U.S. patent application number 14/197086 was filed with the patent office on 2014-09-04 for system and method for increasing production capacity of oil, gas and water wells.
This patent application is currently assigned to TECHNOLOGICAL Organization Name RESEARCH LTD.. The applicant listed for this patent is TECHNOLOGICAL Organization Name RESEARCH LTD.. Invention is credited to Alfredo ZOLEZZI-GARRETON.
Application Number | 20140246191 14/197086 |
Document ID | / |
Family ID | 43926911 |
Filed Date | 2014-09-04 |
United States Patent
Application |
20140246191 |
Kind Code |
A1 |
ZOLEZZI-GARRETON; Alfredo |
September 4, 2014 |
SYSTEM AND METHOD FOR INCREASING PRODUCTION CAPACITY OF OIL, GAS
AND WATER WELLS
Abstract
The invention provides an apparatus, method and system for
stimulating production of a natural resource (e.g., Oil, gas or
water) producing well using vibrational energy delivered to the
geological formation through a device that maybe permanently
installed, and continuously or periodically operated even during
recovery of the natural resource. The apparatus is of a downhole
type. The apparatus is constructed to resist corrosion and provides
one or more heat sink chambers for controlling heat dissipation
during operation. The system provided by the invention is capable
of monitoring production, adapting stimulation parameters based on
user input and other pertinent parameters.
Inventors: |
ZOLEZZI-GARRETON; Alfredo;
(Vina del Mar, CL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TECHNOLOGICAL Organization Name RESEARCH LTD. |
Tortola |
|
VG |
|
|
Assignee: |
TECHNOLOGICAL Organization Name
RESEARCH LTD.
Tortola
VG
|
Family ID: |
43926911 |
Appl. No.: |
14/197086 |
Filed: |
March 4, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12954906 |
Nov 28, 2010 |
8746333 |
|
|
14197086 |
|
|
|
|
61283195 |
Nov 30, 2009 |
|
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Current U.S.
Class: |
166/249 |
Current CPC
Class: |
E21B 43/003 20130101;
E21B 28/00 20130101 |
Class at
Publication: |
166/249 |
International
Class: |
E21B 43/00 20060101
E21B043/00 |
Claims
1. A method for stimulating production in a resource producing well
within the extraction zone of the well, said method comprising the
steps of: deploying an apparatus capable of acoustically delivering
mechanical vibrational energy to a geological formation containing
a natural resource within a well; applying at least one preliminary
treatment to the extraction of the well; and permanently installing
said apparatus for a continuous operation.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 12/954,906 filed on 28 Nov. 2010, which claims priority to U.S.
provisional application No. 61/283,195 filed on Nov. 30, 2009. The
entire text of each of the above-referenced applications is
specifically incorporated by reference herein without
disclaimer.
FIELD OF THE INVENTION
[0002] The invention relates to recovering natural resources such
as oil and natural gas from a geological formation; particularly
the invention related to a system and method for stimulating the
flow of the natural resource toward the recovery zone, i.e. wells,
utilizing high-power elastic waves and a monitoring system to
collect data for optimizing the system's performance.
BACKGROUND OF THE INVENTION
[0003] There exist several extraction methods to improve
productivity from oil wells. However in the upstream crude oil
industry, 60% to 70% of OOIP (Original Oil In Place) are typically
left in the reservoir after the use of normal primary and secondary
recovery techniques (Society of Petroleum Engineers. www.spe.org).
The benefits of improving extraction methods are substantial. For
example, there are thousands of oil wells in Texas, USA, alone,
which could benefit from improving oil production output. If it
were possible to recover even 50% of the heavy oil deposits, the US
could supply 50% of North American demand for another 50 to 75
years (Dr. Franklin Foster, 2006).
[0004] A well for extracting fluids from geological formations is
constructed by drilling a hole from the surface toward the
geological formation that contains a natural resource, and that has
adequate permeability to let fluids produced in the formation flow
toward the well. The well's walls are lined with a cement layer and
a casing that houses and supports a production tube string
coaxially installed in its interior. In addition, perforations are
made in the well lining in order to connect the well with the
reservoir, supplying a path or trajectory inside the formation.
Tubes provide an outlet for the fluids obtained from the
formation.
[0005] Typically, there are numerous perforations that extend
radially from the lined or coated well. Perforations are uniformly
separated in the lining, and pass to the outside of the lining
through the formation. In an ideal case, perforations are only
located within the formation, and their number depends on the
formation thickness. It is rather common to have nine, and up to
twelve perforations per depth meter of formation. Other
perforations extend longitudinally, and yet other perforations may
extend radially from a 0.degree.-azimuth, while additional
perforations, located every 90.degree. may define four sets of
perforations around azimuth. Formation fluids pass through these
perforations and come into the lined (or coated) well.
[0006] Preferably, the oil well is plugged by a sealing mechanism,
such as a shutter element, or with a bridge-type plug, located
below the level of perforations. This shutter element is connected
to a production tube, and defines a compartment. The production
fluid, coming from the formation or reservoir, enters the
compartment and fills the compartment until it reaches a fluid
level. Accumulated oil, for example, flows from the formation and
can be accompanied by variable quantities of natural gas. Hence,
the lined compartment may contain oil, some water, natural gas, and
solid particles, with normally, particles sewing at the bottom of
the compartment.
[0007] The fluid produced in the formation may change its phase
when there is a reduction of pressure around the well; this change
of phase causes the gasification of the lightest molecules. Also,
the oil well can produce very heavy molecules. Over time, due to
several reasons, oil well productivity gradually diminishes. Two
main causes of the reduction in productivity are related to
relative permeability: a decrease of the fluidity of crude oil, and
the deposit of solids in the perforations.
[0008] Crude oil's fluidity diminishes over time and progressively
obstructs pores in a deposit or reservoir. On the other hand,
solids such as clays, colloids, salts, paraffin etc. accumulate in
perforation zones of the well. These solids reduce the absolute
permeability, or interconnection between pores. Problems associated
with the causes mentioned above are: obstruction of pores by
mineral particles that flow jointly with the fluid to be extracted,
precipitation of inorganic scales, decanting of paraffins and
asphalt or bitumen, hydration of clay, invasion of solids from the
mud and filtration of perforation mud, as well as invasion of
termination fluids and solids from brine injections. Each of the
above mentioned causes can produce a permeability reduction, or a
flow restriction in the zone surrounding oil well perforations.
This defines the pore size connecting to the fluid inside
formation, allowing the fluid flow from the formation through
cracks or fissures, or connected pores, and finally the fluid comes
to interstitial spaces within the compartment and is collected.
During that flow, very small solid particles from the formation,
called "fines," may flow; but instead they tend to settle.
[0009] After a certain time, trajectories through perforations
extending inside the formation of a reservoir may become obstructed
with "fines" or residues. While the "fines" can be kept in a
disperse state for some time, they can agglomerate and plug the
pore space, reducing the fluid rate or production quantity. This
may become a problem that is fed back to the well and cause a
production decrease. More and more "fines" can keep sewing on
perforations, plugging them more and more, even tending to haft a
minimum flow rate.
[0010] There exist several treatment methods to improve
productivity from oil wells. Periodic stimulation of oil and gas
wells is done by applying three general types of treatment: acid
treatment, fracturing, and default treatment with solvents and
heat. Acid treatment consists of using mixtures of acids HCl and HF
(hydrochloric acid and hydrofluoric acid), which is injected in the
production zone (rock). Acid is used for dissolving reactive
components (carbonates, clay minerals, and in a smaller quantity,
silicates) in the rock, thus increasing permeability. Frequently,
additives are incorporated, such as reaction retarding agents and
solvents, to improve acid performance in the acidizing
operation.
[0011] While acid treatment is a common treatment to stimulate oil
and gas wells, this treatment has multiple drawbacks. The cost of
acids and the cost of disposing of production wastes are high;
acids are often incompatible with the crude oil, and may produce
viscous oily residues inside the well; precipitates formed once the
acid is consumed, can often be more obnoxious than dissolved
minerals; and the penetration depth of active or live acid is
generally less than 5 inches (12.7 cm).
[0012] Hydraulic fracturing is another technique usually used for
stimulating oil and gas wells. In this process, high hydraulic
pressures are used to produce vertical fractures in the formation.
