U.S. patent application number 13/408898 was filed with the patent office on 2013-08-29 for system for extracting hydrocarbons from underground geological formations and methods thereof.
The applicant listed for this patent is Stephen A. Boyd, John L. Palumbo. Invention is credited to Stephen A. Boyd, John L. Palumbo.
Application Number | 20130220598 13/408898 |
Document ID | / |
Family ID | 49001592 |
Filed Date | 2013-08-29 |
United States Patent
Application |
20130220598 |
Kind Code |
A1 |
Palumbo; John L. ; et
al. |
August 29, 2013 |
System for Extracting Hydrocarbons From Underground Geological
Formations and Methods Thereof
Abstract
An ultrasonic fracking system and methods of using the same to
extract hydrocarbons from underground geological formations (e.g.,
oil shale, coal beds, etc.) are disclosed. The system includes
piezoelectric devices that are used to produce ultrasonic
mechanical vibrations and induce fractures in the geological
formations. In one embodiment, a system for extracting underground
hydrocarbons comprises a plurality of piezoelectric devices capable
of producing mechanical waves sufficient to fracture oil shale and
other geological formations, a system of delivery for innocuous
proppants to create a path of least resistance for enhanced
hydrocarbon flow, and a vacuum pump connected to the fractures
created by the piezoelectric devices to assist in removing the
hydrocarbons.
Inventors: |
Palumbo; John L.; (Wyckoff,
NJ) ; Boyd; Stephen A.; (Manhasset, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Palumbo; John L.
Boyd; Stephen A. |
Wyckoff
Manhasset |
NJ
NY |
US
US |
|
|
Family ID: |
49001592 |
Appl. No.: |
13/408898 |
Filed: |
February 29, 2012 |
Current U.S.
Class: |
166/249 ;
166/177.1 |
Current CPC
Class: |
E21B 28/00 20130101;
E21B 43/26 20130101 |
Class at
Publication: |
166/249 ;
166/177.1 |
International
Class: |
E21B 43/00 20060101
E21B043/00; E21B 28/00 20060101 E21B028/00 |
Claims
1. A fracturing system, comprising: a) one or more piezoelectric
devices capable of insertion into a well in an underground
geological formation and configured to produce and/or detect a
range of vibrational frequencies; b) an apparatus configured to
receive and interpret electrical signals from the one or more
piezoelectric devices; and c) an apparatus configured to induce
vibrations of varying frequencies in the one or more piezoelectric
devices.
2. The fracturing system of claim 1, wherein the apparatus
configured to receive and/or interpret electrical signals from the
one or more piezoelectric devices determines resonant vibrational
frequencies of the underground geological formation.
3. The fracturing system of claim 2, wherein the induced vibrations
have a same range of frequencies as the resonant vibrational
frequencies.
4. The fracturing system of claim 1, further comprising a
vacuum-pump apparatus configured to reduce a pressure in the one or
more wells.
5. The fracturing system of claim 3, wherein the vacuum-pump
apparatus is also configured to pump a proppant into the well.
6. The fracturing system of claim 1, wherein the apparatus
configured to receive and interpret electrical signals from the one
or more piezoelectric devices comprises an amplification system
configured to increase the power of the electrical signals from the
one or more piezoelectric devices.
7. The fracturing system of claim 1, wherein the apparatus
configured to induce vibrations of varying frequencies in the one
or more piezoelectric devices comprises an amplification system
configured to increase the amplitude of the vibrations in the one
or more piezoelectric transducers.
8. The fracturing system of claim 1, wherein each of the one or
more piezoelectric devices comprises one or more piezoelectric
transducers.
9. The fracturing system of claim 8, wherein each of the one or
more piezoelectric transducers comprises a piezoelectric
material.
10. The fracturing system of claim 8, wherein each of the one or
more piezoelectric transducers is tuned to a range of ultrasonic
vibrational frequencies.
11. The method of claim 1, wherein the fracking system is
configured to extract one or more hydrocarbons, said hydrocarbon(s)
comprising natural gas, methane, ethane, propane, or butane.
12. The fracturing system of claim 2, wherein the apparatus
configured to receive and interpret electrical signals from the one
or more piezoelectric devices is further configured to monitor
changes in the resonant vibrational frequencies in the underground
geological formation.
13. The fracturing system of claim 12, wherein the apparatus
configured to induce vibrations of varying frequencies in the one
or more piezoelectric devices is further configured to adjust the
frequencies of the induced vibrations in response to the changes in
the resonant vibrational frequencies in the underground geological
formation.
14. A method of vibrational fracturing, comprising: a) placing one
or more piezoelectric devices capable of producing mechanical
vibrations in a well exposing an underground geological formation;
b) producing mechanical vibrations with the piezoelectric devices
to fracture the underground geological formation; and c) collecting
one or more hydrocarbons released from the underground geological
formation.
