U.S. patent application number 14/123000 was filed with the patent office on 2014-03-27 for x-ray tomography device.
This patent application is currently assigned to UNIVERSITE DE PAU ET DES PAYS DE L'ADOUR. The applicant listed for this patent is Patrice Creux, Gerald Hamon. Invention is credited to Patrice Creux, Gerald Hamon.
Application Number | 20140086385 14/123000 |
Document ID | / |
Family ID | 46201672 |
Filed Date | 2014-03-27 |
United States Patent
Application |
20140086385 |
Kind Code |
A1 |
Creux; Patrice ; et
al. |
March 27, 2014 |
X-RAY TOMOGRAPHY DEVICE
Abstract
An X-ray tomography device for providing a 3D tomography image
of a sample comprising a X-ray source, a cell, a photon detector
and a processing unit. The X-ray source is monochromatic and has a
photon beam solid angle higher than 0.1 degree. The processing unit
computes the 3D tomography image on the basis of acquired images
corresponding to a plurality of cell angles.
Inventors: |
Creux; Patrice; (Lescar,
FR) ; Hamon; Gerald; (Pau, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Creux; Patrice
Hamon; Gerald |
Lescar
Pau |
|
FR
FR |
|
|
Assignee: |
UNIVERSITE DE PAU ET DES PAYS DE
L'ADOUR
Pau
FR
TOTAL SA
Courbevoie
FR
|
Family ID: |
46201672 |
Appl. No.: |
14/123000 |
Filed: |
June 1, 2012 |
PCT Filed: |
June 1, 2012 |
PCT NO: |
PCT/EP2012/060439 |
371 Date: |
November 27, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61492268 |
Jun 1, 2011 |
|
|
|
61492272 |
Jun 1, 2011 |
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Current U.S.
Class: |
378/19 |
Current CPC
Class: |
G01N 2223/419 20130101;
G01N 23/046 20130101 |
Class at
Publication: |
378/19 |
International
Class: |
G01N 23/04 20060101
G01N023/04 |
Claims
1. An X-ray tomography device for providing a 3D tomography image
of a sample, said device comprising: a X-ray source (2) emitting a
photon beam in the direction of a beam axis, said X-ray source
being a near monochromatic source and said photon beam having a
solid angle higher than 0.1 degree around said beam axis, a cell
(3) adapted to include a porous sample to be imaged, said cell
being situated inside the photon beam and being able to rotate
around a cell axis that is substantially perpendicular to the beam
axis, and being adapted to enable the porous sample to be flooded
by at least one fluid, a photon detector (4) receiving a
transmitted photon beam that is transmitted through said cell, said
photon detector providing at least one acquired image for each
angle of a plurality of cell angles, and said acquired images being
taken during a length of time lower than ten minutes, and a
processing unit (5) that computes the tomography image on the basis
of the acquired images corresponding to the plurality of cell
angles.
2. The X-ray tomography device according to claim 1, wherein the
monochromatic and highly brilliant X-ray source is a compact light
source using a collision between a laser beam and an opposing
electron beam.
3. The X-ray tomography device according to claim 1, wherein the
length of time for the volume analysis is lower than one
minute.
4. The X-ray tomography device according to claim 1, wherein the
processing unit is computing the tomography image during a time
period lower than the length of time of used for producing the
acquired images corresponding to the plurality of cell angles.
5. The X-ray tomography device according to claim 1, wherein the
cell has a size comprised in the range of 0.3 cm to 20 cm, and
preferably in the range of 0.6 cm to 10 cm.
6. The X-ray tomography device according to claim 1, wherein the
cell is made of a material in a list comprising the beryllium,
beryllium alloys, and a carbon-carbon composite.
7. The X-ray tomography device according to claim 1, wherein the
cell comprises means for heating the sample to a temperature higher
than 650.degree. Celsius and means for pressuring the cell to a
pressure higher than 1000 bars,
8. The X-ray tomography device according to claim 1, wherein the
photon detector comprises a CCD of at least ten megapixels.
