U.S. patent application number 14/814169 was filed with the patent office on 2015-11-26 for isolation member and isolation member seat for fracturing subsurface geologic formations.
The applicant listed for this patent is Jeffrey Stephen Epstein, Alan J. Garvey. Invention is credited to Jeffrey Stephen Epstein, Alan J. Garvey.
Application Number | 20150337615 14/814169 |
Document ID | / |
Family ID | 54555666 |
Filed Date | 2015-11-26 |
United States Patent
Application |
20150337615 |
Kind Code |
A1 |
Epstein; Jeffrey Stephen ;
et al. |
November 26, 2015 |
ISOLATION MEMBER AND ISOLATION MEMBER SEAT FOR FRACTURING
SUBSURFACE GEOLOGIC FORMATIONS
Abstract
An embodiment of an assembly includes an isolation member and an
isolation member seat to together isolate a first portion of a well
casing from a second portion of the well casing. The isolation
member comprises an exterior surface including at least one of a
ceramic material, metallic glass, a reactive metal or a PGA
material, and the isolation member includes an interior chamber to
receive an explosive device. The explosive device may be surrounded
by a non-compressible fluid, and may include a pressure sensor, a
processor, a battery and an explosive charge. The ceramic, metallic
glass and reactive metal and may comprise one of zirconium oxide,
aluminum oxide, Bulk metallic Glass, silicon nitride, tungsten
carbide, reactive metal alloy or PGA salt. The isolation member is
resistant to deformation within an isolation member seat under the
application of a substantial pressure differential across the
isolation member and isolation member seat. Detonation of the
isolation member prevents the isolation member from presenting an
obstruction to subsequent well operations.
Inventors: |
Epstein; Jeffrey Stephen;
(Houston, TX) ; Garvey; Alan J.; (Suffield,
CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Epstein; Jeffrey Stephen
Garvey; Alan J. |
Houston
Suffield |
TX
CT |
US
US |
|
|
Family ID: |
54555666 |
Appl. No.: |
14/814169 |
Filed: |
July 30, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14741182 |
Jun 16, 2015 |
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14814169 |
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14521662 |
Oct 23, 2014 |
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14741182 |
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61898088 |
Oct 31, 2013 |
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Current U.S.
Class: |
166/65.1 |
Current CPC
Class: |
E21B 43/263 20130101;
E21B 33/1208 20130101; E21B 33/12 20130101; E21B 43/26 20130101;
E21B 33/134 20130101; E21B 34/063 20130101 |
International
Class: |
E21B 33/12 20060101
E21B033/12 |
Claims
1. An assembly, including an isolation member and an isolation
member seat, for securing in a tubular string within a well in the
earth's crust to isolate a pressure within a first portion of the
well from a pressure in a second portion of the well, the assembly
comprising: an isolation member having an interior chamber and an
exterior surface, including at least one of ceramic, metallic
glass, reactive metal or polyclycolic acid, the isolation member
including an exterior sealing surface; an isolation member seat
adapted for being secured in a well casing and having a sealing
surface that is shaped to receive and to sealably engage with the
exterior sealing surface of the isolation member; at least one
mechanical fuse element disposed intermediate the isolation member
seat and the isolation member to secure the isolation member in an
unseated position relative to the isolation member seat, the
mechanical fuse element securing the isolation member in an
unseated position with an open flow passage intermediate the
sealing surface of the isolation member and the sealing surface of
the isolation member seat; a battery received within the interior
chamber of the isolation member; an explosive charge of an
explosive material received within the interior chamber of the
isolation member and conductively coupled to the battery; a
pressure sensor received within the interior chamber of the
isolation member in fluid communication with an aperture extending
from the exterior surface to the interior chamber; and a processor
received within the interior chamber and conductively coupled to
receive an electrical current from the battery, conductively
coupled to receive a signal from the pressure sensor, and
conductively coupled to generate, after a predetermined time
interval, a detonating current to detonate the explosive device in
response to detecting a predetermined pressure sensed using the
pressure sensor; wherein after the isolation member seat is adapted
for being secured within the well casing; wherein the sealing
surface on the isolation member and the sealing surface on the
isolation member seat can sealably engage one with the other upon
release of the isolation member from the unseated position
resulting from the application of force to the isolation member and
the one or more mechanical fuse elements due to a downward flow of
well fluids at a rate sufficient to cause the one or more
mechanical fuse elements to fail and release the isolation member;
and wherein detonation of the explosive charge fragments the
isolation member to limit the size of debris in the well that may
obstruct subsequent well operations and to increase a cumulative
surface area of the isolation member to promote accelerated
dissolution of a plurality of fragments.