Fractures can be filled with polymer plugs, or treated with acid
(in rocks, carbonates, and soft rocks), to form permeability
channels inside the wellbore region; these channels allow oil and
gas to flow. However, the cost of hydraulic fracturing is extremely
high (as much as 5 to 10 times higher than acid treatment costs).
In some cases, fracture may extend inside areas where water is
present, thus increasing the quantity of water produced (a
significant drawback for oil extraction). Hydraulic fracture
treatments extend several hundred meters from the well, and are
used more frequently when rocks are of low permeability. The
possibility of forming successful polymer plugs in all fractures is
usually limited, and problems such as plugging of fractures and
grinding of the plug may severely deteriorate productivity of
hydraulic fractures.
[0013] Another method for improving oil production in wells
involves injecting steam. One of the most common problems in
depleted oil wells is precipitation of paraffin and asphaltenes or
bitumen inside and around the well. Steam has been injected in
these wells to melt and dissolve paraffin into the oil or
petroleum, and then all the mixture flows to the surface.
Frequently, organic solvents are used (such as xylene) to remove
asphaltenes or bitumen whose melting point is high, and which are
insoluble in alkanes. Steam and solvents are very costly (solvents
more so than steam), particularly when marginal wells are treated,
producing less than 10 oil barrels per day (1 bbl=159 liters). The
main limitation for use of steam and solvents is the absence of
mechanical mixing, which is required for dissolving or maintaining
paraffin, asphaltenes or bitumen in suspension.
[0014] Several other methods have been described to increase oil
well output. Challacombe (U.S. Pat. No. 3,721,297) describes a tool
for cleaning wells using pressure pulses: a series of explosive and
gas generator modules are interconnected in a chain, in such a
manner that ignition of one of them triggers the next one and a
progression or sequence of explosions is produced. These explosions
generate shock waves that clean the wells. There are obvious
disadvantages of this method, such as potential damage that can be
caused to high-pressure oil and gas wells.
[0015] Sawyer (U.S. Pat. No. 3,648,769) describes a hydraulically
controlled diaphragm that produces "sinusoidal vibrations in the
low acoustic range". Generated waves are of low intensity, and are
not directed or focused to face the formation (rock). As a
consequence, the major part of energy is propagated along the well
axis.
[0016] Riggs et al. (U.S. Pat. No. 4,343,356) describes an
apparatus for treating shallow wells. Application of a high voltage
produces voltage arcs that liberate from the well walls the
encrusted material. Among difficulties with this apparatus there is
the fact that it is not possible to continually guide the electric
arc for achieving a real cleaning of the well. Additionally, safety
aspects have not been solved (electrical and fire problems).
[0017] Bodine (U.S. Pat. No. 4,280,557) proposes another
hydraulic/mechanical oscillator where pulses of hydraulic pressure,
created inside an elastic elongated tube, are used for cleaning
encased well walls.
[0018] Mac Manus et al. (U.S. Pat. No. 4,538,682) disclosed a
method for removing paraffin from oil wells by introducing a
heating element into an oil well in order to establish a
temperature gradient within the well.
[0019] It is known that oil, gas, and water wells are plugged after
certain operating time; the fluid discharge diminishes and it
becomes necessary to regenerate these wells. Mechanical, chemical,
and conventional techniques to regenerate wells include: intensive
rinsing, pumping hammer and hydraulic treatment.
[0020] Dissolution of sediments using hydrochloric acid, or other
acids, mixed with other chemical agents include: Hosing down with
high-pressure water, carbon dioxide injection, and generation of
pressure shocks using explosives.
[0021] Ultrasound techniques have been developed to increase
production of crude oil from wells. However, there is a great
amount of effects associated with exposing solids and fluids to an
ultrasound field of certain frequencies and energy. In the case of
fluids in particular, cavitation bubbles can be generated. These
are bubbles of gas dissolved in liquid, or bubbles of the gaseous
state of this liquid (change of phase). Other associated phenomena
are liquid degassing and cleaning of solid surfaces.
[0022] Arthur Kuris, in "Method and Apparatus for Fracturing Rock
and the Like" (U.S. Pat. No. 3,990,512), discloses a method for
recovering oil by application of ultrasound generated when
injecting high-pressure fluids, whose purpose is to fracture the
deposit to produce new draining channels.
[0023] Maki Jr. et al. (U.S. Pat. No. 5,595,243) propose an
acoustic device in which a piezoceramic transducer is set as
radiator. The device presents difficulties in its manufacturing and
use, because an asynchronous operation is required of a high number
of piezoceramic radiators.
[0024] Vladimir Abramov et al., in "Device for Transferring
Ultrasonic Energy to a Liquid or Pasty Medium" (U.S. Pat. No.
5,994,818) and in "Device for Transmitting Ultrasonic Energy to a
Liquid or Pasty Medium" (U.S. Pat. No. 6,429,575), propose an
apparatus consisting of an alternating current generator operating
within the range of 1 to 100 kHz to transmit ultrasonic energy, and
a piezoceramic or magnetostrictive transducer emitting ultrasound
waves, which are transformed by a tubular resonator or waveguide
system (or sonotrode) in transversal oscillations that contact the
irradiated liquid or pasty medium. However, these systems are
conceived to be used in containers of very large dimensions, at
least as compared with the size and geometry of perforations
present in wells. This shows limitations from a dimensional point
of view, and also for transmission mode if it is desired to enhance
production capacities of oil wells.
[0025] Julie C. Slaughter et al., in "Ultrasound Radiator of
Downhole Type and Method for Using It" (In U.S. Pat. No.
6,230,788), propose a device that uses ultrasonic transducers
manufactured of Terfenol-D alloy and placed at the well bottom, and
fed by an ultrasonic generator located at the surface. Location of
transducers, axially to the device, allows the emission along a
transversal direction. This invention proposes a viscosity
reduction of hydrocarbons contained in the well through
emulsification, when reacting with an alkaline solution injected to
the well. This device considers a forced shallow circulation of
fluid as a refrigeration system, to warrant continuity of
irradiation.
[0026] Dennos C. Wegener et al., in "Heavy Oil Viscosity Reduction
and Production," (U.S. Pat. No. 6,279,653), describe a method and a
device for producing heavy oil (API specific gravity less than 20)
applying ultrasound generated by a transducer made of Terfenol
alloy, attached to a conventional extraction pump, and powered by a
generator installed at the surface. In this invention the presence
of an alkaline solution is also considered, similar to an aqueous
sodium hydroxide (NaOH) solution, to generate an emulsion with
crude oil of lower density and viscosity, thereby facilitating
recovery of the crude by impulsion with a pump. Here, a transducer
is installed in an axial position to produce longitudinal
ultrasound emissions. The transducer is connected to an adjacent
rod that operates as a waveguide or sonotrode.
[0027] Robert J. Meyer et al., in "Method for improving Oil
Recovery Using an Ultrasonic Technique" (U.S. Pat. No. 6,405,796),
propose a method to recover oil using an ultrasound technique. The
proposed method consists of disintegration of agglomerates by means
of an ultrasonic irradiation technique, and the operation is
proposed within a certain frequency range, for the purpose of
handling fluids and solids in different conditions. Main oil
recovery mechanism is based in the relative momentum of these
components within the device.
[0028] The above-mentioned prior art using ultrasonic waves via a
transducer, externally supplied by an electric generator and the
transmission cable generally is longer than 2 km. This has the
disadvantage of signal transmission losses, which means that a
signal must be generated to have enough intensity (or energy) for
an adequate operation of transducers within the well, since
high-frequency electric current transmission to such depths is
reduced to 10% of its initial value. Furthermore, since transducers
need to operate at a high-power regime, water or air cooling system
is required, which poses great difficulties when placed inside the
well. The latter implies that ultrasound intensity must not exceed
0.5-0.6 W/cm2. This level is insufficient for the desired purposes,
because threshold of acoustic effects in oil and rocks is from 0.8
to 1 W/cm2.
[0029] Andrey a. Pechkov, in "Method for Acoustic Stimulation of
Wellbore Bottom Zone for Production Formation" (RU Patent No.
2,026,969), disclose methods and devices for stimulating production
of fluids within a producing well. These devices incorporate, as an
innovating element, an electric generator attached to the
transducer, and both of them integrated in the well bottom. These
transducers operate in a non-continuous mode, and can operate
without needing an external cooling system. The impossibility of
operating in a continuous mode to prevent overheating is one of the
main drawbacks of this implementation since the availability of the
device is reduced. Moreover, as the generator is located in the
well bottom, this equipment maintenance cost rises as it is likely
to fail, especially when working in high power applications.