9. The X-ray tomography device according to claim 1, further
comprising a grating based interferometer situated between the cell
and the photon detector.
10. The X-ray tomography device according to claim 1, further
comprising a microscope situated between the cell and the photon
detector.
Description
PRIORITY CLAIM
[0001] The present application is a National Phase entry of PCT
Application No. PCT/EP2012/060439, filed Jun. 1, 2012, which claims
priority from U.S. Provisional Patent Application No. 61/492,268,
filed Jun. 1, 2011, and U.S. Provisional Patent Application No.
61/492,272, filed Jun. 1, 2011, said applications being hereby
incorporated by reference herein in their entirety.
FIELD OF THE INVENTION
[0002] The present invention concerns an X-ray tomography
device.
BACKGROUND OF THE INVENTION
[0003] The present invention concerns an X-ray tomography device
adapted to petrophysics application, such as to study the flow of
fluids into a porous medium. For example, the aim is to study the
multiphase flow of a mix of two or three fluids inside a porous
medium: a mix of any two of water, gas and oil or the three of
them.
[0004] The known X-ray tomography systems are adapted to study the
morphology of rock pores, to identify the minerals comprised into
the rock sample (the porous medium) or the topology of various
fluid phases present in the rock sample under static (ie non
flowing) conditions.
[0005] Because of use of polychromatic X-ray source, these systems
develop approximative results due to non linear absorption and
therefore image artefacts. The quality of images is therefore
strongly impacted, especially with respect to the identification of
materials (fluid or rock). The laboratory sources used in these
systems have a very low photon flux that requires a very long
recording time for the acquisition of high resolution images. These
systems thus do not provide an acquisition time compatible with the
study of multiphase flow in porous media. These systems also use
image reconstruction algorithms that must deal with large volumes
of data to calculate only one 3D tomography image. Moreover the
strong diverging angle of polychromatic X-ray microtomographs
introduces artifacts in the 3D image reconstructions resulting from
compromises in the complex reconstruction process in a very
diverging geometry. These systems are unable to provide rapidly 3D
tomography images for generating a movie of fluid transport within
the porous medium sample.
[0006] Consequently, these devices are only able to provide static
characteristic values inside the porous medium, such as irreducible
water saturation or residual oil saturation. They are unable to
visualise the flow of a fluid or the flow of a plurality of fluids
inside the porous medium.
[0007] Synchrotron X-ray sources provide enough photon flux.
[0008] But, these devices provide a parallel photon beam having a
very small focus spot size, varying about a few mm.sup.2, that is
incompatible with a large field of view needed to observe
macroscopic flow of fluids inside a porous medium and especially in
realistic porous media where dispersion, anisotropy, viscous
fingering requires to be able to record the whole sample view.
Additionally, these devices have huge size, are very expensive and
they are for scientific use only. It is difficult to have access to
such instrument for analysis of a petroleum porous medium where
experimental time may require waiting for several weeks up to
several months.
OBJECTS AND SUMMARY OF THE INVENTION
[0009] One object of the present invention is to provide an X-ray
tomography device that can be used to analyse the flow of fluids
inside a porous medium, such as a rock sample of a geological
formation.
[0010] To this effect, the X-ray tomography device according to the
invention is adapted for providing a 3D tomography image of a
sample, and it comprises:
a X-ray source emitting a photon beam in the direction of a beam
axis, said X-ray source being a near monochromatic source and said
photon beam having a solid angle higher than 0.1 degree around said
beam axis, a cell adapted to include a porous sample to be imaged,
said cell being situated inside the photon beam and being able to
rotate around a cell axis that is substantially perpendicular to
the beam axis, and being adapted to enable the porous sample to be
flooded by at least one fluid, a photon detector receiving a
transmitted photon beam that is transmitted through said cell, said
photon detector providing at least one acquired image for each
angle of a plurality of cell angles, and said acquired images being
taken during a length of time lower than ten minutes, and a
processing unit that computes the tomography image on the basis of
the acquired images corresponding to the plurality of cell
angles.
[0011] Thanks to these features, the X-ray tomography device is
able to have simultaneously, a high level of photons and a large
field of view.