2. The assembly of claim 1, further comprising: one or more
retainer members connected to the isolation member seat and
positioned to prevent separation of the isolation member from the
isolation member seat in the event of premature failure of the one
or more mechanical fuse elements.
3. The assembly of claim 1, wherein the explosive charge is formed
with a recess to receive at least a portion of the battery; and
wherein the recess in the explosive charge is shaped to prevent
battery shielding of a portion of the isolation member upon
detonation of the explosive charge.
4. The assembly of claim 1, wherein the isolation member includes a
plurality of separate portions coupled together form the isolation
member.
5. The isolation member of claim 1, wherein the exterior surface of
the isolation member is comprised of at least one of a ceramic
material, metallic glass, a reactive metal or polyclycolic
acid.
6. An assembly, including an isolation member and an isolation
member seat, for securing in a tubular string within a well in the
earth's crust to isolate a pressure within first portion of the
well from a pressure in a second portion of the well, the assembly
comprising: an isolation member having an interior chamber and an
exterior surface, including at least one of ceramic, metallic
glass, reactive metal or polyglycolic acid, the isolation member
including an exterior sealing surface; an isolation member seat
adapted for being secured in a well casing and having a sealing
surface that is shaped to receive and to sealably engage with the
exterior sealing surface of the isolation member; a cage connected
to the isolation member seat to secure the isolation member within
a space within the cage and to prevent unwanted separation between
the isolation member and the isolation member seat; a battery
received within the interior chamber of the isolation member; an
explosive charge of an explosive material received within the
interior chamber of the isolation member and conductively coupled
to the battery; a pressure sensor received within the interior
chamber of the isolation member in fluid communication with an
aperture extending from the exterior surface to the interior
chamber; and a processor received within the interior chamber and
conductively coupled to receive an electrical current from the
battery, conductively coupled to receive a signal from the pressure
sensor, and conductively coupled to generate, after a predetermined
time interval, a detonating current to detonate the explosive
device in response to detecting a predetermined pressure sensed
using the pressure sensor; wherein after the isolation member seat
is adapted for being secured within the well casing; wherein the
sealing surface on the isolation member and the sealing surface on
the isolation member seat can sealably engage one with the other
upon movement of the isolation member from the unseated position
within the cage by the application of a force to the isolation
member by a downward flow of well fluids at a rate sufficient to
cause the isolation member to move downwardly within the cage and
engage the isolation member seat; and wherein detonation of the
explosive charge fragments the isolation member to limit the size
of debris in the well that may obstruct subsequent well operations
and to increase a cumulative surface area of the isolation member
to promote accelerated dissolution of a plurality of fragments.
7. The assembly of claim 6, wherein the assembly further includes
at least one mechanical fuse element disposed intermediate the
isolation member seat and at least one of the cage and the
isolation member to secure the isolation member in an unseated
position relative to the isolation member seat, the mechanical fuse
element securing the isolation member in an unseated position
within the cage with an open flow passage intermediate the sealing
surface of the isolation member and the sealing surface of the
isolation member seat.
Description
STATEMENT OF RELATED APPLICATIONS
[0001] This application is a continuation-in-part depending from
and claiming priority to U.S. Non-Provisional application Ser. No.
14/741,182 filed On Jun. 16, 2015, which is a continuation-in-part
application depending and claiming priority to U.S. Non-Provisional
application Ser. No. 14/521,662 filed on Oct. 23, 2014 which, in
turn, claims priority to U.S. Provisional Application No.
61/898,088 filed on Oct. 31, 2013.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to an improved sacrificial
isolation plug and plug seat for use in fluidically isolating a
targeted geologic zone for hydraulic fracturing operations to
enhance production of hydrocarbons from a well drilled into the
targeted geologic zone.
[0004] 2. Background of the Related Art
[0005] Hydraulic fracturing is the fracturing of rock by a
pressurized liquid. Some hydraulic fractures form naturally.