15. The method of claim 14, further comprising detecting vibrations
reflected by the underground formation to determine one or more
resonant frequencies in the underground geological formation.
16. The method of claim 15, wherein the produced mechanical
vibrations are in the range of resonant frequencies in the
underground geological formation.
17. The method of claim 16, wherein the resonant frequencies in the
underground geological formation change while fracturing the
underground geological formation, and the method further comprises
adjusting the mechanical vibrations to match the changed resonant
frequencies in the underground geological formation.
18. The method of claim 14, wherein the one or more hydrocarbons
comprise one or more of natural gas, methane, ethane, propane, and
butane.
19. The method of claim 14, wherein the produced mechanical
vibrations are comprise ultrasonic waves.
20. A system for extracting one or more hydrocarbons from an
underground geological formation, comprising: a) a plurality of
piezoelectric devices, each of the plurality of piezoelectric
devices configured to be placed into one of a plurality of wells in
the underground geological formation, and to produce and detect a
range of vibrational frequencies; b) an apparatus configured to
receive and interpret data from the piezoelectric devices; c) an
apparatus configured to induce vibrations of variable frequencies
in the one or more piezoelectric devices; d) an apparatus
configured to pump a proppant fluid into the plurality of wells;
and e) an apparatus configured to extract the hydrocarbon(s) from
the wells.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to the field of
mining (e.g., extracting, drilling or recovering) hydrocarbons.
Embodiments of the present invention relate to a system for
extracting hydrocarbons (e.g., hydrocarbon-based fuels) from
underground formations utilizing ultrasound, and methods of using
the same. More specifically, embodiments of the present invention
relate to a system and method for creating controlled fractures in
underground geological formations, allowing the extraction of
hydrocarbons trapped therein.
DISCUSSION OF THE BACKGROUND
[0002] Increasing demands for domestic fuel sources have led to
widespread attention to a technique of underground natural gas and
oil exploitation called hydraulic fracturing (fracking) While the
technique has merit, environmental concerns have recently arisen
regarding the environmental impacts of fracking, including possible
contamination of ground water, surface water, and soil, as well as
the release of greenhouse gases into the atmosphere. Additionally,
current fracking techniques have several inefficiencies.
[0003] Natural underground oil shale and coal deposits offer an
abundant supply of petroleum and natural gas resources. Many
variables must be considered in the application of fracking
techniques to extract these hydrocarbons. For instance, the
question of whether the extraction of natural gas and hydrocarbons
from a particular oil shale or coal bed formation is efficient and
economical depends on the flow rate of these materials through the
formation. Darcy's Law describes the flow rate of materials through
porous media, which is measured in
[0004] Darcy (D). The flow rates of hydrocarbons in shale and coal
bed formations is low (e.g., in the 1 nD to 1 .mu.D range), due to
the low permeability of shale and coal. Fracking of such
underground formations must result in a flow rate of the
hydrocarbons that is sufficient to extract economically sufficient
amounts of the hydrocarbons.
[0005] To achieve such flow rates, wellbores are often drilled
using vertical drilling techniques. In order increase flow rates to
economical levels, underground formations are pumped with large
amounts of water and chemicals (fracking fluids) at extreme
pressures to achieve fracturing of the natural underground geologic
formations. Materials known as proppants are then pumped into the
newly created fractures to prop open the fractures, creating paths
of least (or lower) resistance for hydrocarbons to flow.
[0006] However, fracking fluids typically include a wide range of
potentially hazardous chemicals (e.g., acids, buffering agents,
bactericides, corrosion inhibitors, friction reducers, surfactants,
gelling agents, etc.). Large amounts of these fracking fluids can
be used in a fracking operation (e.g., greater than 10.sup.6
gallons in deep oil shale deposits). A portion of the fracking
fluids can find its way into water and soil by leaking through
waste pipelines transporting the fluid from the well to disposal
areas and from the disposal areas themselves. Also, a portion of
the fracking fluid injected into the well can remain underground.
The chemicals in the fracking fluid can migrate into aquifers,
surface water, and soils. Thus, the use of fracking fluids can
result in the contamination of these important resources.
[0007] Presently, hydraulic fracturing techniques have multiple
problems, including: [0008] Low efficiency in capturing the
released hydrocarbons; [0009] Due to economic considerations, once
the flow rate of the well is past a premium flow rate, the well may
be abandoned; [0010] Capping the abandoned well may not eliminate
leeching of greenhouse gases into the atmosphere; [0011] If left
uncapped, methane (CH.sub.4) can leach from the well into the air,
and methane is greater than 30 times more powerful in inducing
greenhouse effects than CO.sub.2; [0012] Ground and surface water
and soil can be polluted by fracking fluid and chemicals released
from wells; and [0013] Horizontal drilling techniques may result in
seepage of natural gas into the environment, resulting in loss of
potential revenue and significant risk of injury and death to local
fauna.