[0012] It is also able to have a very high level of photons and a
small field of view permitting to work in stitching mode or local
tomography mode
[0013] The volume analysed can be imaged during a length of time
lower than ten minutes, which is very competitive with what is
achieved with a 3.sup.rd generation synchrotron,
[0014] It is therefore possible to get a plurality of 3D tomography
images showing a movie of the flow of fluids inside the porous
medium of the sample. Moreover, it may possible to scan the whole
volume and to identify areas of fluid fluctuations before to zoom
in to reach the best resolution.
[0015] In various embodiments of the X-ray tomography device, one
and/or other of the following features may optionally be
incorporated.
[0016] According to an aspect, the monochromatic and highly
brilliant X-ray source is a compact light source using a collision
between a laser beam and an opposing electron beam.
[0017] According to an aspect, the length of time for the volume
analysis is lower than one minute.
[0018] According to an aspect, the processing unit is computing the
tomography image during a time period lower than the length of time
of used for producing the acquired images corresponding to the
plurality of cell angles.
[0019] According to an aspect, the cell has a size comprised in the
range of 0.3 cm to 20 cm, and preferably in the range of 0.6 cm to
10 cm.
[0020] According to an aspect, the cell is made of a material in a
list comprising the beryllium, beryllium alloys, and a
carbon-carbon composite.
[0021] According to an aspect, the cell comprises means for heating
the sample to a temperature higher than 650.degree. Celsius and
means for pressuring the cell to a pressure higher than 1000
bars,
[0022] According to an aspect, the photon detector comprises a CCD
of at least ten megapixels.
[0023] According to an aspect, the X-ray tomography device further
comprises a grating based interferometer situated between the cell
and the photon detector.
[0024] According to an aspect, the X-ray tomography device further
comprises a microscope situated between the cell and the photon
detector.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Other features and advantages of the invention will be
apparent from the following detailed description of one of its
embodiments given by way of non-limiting example, with reference to
the accompanying drawings. In the drawings:
[0026] FIG. 1 is a schematic view of a X-ray tomography device
according to the invention, and
[0027] FIG. 2 is an example of a 3D tomography image provided by
the device of FIG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
[0028] In the various figures, the same reference numbers indicate
identical or similar elements. The direction Z is a vertical
direction. A direction X or Y is a horizontal or lateral direction.
These are indications for the understanding of the invention.
[0029] The X-ray tomography device 1 shown on the FIG. 1
comprises:
a X-ray source 2 emitting a photon beam PB in the direction of a
beam axis BA, a cell 3 comprising a porous sample 10 to be imaged,
a photon detector 4 receiving a transmitted photon beam TPB that is
transmitted through said cell 3, and a processing unit 5 computing
the 3D tomography image on the basis of the acquired images
provided by the photon detector 4.
[0030] The X-ray source 2 is preferably a monochromatic source, so
that the cell is illuminated with a high level of brilliance by an
X-ray beam of small diverging angle. The polychromatic sources
spread their energy into a wide frequency bandwidth. It is possible
to produce a natural monochromatic flux of photons or to filter the
photon beam PB to obtain a quasi-monochromatic photon beam.
However, this decreases a lot the photon flux. The monochromatic
source concentrates the energy on a very narrow frequency
bandwidth. The length of time needed by a detector for acquiring an
image is then very low, and then it is compatible with multiphase
flow tracking.
[0031] The photon beam PB generated by said X-ray source 2 is a
diverging cone beam having a solid angle SA that is wide, and for
example higher than 0.1 degree or a few mrad around the beam axis
BA. It is possible to illuminate a complete cell having a size of
10 cm at a distance from the X-ray source 2 that is a small
distance, for example lower than 25 m, and preferably lower than 10
m. The solid angle SA may be higher than 0.5 degree.
[0032] Preferably, the X-ray source is able to emit a photon beam
having a high level of energy, for example comprised between 10 and
200 KeV. The photon flux may be higher than 10.sup.8 photons/s near
the photon detector 4, and preferably higher than 10.sup.11
photons/s. The device is then able to image thick cells and thick
samples (between 0.3 cm and 10 cm). The X-ray source may have a
tuneable X-ray energy level.