Induced hydraulic fracturing or hydro-fracturing, commonly known as
"fracing," is a technique in which a fluid, typically water, is
mixed with a proppant and chemicals to form a mixture that is
injected at high pressure into a well to create small fractures in
a hydrocarbon-bearing geologic formation along which the
hydrocarbon fluids such as gas, oil or condensate may migrate to
the well for production to the surface. Hydraulic pressure is
removed from the well, then small grains of the proppant, for
example, sand or aluminum oxide, hold the fractures open once the
formation pressure achieves an equilibrium. The technique is
commonly used in wells for shale gas, tight gas, tight oil, coal
seam gas and hard rock wells. This well stimulation technique is
generally only conducted once in the life of the well and greatly
enhances fluid removal rates and well productivity.
[0006] A hydraulic fracture is formed by pumping fracturing fluid
into the well at a rate sufficient to increase pressure downhole at
the target zone (determined by the location of the well casing
perforations) to exceed that of the fracture gradient (pressure
gradient) of the rock. The fracture gradient is defined as the
pressure increase per unit of the depth due to its density and it
is usually measured in pounds per square inch per foot or bars per
meter. The rock cracks and the fracture fluid continues further
into the rock, extending the crack still further, and so on.
Fractures are localized because pressure drop off with frictional
loss attributed to the distance from the well. Operators typically
try to maintain "fracture width," or slow its decline, following
treatment by introducing into the injected fluid a proppant--a
material such as grains of sand, ceramic beads or other
particulates that prevent the fractures from closing when the
injection is stopped and the pressure of the fluid is removed. The
propped fracture is permeable enough to allow the flow of formation
fluids to the well. Formation fluids include gas, oil, water and
fluids introduced to the formation during completion of the well
during fracturing.
[0007] The location of one or more fractures along the length of
the borehole is strictly controlled by various methods that create
or seal off holes in the casing of the well. A well may be fraced
in stages by setting an isolation member seat below the geologic
formation to be fraced to isolate one or more lower zones open to
the well from the anticipated pressure to be later applied to a
zone closer to the surface.
[0008] Hydraulic-fracturing equipment used in oil and natural gas
fields usually consists of a slurry blender, one or more
high-pressure, high-volume fracturing pumps (typically powerful
triplex or quintuplex pumps) and a monitoring unit. Associated
equipment includes fracturing tanks, one or more units for storage
and handling of proppant, high-pressure treating iron, a chemical
additive unit (used to accurately monitor chemical addition),
low-pressure flexible hoses, and many gauges and meters for flow
rate, fluid density, and treating pressure. Chemical additives are
typically 0.5% percent of the total fluid volume. Fracturing
equipment operates over a range of pressures and injection rates,
and can reach up to 100 megapascals (15,000 psi) and 265 litres per
second (9.4 cu ft/s) (100 barrels per minute).
[0009] A problem that can be encountered in a fracing operation
involves the impairment to subsequent operations that can result
from the presence of a common frack plug. After the fracing
operation is concluded, the surface pressure is restored to a
pressure at which the well will flow and produce formation fluids
to the surface for recovery. A fracing plug having a sufficiently
low density can be floated or back-flowed from the well, but a plug
having a low density may be deformed by the large pressure
differential applied across the plug and plug seat and thereby
compromised during fracturing operations. Most of the time, a
phenolic or composite plug gets lodged in the seat and cannot be
flowed to the surface. This unwanted obstruction has to be removed
from the well to prevent impairment of subsequent well operations.
This obstruction also prevents oil from flowing to the surface.
[0010] A workover operation can be implemented in which a drilling
instrument is introduced into the well to drill out and
mechanically destroy the plug, but a workover operation requires
that a workover rig be brought to the surface end of the well for
downhole operations. The need for the rental, transportation and
use of a rig imposes substantial delays, substantial costs and the
added risk of a well blow-out.
[0011] What is needed is a fracing plug that has as sufficient
density and resistance to deformation so that it can be used in
conjunction with a seat to reliably isolate geologic formation
zones below the plug seat from anticipated fracturing pressures
applied to geologic formation zones above the plug seat and that
does not impair subsequent well operations. What is needed is a
fracing plug that can be manipulated to engage and seal after it is
seated at the targeted interval of a well casing. What is needed is
a fracing plug that can be run into a well and set at the targeted
interval of the well casing, and that will not present a well
obstacle to the flow of fluid after the fracing operation is
completed.