[0014] An additional drawback to fracking is the release of
Naturally Occurring Radioactive Materials (NORMS). These NORMS are
salts of radioactive species which potentially can be solubilized
in the presence of water. It is conceivable that ground water
bodies may then be contaminated with labile radioactive species,
lending to worsening environmental damages.
[0015] Thus, new techniques for extracting hydrocarbons that lower
the costs, minimize environmental impacts, and increase the
efficiency of extracting geologic hydrocarbons are needed.
SUMMARY OF THE INVENTION
[0016] Embodiments of the present invention are generally related
to systems for extracting hydrocarbons (e.g., natural gas) from
underground formations utilizing ultrasonic vibrations and methods
of extracting hydrocarbons using such systems. More specifically,
embodiments of the present invention relate to a system and method
for creating controlled fractures in underground geological
formations, allowing the extraction of hydrocarbons trapped
therein.
[0017] In accordance with the present invention, a system for
fracturing underground formations utilizing ultrasonic mechanical
vibrations may comprise a plurality of piezoelectric devices for
producing mechanical vibrations capable of fracturing underground
geological formations, including oil shale, coal beds, sandstone,
and other geological formations in which hydrocarbons may be
deposited. The piezoelectric devices may be inserted into one or
more wellbores, down to the position of a geological formation
containing hydrocarbons, where the piezoelectric devices can be
used to create ultrasonic vibrations in the wellbore to shake and
expand existing fractures. The piezoelectric devices are also
capable of sensing resonant vibration frequencies (typically
ultrasonic) of existing fractures, which can be enlarged by pulsing
the formation with the detected resonant frequency(ies).
[0018] The system may also include a reversible vacuum/pump system
to create a path of least or lower resistance for hydrocarbons
freed from the geological formation by the fracturing system,
effectively drawing the hydrocarbons toward the surface. The
vacuum/pump system may be further configured to flush an innocuous
or relatively harmless fluid or gas (e.g., N.sub.2 or air) into a
wellbore as a proppant to prevent the fractures in the geological
formation from (1) closing up and/or (2) trapping the hydrocarbons
contained therein.
[0019] The fracturing system may be used in a method for extracting
hydrocarbons from underground geological formations by (1)
determining the resonant frequencies of the fractures present in
the geological formation, (2) producing vibrations at the resonant
frequencies in order to cause spreading and growth of the fractures
and free the hydrocarbon deposits contained in the geological
formation, (3) pumping a proppant from the surface into the
fractures (e.g., through a wellbore) in order to maintain the
enlarged fracture and facilitate the flow of hydrocarbons out of
the formation, and (4) collecting the hydrocarbons (e.g., through
the wellbore, optionally using [i] a negative pressure created in
the wellbore by the vacuum/pump system and/or [ii] a higher
pressure that may naturally be present in an underground
hydrocarbon deposit).
[0020] In one embodiment, the present invention relates to a system
for fracturing underground formations, comprising (a) a plurality
of piezoelectric devices, the plurality of piezoelectric devices
being capable of insertion into a plurality of underground wells in
the underground formation and producing and detecting a broad range
of vibrational frequencies; (b) an apparatus for receiving and
interpreting data from the piezoelectric devices regarding detected
vibrational frequencies; and (c) an apparatus for inducing
vibrations of desired frequencies in the plurality of piezoelectric
devices.
[0021] In another embodiment, the present invention relates to a
system of extracting hydrocarbons from underground formations,
comprising (a) a plurality of piezoelectric devices, the plurality
of piezoelectric devices being capable of insertion into a
plurality of underground wells in the underground formation and
producing and detecting a broad range of vibrational frequencies;
(b) an apparatus for inducing vibrations of desired frequencies in
the plurality of piezoelectric devices; (c) an apparatus for
pumping a proppant fluid into the plurality of underground wells;
and (d) an apparatus for extracting hydrocarbons from the
wells.
[0022] In another embodiment, the present invention relates to a
method of enlarging fractures in underground geological formations,
comprising embedding a plurality of piezoelectric devices capable
of producing ultrasonic mechanical vibrations having (or within) a
predetermined range of frequencies in wells exposing the
underground formation; and inducing the mechanical vibrations in
the wells using the piezoelectric devices to fracture the
underground formation.
[0023] In another embodiment, the present invention relates to a
method of extracting hydrocarbons from an underground geological
formation, comprising (1) inserting a plurality of piezoelectric
devices into a plurality of wells near a deposit of hydrocarbons in
the underground formation, (2) inducing vibrations (e.g., within a
predetermined frequency range) in the formation using the
piezoelectric devices, (3) detecting vibrations reflected by the
formation and determining the resonant frequencies of fractures in
the formation, (4) inducing vibrations in the formation at the
resonant frequencies using the piezoelectric devices (e.g., to
shake and enlarge the existing fractures), and (5) collecting
hydrocarbons released through the enlarged fractures. The method
may further include flowing a proppant into the enlarged fractures
to prevent them from closing or narrowing, and to aid in freeing
physisorbed hydrocarbons from the underground formation.
