of the reference member using the impedance of the reference member, the impedance of the reference sample and the amplitude of the reflected signal. The method may comprise determining the signal amplitude at the surface of the reference member using the relation: A (Z2+Z1)A 1 (Z2-Z1) 2 where A1 is the impedance at the surface of the reference member, A2' is the measured amplitude of the reflected signal, Z1 is the impedance of the reference member and Z2 is the impedance of the reference sample.

In embodiments where the reference sample comprises a layered structure or is a layer of a layered structure, the method may comprise providing a plurality of reference samples, wherein each reference sample comprises a layer of the layered structure.

The method may comprise collecting reflections from a plurality of interfaces between the reference materials. The method may comprise determining the signal amplitude at the plurality of interfaces. The method may comprise sequentially determining the amplitude at adjacent interfaces starting from the interface between the reference member and a reference sample adjacent the reference member. The method may comprise using the signal amplitude at an interface using a reflected signal associated with the interface and a determined signal amplitude at a preceding interface.

According to a fourth aspect of the present invention is a computer program product for implementing any of the first to third aspects.

According to a fifth aspect of the present invention is an apparatus or carrier medium comprising or programmed with the computer program product of the fourth aspect.

The apparatus may be a computer.

It will be appreciated that features described above in relation to the first to fifth aspects described above may be applicable to, or may be implemented by, other of the first to sixth aspects.

Description of the Drawings

Various aspects of the invention will now be described by way of example only and with reference to the accompanying drawings, of which: Figure 1 is a schematic of a measurement device according to an embodiment of the invention; Figure 2 is a flowchart showing a method for determining the amplitude of a signal at an interface between a reference member and a sample using the device of Figure 1; Figure 3(a) is a schematic showing the operation of the measurement device of Figure 1 during a calibration operation; Figure 3(b) is a schematic showing the operation of the measurement device of Figure 1 during a measurement operation Figure 4 is a flowchart showing a method for the determining the density of a sample using the device of Figure 1; Figure 5 is a flowchart showing a method for determining the viscosity of a sample using the device of Figure 1; Figure 6(a) is a schematic of a measurement device according to an embodiment of the present invention; Figure 6(b) is an example of reflected signals received by a transducer arrangement of the measurement device of Figure 6(a); Figure 7 is a schematic of an alternative configuration of the measurement device of Figure 6(a); Figure 8 is a schematic of an alternative configuration of the measurement device of Figure 6(a); Figure 9 is a schematic of a measurement device according to an embodiment of the present invention; Figure 10 is a schematic an alternative configuration of the measurement device of Figure 9; Figure 11 is a schematic of an alternative configuration of the measurement device of Figure 1; and Figure 12 is a schematic of an alternative configuration of the measurement device of Figure 1.

Specific Description

Figure 1 shows a first embodiment of a measurement device 5 comprising a first ultrasonic transducer 10, a second ultrasonic transducer 15 and a reference member in the form of a cylinder 20, for example, a section of pipe. The first transducer 10 is arranged on an exterior surface of a wall 25 of the cylinder and adapted to apply a signal to the cylinder 20. The second transducer 15 is located within the cylinder 20, a distance D from the cylinder wall 25. The second transducer is shown in dashed line in Figure 1 to indicate that it is within the cylinder 20.

The cylinder 20 is formed from a material, such as stainless steel, whose properties are known. In particular, the cylinder 20 is of known diameter, thickness and density and the speed of sound travelling in the material of the cylinder 20 is known.

The transducers are operable under the control of a processing module 30, which is arranged to control the signal produced by the first transducer 10 and process the output produced by the first and second transducers 10, 15. The processing module 30 comprises a processor 35 for controlling the device 5, the processor 35 being operably connected to a signal generator 40 for generating a signal for driving the first transducer under the control of the processor 35, memory 45 for storing measurement results and data for use by the processor 35 and communications module 50 for providing communications with the user and for communicating with remote systems, such as centralised databases to obtain and/or provide data and measurement results.

The device 5 is operable under the control of the processing module 30 to generate ultrasonic signals using the first transducer, measure transmitted and reflected signals using the second and first transducers respectively and process the measurements to determine physical properties of materials, such as the density and viscosity of samples provided within the cylinder 20.