[0030] Oleg Abramov et al., in "Acoustic Method for Recovery of
Wells, and Apparatus for its Implementation" (U.S. Pat. No.
7,063,144), disclose an electro-acoustic method for stimulation of
production within an oil well. The method consists of stimulating,
by powerful ultrasound waves, the well extraction zone, causing an
increase of mass transfer through its walls. This ultrasonic field
produces large tension and pressure waves in the formation, thus
facilitating the passage of liquids through well orifices. It also
prevents accumulation of "fines" on these holes, thereby increasing
the life of the well and its extraction capacity.
[0031] Some problems encountered in the solutions proposed by
Robert J. Meyer et al., in "Method for improving Oil Recovery Using
an Ultrasonic Technique" (U.S. Pat. No. 6,405,796), Andrey A.
Pechkov, in "Method for Acoustic Stimulation of Wellbore Bottom
Zone for Production Formation" (RU Patent No. 2,026,969), Dennos C.
Wegener et al., in "Heavy Oil Viscosity Reduction and Production,"
(U.S. Pat. No. 6,279,653), Oleg Abramov et al., in "Acoustic Method
for Recovery of Wells, and Apparatus for its Implementation" (U.S.
Pat. No. 7,063,144) and Julie C. Slaughter et al., in "Ultrasound
Radiator of Dowhole Type and Method for Using It" (In U.S. Pat. No.
6,230,788), are:
[0032] a) some devices to be introduced in the well containing the
ultrasound radiator are sensible to degradation by hydrocarbons and
corrosion by acids present at the well bottom;
[0033] b) some devices are not intended to be used in oil/water
wells with high content or presence of gas, due to their almost
null capacity to dissipate the heat generated by the mechanic wave
radiators when said radiators are not in contact with liquid
fluids, situation that eventually will destroy the radiators or
other components (cables, wires, coils, others); and
[0034] c) some devices are not meant to be used in Gas Reservoirs
or Gas wells.
[0035] d) some devices have associated environmental treatment
costs due to the use of chemicals.
[0036] Therefore, what is needed is a method, apparatus and system
for improving well productivity that does not present (or at least
minimizes) the drawbacks of the existing technologies. The
invention provides a system, apparatus and method for increasing
production capacity of oil, gas and water wells.
SUMMARY OF THE INVENTION
[0037] The invention provides a system, an apparatus and methods
for increasing productivity of a natural resource producing-well.
The invention provides an apparatus that utilizes one or more
elastic-waves generators hosted inside a chamber. The chamber is
made of (or protected by) a corrosion-resistant material, that
allow the apparatus to be efficiently used in harsh chemical
environments.
[0038] The invention provide a highly efficient and versatile means
to increase the mobility of fluids within the well bore region of
an oil/water/gas well. The method and system may be adapted to the
geology of the reservoir. In one embodiment of the invention, the
system utilizes an acoustic device of the "downhole" type, that is,
at the bottom of the well and/or the perforated zone of the well,
to generate mechanical waves of an extremely high energy. Such high
energy is capable of removing deposits of fines, organics, scales
and inorganic deposits inside the well and in the wellbore region.
A device implementing the invention may have an insulated and
controlled-environment chamber, for protection against mechanical
waves generated by the acoustic generators, and against corrosion
by hydrocarbons present in the formation, and from high
temperature. The later configuration allows for the installation of
several types of sensors and devices to acquire data from the well
bottom, wellbore and/or the perforated zone.
[0039] One or more embodiments of the invention deliver an acoustic
device for oil, gas, and water well, which does not require
injection of chemicals for their stimulation.
[0040] One of the advantages of the invention compared to prior art
is that the system delivers an acoustic device for downhole that
has no environmental burden that is typically associated with
treatment with liquids which are typically returned to the well
after the treatment.
[0041] The invention provides an acoustical device for stimulating
wells in the perforation zone (downhole) that can operate inside a
tube without needing the withdrawal or elimination said tube.
Alternatively, the device may be coupled to the tube using an
adapter, in order to operate while being during production.
[0042] The regime of operation in accordance with the invention may
be adapted to the type of well (e.g., Oil, Gas or any combination
of both), to type geology and all other aspects of factors that
limit the production in a well. The method and system embodying the
invention are highly versatile and may be adapted for use
specifically to treat any of a plurality of conditions. Embodiments
of the invention may comprise an acoustic device capable of being
used in one or more different types of reservoirs, crude type, gas
content, and combined environments. The acoustic device may operate
with an corrosion-resistant heatsink chamber that emits and/or
radiates power as elastic waves directed to the formation, and that
likewise avoids the contact of hydrocarbons and other fluids with
the radiator and other inner components of the system preventing
corrosive damage.
[0043] Another embodiment of the invention provides a
corrosion-resistant heatsink chamber that acts as an acoustic
resonance chamber. The invention takes into account the disposition
of the wave generator and provides a plurality of geometries that
are adequate to address a plurality of conditions. The
corrosion-resistant heatsink chamber also prevents the system from
overheating, by means of a heatsink liquid which fills the device,
allowing the system to work in gas reservoirs or oil wells with
high concentration of gas. When working in heavy oil wells, the
capacity to efficiently transfer the heat generated by the wave
radiators to the environment, also improves the capacity of the
system to reduce the viscosity of the crude oil, for example, thus
facilitating the crude oil flow and extraction.
[0044] Furthermore, an embodiment of the invention provides a
device that allows the connection of one or more acoustic devices
in a single well, thus allowing an installation that fulfills the
specific requirements for each well.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] FIG. 1 is a block diagram that represents components of a
system utilized to increase well production in accordance with one
embodiment of the invention.
[0046] FIG. 2 shows a schematic representation of a typical well
for extracting oil and/or gas, aiming at presenting the context in
which an embodiment of the invention is utilized.
[0047] FIG. 3 is a block diagram representing components of a well
stimulation device in accordance with embodiments of the
invention.
[0048] FIG. 4 represents a longitudinal section view through a
device for stimulating wells in accordance with an embodiment of
the invention.
[0049] FIG. 5 is a block diagram representing components of a
high-power generator for powering one or more magnetostrictive
transducers in accordance with one embodiment of the invention.
[0050] FIG. 6A and FIG. 6B show a cross section view and a
perspective section view, respectively, of a submersible cable as
used in one embodiment of the invention.
[0051] FIG. 7A is a flowchart diagram of method steps involved in
fabricating elastic waves generator using magnetostrictive material
in accordance with an embodiment of the invention.
[0052] FIG. 7B is a plot of the temperature for curing resin versus
time of curing in accordance with embodiments of the invention.
[0053] FIG. 8 shows a set of plots that represent vibrational
energy transfer along the longitudinal and radial axes between a
device implementing the invention and the surrounding area in the
operation zone.
[0054] FIG. 9 illustrates the geometry of a device implementing the
invention where the layout of transducers in relation with wave
propagation properties is used to optimize the amount of vibration
energy transferred to the surrounding operation zone.
[0055] FIG. 10 illustrates the interaction between the transducer
and the wall of the chamber when geometry is adequately configured
to utilize the resonance properties of the device implementing the
invention.
[0056] FIG. 11A illustrates examples of geometries for the layout
of a plurality of acoustic wave sources hosted within one or more
devices implementing the invention.
[0057] FIG. 11B illustrates geometries of various dispositions of a
acoustic wave source with regard to the wall of the chamber in
accordance with one or more embodiments of the invention.
[0058] FIG. 12A and FIG. 12B represent a longitudinal and
transversal section views, respectively, of a device implementing
the invention where one or more acoustic waves generators are in
direct contact with the wall of the radiating chamber.
[0059] FIG. 13 shows a longitudinal section view of a device
implementing the invention where the diameter of the device exceeds
that of the tubing in a well, and the means to attach the device to
the tubing.
[0060] FIG. 14 a longitudinal section view illustrating several
layers that allow a tubing in accordance with an embodiment of the
invention to enhance the heat transfer rate to the crude in the
reservoir in order to reduce viscosity of crude oil.
[0061] FIG. 15 is a flowchart diagram representing the overall
steps comprised in deploying a system embodying the invention,
applying one or more preliminary treatment, and permanently
operating the system.
[0062] FIG. 16 is a flowchart diagram showing steps involved in
deploying a device implementing the invention.