BRIEF SUMMARY
[0012] One embodiment of the apparatus of the present invention
provides an isolation member and a corresponding isolation member
seat. The isolation member sealably engages the isolation member
seat after the isolation member seat is secured at the targeted
depth in the well casing. The isolation member is secured to the
isolation member seat in an unseated condition, and the isolation
member can be selectively engaged with the isolation member seat to
enable fracing operations by manipulation of the direction and rate
of flow of fluid within the well casing at the isolation member
seat.
[0013] One embodiment of the apparatus of the present invention
provides an isolation member such as, for example, a plug of a
predetermined diameter is shaped for sealing engagement with a
corresponding isolation member seat which, in the case of a plug,
is a plug seat. In one embodiment, the isolation member, such as a
plug, is captured within a cage connected to the isolation member
seat. These components together provide a selectively activatable
check valve that can be run into a well and secured within the well
casing at a targeted depth prior to activation. The isolation
member captured within the cage connected to the isolation member
seat assembly may be introduced into the well at the surface and
pumped or run on a wireline downhole for being secured within the
casing. Activation of the apparatus is obtained by pumping fluid
into the well at the surface to induce fluid to flow downwardly
through the cage and through the isolation member seat. The force
imparted by the fluid flow urges the isolation member captured
within the cage into sealing engagement with the isolation member
seat.
[0014] One embodiment of the apparatus of the present invention
provides an isolation member secured in an unseated position to the
isolation member seat using a mechanical fuse element. The
mechanical fuse element may position the isolation member proximal
to, but disengaged with, the corresponding sealing portion of the
isolation member seat.
[0015] It will be understood that these arrangements, the caged
isolation member and the isolation member secured in an unseated
position using one or more mechanical fuse elements, allow well
fluids to flow around the isolation member seat as the isolation
member seat and the isolation member secured thereto, either by
mechanical fuse element or using a cage, or both, is run into the
well and positioned at the targeted depth, and for the movement of
the isolation member into engagement with the corresponding
isolation member seat upon pressurization of the wellhead and the
casing above the isolation member seat to induce a fluid flow
downwardly into the isolation member seat. For example, for the
embodiment of the apparatus comprising an isolation member captured
in a cage connected to the isolation member seat, the isolation
member is moved from a disengaged position within the cage to a
sealing position by the flow of fluid in a downwardly direction to
engage and seal the isolation member with the isolation member seat
that is exposed to the cage. As another example, for the embodiment
of the apparatus comprising an isolation member secured in an
unseated position to the isolation member seat by one or more
mechanical fuse elements, a downwardly flow of fluids in the well
at a sufficient rate will dislodge the isolation member from the
unseated position when the force applied to the isolation member by
the movement of well fluids exceeds a threshold amount of force
needed to cause the one or more mechanical fuse elements to
sacrificially fail and thereby release the isolation member from
the unseated position to engage and seal with the isolation member
seat. It will be understood that the amount of force imparted to
the unseated isolation member is a function of several factors
including, but not limited to, the rate of flow of well fluids
downwardly against the isolation member, the size of the isolation
member, the size of the well casing in which the isolation member
seat is secured, and the density of the well fluids. It will be
further understood that the flow area between the isolation member,
secured in an unseated position by the one or more mechanical fuse
elements, and the isolation member seat, is another factor that
affects the flow rate required to compromise the mechanical fuse
element(s) to release the isolation member to engage and seal with
the isolation member seat.
[0016] One embodiment of the apparatus of the present invention
provides an isolation member, either caged or secured in an
unseated position using one or more mechanical fuses, for sealing
with an isolation member seat and the isolation member contains an
explosive charge for fragmenting the isolation member after use.
The isolation member is constructed in a manner that provides
sufficient resistance to deformation of the isolation member as a
large pressure differential is applied across the seated isolation
member and the engaged isolation member seat. The explosive charge
can be disposed within the isolation member and activated by a
pressure sensor that senses when the pressure in the well is above
a predetermined threshold. The pressure sensor then generates a
signal to a processor that will not enable the explosive charge
until the pressure sensor senses a substantially decreased pressure
far below the pressure at which the well is fractured. In this
manner, the processor and pressure sensor will not enable the
explosive charge to detonate until after the pressure sensor has
detected both an elevated pressure, indicative of hydraulic
fracturing of the formation adjacent to the open perforations above
the depth at which the isolation member seat is secured in the well
casing, and a subsequent low pressure, indicative of the hydraulic
fracturing of the for motion having been completed.