In use, the device 5 is arranged such that it can be calibrated in-situ.

Although the first transducer 10 may be controlled by the processing module to produce a defined ultrasonic signal, in practice, some of the signal may be lost or distorted such that the signal generated by the signal generator 40 may vary from the signal received by the sample from the internal surface of the cylinder 20.

Additionally, the signal produced may change over time due, for example, to aging of the equipment or changing environmental conditions. In order to account for these effects, a calibration 55 may be performed, as detailed in Figure 2. The calibration involves determining the amplitude of the signal at the interior surface of the cylinder, i.e. the signal actually applied to any sample within the cylinder.

The cylinder 20 is filled with a reference sample at step 60. The reference sample comprises a material having known impedance.

Alternatively, the reference sample may have known density and the speed of sound in the reference sample is known. In this case, the impedance of the reference sample may be calculated using: Z2=p2v2 where Z2 is the impedance of the reference sample, P2 is the density of the reference sample and v2 is the speed of sound in the reference sample.

For example, the reference sample may be water.

In step 65, which is diagrammatically illustrated in Figure 3(a), the first transducer 10 is operable to apply an ultrasonic signal 11 of amplitude A and known frequency w to the cylinder 20. The signal 11 passes through the cylinder wall 25. At the interface 26 between the cylinder wall 25 and the reference sample 27, some of the signal 11 is reflected and some of the signal 11 is transmitted through the reference sample 27. The component 28 of the signal that is reflected from the interface 26 between the cylinder waIl 25 and the reference sample 27 has an amplitude A2 whilst the component 29 of the signal that is transmitted into the reference sample has an amplitude T. The reflected component 28 of the signal is measured using the first transducer 15 in step 70 and the amplitude A2 of the reflected component of the signal is determined in step 75.

In step 80, the processing module 30 is then operable to acquire the impedance Z1 of the cylinder wall 25, acquire the impedance Z2 of the reference sample 27 (or to calculate it, as detailed above). The processing module 30 is operable to use the impedances Z1, Z of the cylinder wall 25 and the reference sample 27 and the measured amplitude A2 of the reflected component 28 of the signal to determine the amplitude A1 of the input signal at the internal surface 26 of the cylinder 20, i.e. the signal actually provided to the sample, using the relation: A (Z2+Z1)A 1 (Z2-Z1) 2 The amplitude A1 of the input signal at the internal surface of the cylinder 25 is then stored in the memory 45 for use by the device 5 until the next time the calibration process is carried out.

The respective impedances Z1, Z of the reference sample 27 and the cylinder wall (or the density and speed of sound data used to calculate them) may be pre-provided, for example, in the memory 45 of the processing module 30 in the form of a look up table. Alternatively, the impedances Z1, Z2 may be obtained from a remote database (not shown) via the communications module 50 over a network or input by a user using an input device (not shown).

The device 5 is operable to determine the density of a measurement sample 51, as shown in Figures 3(b) and 4. The measurement sample 51, which may be an unknown material, is provided in the cylinder 20, as indicated in step 85 of Figure 4.

The first transducer 10 is operable to produce a signal 11 equivalent to that produced in the calibration process in step 90. The signal 52 reflected from an interface 53 between the cylinder wall 25 and the measurement sample 51 is measured by the first transducer 10 in step 95 and the amplitude A2' of the reflected signal 52 is determined in step 100, i.e., the signal provision and measurement process carried out during calibration is repeated, only with the measurement sample 51 in the cylinder, rather than the reference sample 27.

Using the value of the amplitude A1 of the input signal at the internal surface of the cylinder 20 as determined by the most recent calibration and stored in the memory 45 of the processing module 30, the amplitude A2' of the signal 52 reflected from the interface 53 between the cylinder wall 25 and the measurement sample 51, and the impedance Z1 of the cylinder wall 25, the processing module is then operable to determine the impedance Z2'of the measurement sample 51 using the relation: (A1 -A2) The speed of sound in the cylinder wall 25 is known and can be, for example, estimated or pre-stored in the memory 45 of the processing module 30 or retrieved by the processing module 45 from a database (not shown) over a communications network using the communications module 40 or input by the user.