[0063] FIG. 17 is a flowchart diagram representing steps of
cleaning a well before permanent operation in accordance with one
embodiment of the invention.
[0064] FIG. 18 is a flowchart diagram representing steps comprised
in the process of cleaning a well in accordance with an embodiment
of the invention.
[0065] FIG. 19 is a flowchart diagram representing steps comprised
in heat treatment of heavy oil in accordance with one embodiment of
the invention.
[0066] FIG. 20 is a flowchart diagram representing steps comprised
in the permanent installation of a system embodying the
invention.
[0067] FIG. 21A is a plot of the power as a function of time of a
high frequency continuous signal for driving a wave generator, in
accordance with one embodiment of the invention.
[0068] FIG. 21B is a plot of the power as a function of time of a
high frequency signal for driving a wave generator, where the
signal is applied in an ON/OFF fashion, in accordance with one
embodiment of the invention.
[0069] FIG. 21C is a graph showing the power level as a function of
time of a high-frequency signal that is applied in a pulsed mode,
in accordance with an embodiment of the invention.
[0070] FIG. 21D is a bode diagram showing the magnitude of the
signal and the phase of the signal as a function of frequencies of
signals propagated through a geological formation in accordance
with applications of the invention.
[0071] FIG. 21E is a plot of a low frequency wave 2175 resulting
from the application of a burst of high-frequency signal.
[0072] FIG. 22A is a plot of a modulated high frequency signal used
to apply low-frequency acoustic vibrations in accordance with an
embodiment of the invention.
[0073] FIG. 22B shows a plot of a signal having a low-frequency
that results from the application of the signal shown in FIG.
22A.
[0074] FIG. 23 is a plot representing a signal whose frequency is
modulated in accordance with an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0075] The invention provides an apparatus, method and system for
increasing production capacity of oil, gas and water wells
utilizing a versatile device that is adaptable to various
applications. The invention also provides methods and a system to
use the device in various exploitation reservoirs that have various
geologies.
[0076] In the following description, numerous specific details are
set forth to provide a more thorough description of the invention.
It will be apparent, however, to one skilled in the pertinent art,
that the invention may be practiced without these specific details.
In other instances, well known features have not been described in
detail so as not to obscure the invention. The claims following
this description are what define the metes and bounds of the
invention.
[0077] The following detailed description is frequently concerned
with oil wells; the invention however is intended to be adapted for
other types of wells to extracting other types of natural resources
such as natural gas and water from geological formations.
[0078] FIG. 1 is a block diagram that represents components of a
system utilized to increase well production in accordance with one
embodiment of the invention. A system embodying the invention
comprises a wave radiator 120. The wave radiator is a device
capable of delivering vibrational power 125 to a geological
formation 150 such as an oil or gas containing reservoir. In
embodiments of the invention, the wave radiator 120 is capable of
delivering power in a wide range of power and frequency, the level
of which is determined by a user (e.g., an oil/gas field manager)
and/or a control system 110.
[0079] In embodiments of the invention, the wave radiator may
deliver acoustic waves, mechanical waves, electromagnetic waves or
any type of physical phenomenon capable of delivering vibrational
energy to a geological formation.
[0080] The system embodying the invention comprises a sub-system
130 for collecting data 136 from the operating area, including the
geological formation. The data collection/monitoring system 130
comprises one or more sensors for collecting a plurality of
environmental data. For example, the sensors may collect
temperature, pressure, viscosity, conductivity or any other
physical parameter that may indicate one or more characteristics of
a well. The data once collected may be transmitted, through data
transmission means (e.g., copper cables, fiber optics or any other
available data transmission means) 132 to a processing and control
system 110.
[0081] The data processing and control system comprises one or more
data processing devices, including digital computers, data
visualization machines and power control units. The data processing
and control system also allows a user to monitor operations and
provide manual input for adjustment. The data processing and
control system may execute one or more computer programs for
analyzing data and one or more computer programs to provide
optimization solutions to maximize the system's efficiency.
[0082] The output 122 of the data processing and control system 110
may be utilized to drive the wave radiator 120, by providing for
example, instructions to the wave radiator 120, which instructions
will be used by the wave radiator 120 to vary the power output to
the geological formation 150 in order to achieve the best results
in terms of productivity. The data processing and control unit 110
may on the other hand control the power directly fed into the wave
radiator 120 in order to control the amount of power delivered to
the reservoir.
[0083] The data processing and control system 110 may also feed
data back to the sensing and monitoring system (e.g., 134) in order
to better control the data collection process.
[0084] FIG. 2 shows a schematic representation of a typical well
for extracting oil and/or gas, aiming at presenting the context in
which an embodiment of the invention is utilized. Well 220, for
extracting fluids from a geological formation, comprises a hole
drilled in the ground. The inner side of the hole then lined with a
cement layer 225 and a casing 228 that houses and supports a
production tube string 230 coaxially installed in its interior.
Perforations 240, in the well lining, provide a path or trajectory
that allow fluids produced in the reservoir 210 to flow from the
reservoir 210 toward the collection area of the well.
[0085] Typically, there are numerous perforations (e.g., 240) that
extend radially from the lined or coated well. Perforations are
generally uniformly separated in the lining, and pass to the
outside of the lining through the formation. In an ideal case,
perforations are only located within the formation, and their
number depends on the formation thickness. It is rather common to
have nine (9), and up to twelve (12) perforations per depth meter
of formation. Other perforations extend longitudinally, and yet
other perforations may extend radially from a 0.degree.-azimuth,
while additional perforations, located every 90.degree. may define
four sets of perforations around azimuth. Formation fluids pass
through these perforations and pass into the lined (or coated)
well.
[0086] Preferably, the oil well is plugged by a sealing mechanism,
such as a shutter element (e.g., 232), and/or with a bridge-type
plug, located below the level of perforations (e.g., 234). The
shutter element 232 may be connected to a production tube, and
defines a compartment 205. The production fluid, coming from the
formation or reservoir, enters the compartment and fills the
compartment until it reaches a fluid level. Accumulated oil, for
example, flows from the formation and can be accompanied by
variable quantities of natural gas. Hence, the lined compartment
205 may contain oil, some water, natural gas, and solid residues,
with normally, sand sewing at the bottom of the compartment.
[0087] A tool 100 for stimulating the well in accordance with
embodiments of the invention, may be lowered into the well to reach
the level of the formation. The tool may be connected to the ground
surface through an attachment means 250 or simply attached to the
extremity of the tube 230 using an adapter (see below), or even
between two portions of the tube 230 (e.g. when the well has more
than one extraction zone, more than one tool may be lowered). Thus,
a tool 100 may be lowered momentarily into a well for well
treatment, or alternatively by attaching the tool between two
portions of the tube 230 or to the end of the tube 230, the tool
may be operated even as the production continues from the well. The
attachment means comprises a set of cables for providing the
mechanical strength for holding the weight of tool 100. The
attachment means may also comprise power cables for transmitting
electrical energy to the tool, and communication cables such as
copper wires and/or fiber optics for providing a means of
transmitting data between control computers on the ground and the
tool.
[0088] FIG. 3 is a block diagram representing components of a well
stimulation device in accordance with embodiments of the invention.
Device 100 comprises one or more elastic waves radiating means 310.
The elastic waves radiating means may be any device capable of
generating vibration power, which is transmitted to the geologic
formation in order to facilitate the movement of the natural
resource toward the well for collection. Device 100, in accordance
with an embodiment of the invention, comprises one or more chambers
(e.g., 320) for hosting the wave radiators, power supply units,
sensing equipment and any other component of the device.
[0089] Chamber 320 provides an important role for implementing
embodiments of the invention. Chamber 320 provides an environment
in which temperature, pressure and other physical parameters may be
controlled in order to provide an adequate environment for an
efficient functioning of device 100. For example, chamber 320 may
be filled with a liquid that acts as a heat sink in order to
protect equipment from the heat generated during operation. Chamber
320 may be designed with specific resonance properties to optimize
the efficiency of the vibrations. Chamber 320 may be sealed to
allow for high pressure inside the chamber in order to counteract
the cavitation phenomena that may accompany application of sound
waves to the liquid filling the chamber.
[0090] Device 100 comprises a power supply unit 330. The power
supply unit comprises electronic circuitry, such as one or more
circuit boards for converting power (Alternating and/or direct
power) into one or more regimes of power as required by any
specific type of wave radiation means comprised in the device 100.