[0017] One embodiment of the present invention provides an
isolation member such as, for example, a plug, that can be
fragmented by detonation of an explosive charge within an interior
chamber of the plug to produce a plurality of plug fragments that
do not interfere with subsequent well operations. In one
embodiment, the use of a ceramic, metallic glass, reactive metal or
PGA (polyglycolic acid) salt body provides sufficient resistance to
plug deformation under large pressure differentials across the plug
and seat applied during fracing operations. In addition, these
materials can provide for favorable fragmentation of the plug upon
detonation of the explosive charge stored within an interior
chamber of the plug to prevent unwanted obstacles having a
substantial size obstructing flow in the well.
[0018] In one embodiment of the isolation member of the present
invention, a battery, a pressure sensor and a circuit are included
within an interior chamber along with the explosive charge. The
pressure sensor is disposed in fluid communication with an exterior
surface of the isolation member through an aperture in the ceramic
outer structure of the isolation member, which may be in the form
of a plug. The pressure sensor detects a predetermined pressure
threshold and initiates a predetermined delay period prior to
detonation. Upon elapse of the predetermined delay period, a
circuit is completed that generates a high voltage electrical
current from the battery to the explosive charge to detonate the
explosive charge and thereby fragment the isolation member. It will
be understood that the fragmentation of the plug dramatically
increases the surface area that is exposed to the fluids in the
well. As with the case with a dissolvable frack plug, a much more
rapid rate of dissolution of the fragments is obtained as a result
of the dramatically increased surface area at which dissolution may
occur.
[0019] The higher fracing pressures achievable by use of
embodiments of the isolation member of the present invention
increase the success and effectiveness of the fracing process,
lowers or eliminates workover rig rental costs, and prevents
unwanted delays after the fracing process.
[0020] In one embodiment of the apparatus of the present invention,
a mechanical fuse element such as, for example, a shear pin or a
rupture ring is installed between the isolation member and the
isolation member seat will secure the isolation member in an
unseated position relative to the isolation member seat in order to
keep the seat open and to allow well fluids to flow from beneath
the seat and through the seat, and around the isolation member
secured in the unseated position off of, but near the seat, to
enable the isolation member and the isolation member seat
combination into the well casing to the targeted interval for
installation. The mechanical fuse element may be adapted to fail
and to release the isolation member from its unseated position to
engage and seal with the isolation member.
[0021] In one embodiment of the apparatus of the present invention,
the isolation member, the isolation member seat and one of the cage
or the mechanical fuse element that secures the isolation member to
the isolation member seat can be run into a well casing along with
a perforating gun disposed above the apparatus. The perforating gun
can be used to perforate the well casing above the targeted
interval in which the isolation member and the isolation member
seat are to be activated by a downward flow of well fluids across
the isolation member and the isolation member seat. It will be
understood that in the event that the perforating gun does not
discharge properly and must be removed from the well, the isolation
member will remain in the unseated position while the perforating
gun is removed, re-tooled or repaired, or while another perforating
gun is run into the well casing and positioned above the isolation
member and isolation member seat. After perforation is complete,
the fracing pressure will shear the pin causing the isolation
member to sealably engage the isolation member seat to isolate the
portion of the well casing below the isolation member seat from the
perforations above the isolation member seat, which are open to an
adjacent geologic formation to be fractured.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0022] FIG. 1 is a sectional view of a well drilled into the
earth's crust and illustrating a series of hydraulic fractures
disposed at a predetermined spacing to enhance production and
recovery of formation fluids from a hydraulically fractured
subsurface geologic formation.
[0023] FIG. 2 is the sectional view of the well of FIG. 1
illustrating the lack of fractures within the targeted geologic
formation prior to the creation of the hydraulic fractures and
illustrating a location of a desired placement of a plug and a seat
isolate zones deeper in the well than the plug/seat (to the right)
from zones shallower in the well than the plug/seat (to the
left).
[0024] FIG. 3 is a sectional elevation of an embodiment of a
plug-shaped isolation member received in a partially-caged
isolation member seat set within the casing of the drilled well
illustrated in FIG. 2 with the isolation member secured in an
unseated position relative to the isolation member seat.
[0025] FIG. 4 is a disassembled view of the isolation member of
FIG. 3.
[0026] FIG. 5 is a sectional view of an embodiment of a plug-shaped
isolation member.
[0027] FIG. 6 is an embodiment of an assembly of the present
invention including an isolation member, and a cage connected to an
isolation member seat secured within a well casing to isolate a
first portion of the well casing from a second portion of the well
casing upon activation to engage the isolation member with the
isolation member seat.