At least a portion 54 of the signal, having an amplitude T', travels through the measurement sample 51 and is detected by the second transducer 15. The time that the signal 11 is initiated is recorded in the memory 45 and the time that the transmitted portion 54 of the signal arrives at the second transducer 15 is determined and stored in the memory 45. In step 105 the processing module 30 is operable to determine the speed of sound v2' in the measurement sample 51 using the time of flight of the signal from the first transducer 1 0 to the second transducer 15 using the relation:

D V2 =

df.eJ me/ni)

-_______

Vrefmemb where D is the distance between the second transducer 15 and the cylinder wall 25, ttof is the transit time of the signal between the first transducer 1 0 and the second transducer 15, dref memb is the thickness of the cylinder wall 25 and Vref memb is the speed of sound in the cylinder wall 25. The determined speed of sound in the measurement sample 51 is then stored in the memory 45 of the processing module 30.

As the processing module 30 has determined and stored both the impedance Z2' of the measurement sample 51 and the speed of sound v2' in the measurement sample 51, in step 110 the processing module 30 is operable to determine the density P2' of the measurement sample 51 using the relation: z2 P2. V2

The device 5 is also operable to determine the viscosity of the measurement sample 51, as detailed below, with reference to Figure 5.

A calibration process 55-80 is carried out as detailed above in relation to Figure 3(a) in order to obtain the amplitude A1 of the input signal at the internal surface of the cylinder 20, which is stored in the memory 45 of the processing module 30.

Measurements of viscosity are carried out on a sample in the cylinder 20 as indicated at step 115 of Figure 5 with reference to Figure 3(b). At step 1 20, the first transducer 10 is operable under the control of the processing module 30 to transmit an ultrasonic signal 11 having a specified frequency to the cylinder wall 25. The signal 11 is substantially the same as that used during the calibration process 55-80. A portion 54 of the signal 11 is transmitted through the cylinder wall 25 and through the measurement sample 51, whereupon it is detectable by the second transducer 15 at step 125.

The processing module 45 is also operable to determine the amplitude T' of the transmitted signal 54 as received by the second transducer 15 at step 130. The processing module 45 is operable to use the determined amplitude T' of the transmitted signal 54 and the amplitude A1 of the input signal at the internal surface of the cylinder wall 25 as determined during the calibration process 55-80, in order to determine the attenuation of the signal using the relation: (2o (F a = ---loio--where a is the attenuation co-efficient in dB.m1 and 0 is the distance between the second transducer 15 and the cylinder wall 25.

The processing module 45 is adapted to determine the time taken for the signal to be transmitted between the first and second transducers 10, 15 at step 135. The processing module 45 is also operable to determine the speed of sound v2' in the measurement sample using the time between the signal being emitted by the first transducer 10 and being received by the second transducer 15, as detailed above.

At step 140, for low frequencies of signal (i.e. less than 1GHz), the processing module 30 is operable to use the attenuation a, speed of sound v2' in the measurement sample 51 and frequency w of the signal to determine the kinematic viscosity v of the measurement sample 51 using the relation: v= 5.79 12 It will be appreciated that an equivalent expression in terms of Nepers.m1 rather than dB.m1 could be used, for example the determination of the attenuation coefficient becomes: (8.686 (T' in H-D) eA where a has units of Nepers.m1 and the corresponding determination of viscosity becomes: = The device 5 is operable to determine dynamic viscosity (1u) of the measurement sample 51 by determining both the density (p) and kinematic viscosity (v) of the measurement sample 51 using the methods as detailed above and determining the dynamic viscosity p of the measurement sample 51 using the relation: 1u=vp.

A second embodiment of a measurement method and device 600 is shown in Figures 6 to 8. This embodiment relates to a method and device for use in seismic investigations.

Figure 6(a) shows a device 600 comprising a transducer arrangement 605, arranged to produce and receive seismic signals. The transducer arrangement 605 comprises a plurality of transducers, at least one of which is operable as a seismic signal generator 605a and at least one of which is operable as a seismic signal receiver 605b. Optionally, the same transducer may be operable as both the seismic signal generator 605a and seismic signal receiver 605b.

The seismic signal generator 605a is arranged to apply a seismic signal 610 to a reference member 615. The reference member 615 is formed from a material of known impedance or whose impedance may be calculated, as described above in relation to the first embodiment.