Power supply unit 330 also comprises energy storing components
(e.g., one or more capacitors) capable of storing electric power
and delivering the power, either automatically and/or under the
control of an electronic signal.
[0091] Device 100 comprises a sensing system 340 which includes one
or more sensors capable of detecting physical parameters in the
well and collecting data that can be transmitted to and processed
by data processing centers. The sensors may be hosted within a
chamber that may be part of other chambers of device 100.
Alternatively, the sensors may be hosted in a chamber that is
connected with other chambers through an opening 250. The latter
may be useful for allowing the liquid acting as a heat sink to
freely flow and protect the sensors.
[0092] Device 100 may be constructed partly or in its entirely from
corrosion-resistant materials. In accordance with embodiments of
the invention, device 100 is designed to resist the harsh chemical
environment attacks present in the operation zone. For example,
device 100 may be constructed using a steel cylinder having a wall
thickness adequate for heat dissipation and vibration transmission
adequate for desired sound and temperature properties for a
specific application environment, while the surfaces are coated
with a corrosion-resistant compound in order to protect the device
and its components from chemical attacks.
[0093] FIG. 4 represents a longitudinal section view through a
device for stimulating wells in accordance with an embodiment of
the invention. The device 400 is one example of an implementation
of the device and system as provided by the invention. Device 400
comprises a chamber 460. The chamber 460 preferably having a
cylindrical shape, possesses anticorrosive properties and provides
a heatsink. Device 400 may be lowered inside the well using a cable
410. The cable 410 comprises one or more electrical conductors, and
is strong enough to support its own weight and the weight of device
400.
[0094] The chamber 460 may be made of a corrosion-resistant
material, elastic enough for resisting mechanical vibrations.
Chamber 460 comprises two (2) sections: a protective chamber 462
and a controlled-environment chamber 464. The protective chamber
462 comprises an upper cover 420, a separator 450, and a chamber
wall 440. The controlled-environment chamber 464 houses measurement
and control sensors 435, and is resistant to mechanical waves
produced by the wave radiator.
[0095] Device 400 comprises a wave radiator 430. The wave radiator
may have any form, and may be fabricated using materials that
conducive to producing vibration waves such one or more
magnetostrictive transducers. The invention allows for implementing
transducer of several types and shapes depending of the target
application, which in turn depends on the conditions in each
formation.
[0096] In the example of FIG. 4, the wave radiator 430 is powered
by wires 410, adequately connected through the upper seal 420. The
radiator may be in other instances powered by a local power supply
unit comprised within device 400.
[0097] The upper cover 420 and the separator 450 may be made of
corrosion-resistant materials, and are specially designed to
support the high pressure present in perforated zone of the well
210. The controlled deformation chamber is flooded with an
insulator heat-sink liquid 445. This heat-sink liquid 445 surrounds
the wave radiator 430. Said liquid 445 has a cooling function,
allowing dissipation of heat generated by the acoustic wave
radiator, and efficiently transferring said heat to the
surroundings. The corrosion-resistant heat-sink chamber 460 is
pressurized to prevent cavitation phenomena that may be generated
through the application of sound waves. The value of internal
pressure in the corrosion-resistant heat-sink chamber is adjusted
depending on individual characteristics of formation and of the
power level used.
[0098] The controlled environment chamber 464 may be fabricated of
a material resistant to mechanical waves generated by the wave
radiators 430. Inside the controlled environment chamber are
measurement and control sensors 435. The main objective of this
controlled environment chamber is to protect said sensors from
corrosion and degradation due to hydrocarbons present in the
formation, and from the waves produced by the one or more wave
radiators 430.
[0099] Chamber 460 may be compartmentalized into two or more
sub-chambers (e.g., 462 and 464) and the sub-chambers may be
interconnected to allow free passage of the heat-sink liquid.
[0100] The purpose of measurement and control sensors 435 is to
acquire information about temperature in the internal space of the
chambers, reservoir pressure, and structural integrity of the
chamber wall 440. This information is used to affect an automatic
and/or manual control of the acoustic device 400, to optimize
hydrocarbon extraction from the formation, or to detect operation
failures of the device.
[0101] In embodiments of the invention, magnetostrictive
transducers may be used. Such transducers need to be coiled by a
special kind of wire. The wire must resist high electric currents
(which in some cases may rise over 200 Amperes), and high
temperatures (over 200.degree. C.) and corrosion. Teflon insulated
wires could be used to surpass the corrosion and high temperature
issues. To resist high electric currents the cable's gauge should
be determined to fit the specific requirements of the application
(e.g. to resist currents up to 41 Amperes, a AWG #12 cable is
advised).
[0102] In other embodiments, where the magnetostrictive transducers
are protected from corrosion and from high temperatures, the
cable's insulation could be modified in order to diminish the
volume occupied by the coil, e.g., enameled wire could be used
instead of Teflon.
[0103] FIG. 5 is a block diagram representing components of a
high-power generator for powering one or more magnetostrictive
transducers in accordance with one embodiment of the invention. An
implementation of the invention may use one or more
magnetostrictive transducers as ultrasonic radiators.
[0104] Block 510 represents a control unit, that provide a user
and/or system to select the power level and regime (e.g., operating
frequencies) to drive the magnetostrictive devices. Block 520
represents a power supply unit that receives power 530 input (e.g.,
from a tri-phasic power line having three lines of 380 Volts).
Block 540 represents a component for generating power for an
ultrasonic power generator. Its output (e.g., 550) may for example
be a 520 Volts at 23,000 KHz. Block 560 represent the power
generator for a magnetizing current. The output current (e.g. 570)
may be for example a 10 Amperes current.
[0105] The power generator, as represented in FIG. 5, may produce
high power ultrasonic signals that travel trough a submersible
cable to the radiator placed in the wellbottom, wellbore region or
perforated zone of the well.
[0106] FIGS. 6A and 6B show a cross section view and a perspective
section view, respectively, of a submersible cable as used in one
embodiment of the invention. Embodiments of the invention may use a
submersible cable to carry high power signals produced by a
generator to one or more magnetostrictive transducers placed inside
the well, e.g., when the generator is installed on the ground
surface. Such submersible cable should have minimal energy losses.
The submersible cables of FIGS. 6A and 6B comprise a plurality of
conducting cables, each of which having a conductor core (e.g., 620
and 622), a dielectric (e.g., 630 and 632) and a lead (e.g., 610
and 612). The conducting cables may be surrounded, for strength, by
an iron cover (e.g., 640 and 642).
[0107] Acoustic waves may be generated by means of a transducer
(e.g., 310). This transducer may utilize a piezoelectric or
magnetostrictive, or any other means capable of generating elastic
waves. In one embodiment of the invention, the device 400 utilizes
a magnetostrictive transducer. It is preferred that the material of
the transducer was not only magnetostrictive, but also soft
magnetic. A magnetostrictive material is one that undergoes
physical change in shape and size when subjected to a magnetic
field. On the other hand, soft magnetic materials become magnetic
in the presence of an electric field, but retain little or no
magnetism after the field is removed. Many well known alloys have
these characteristics, being suitable for this application, for
example nickel-iron or cobalt-iron alloys. An iron-cobalt-vanadium
alloy was used in embodiments of the invention, such alloys are
available for example under the commercial names of Permendur and
Supermendur. The invention may be practiced, however, with any
alloys that presents the characteristics described above.
[0108] To avoid losses due to eddy currents, it is preferred to
form each transducer with a stack of plates of the magnetostrictive
material with a layer of a dielectric material in between each
plate. The plates need to be thin enough to avoid eddy currents but
sufficiently thick to have a magnetostrictive effect that would
successfully produce the required acoustic waves. According to the
invention, plates may have a thickness of between 0.1 mm and 4 mm.
In one embodiment of the invention, the plates have a thickness of
0.15 mm thickness.
[0109] The magnetostrictive principle works with a plurality of
geometries. The device, according to one embodiment of the
invention, utilizes the length of the plates as determined to be
half of the wavelength of the mechanical waves in said
magnetostrictive material. The latter maximizes the elastic wave
generation.
[0110] FIG. 7A is a flowchart diagram of method steps involved in
fabricating elastic waves generator using magnetostrictive material
in accordance with an embodiment of the invention. At step 710, the
material is stamped into plates. For optimal magnetic properties,
an annealing heat treatment may be required, after the stamping
process and before stacking. At step 720, the plates are heat
treated. One of the recommended heat treatment has to be done in a
dry hydrogen or argon atmosphere, or in a vacuum atmosphere, to
minimize oxide contamination. The entry due point should be dryer
than -51.degree. C. and the exit due point dryer than -40.degree.