DETAILED DESCRIPTION
[0028] One embodiment of the present invention provides a
plug-shaped isolation member having an outer surface with a
frusto-conical portion of sufficient smoothness to enable the
frusto-conical sealing portion of the plug-shaped isolation member
to engage and to seal with an isolation member seat having a
sealing surface conforming to at least a portion of the
frusto-conical portion of the isolation member seat, wherein the
plug-shaped isolation member seat has substantial resistance to
deformation by an applied pressure differential across the seal
created by the plug-shaped isolation member received within the
isolation member seat. The embodiment of the plug-shaped isolation
member contains an explosive device that can be detonated to
destroy the isolation member from within and to thereby fragment
the isolation member into a large plurality of small fragments. The
embodiment of the plug-shaped isolation member may include a hollow
interior of the isolation member, along with the explosive device,
wherein a filler material comprises a non-compressible fluid like
an oil.
[0029] The manner in which an embodiment of the isolation member of
the present invention is made may vary, but will generally include
the steps of providing a ceramic, metallic glass, reactive metal or
PGA outer shell having a hollow interior and, optionally, a hole
through which a pressure sensor may be inserted into the isolation
member. An embodiment of an isolation member of the present
invention may include an explosive device and a filler material
that can be disposed within the hollow interior. In one embodiment
of the isolation member, a first upper portion and a second lower
portion are secured together to form an isolation member that seals
with the isolation member seat along a tapered portion of the
isolation member.
[0030] In one embodiment, a ceramic, metallic glass, reactive metal
or PGA isolation member may consist of two or more pieces secured
together to form a body. In another embodiment, the isolation
member consists of a unitary body having a hole for insertion of a
pressure sensor to enable the explosive charge and the
timer-controlled detonator.
[0031] In one embodiment, the isolation member may comprise one of
zirconium oxide, silicon nitride, tungsten carbide, zirconia
toughened alumina, Bulk Metallic Glass (BMG), aluminum oxide,
reactive metal or polyglycolic acid ("PGA"). The high compressive
strengths of these materials enable the isolation member to seat in
the isolation member seat and to seal together to isolate deeper
well zones from shallower well zones to be fraced. This requires
the isolation member and isolation member seat to withstand a very
high fracing pressure on an uphole side of the isolation member and
isolation member seat and a substantially lower pressure on a
downhole side of the isolation member and isolation member seat.
Embodiments of the ceramic, metallic glass, reactive metal or PGA
fracing plug of the present invention may be manufactured by, for
example, but not by way of limitation, isostatic pressing, hot
isostatic processing, (HIP), injection molding, slip casting, or
other casting techniques. It is possible that an isolation member
comprising zirconia or BMG with a thin wall thickness of 0.250''
can be cast and subsequently hot isostatically pressed to increase
the flexural strength of the isolation member so it can withstand
very high differential pressures, yet have less material to
interfere with fracing other zones when the plug is fragmented by
detonation of the explosive device.
[0032] FIG. 1 is a sectional view of a well 20 drilled from the
surface 21 into the earth's crust 29 and illustrating a series of
hydraulic fractures 26 disposed at a predetermined spacing 28 to
enhance production and recovery of formation fluids from a
hydraulically fractured subsurface geologic formation 24. The
drilled well 20 may include multiple layers of surface casing as is
known in the art. The drilled well 20 may include one or more turns
or changes in direction to align the portion of the well 20 to be
perforated or otherwise to gather fluids within a known geological
structure, seam or formation 24. The fractures 26 created in the
formation 24 are generally disposed at a predetermined spacing 28
selected for optimal drainage. The targeted formation 24 may reside
between a top layer 22 and an underlying layer 23 within the
earth's crust 29. It will be understood that fluids entering the
well 20 flow according to a pressure gradient in the direction of
the arrow 27 to the surface for processing, storage or
transportation.