[0024] The present invention advantageously improves the efficiency
of extracting hydrocarbons from underground deposits in geological
formations such as oil shale, coal beds, sandstone, and other
geological formations that contain hydrocarbons. The current
apparatus and method reduce or eliminate the need for hydraulic
fluids in the process of fracking underground geological
formations. Thus, the present invention reduces the costs
associated with hydraulic fracturing, including the cost of the
hydraulic fluid (e.g., the water and the additives, such as acids,
buffering agents, bactericides, corrosion inhibitors, friction
reducers, surfactants, gelling agents, etc.), the pumping and
equipment costs for introducing the hydraulic fluids into wells,
and the cost of storing the used hydraulic fluid once it is removed
from wells. The present invention also reduces or eliminates the
environmental impacts of hydraulic fracking resulting from the use
of fracking fluids, since the present invention enables fracking
underground without fracking fluids. These and other advantages of
the present invention will become readily apparent from the
detailed description of various embodiments below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a diagram showing the major components of a
fracking system according to one embodiment of the present
invention.
[0026] FIG. 2 is a diagram of a probe head containing one or more
variable window piezoelectric transducers for delivering and
sensing mechanical vibrations in an underground geological
formation.
[0027] FIG. 3 is a schematic of an amplifier system for inducing
mechanical vibrations in an array of piezoelectric devices.
[0028] FIG. 4 is a flow chart of a feedback process for determining
specific ranges of resonance frequencies for an underground
geological formation.
[0029] FIG. 5 is a diagram showing a process of extracting
hydrocarbons from an underground geological formation.
DETAILED DESCRIPTION
[0030] Reference will now be made in detail to various embodiments
of the invention, examples of which are illustrated in the
accompanying drawings. While the invention will be described in
conjunction with the following embodiments, it will be understood
that the descriptions are not intended to limit the invention to
these embodiments. On the contrary, the invention is intended to
cover alternatives, modifications and equivalents that may be
included within the spirit and scope of the invention as defined by
the appended claims. Furthermore, in the following detailed
description, numerous specific details are set forth in order to
provide a thorough understanding of the present invention. However,
it will be readily apparent to one skilled in the art that the
present invention may be practiced without these specific details.
In other instances, well-known methods, procedures, components, and
circuits have not been described in detail so as not to
unnecessarily obscure aspects of the present invention.
[0031] So that the manner in which various features of the present
invention can be understood in detail, a more particular
description of embodiments of the present invention, briefly
summarized above, may be had by reference to various embodiments as
described below and shown in the drawings. It is to be noted,
however, that the appended drawings show illustrative embodiments
encompassed within the scope of the present invention, and
therefore, are not to be considered limiting, for the present
invention includes additional embodiments.
[0032] The headings used herein are for organizational purposes
only and are not meant to be used to limit the scope of the
description or the claims. As used throughout this application, the
word "may" is used in a permissive sense (i.e., meaning having the
potential to), rather than the mandatory sense (i.e., meaning
must). Similarly, the words "include", "including", and "includes"
mean including, but not limited to. To facilitate understanding,
like reference numerals have been used, where possible, to
designate like elements common to the figures. For the sake of
convenience and simplicity, the terms "connected to," "coupled
with," "coupled to," and "in communication with," may be used
interchangeably, but these terms are also generally given their
art-recognized meanings
[0033] The invention, in its various aspects, will be explained in
greater detail below with regard to exemplary embodiments.
[0034] An Exemplary Fracking System
[0035] Embodiments of the present invention generally relate to a
system for inducing or enlarging fractures (fracking) in
underground geological formations. In one aspect, embodiments of
the present invention relate to a system that includes
piezoelectric devices and is capable of determining resonant
frequency ranges of fractures in underground geological formations.
For example, the system is capable of producing mechanical
vibrations in the resonant frequency ranges in a well to induce
further fracturing of the material in the underground geological
formation. In one embodiment of the system, the piezoelectric
devices include ultrasonic piezoelectric transducers that are
capable of detecting and producing mechanical vibrations. In
another embodiment, the system further includes titanium horns
coupled to the piezoelectric transducers to enhance the mechanical
vibrations of or from the piezoelectric transducers.