C. when the inside retort temperature is above 482.degree. C. (See
FIG. 7B).
[0111] At step 730, a resin is applied to the plates. Then, at step
740, the plates are stacked. Each transducer may have, for example,
between 100 and 400 plates, and in one embodiment of the invention
a transducer may utilize between 250 and 350 plates. To avoid
losses due to undesired longitudinal waves, the transducer height
(given by the number of plates) and width should be similar. The
dielectric material can be for example an epoxy resin. In this
case, the resin under the trade name Sintepox LE 828 was used. The
thickness of the dielectric layer can be between 0.01 mm and 0.05
mm, and a 0.025 mm thickness was used in the present device. The
application of the resin can be done in several ways. For example,
the resin may be manually applied using a brush, soaking the plates
in the resin, with an aerosol or with any other available means for
applying resin.
[0112] The stacking of the plates can be done manually or
automatically. After applying the resin the plates are stacked
applying pressure to eliminate resin excess and control the
dielectric layer thickness. At step 750, the plates are dried using
an optimal curing temperature according to the resin data
sheet.
[0113] FIG. 7B is a plot of the temperature for curing resin versus
time of curing in accordance with embodiments of the invention.
Cure 750 generally shows that curing is applied between 1 and 13
hours with a temperature of 0 to around 900.degree. C.
[0114] During operation, a wave generator in accordance to the
invention produces mechanical vibrations. The mechanical vibrations
promote formation of shearing vibration in an extraction zone, due
to phase displacement of mechanical vibrations produced along one
axis of the well, thus achieving alternating tension and pressure
forces due to superposition of longitudinal shear waves, and so
stimulating the mass transfer processes within the well.
[0115] FIG. 8 shows a set of plots that represent vibrational
energy transfer along the longitudinal and radial axes between a
device implementing the invention and the surrounding area in the
operation zone. The oscillating velocity vector VR1 (28) from
longitudinal vibrations, propagated within the chamber of the
device (e.g., 460) is directed along the axis of said chamber.
Simultaneously, the amplitude distribution of vibratory
displacements .xi..sup.R.sub.ml (30) of longitudinal vibrations is
also propagated along the chamber. In place of the above, and as a
result of Poisson effect, radial vibrations are generated in the
chamber, which has a characteristic distance, and an amplitude of
displacement .xi..sup.R.sub.nV (31).
[0116] Radial vibrations through the radiant surface (32) of either
the elastic wave radiator (32) or the chamber are transmitted to
the inside of the reservoir (33) surrounding the well. Velocity
vector V.sup.Z.sub.1 (34) of longitudinal vibrations is propagated
to the reservoir (33) surrounding the well in a direction
perpendicular to the longitudinal axis of the chamber. Diagram 35
shows the radial distribution characteristic of displacement
amplitudes .xi..sup.Z.sub.ml (39) of radial vibrations propagated
to the reservoir (33) surrounding the well; they are radiated from
points of the chamber that may be located at a distance equal to
.lamda./2, .lamda. being the wavelength of longitudinal waves in
the material of resonance chamber.
[0117] Phase displacement of radial vibrations propagating in the
medium generates shearing vibrations in a perforated region of the
well, whose oscillating velocity vector V.sub.ZS (36) is directed
along the axis of the chamber. Diagram 37 shows the characteristic
distribution of displacement amplitudes of shearing vibrations
.xi..sup.Z.sub.mS.
[0118] As a result of the superposition of longitudinal and
shearing waves, an acoustic flow (jet streaming 38) is produced in
the perforated region of the well (e.g., 210), improving the
desired effect of viscosity reduction and mass transfer.
[0119] FIG. 9 illustrates the geometry of a device implementing the
invention where the layout of transducers in relation with wave
propagation properties is used to optimize the amount of vibration
energy transferred to the surrounding operation zone. FIG. 9
illustrates an implementation where one or more transducers (e.g.
910 and 912) are mounted within the chamber of the device, thus
allowing the transducers to be submerged in the heat-dissipating
liquid. In the latter configuration, the radiation of elastic waves
is carried out by the wall of the chamber 902. Therefore, the
geometry of the each of the component of the device and their
respective specific resonance frequencies are taken into account
when implementing the invention. For example, while waves are
propagating through the device from one or more transducers,
oscillating waves of similar frequencies cancel each other in some
regions (e.g. nodes 920, 921 and 822), and superimpose in other
regions (e.g., anti-nodes 930 and 931). The distance of the
transducers (e.g., 910 and 912) with respect to each other (e.g.,
940) and with respect to the wall of the chamber (e.g. 942) and
with respect to the wavelength of the elastic wave (e.g. 944) may
be critical to the resonance to the device implementing the
invention. Therefore, the invention provides a method for laying
out the one or more transducers with the device in order to
optimally apply the vibration energy to the operation zone.
[0120] For example, a radiant surface 902 having a tubular
geometric shape, with an external diameter D.sub.O, and geometric
dimensions of radiant surface, length "L" and wall thickness
".lamda." may be determined by working conditions under resonance
parameters of radial and longitudinal vibrations, at natural
resonance frequency of the wave radiator. To implement the
principle above indicated, regarding formation of a superposition
of longitudinal- and shear waves in the perforated region of the
well, the length "L" of the chamber should be at least half of the
longitudinal wavelength .lamda. of the acoustic wave inside the
material of the radiant surface; that is, L.gtoreq..lamda./2, e.g.,
in an oil well with a chamber made of stainless steel, the sound
velocity in such stainless steel at 100 atm pressure is
approximately 6000 m/s, and the radiator operating at a 25 KHz
frequency, the wavelength is 24 cm, thus the length `L` must be at
least 12 cm long.
[0121] FIG. 10 illustrates the interaction between the transducer
and the wall of the chamber when geometry is adequately configured
to utilize the resonance properties of the device implementing the
invention. A wave generating source 1010 may be situated within a
quarter if the wave length 1030 (.lamda./4) from the chamber wall
1020. An incident wave 1040 emitted by the wave generating source
1010 causes the wall 1020 to vibrate within a given deformation
distance 1022. The vibration of the wall, in turn, becomes a
powerful source of a sound wave 1050. In addition, the incident
wave cause a reflected acoustic wave 1042. The reflected acoustic
waves, although will be attenuated as they travel in the liquid
filling the chamber, contribute to the amplification of the
vibrations in accordance with the resonance properties of the
device. The radiation of power as elastic waves to the extraction
zone in the geologic formation is thus carried without bringing the
wave generator in contact with the geologic formation. The acoustic
waves generated by the wave generator are transmitted through the
liquid to the chamber wall which has a geometry that is critical to
transmitting (and eventually) amplifying the acoustic waves. The
adequate geometry in accordance with embodiments of the invention
comprises a chamber whose length is a multiple of the wave length
of the vibration.
[0122] FIG. 11A illustrates examples of geometries for the layout
of a plurality of acoustic wave sources hosted within one or more
devices implementing the invention. The devices represented in 1110
and 1120 have respective device length of 1112 and 1122, which
attribute to their respective device a resonance frequency. In
device 1110, the distance separating a pair of acoustic sources may
be a multiple of the wave length, whereas in device 1120, the
distance separating a pair of liquid acoustic sources may be half
the wave length. In either case, these embodiments of the invention
result in using the resonance properties of the device to amplify
and transfer the wave's energy to its surrounding.
[0123] FIG. 11B illustrates geometries of various dispositions of
an acoustic wave source with regard to the wall of the chamber in
accordance with one or more embodiments of the invention. An
acoustic wave source (e.g. 1130) may be mounted in contact with the
wall 1135. Wave energy is then transmitted to the wall 1135 both
through direct contact and through the heat dissipating liquid
1131.
[0124] An acoustic wave generator, such as 1140, may be mounted so
as not directly touch the wall 1145. The acoustic wave energy is
then transmitted to the wall 1145 through the liquid 1141. In an
other instance, an acoustic wave generator, such as 1150 may be
connected to the wall 1155 through a wave guide 1158. The wave
energy, in the latter case, is transmitted to the wall 1155 through
both the liquid 1151 and the wave guide 1158.