[0033] For example, the X-ray source 2 may be a compact photon
source using collision between a laser beam and an opposing
electron beam. Such X-ray source 2 preferentially uses Inverse
Compton Effect (Thomson scattering) to generate a natural
monochromatic photon beam PB having a high level of energy. The
main advantage of such X-ray sources is that they are very compact
compared to classical synchrotron devices. Known Table-top
synchrotron device using such physical properties are the "Compact
Light Source" (CLS) from Lyncean Technologies Inc., but filtering
very brilliant polychromatic flux such "Mirrorcle" from Photon
Production Lab may produce a quite similar result.
[0034] The X-ray source 2 may be tuneable according to the energy
level (brilliance) so as to proceed to various experiments above
the porous sample.
[0035] The cell 3 is situated inside the photon beam PB. The cell
position can be controlled via a rotation mean 8 (Z rotation) and a
translation mean 9 (XYZ translations).
[0036] Thanks to the rotation mean 8, the cell 3 can be rotated
around a cell axis CA substantially parallel to axis Z and
perpendicular to the X axis, the beam axis BA on FIG. 1. The cell 3
is rotated of a cell angle around the cell axis CA. The detector 4
can then provide images from the cell (sample) from various view
angles and the processing unit 5 can compute a 3D tomography image
of the sample.
[0037] Thanks to the translation mean 9, the cell 3 can be
positioned inside the photon beam PB.
[0038] The cell 3 can be placed or positioned between a first
distance from the source 2 and a second distance from the source 2.
The first distance may be short and the cell 3 is close to the
X-ray source 2 (see position P1 on FIG. 1). This configuration
optimizes the maximal flux in high resolution (stitching mode or
local tomography). The second distance is much higher than the
first distance, the cell 3 being away from the X-ray source 2 In
this configuration, it is possible to illuminate the whole region
of interest permitting to easily switch from a global tomography
mode to local tomography based on observed changes induced by the
multiphase flow. The acquisition time in this last configuration is
less performing than the first one but it permits to analyse the
sample in interactive mode
[0039] For example, the cylindrical rock sample contained inside
the cell 3 has a size comprised in the range of 0.3 cm to 10 cm.
The size is preferably in the range 0.6 cm to 3 cm in diameter and
in the range of 2 cm to 10 cm in length. The size of the rock
sample is chosen big enough to study multiphase transport
properties at a scale representative of macroscopic transport
properties in the said rock and small enough to enable high
resolution tomography of the sample in a length of time that allows
imaging the whole sample in less than ten minutes: acquiring the
images from the plurality of cell angles within said length of
time.
[0040] The cell 3 is for example a tube extending along the cell
axis CA, said tube receiving the sample of porous medium. The cell
3 comprises an input conduct 6 that input the fluid to the cell 3
and an output conduct 7 that outputs the fluid from the cell. The
cell is adapted to be crossed by the fluid.
[0041] The X-ray tomography device 1 also comprises hydraulic
devices to provide the fluid to the input conduct and to get back
this fluid from the output conduct. These hydraulic devices can
also add physical conditions to the fluid: temperature, pressure.
To this end, these hydraulic devices include a thermal regulator,
and a pressure regulator. The sample 10 inside the cell 3 can be
tested according to the physical conditions of the geologic
formation.
[0042] The thermal regulator can heat the sample up to a
temperature of 650.degree. Celsius.
[0043] The pressure regulator can pressurize the sample up to a
pressure of 1000 bars.
[0044] The cell 3 is a sort of Hassler cell meeting the
requirements of X-ray tomography imaging. The cell 3 is adapted to
enable the porous sample 10 to be flooded by one or several fluids
under controlled pressure and temperature conditions.
[0045] The cell 3 is made of a material that is transparent to the
X-ray photon beam. Advantageously, it is made of beryllium, or
beryllium alloy such beryllium aluminium alloy, or a carbon-carbon
composite.