[0036] FIG. 1 provides an illustration of an exemplary fracking
system 100. The system includes a housing 110 that may contain a
pulser/receiver system capable of (1) producing electrical signals
to be transmitted to an array of variable window piezoelectric
transducers and (2) receiving and interpreting electrical signals
from the piezoelectric transducers. The array of piezoelectric
transducers can be contained in housing 170, which organizes and
protects the array of transducers 120 as they are introduced into
an underground geological formation through a wellbore 160. The
piezoelectric transducers in the array may each be coupled to a
horn assembly configured to amplify the vibrations of the coupled
piezoelectric transducer. The horn assemblies are contained in the
housing 170 along with the associated piezoelectric transducers.
The piezoelectric transducers may be coupled to the pulser/receiver
system by coupling cables 150, configured to carry electrical
signals between the pulser/receiver system and the piezoelectric
transducers. The fracking system may also include components for
introducing an innocuous proppant material (e.g., nitrogen gas,
air, etc.) into the well bore to maintain fractures created by the
fracking system in the underground geological formation, and a
vacuum system for creating negative pressure in the wellbore to
create a path of lower (e.g., least) resistance for the
hydrocarbons released from the formation. For example, a reversible
vacuum/pump system 140 that can both reduce pressure in the
wellbore 160 and draw hydrocarbons toward the surface. Also, a
storage tank 130 for the proppant (e.g., N.sub.2 gas) may be
coupled with the vacuum/pump system 140, such that the proppant can
be introduced into the wellbore 160 by the reversible vacuum/pump
system 140.
[0037] In one embodiment, the fracking system 100 may be configured
to work in several wellbores simultaneously. Specifically, the
fracking system may include one or more piezoelectric transducer
arrays that can be introduced into one or more wellbores. Each
transducer array can be introduced into a separate wellbore, and
each array may contain variable window piezoelectric transducers
that vary in the frequency ranges in which they can produce and
detect vibrations. Additionally, the vacuum/pump system 140 may
include a manifold with several wellbore couplings, each connected
to a different wellbore. Thus, the vacuum/pump system 140 may be
used to reduce pressure and introduce proppant in multiple
wellbores simultaneously. In an alternative embodiment, the
fracking system can be configured to operate on a single wellbore
(e.g., 160).
[0038] Each variable window transducer array may include one or
more probe heads that contain piezoelectric transducers. FIG. 2
shows a probe head 230 that may house one or more piezoelectric
transducers and associated horn assemblies (not shown). The probe
head 230 can be safely introduced into a well exposing an
underground geological formation containing hydrocarbon deposits
(e.g., shales, coal beds, sandstone, etc.) without damage to the
piezoelectric transducers and horn assemblies therein. One or more
probe heads 230 can be introduced into a single wellbore. The probe
head 230 may include a tough metal housing constructed of a strong
metal, such as iron, titanium, tungsten, aluminum, and alloys
thereof (e.g., stainless steel), which may contain additional
corrosion-resistant metals (e.g., chromium, zinc, nickel, etc.) or
may be coated with corrosion-resistant metals. For instance, the
probe head 230 may be made of titanium or steel (e.g., surgical
grade stainless steel).
[0039] The piezoelectric transducers may be ultrasonic and
polyphonic, able to produce a range of sonic to ultrasonic
vibration frequencies upon the application of a voltage to the
transducers from a pulser/receiver system that may be connected to
the piezoelectric transducers via coupling cables 210 (or 150, as
shown in FIG. 1). The transducers are also able to transduce
mechanical vibrations into electrical signals. Thus, the
piezoelectric transducers are able to act as both sensors for sonic
and ultrasonic mechanical vibrations, creating electrical current
upon deformation by a mechanical vibration (the piezoelectric
effect), and as oscillators for generating sonic and ultrasonic
mechanical vibrations, changing molecular or crystalline structure
upon the application of an electrical current (electrostriction).
The piezoelectric transducers contain a piezoelectric material that
behaves in this manner, such as piezoelectric ceramics and
crystals. The piezoelectric transducers may include one or more
piezoelectric ceramics, such as lead zirconate titanate (PZT),
barium titanate (BaTiO.sub.3), lead titanate (PbTiO.sub.3),
potassium niobate (KNbO.sub.3), lithium niobate (LiNbO.sub.3),
lithium tantalate (LiTaO.sub.3), zinc oxide (Zn.sub.2O.sub.3), and
sodium tungstate (Na.sub.2WO.sub.3); or piezoelectric crystals,
such as quartz (SiO.sub.2), gallium orthophosphate (GaPO.sub.4), or
langasite (La.sub.3Ga.sub.5SiO.sub.14). In one embodiment, the
piezoelectric material is PZT.
[0040] The individual piezoelectric transducers within the probe
head 230 can be tuned to different vibrational frequencies,
depending on the structure of the transducer. For instance, the
thickness of the piezoelectric material can be varied, in order to
cover various and/or different frequency ranges. Additionally, a
damping layer (e.g., a resin or metal layer, such as steel or
aluminum) may be included in the transducer in order to widen the
range of vibration frequencies that the transducer can detect and
thus increase the transducer's sensitivity.