In an optional embodiment, as shown in Figure 6(a), the device 600 comprises the reference member 615. For example, the reference member 615 is a planar member formed from a material having known properties, such as a stainless steel plate, whose impedance and thickness are accurately known.

In an optional embodiment, as shown in Figure 7, the reference member 615 is a surface stratum of a layered geological formation and the transducer arrangement 605 is arranged to provide signals directly to, and receive signals from, the surface stratum. The surface stratum is a layer of the geological formation that has an exposed surface to which the transducer arrangement 605 may be directly coupled.

The impedance of the surface stratum is known or estimated. Alternatively, the density of, and speed of sound in, the surface stratum is known and the impedance of the surface stratum can be determined as described above in relation to the first embodiment.

In an optional embodiment, as shown in Figure 8, the transducer arrangement 605 is provided in or on the surface of a body of liquid, such as the sea or a lake. The impedance and separation between the transducer arrangement and the sea or lake bed is known or may be calculated. In this way, the device 605 is operable using the body of liquid as the reference member 615.

The reference member 615 is located such that it is in contact with a geological formation comprising vertically layered strata 620a to 620d. It will be appreciated that the strata may comprise varying rock types, sand or the like and/or may comprise a liquid such as oil, water or the like.

The transducer arrangement 605 is operable to apply a seismic signal 610 to the reference member and thereby to the geological formation. The signal 610 is transmitted through the reference member 615 to the stratum 620a of the geological formation adjacent the reference member 615. The signal 610 is partially reflected at the interface between the reference member 615 and the adjacent stratum 620a to give a reflected signal 61 Oa and a transmitted signal 61 Ob.

The reflected signal 610a is detected and measured by the transducer arrangement 605. The transducer arrangement 605 receives time separated reflected signals 610a-610c from the interfaces between each of respective strata 620a-620c, as shown in Figure 6(b).

This reflected signal 610a may be used along with the impedance of the reference member 610 to determine the impedance of the stratum 620a. The impedance of the stratum 620a may then be used along with an estimation or determination of the speed of the signal 61 Oa in the stratum 620a to determine the density of the stratum 620a, as detailed above in relation to the first embodiment.

It will be appreciated that it is possible to extend this analysis to subsequent strata 620b, 620c, etc., using the reflected signals from each of these strata 620b, 620c, and properties determined in relation to preceding strata 620a, such as impedance, signal amplitude at interfaces and/or signal speed, in determining the impedance and/or the density of the subsequent strata 620b, 620c. In this regards, the preceding stratum 620a may be considered as part of a reference member when determining the properties of the stratum 620b adjacent to it. In this way, once the properties of each stratum 620a are determined, then that stratum 620a may be considered as part of a reference member of known properties in determining the properties of an adjacent stratum 620b using the signal 610b reflected from the interface between the stratum 620a whose properties have already been determined and the stratum 620b having unknown properties.

It will be appreciated that some of the required properties may be estimated from typical or known data for a particular stratum or be calculated by other methods known in the art.

In a third embodiment, as shown in Figure 9, a measurement device 905 is provided in a crosshole arrangement. In this arrangement, transducer arrangement 910a, 910b is split between two bores 915a, 915b. Transducer arrangement 910a for transmitting signals arid receiving reflected signals is provided in the first bore 91 5a, whilst transducer arrangement 91 Ob for receiving the transmitted signals is provided in the second bore. In this way, the device 905 is operable to determine properties such as density, viscosity and impedance of structure 920 lying between the two bores 915a, 915b. This device 905 and method is particularly suitable for seismic applications where the structure 920 is a geological structure.

It will be appreciated that although the above example is described in terms of one transducer array 915a transmitting signals and another transducer array 915b receiving the signals, it will be appreciated that either of the transducer arrays may optionally function as transmitters and/or receivers.

In an optional variation of the device 905', at least one, and optionally both, of the transducer arrangement 910a', 910b' may comprise arrays of transducers, as shown in Figure 10. In this way, signals may be transmitted or provided from selected transducers of the transducer arrays 910a', or 910b'. Transmitted and/or reflected signals may be detected by transducers from the transducer arrays 91 Oa', or 91 Ob'.

In this way, it may be possible to determine the properties of a structure 920 between the bores 915a, 915b along defined paths 925 between the transducers of the transducer arrays 910a', 910b'. Such a technique is usable to construct a 2D property map of properties of regions of the structure 920 between the bores 915a, 915b and along the paths between the transducers of the transducer arrays 910a'.