The photon detector 4 can be tuned to have a sensitivity
corresponding to the sample and fluids. Small variations of fluid
densities can be therefore detected. Oil and water can be
distinguished in the acquired images provided by the photon
detector 4 using very fast classical absorption mode, or phase mode
or dark field mode.
[0046] The photon detector 4 is providing at least one image for
each angle of a plurality of cell angles. All these acquired images
are taken during a length of time lower than ten minutes for the
whole volume to analyse. It is assumed that the state of the sample
does not change much during this length of time: the fluid
movements inside the porous medium remain very small. All the
acquired images from various cell angles are then supposed to
represent a unique state of the sample.
[0047] Advantageously, the length of time is lower than one minute.
The images represent more precisely a unique state of the sample,
and the tomography device is acquiring images in real time and
stores all these images for the processing unit 5.
[0048] The photon detector 4 can be a flat panel, or an X-ray CCD
(Charge-Coupled Device) or a CMOS. The photon detector 4 has a high
resolution. It is for example a CCD having at least ten megapixels.
The acquired images are enough accurate to visualise at the same
time (simultaneously) the complete field of view of the sample or
very small details inside the sample thanks to a stitching mode or
local tomography process. In this way several ways are possible to
scan the sample, and the acquired image can be taken in a very
short length of time and the acquired image is enough exposed to
photon flux to show small details and small variations of
densities.
[0049] The processing unit 5 is computing the 3D tomography image
on the basis of the acquired images corresponding to the plurality
of cell angles. Such reconstruction method is known and efficient
(fast and providing a very good image quality) benefiting from the
quasi parallel approximation. Examples of reconstruction methods
can be found in the following document:
A. C. Kak and Malcolm Slaney, Principles of Computerized
Tomographic Imaging, IEEE Press, 1988.
[0050] In the present invention, the processing unit 5 may comprise
parallel computing means so that the 3D tomography image can be
computed during a very short time period. This high performance for
reconstruction time and imaging are mainly due to the quasi
parallel beam geometry. The time period can be lower than the
length of time for acquiring the images from various cell angles of
the sample. The X-ray tomography device is therefore generating
real time 3D tomography images, and can visualize a real time movie
showing the fluids movements inside the porous medium.
[0051] The tomography device 1 may comprise a microscope to obtain
high (accurate) resolutions. In that case, the resolution may reach
200 nm of voxel size which is the theoretical limit of microscopes
due to Rayleigh criterion.
[0052] The tomography device 1 may also comprise a grating based
interferometer, situated between the cell 3 and the microscope or
the photon detector 4. Such gratings improve the contrast of the
acquired images by adding absorption contrast image, phase contrast
image and dark field contrast image: materials having similar
densities can be distinguished on the acquired images by photon
detector 4. In that case, the same resolution than obtained only by
the microscope can be obtained.
[0053] The gratings, the microscope and the detector 4 compose an
optical station of the X-ray tomography device 1.
[0054] The FIG. 2 is showing an example of a projection of 3D image
20 provided by the X-ray tomography device 1 of the invention. The
3D tomography image comprises various gray levels or various
colours, each representing a constituent of the sample. The
reference 21 represents the porous medium. The reference 22
represents a first fluid having a first density. The reference 23
represents a second fluid having a second density.
[0055] The embodiments above are intended to be illustrative and
not limiting. Additional embodiments may be within the claims.
Although the present invention has been described with reference to
particular embodiments, workers skilled in the art will recognize
that changes may be made in form and detail without departing from
the spirit and scope of the invention.
[0056] Various modifications to the invention may be apparent to
one of skill in the art upon reading this disclosure. For example,
persons of ordinary skill in the relevant art will recognize that
the various features described for the different embodiments of the
invention can be suitably combined, un-combined, and re-combined
with other features, alone, or in different combinations, within
the spirit of the invention. Likewise, the various features
described above should all be regarded as example embodiments,
rather than limitations to the scope or spirit of the invention.
Therefore, the above is not contemplated to limit the scope of the
present invention.
* * * * *