[0041] The piezoelectric transducers may also include other known
components, such as electrodes for collecting and delivering
electrical current to and from the piezoelectric material, an
electrical connector between the piezoelectric transducers and the
coupling cables 210, electrical wires connecting the electrodes to
the electrical connector, a housing 220 for the electrical
connector between the piezoelectric transducer and the coupling
cables 210, a housing for each piezoelectric transducer within the
probe head 230, etc. Ultrasonic horns (not shown) may be coupled to
each of the piezoelectric transducers in a given probe head. The
ultrasonic horns vibrate with the piezoelectric transducers to
increase the amplitude of the mechanical vibrations created by the
piezoelectric transducer. The ultrasonic horns may comprise
titanium or aluminum.
[0042] The piezoelectric transducers can be coupled to a
pulser/receiver instrumentation system by coupling cables. FIG. 1
shows a housing 110 for this pulser/receiver instrumentation system
coupled to a transducer array 120 by coupling cables 150. The
pulser/receiver system may include a phase-coupled inverse
frequency-spectrum analyzer, an attenuator, one or more amplifiers,
one or more display devices, and a quarter-wave filter assembly.
The pulser/receiver instrumentation system includes a pulsing
system for inducing high frequency mechanical vibrations in the
piezoelectric transducers and a receiving system for electrical
signals created by the detection of vibrations by the piezoelectric
transducers (e.g., the phase-coupled inverse frequency-spectrum
analyzer). The pulser section of the system can generate short,
large amplitude electric pulses of controlled energy, which are
converted into short sonic to ultrasonic pulses (e.g., about 1 kHz
to about 15 MHz, about 2 kHz to about 5 MHz, about 10 kHz to about
3 kHz, or any value or range of values therein) when applied to a
piezoelectric transducer. The receiver section of the system can
receive and interpret the electrical signals (e.g., currents)
produced by the piezoelectric transducers when they are deformed by
mechanical vibrations.
[0043] The receiver section may include a frequency-spectrum
analyzer capable of receiving and converting the electrical signals
generated by the piezoelectric transducers into digital frequency
data that can be displayed on a display device. Example, frequency
spectrum analyzers that may be used include the Digital Mobile
Radio Transmitter Tester, model no. MS8604A, manufactured by
Anritsu, and the Agilent/HP 7000x series of spectrum analyzers.
[0044] The pulser instrumentation system may also include one or
more multi-channel amplifiers for increasing the power of the
signals created by the pulser for creating mechanical vibrations in
the piezoelectric transducers, thereby increasing the amplitude of
the mechanical vibrations of the piezoelectric transducers. The
pulser and multi-channel amplifier are capable of producing signals
for inducing vibrations at multiple frequencies in multiple
piezoelectric transducers simultaneously. The receiver
instrumentation may also include one or more multi-channel
amplifiers to amplify the voltage signals produced by the
piezoelectric transducers and transmitted to the receiver
instrumentation by coupling cables 150. The amplified voltage
signal can be processed and converted to digital data by the
frequency-spectrum analyzer and displayed as an output on the
display device. The receiver and multi-channel amplifier are
capable of receiving and processing electrical signals (e.g.,
currents or voltages) from multiple piezoelectric transducers
simultaneously.
[0045] FIG. 3 is a schematic of a typical multi-channel amplifier
circuit 310, including the basic components of the amplifiers and
filters. Electrical signals from one or more piezoelectric
transducers 320 are received by a mixer 350, which may combine the
voltage signal of the transducer(s) 320 with a voltage from a
pre-amp 340 to boost the signal. The low pass filter (LPF) 360
filters the frequency of the electrical signal from the mixer for
processing in a frequency analyzer (as discussed above), and the
audio amp 370 strengthens the signal from the transducer(s) 320 to
enable analysis of the electrical signals produced from the
piezoelectric transducer(s) 320. These components are utilized in a
feedback loop 330 that provides real-time feedback from the
piezoelectric transducer(s) 320 regarding the changing resonant
frequencies in the underground geological formation during the
ultrasonic fracking process. The feedback loop 330 allows
monitoring of the wave response of the oil shale or other material
in the geological formation during the ultrasonic fracking
process.
[0046] The presently described embodiments of an ultrasonic
fracking system are not limiting, and the invention is intended to
cover alternatives, modifications and equivalents that may be
included within the spirit and scope of the invention as defined by
the appended claims. It is also understood that various embodiments
described herein may be utilized in combination with any other
embodiment described, without departing from the scope contained
herein. In addition, embodiments of the present invention are
further scalable to allow for additional clients and servers, as
particular applications may require.