910b'.

It will be appreciated that the signals may be provided using a variety of techniques, such as time division multiplexing, frequency division multiplexing and code division multiplexing, which allow signals from various transducers to be separated from each other.

It will be appreciated that one or more further bores 915c may be provided and transducer arrays 910c' may be provided in these further bores 915c. If these further bores 915c are placed outwith the plane formed by the first and second bores 915a, 915b, then the device 905' may be operable to produce a 3D property map of the structure between the bores 915a, 915b and 915c.

It will also be appreciated that this 2D and 3D property mapping technique may be applied to other applications of the measurement device arid method. For example, the cylinder 20 of the device 5 of the first embodiment may be provided with arrays of first 10' and/or second transducers 15', as shown in Figure 11.

Figure 11 shows an example of a 2D property mapping arrangement, wherein a plurality of first transducers 1 0' are located circumferentially around the outside of the cylinder 20. In this way, a 2D map of the properties of material flowing within the cylinder 20 may be determined.

This may be particularly useful in analysing multi-component flow systems, for example, in mixed flow systems comprising components such as oil, water and/or air.

If a substantially horizontal cylinder 20 is provided, the components of the flow may stratify as they flow through the cylinder. By providing first and/or second transducer arrangements 10', 15' in the form of a transducer array, properties, such as density, viscosity and/or impedance, of each of the stratified layers and thereby each of the components of the multi-component flow may be analysed. The device 5' may be adapted to repeat the determination at regular time intervals and time evolution of the flow can be determined, which may include a time evolved characterization of each of the components of the flowing material and/or time evolved determination of properties of the components and any changes therein.

Although the above example shows only the first transducer arrangement 10' being in the form of a transducer array, it wiJI be appreciated that only a single first transducer 10 may be provided and an array of second transducers 15' may be used instead. Similarly arrays of both first 10' and second 15' transducers may be used.

Furthermore, although the transducer arrays 10', 15' are described as being circumferentially extending, it will be appreciated that the arrays 10', 15' may extend in other dimensions such as along the length of the cylinder 20' or obliquely or helically around the cylinder 20.

Additionally, it will also be appreciated that one or both of the first and/or second transducer arrays 10', 15' may extend along the length of the cylinder 20 as well as extending circumferentially, as shown in Figure 12. In this way, 3D property maps and/or time evolved determination of the properties of the flowing material may be determined.

A skilled person will also appreciate that variations of the disclosed arrangements are possible without departing from the invention.

Although one method for determining the speed of sound in the sample has been described above, it will be appreciated that other methods of determining the speed of sound in the sample may be used.

For example, the device 5, 5', 600, 905, 905' may be provided with a reflection member for reflecting signals, positioned such that the reference member and at least part of the sample are locatable between the first transducer 10 and the reflection member. In this way, the time elapsing between emission of the signal by the first transducer 10 and receipt of the signal reflected from the reflection member may be used to determine the speed of sound in the sample. It will be appreciated that the reflection member may be another surface or wall or part of the reference member.

As a further example of a possible method for determining the speed of sound in the sample, the device 5, 5', 600, 905, 905' may comprise two or more second transducers 15, wherein each of the second transducers 15 is spaced apart from adjacent second transducers 15 by a set distance dtrans. In this way, when determining the speed of sound in the sample, the speed of sound in the sample v2' can be determined using the relation V2' = 2dtrans/(t2t1), where t1 and t2 are the two way travel times for the signal between the respective second transducers 15 and the reference member. Using this technique, the distance from the reference member to the second transducers 15 may be arbitrary.

The physical properties determined by the device 5, 5', 600, 905, 905' may be used for various purposes such as process control, quality control and/or material characterisation.

For example, the device 5, 5', 600, 905, 905' may be used to feed back viscosity and/or density measurements to a process controller (not shown), such that the process controller is operable to alter a parameter of a process, such as temperature, flow rate, pump rate or stirring rate, in order to achieve a viscosity and/or density within a target window.

As another example, the device 5, 5', 600, 905, 905' may compare the viscosity and/or density measurements with characteristic data in order to identify or characterise the material in the cylinder.