[0125] Several dispositions of one or more wave radiators may be
implemented. For example: [0126] in-phase wave radiators placed
every integer multiples of the wavelength (n.lamda.), in direct
contact with the chamber wall, [0127] in-phase wave radiators
placed every n.lamda., without direct contact with the chamber
wall, [0128] in-phase wave radiators placed every n.lamda., with a
waveguide which connects said radiators with the chamber wall,
[0129] 180.degree. out-of-phase wave radiators placed every
n.lamda.+.lamda./2, in direct contact with the chamber wall, [0130]
180.degree. out-of-phase wave radiators placed every
n.lamda.+.lamda./2, without direct contact with the chamber wall,
[0131] 180.degree. out-of-phase wave radiators placed every
n.lamda.+.lamda./2, with a waveguide which connects said radiators
with the chamber wall.
[0132] FIG. 12A and FIG. 12B represent a longitudinal and
transversal section views, respectively, of a device implementing
the invention where one or more acoustic waves generators are in
direct contact with the wall of the radiating chamber.
[0133] In the embodiment shown in FIGS. 12A and 12B, the device
implementing the invention 1200 comprises one or more acoustic wave
radiators (e.g., 1220, 1224 and 1230) the radiant surface of which
is in direct contact with the fluids of the formation. The acoustic
radiators e.g., 1220, 1224 and 1230) emerge through orifices 1240
in the chamber wall 1210. The chamber maintains its capacities to
protect the inner components of the system and provide a heat
dissipating capacity, through the use of the heat dissipating
liquid 1250, because the gap between the wave radiator(s) and the
orifices may be completely sealed with a seal 1245. This
disposition is primarily used to avoid major losses due to wave
reflection and/or attenuation of the mechanical waves produced by
the wave radiators (e.g., 1220, 1224 and 1230).
[0134] FIG. 13 shows a longitudinal section view of a device
implementing the invention where the diameter of the device exceeds
that of the tubing in a well, and the means to attach the device to
the tubing. Device 1300 has a diameter 1302 larger than the
diameter 1312 of the tubing 1310, but smaller than that of the
casing or external tube. In the latter particular case, the tubing
1310 must be completely withdrawn, and the elastic wave device
implementing the invention must be connected in between two
sections of the tubing 1320 or to the end of the tubing 1320. The
cable 1330, in the latter case, must run along outside the `tubing`
1310 and must be introduced into the device through a hole (e.g.,
1332) in the adapter 1320.
[0135] FIG. 14 a longitudinal section view illustrating several
layers that allow a tubing in accordance with an embodiment of the
invention to enhance the heat transfer rate to the crude in the
reservoir in order to reduce viscosity of crude oil. To maintain
the higher temperature of the crude oil and therefore reduce its
viscosity, a heating device 1420 may be installed alongside the
tubing 1440, which heats the tubing across the whole length of the
well. E.g., the heating device 1420 may be installed in the space
between the tubing and the casing 1410, being the tubing thermally
isolated 1430 from the surrounding environment; and it could be
powered by a generator placed in the well surface.
[0136] FIG. 15 is a flowchart diagram representing the overall
steps comprised in deploying a system embodying the invention,
applying one or more preliminary treatment, and permanently
operating the system. Step 1510 represents several stages in the
planing of the deployment, adapting the system to the type of the
intended treatment, connecting the various parts of the system, and
testing the functioning of the system. Step 1510 may be viewed as a
pre-installation phase, since the system may be moved several
times, and operation may be alternately started and stopped in
order to determine an operation location, take measurements and
carry out any necessary task required for the well functioning of
the system at later stages.
[0137] Following the pre-installation, one or more treatments may
be carried depending on the type of well, the resource to be
extracted and the state of the resource to be extracted. For
example, depending on the content in gas of an oil well, or the
viscosity of the crude oil in the well, a determination may be made
to treat the well in one or many ways before the system is
permanently installed and operated.
[0138] For example steps 1520, 1530 and 1540, respectively
represent stages of well cleaning, heat treatment of the well
and/or cleaning a well under pressure. Once the well has undergone
one or more treatments (e.g, steps 1520, 1530 and 1540), the tool
can be permanently installed and operated in-situ.
[0139] FIG. 16 is a flowchart diagram showing steps involved in
deploying a device implementing the invention. At step 1605, a
device implementing the invention is connected to the power supply.
A series of electrical connections made on the surface that are
necessary for the proper operation of the system. For example, the
connection may be made through a tri-phasic power line (see above)
to the ultrasonic generator, electric connection between the
ultrasonic generator and the geophysical cable and electrical
checking of the connections through continuity tests.
[0140] At step 1610, the device geophysical cable is connected.
Connection is made between the acoustic tool and the geophysical
cable. Step 1610 involves connecting the positioned tool in the
wellbottom, wellbore or perforated zone of the well, to a
geophysical cable of a proper length. In addition, step 1610
involves checking the electrical connections through continuity
tests.
[0141] At step 1615, the device implementing the invention is
joined to the tubing. The latter step involves connecting the
device to the tubing, using for example, a standard couple in the
oil industry.
[0142] At step 1620, a device implementing the invention is
deployed. The latter step involves installing a tuning string with
the acoustic tool attached to its end through a rig truck and a
temporal wellhead. The latter step also comprises checking the
electrical connections through continuity test.
[0143] FIG. 17 is a flowchart diagram representing steps of
cleaning a well before permanent operation in accordance with one
embodiment of the invention. At step 1725, a swabbing operation of
an oil well, for example, may be carried out to extract the liquids
inside the well through a rig truck, in order to attain a certain
objective liquid level inside the oil well.
[0144] At step 1730, pressure and temperature are surveyed, among
other physical variables (e.g. viscosity). The latter step involves
measuring temperature and pressure profiles before the acoustic
well stimulation. Further temperature and pressure measurements are
conducted after the acoustic stimulation, and the profiles are
compared in order to determine the changes that are the result of
the acoustic treatment.
[0145] At step 1735, a device implementing the invention is
temporarily positioned at a point of interest (e.g., wellbottom,
wellbore or perforated zone of the well) in order to conduct well
cleaning at that particular point of interest.
[0146] At step 1740, the device is started, which involves
switching on the ultrasonic generator, setting up the working
parameters (frequency, current and power). The latter step further
involves checking the correct functioning of the system through
current and voltage measurements at the output of the
generator.
[0147] At step 1745, the point of interest previously selected is
cleaned by temporarily operating the acoustic device in a specific
depth, and its subsequent repositioning to another point of
interest.
[0148] At step 1750, a measurement of fluid level is carried out of
the liquid in the wellbottom, wellbore and/or the perforated, by
means of adequate tools (e.g. EchoMeter). The latter measurement
may be crucial in order to maintain the pressure in the wellbottom
so that an efficient acoustic power transmission is achieved.
[0149] FIG. 18 is a flowchart diagram representing steps comprised
in the process of cleaning a well in accordance with an embodiment
of the invention. At step 1820, a well is flooded. In the latter
step, completely flooding the well to helps the acoustic power
transmission to the operating zone (wellbottom, wellbore and
perforated zone of the well). At step 1830, the well is sealed.
Sealing the well by means of a standard retention valve prevents
high pressure gas from escaping. At step 1840, a device
implementing the invention is positioned in the well. The device is
temporarily positioned at a point of interest (e.g. wellbottom,
wellbore or perforated zone of the well). At step 1850, the device
is started. At step 1850, the one or more ultrasonic generators are
started, and working parameters (frequency, current and power) are
setup. The latter step comprises checking the correct functioning
of the system through current and voltage measurements at the
output of the generator.
[0150] At step 1860, the point of interest where the device was
positioned is cleaned by temporary action of the acoustic tool at a
specific depth, and its subsequent repositioning to another point
of interest.
[0151] At step 1870, the pressure is released following the
cleaning at every depth in order to stimulate the movement of the
obstructive particles and their natural decantation to the
wellbottom.
[0152] FIG. 19 is a flowchart diagram representing steps comprised
in heat treatment of heavy oil in accordance with one embodiment of
the invention. Oil wells with a high content of paraffin may be
treated using an in-situ heating system.
[0153] At step 1905, a well is flooded (similarly as described
above). At step 1910, the heating device is installed along the
tubing (as described in FIG. 14). At step 1930, the device
implementing the invention is inserted in to the well. At step
1940, the device is positioned at a point of interest (as described
above). At step 1950, the heating device is started. At step 1960,
the one or more acoustic generators comprised within a stimulation
device are started. At this stage, the heat cause to lower the
viscosity of the oil, and the acoustic waves cause the mechanical
displacement of the oil and the removal of fines.