[0047] An Exemplary Method for Extracting Hydrocarbons Using
Ultrasonic Fracking
[0048] The present invention also concerns a method of extracting
hydrocarbons from underground geological formations using
ultrasonic vibrations created using piezoelectric devices (e.g., a
variable window transducer array, as discussed above). One or more
of the piezoelectric devices can be introduced into each of one or
more wellbores so that each piezoelectric device is near a
hydrocarbon deposit in the underground geological formation.
Subsequently, a predetermined range of mechanical vibrations can be
induced in the piezoelectric device using the pulser/receiver
instrumentation to induce fractures in the geological formation and
release hydrocarbons therefrom.
[0049] FIG. 4 is a flowchart 400 for the general steps of
ultrasonic fracking, including a feedback loop system for adjusting
the frequencies used to fracture the underground geological
formation. Once determined, these frequencies are used to adjust
the range of ultrasonic vibrations produced from a piezoelectric
device array for creating or extending fractures in the underground
geological formation.
[0050] The method starts at 410, and at 420, a range of vibrational
frequencies that are predicted to induce fracturing in the
underground geological formation (e.g., oil shale, coal bed,
sandstone, or other geological formation that may contain
hydrocarbon deposits) are introduced by piezoelectric devices into
the geological formation. Vibrations of certain frequencies are
absorbed by fractures in the geological formation (resonant
frequencies), and thus are attenuated when they are reflected back
to the piezoelectric devices. The pulser/receiver can determine the
resonant frequencies of the geological formation, based on the
attenuation (lower or reduced amplitude) of the resonant
frequencies that are reflected back to the piezoelectric device. At
430, the amplitudes of the resonant frequency response are
determined. Determination of the resonant frequencies at 420 and of
the amplitude(s) at 430 can be repeated until the resonant
frequencies of the underground formation are mapped.
[0051] At 440, the pulser and amplifier instruments can be tuned to
the resonant frequencies and amplitudes to enable further
fracturing the underground geological formation. At 450, controlled
ultrasonic vibrations are induced in the piezoelectric transducers
at the resonant frequencies of the fractures in the geological
formation. These ultrasonic vibrations result in the shaking,
fracturing, and/or enlarging of fractures in the geological
formation. As mentioned above, the fracking system described above
is capable of monitoring changes in the resonant frequencies of the
fractures in the geological formation.
[0052] At 460, the pulser/receiver instrumentation of the fracking
system continually or intermittently monitors changes to the
resonant frequencies of the fractures in the geological formation,
in order to adjust the frequency of the ultrasonic pulses to the
changing resonant frequencies during the fracking process (e.g., at
420, via feedback loop 320 in FIG. 3). Thus, FIG. 4 shows a
cyclical process, wherein frequency monitoring at 460 and analysis
of the resonant frequencies at 420 and 430 are ongoing, and the
frequencies delivered to the piezoelectric transducers at 440 and
450 are adjusted in response to changes detected in the resonant
frequency or frequencies of the geological formation.
[0053] More specifically, the piezoelectric devices (e.g., a probe
head) comprise an array of piezoelectric transducers that are each
tuned to a different range of frequencies in the sonic to
ultrasonic range of about 1 kHz to about 15 MHz (e.g., about 2 kHz
to about 5 MHz, about 10 kHz to about 3 kHz, or any value or range
of values therein), which generally covers the frequencies at which
geological formations such as oil shale, coal beds, sandstone and
other geological formations that contain hydrocarbons absorb
vibrations. The piezoelectric transducers also absorb mechanical
vibrations in their tuned range, and transduce the vibrations to
electrical signals, which are transmitted back to the
pulser/receiver instrumentation. Fractures in the geological
formation will absorb the vibrations produced by the piezoelectric
device at resonant frequencies, resulting in an attenuation of the
vibrations at that resonant frequency. Thus, the piezoelectric
transducers that are tuned for the frequency range that includes
the resonant frequency will produce a weaker electrical signal when
the vibrations are reflected by the geological formation. The
attenuated signal allows pulser/receiver to identify the resonant
frequency range. Subsequently, the pulser/receiver system may
induce mechanical vibrations at the resonant frequencies (e.g.,
mechanical waves 240 and their associated nodal planes 250, shown
in FIG. 2) by sending an electrical current to the piezoelectric
transducer(s) that is tuned for the range that includes the
resonant frequencies, resulting in shaking and enlargement of the
fractures. For example, FIG. 2 shows a destructive mechanical
vibration 260 at the resonant frequency of a fracture in the
underground formation inducing damage and enlargement of the
fracture.
[0054] Prior to the fracking process, a series of relatively small
diameter wellbores may form a horizontal x-y array on the ground
surface. The wellbores may have variable depths, thereby creating a
three-dimensional array of wellbores penetrating the underground
geological formation. The varying depths of each wellbore may be
used to create an optimized three-dimensional array of the
piezoelectric transducers introduced into the wellbores. The three
dimensional array may be predetermined. Ground penetrating radar,
satellite-based imagery and geologic/seismic survey data can be
used to topographically map the target geological formation for
volume, density, composition, etc. After these data are acquired
(given that the properties of each geological body or locale is
unique), the correct x-y positions (.+-.0.5 m.sup.2) over the body
can be identified. Precise depths for each bore hole can then be
calculated.