For example, the device 5, 5', 600, 905, 905' may be adapted to characterize rock formations and/or oil bearing formations and/or produce property maps. This may be used to identify and locate potential oil bearing formations. In another example, the device 5, 5', 600, 905, 905' is operable to control and/or guide a drilling operation, for example, to take into account the properties of rock formations and/or to guide it towards the potential oil bearing formations.

Further applications of the device may be for use in determining characteristics of multiple layers within a pipe. Also, one or more of the various embodiments defined above may be configured for use in determining characteristics of material flowing within a pipe.

Although the device 5, 5', 600, 905, 905' has been described in relation to its application to process control, material characterization and quality control, it will be appreciated that the device 5, 5', 600, 905, 905' may be used for any suitable application known in the art.

Although the transducers are described as being ultrasonic transducers, it will be appreciated that other transducer systems may be used, such as optical, electric

field, magnetic field or microwave based systems.

Furthermore, whilst the reference member has been exemplified as being a cylinder, which may be a section of pipeline, it will be appreciated that other reference members having other configurations, materials, shaped and/or structures may be used. For example, the reference member may be a planar member or a wall of a tank or reactor.

In addition, whilst the reference member is described as being composed of stainless steel and the reference material as being water, it will be appreciated that other materials may be used, conditional on the required properties of the materials are accurately known.

In embodiments described above, determination of properties from measurements of the transducers is described as being carried out by a processing module. However, it will be appreciated that this is merely a preferred implementation option arid other implementation options may be available to implement the functionality described above in relation to the processing module. For example, such features could be provided by a dedicated circuit or other suitable electronics, by a microcontroller or a computer based system. Similarly, it will be appreciated that the exact equations provided are merely implementation options and other means of processing the measurements obtained by the transducers are possible.

Furthermore, determination of properties of subsequent strata 620b, 620c, etc. Using reflected signals from the subsequent strata 620b, 620c and the properties determined in relation to previous strata is described in relation to application of the method and apparatus to seismic applications. However, it will be appreciated that this approach may be used in other applications, for example, in determining the properties of layers of materials in a laminar flow in the cylinder of the first embodiment.

Although, in embodiments described above, the second transducer 15 is spaced apart from the cylinder wall 25, it will be appreciated that the second transducer may be embedded in the cylinder wall.

Accordingly the above description of the specific embodiment is made by way of example only and not for the purposes of limitation. It will be clear to the skilled person that minor modifications may be made without significant changes to the operation described.