[0154] At step 1970, the well is cleaned as described above. At
step 1980, the level of fluid is measured for further adjustment of
the treatment time and parameters.
[0155] FIG. 20 is a flowchart diagram representing steps comprised
in the permanent installation of a system embodying the invention.
At step 2010, a device implementing the invention is positioned at
a specific operating depth for permanent operation.
[0156] At step 2020, well landing is carried out. The latter step
involves installing and deploying a pumping device. This stage
includes the removal of the temporal wellhead of the well, the
disconnection of the geophysical cable from the generator, the
connection of the geophysical cable to the permanent wellhead of
the well. The well is closed and sealed
[0157] At step 2030, the permanent regime is started. The latter
step involves acoustically stimulating the well in a permanent
regime, which may be carried out concomitantly with oil
extraction.
[0158] At step 2040, the well and the device are monitored, and one
or more operating parameters of the acoustic stimulation system
(frequency, power and magnetizing current) may be modified to
optimize the performance of the treatment.
[0159] During operation, a device for generating acoustic waves in
accordance with embodiments of the invention may be operated using
a continuous power signal, a pulsed signal or any other mode a user
may determined appropriate for any given treatment. For example,
control system 110, may deliver power to the wave generator in wide
range of power and frequency, where the level may be determined by
the user and/or a control system 110.
[0160] In embodiments of the invention, the data processing and
control system (e.g., 110) may be utilized to drive the wave
radiator, by providing for example, instructions to the wave
radiator, which instructions will be used by the wave radiator to
vary the power output to the geological formation in order to
achieve the best results. The data processing and control unit may
on the other hand control the power directly fed into the wave
radiator in order to control the amount of power delivered to the
reservoir.
[0161] In embodiments of the invention, the wave radiator may be
deliver acoustic waves, mechanical waves, electromagnetic waves or
any type of physical phenomenon capable of delivering vibrational
energy to a geological formation.
[0162] A control system implementing the invention enables the
system to irradiate the geological formation in any operating
regime the user desires. Including continue, alternated, pulsed, in
amplitude modulation, frequency modulation, among many other
possibilities.
[0163] FIG. 21A is a plot of the power as a function of time of a
high frequency continuous signal for driving a wave generator, in
accordance with one embodiment of the invention. Signal 2120 in the
example of FIG. 21A possesses a sine-shape, however the signal may
possess any other signal shape, such as a square, saw tooth, ramp
or any other chosen signal shape. The signal may be applied at a
constant amplitude of power 2110, either continuously or for any
given length of time 2112 at any chosen periodicity. The latter
operating regime, i.e. continuous regime, is useful for reducing
skin effect in the wellbore, decreasing oil's viscosity and
increasing the formation's permeability, and treating wells with
formation damage.
[0164] FIG. 21B is a plot of the power as a function of time of a
high frequency signal for driving a wave generator, where the
signal is applied in an ON/OFF fashion, in accordance with one
embodiment of the invention. In the latter example of power
application, signal 2135 may be applied for any given length of
time. Each burst may, for example, have a sine waveform of a
constant amplitude 2130, and the burst application may be repeated
at a constant or variable rate over time 2132. In the latter regime
of operation, a control system (e.g., 110) may intermittently
activate and deactivate a high-frequency power source that drive
the acoustic wave generator. The latter ON/OFF operation mode is
known in the industry of oil well stimulation as "keying".
[0165] FIG. 21C is a graph showing the power level as a function of
time of a high-frequency signal that is applied in a pulsed mode,
in accordance with an embodiment of the invention. The graph 2145
of FIG. 21C is the power plot of signal 2135. The power of the wave
indicated in scale 2140 follows the burst mode as a function of
time 2142.
[0166] The soil is expected to behave as a natural low-pass filter.
At a certain distance, the soil filters the signal, attenuating the
high frequency components, thus acting as a demodulator of an
amplitude modulated (AM) signal.
[0167] FIG. 21D is a bode diagram showing the magnitude of the
signal and the phase of the signal as a function of frequencies of
signals propagated through a geological formation in accordance
with applications of the invention. Curves 2155 and 2165,
respectively, show the magnitude and 2150 and phase 2160 of signals
applied to a geological formation as a function of the frequency of
the signal 2162 at a given distance from the source where the
acoustic wave was initiated. Plot 2150 shows that the power
transfer within the geological formation decreases as the frequency
of the vibration increases.
[0168] Because of the integration properties of a low pass-filters
in general, and of the soil with regard to acoustic waves in the
present case, a burst of high-frequency waves results in a low
frequency power transfer wave.
[0169] FIG. 21E is a plot of a low frequency wave 2175 resulting
from the application of a burst of high-frequency signal. The
amplitude of wave 2175 on a scale of power as a function of time,
in this case, has a square-like shape that reflects the short
period of application of the high-frequency signal (see FIG.
21B).
[0170] Low-frequency acoustic waves are able to travel longer
distances. The generation of low-frequency signals provided by a
system embodying the invention by modulating high-frequency signals
allows for a wide range of application of low-frequency stimulation
along with high-frequency stimulation.
[0171] The soil's properties to dampen acoustic vibrations
amplitude as the vibration frequency increases may modeled as a
low-pass filter having a bandwidth of
Bw=[0,f.sub.c]
[0172] Where "f.sub.c" is the soil's cutoff frequency, that may
vary depending on the type of soil being treated.
[0173] This low-pass filter can be modeled as follows:
H ( s ) = K ( s 2 / w 2 + 2 .xi. s / w + 1 ) ##EQU00001## where
##EQU00001.2## w = 2 .pi. f c ; ##EQU00001.3##
[0174] and where "H(s)" is the low pass filter transfer function;
"K" is the gain of the filter, "s" is the frequency domain
variable; ".xi." is a damping ratio of the system; and "f.sub.c" is
cutoff frequency of the low-pass filter.
[0175] A system embodying the invention is enabled to exploit the
inherent low-pass filter properties of the soil, coupled with the
ability of embodiments of the invention to generate and modulate
high-frequency signals in order to apply low-frequency acoustic
waves to the geological formation.
[0176] FIG. 22A is a plot of a modulated high frequency signal used
to apply low-frequency acoustic vibrations in accordance with an
embodiment of the invention. Signal 2215 is a high-frequency signal
whose amplitude is represented on scale 2210 as a function of time
2212. Signal 2215 exhibits a high-frequency component whose
amplitude has been modulated at a lower oscillating pattern.
[0177] FIG. 22B shows a plot of a signal having a low-frequency
that results from the application of the signal shown in FIG. 22A.
Signal 2225 represents the power transfer waveform as a function of
time 2222 on a scale of power 2220. The wave shape of 2225 results
from the lower-frequency modulation of the high-frequency
signal.
[0178] In a system embodying the invention, amplitude modulation
can be achieved when the control system regulates the output power
of the ultrasonic generator. If the generator gradually
periodically decreases and increases the output power repeatedly
the amplitude can thus be modulated.
[0179] FIG. 23 is a plot representing a signal whose frequency is
modulated in accordance with an embodiment of the invention. Signal
2315 is a plot of power of the signal on a power scale (e.g., 2310)
as a function of time. Using such a frequency modulated signal,
coupled with the integration properties of low-pass filter provided
by the soil, it is possible to transfer both high and low-frequency
vibrations into the geologic formation.
[0180] Frequency modulation of signals allows for irradiating in a
wide bandwidth; where the user via the control system sets the
stimulation bandwidth. This is very useful when information about
the treated well is unavailable. This stimulation bandwidth could
be for example between 15 kHz to 25 kHz, in this case the control
system would gradually increase the ultrasonic generator's
frequency from 15 kHz to 25 kHz and then gradually decrease it to
15 kHz, this process may be repeated while the frequency modulation
operating regime is enabled.
[0181] Pulsed and AM modulated operation, as they radiate high
frequency and also low frequency acoustic waves, they are useful to
increase the mobility of oils deep into the reservoir, because low
frequency acoustic waves travel further than high frequency.
[0182] Thus an apparatus, method and system for increasing
production of a natural resource producing-well, by utilizing an
acoustic waves generating device to deliver vibrational energy to
the geological formation and continuously monitoring and optimizing
the stimulation parameters.
* * * * *
References