[0055] Given that the general equation for a wave function is
known, calculating the frequency windows needed on a Riemannian
surface (the volume of the geological formation, e.g., shale body)
begins by calculating the length in the time domain, then the
material-dependent impedance of the ith piezoelectric transducer
array by beginning, for example, with calculating the
Lagrangian:
L.sub.a.sup.b(.phi.)=.intg..sub.a.sup.b.parallel.{dot over
(.phi.)}(t).parallel.dt=.intg..sub.a.sup.b(<{dot over
(.phi.)}(t)|{dot over (.phi.)}(t)>.sub..gamma.(t)).sup.1/2dt
A Fourier Transform of this to the frequency domain would then
permit determination of the frequency window for the ith
transducer. As indicated above, this is merely the expectation
value. Real-time data from each transducer can then optimize the
pulse for the ith transducer, as it relates to the NNNth transducer
(NNN=next nearest neighbor), accommodating for response time of the
material surrounding each. After the body volume has been
calibrated, each transducer can then be fitted with the correct
titanium horn, thereby allowing each transducer to constructively,
polyphonically participate in generating the disruptive manifold.
Following titanium-horn installation, a total signal gain can be
applied until the optimal power, power spectrum, and phase
characteristics of the pulse have been achieved.
[0056] The piezoelectric devices may then be inserted into the
wellbore to the point that they are within or near the underground
geological formation. For example, a piezoelectric device connected
to a fracking system 510 may be lowered through a wellbore 520 into
geological formation 530 (see FIG. 5). One or more piezoelectric
devices (e.g., probe heads) can be inserted into a single wellbore.
Once the piezoelectric devices are sufficiently close to the
geological formation 530, the ultrasonic fracking process (as
described above) can commence. In the case of vertical well bores
(see, e.g., wellbore 160 in FIG. 1), the piezoelectric devices may
be introduced into the wellbores by simply lowering them into the
well. However, in the case of horizontal wells (see, e.g., wellbore
520 in FIG. 5), the piezoelectric devices can be inserted into the
wellbores using a drilling string or a small mechanical
tunnel-traversing vehicle.
[0057] As shown in FIG. 5, during or immediately after ultrasonic
fracking, vacuum or suction may be applied to the wellbore(s) 520
to reduce pressure in the opening and upper portion of the
wellbore(s) 520 to draw hydrocarbons (e.g., natural gas) 550 to the
surface, where it can be collected. Additionally, an innocuous
proppant (e.g., N.sub.2 gas) may be pumped into the underground
geological formation in order to aid in (1) keeping the fractures
in the formation (see, e.g., fractures 540 in FIG. 5) open and (2)
de-sequestration of natural gas components (e.g., methane) that may
be physisorbed to the material of the formation (e.g., oil shale,
coal, sandstone, etc.). Disruption of the matrix of the geological
material, followed by infusion and extraction of gases along the
natural z-gradient of the formation (which results in greater local
pressure at greater depths) is carried out as a cyclic, periodic
process. For example, ultrasonic fracking, can be followed by
infusing N.sub.2 gas into the well bore 520 and then applying a
vacuum to the wellbore 520 to draw hydrocarbons 550 (see FIG. 5)
freed from the formation by the fracking process.
[0058] The presently described embodiments of a method of
extracting one or more hydrocarbons (e.g., one or more gases at
room temperature and atmospheric pressure, consisting essentially
of carbon and hydrogen, such as natural gas, methane, ethane,
propane, butane, etc.) from underground geological formations using
ultrasonic vibrations are not limiting, and the invention is
intended to cover alternatives, modifications and equivalents that
may be included within the spirit and scope of the invention as
defined by the appended claims.
Conclusion/Summary
[0059] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof. It
is also understood that various embodiments described herein may be
utilized in combination with any other embodiment described,
without departing from the scope contained herein. In addition,
embodiments of the present invention are further scalable to allow
for additional clients and servers, as particular applications may
require.
[0060] The foregoing descriptions of specific embodiments of the
present invention have been presented for purposes of illustration
and description. They are not intended to be exhaustive or to limit
the invention to the precise forms disclosed, and obviously many
modifications and variations are possible in light of the above
teachings. The embodiments were chosen and described in order to
best explain the principles of the invention and its practical
application, to thereby enable others skilled in the art to best
utilize the invention and various embodiments with various
modifications as are suited to the particular use contemplated. It
is intended that the scope of the invention be defined by the
Claims appended hereto and their equivalents.
* * * * *