Claims

CLAIMS: 1. A method for determining a property of a sample, comprising: providing a reference member in contact with a sample; applying a signal to the reference member; measuring a reflection of the signal from an interface between the reference member and the sample and/or a transmitted signal that has been transmitted at least partially through the sample; and determining a property of the sample using the measurement of the reflection of the signal and/or the transmitted signal.
2. The method according to claim 1, wherein the property comprises at least one of density, viscosity and impedance.
3. The method according to claim 1 or 2, comprising using a transducer arrangement for applying or transmitting the signal to the reference member.
4. The method according to claim 3, comprising receiving the reflection of the signal by the transducer arrangement
5. The method according to claim 3 or 4, wherein the transducer arrangement comprises an ultrasonic transducer and the signal comprises sound.
6. The method according to claim 3, 4 or 5, wherein the transducer arrangement comprise a seismic signal generator.
7. The method according to any one of claims 3 to 6, wherein the transducer arrangement comprises a seismic signal receiver.
8. The method according to any preceding claim, comprising determining the properties of the reference member, including at least one of impedance, the speed of the signal in the reference member and density of the reference member.
9. The method according to any preceding claim, wherein the reference member defines a receptacle configured to receive the sample.
10. The method according to any preceding claim, wherein the reference member comprises a layer or stratum of a layered structure.
11. The method according to any preceding claim, wherein the sample comprises a layer or stratum of a layered structure.
12. The method according to any preceding claim, wherein the sample comprises or forms at least part of a geological structure.
13. The method according to any preceding claim, comprising performing a calibration, wherein the sample comprises a reference sample and the calibration comprises: providing the reference sample in contact with the reference member; applying a signal to the reference member whilst the reference member is in contact with the reference sample; and measuring the amplitude of a reflection of the signal reflected from an interface between the reference member and the reference sample whilst the reference member is in contact with the reference sample.
14. The method according to claim 13, wherein the calibration provides at least one of the impedance, density and speed of sound in the reference sample may be known, previously determined and/or estimated.
15. The method according to claim 13 or 14, wherein the calibration comprises determining the impedance of the reference member and/or the reference sample using the density and the speed of the signal in that material.
16. The method according to claim 13, 14 or 15, wherein the calibration comprises determining the amplitude of the signal at a surface of the reference member defined at an interface between the reference member and the reference sample.
17. The method according to claim 16, wherein the calibration comprises determining the signal amplitude at the surface of the reference member using the impedance of the reference member, the impedance of the reference sample and the amplitude of the reflected signal.
18. The method according to any preceding claim, comprising: applying a signal to the reference member whilst the reference member is in contact with the measurement sample; measuring the amplitude of a reflected signal reflected from an interface between the reference member and measurement sample; and determining the impedance of the measurement sample.
19. The method according to claim 18, wherein determining the impedance of the measurement sample comprises the amplitude of the signal at the surface of the reference member and/or the amplitude of the reflected signal obtained when the reference member is in contact with the reference sample and/or the amplitude of the reflected signal obtained when reference member is in contact with the measurement sample and/or the impedance of the reference member.
20. The method according to claim 19, wherein the amplitude of the signal at the surface of the reference member is determined using a calibration method.
21. The method according to any preceding claim, comprising determining the speed of the signal in the measurement sample.
22. The method according to claim 21, wherein determining the speed of the signal in the measurement sample comprises measuring the time taken for a signal to travel from a transducer for transmitting the signal, via at least part of the sample to a transducer for receiving the signal.
23. The method according to any preceding claim, comprising determining the density of the measurement sample using the impedance of the measurement sample and the speed of sound in the measurement sample.
24. The method according to any preceding claim, comprising providing a plurality of measurement samples, the or each measurement sample forming at least one layer or stratum of a layered structure.
25. The method according to claim 24, wherein each layer or stratum comprises a material having at least one physically distinct property.
26. The method according to claim 24 or 25, wherein the layered structure comprises or forms at least part of a geological structure.
27. The method according to claim 24, 25 or 26, comprising collecting a plurality of reflected signals reflected from a plurality of interfaces between strata or layers.
28. The method according to claim 27, comprising determining a property of the plurality of measurement samples using the plurality of reflected signals.
29. The method according to any one of claims 24 to 28, comprising sequentially determining the property of layers or strata.
30. The method according to any preceding claim, comprising determining attenuation of the transmitted signal.
31. The method according to claim 30, comprising determining a property of the sample using the attenuation of the transmitted signal by the sample.
32. The method according to claim 30 or 31, comprising determining the attenuation of the signal using the signal amplitude at the surface of the reference member and the amplitude of the signal after the signal has passed though at least a portion of the measurement sample.
33. The method according to claim 30, 31 or 32, comprising determining the attenuation of the signal by taking the log or natural log of the ratio of the amplitude of the signal at the surface of the reference member and the amplitude of the signal after the signal has passed though at least a portion of the reference member and at least a portion of the measurement sample.
34. The method according to any preceding claim, wherein the signal comprises a signal having a specified frequency.
35. The method according to any preceding claim, comprising determining the kinematic viscosity of the measurement sample using the speed of the signal in the measurement sample, the attenuation of the signal by the measurement sample and the frequency of the signal.
36. The method according to any preceding claim, comprising providing an array of transducers for applying or transmitting the signal and/or an array of transducers for receiving the reflected and/or transmitted signal.
37. The method according to claim 37, comprising producing a property map which comprises properties of material located on pathways between the transducers for applying the signal and transducers for receiving the reflected and/or transmitted signals.
38. The method according to any preceding claim, comprising determining a property of a sample within a pipe.
39. The method according to any preceding claim, comprising determining a property of a sample flowing through a pipe.
40. A measurement device, comprising a reference member and a transducer arrangement for applying a signal to the reference member such that the signal is transmitted through at least a portion of the reference member to a sample contact surface of the reference member, the transducer arrangement being adapted to measure a reflection or transmission of the signal.
41. The measurement device according to claim 40, adapted to implement a method according to any one of claims 1 to 39.