[0033] FIG. 2 is the sectional view of the well 20 of FIG. 1
illustrating the lack of fractures 26 (seen in FIG. 1) within the
targeted geologic formation 24 prior to the creation of the
hydraulic fractures shown in FIG. 1. FIG. 2 illustrates, using a
circle, a location of a desired placement of a plug (not shown) and
a seat (not shown to receive the plug to thereby isolate a zone 50,
that is deeper in the well than the plug seat (i.e., to the right)
from a zone 51 that is shallower in the well 20 than the plug seat
(i.e. to the left). It will be understood that the plug and plug
seat are to be placed in a portion of the casing 62 that lies
within the targeted geologic formation 24 and that the pressure at
any given location within the well 20 is approximately equal to the
pressure at a wellhead 49 at the surface 21 plus the product of the
vertical elevation change 46 times the density (as measured in
units corresponding to the unit used to measure depth) of a fluid
residing in the well 20, assuming that the well 20 is tilled with
the fluid.
[0034] FIG. 3 is a sectional elevation of an embodiment of a
plug-shaped isolation member 10 of the present invention secured in
an unseated position relative to an isolation member seat 44 that
has been set within a section of a casing 62 of the drilled well 20
(not shown in FIG. 3) illustrated in FIG. 2 to create an isolating
seal. It will be understood that a number of tools exist for
setting the isolation member seat 44 within the portion of the
casing 62 in which the seal is to be affected, and that those tools
and the methods of setting those tools are not within the scope of
the present invention. FIG. 3 is provided merely to illustrate the
manner in which an embodiment of an isolation member 10 moves
through the bore 70 of the casing 62 to engage the isolation member
seat 44 after the seat 44 is set in the portion of the casing 62
with the isolation member 10 secured in an unseated position
relative to the isolation member seat 44. The isolation member 10
and the isolation member seat 44 do not form a seal to isolate a
lower portion of the bore 71 from the upper portion of the bore 70
that is uphole to the isolation member 10 and isolation member seat
44 as long as the isolation member 10 remains in the unseated
position relative to the isolation member seat 44 shown in FIG. 3.
The isolation member 10 is secured in the unseated position shown
in FIG. 3 by one or more mechanical fuse elements 81 disposed
intermediate the isolation member 10 and the isolation member seat
44. The unseated position causes an open flow passage 92, which
surrounds the tapered portion 13 of the plug-shaped isolation
member 10 shown in FIG. 3. FIG. 3 further shows a pair of optional
inwardly disposed retainer members 91 coupled to the isolation
member seat 44 to ensure that the isolation member 10 does not
become separated from the isolation member seat 44 if the
mechanical fuse elements 81 were to fail prematurely. It will be
understood that the isolation member 44 may, in one embodiment, be
introduced into the unseated position illustrated in FIG. 3 prior
to the connection or installation of the inwardly-disposed retainer
members 91 on the isolation member seat 44. It will be further
understood that the open flow passage 92 may be larger or smaller
than that shown in FIG. 3 which is for illustration purposes only.
The isolation member seat 44 with the isolation member 10 secured
in the unseated position shown in FIG. 3 can be run into the well
casing 62 because fluid can easily pass through the open flow
passage 92 between the isolation member 10 and the isolation member
seat 44.
[0035] FIG. 4 is an exploded view of an embodiment of a plug-shaped
isolation member 10 of the present invention. The isolation member
10 of FIG. 4 comprises a hollow interior consisting of a hollow
interior 15 of an upper portion 11 and a hollow interior 16 of a
lower portion 12. Securing of the upper portion 11 to the lower
portion 12 provides a plug-shaped isolation member 10 having an
exterior surface consisting of the exterior surface 17 of the first
hemispherical portion 11 and the exterior surface 18 of the lower
portion 12. Returning to FIG. 3, the sealing surface 85 of the
lower portion 12 of the isolation member 10 can be fluoropolymer
coated to prevent the isolation member 10 from wedging and getting
stuck in the isolation member seat 44. Optionally, the sealing
surface 84 of the isolation member seat 44 can also be
fluoropolymer coated. Optionally, both the sealing surface 84 of
the isolation member seat 44 and the sealing surface 85 of the
isolation member 10 may both be fluoropolymer coated.
[0036] FIG. 5 is a plan view of a hollow interior 15 of the upper
portion 11 of FIG. 4. An aperture 30 in the upper portion 11 of the
may be fluidically connected by a conduit 31 to a pressure sensor
32. The pressure sensor 32 closes a switch 33 upon sensing a
predetermined threshold pressure through the aperture 30.
[0037] Upon receiving the signal from the pressure sensor 32, a
timer is activated. After a predetermined time, a signal will be
sent to a detonator to detonate the explosive charge to fragment
the isolation member 10. Upon detonation of the explosive charge
36, the outer shell of the plug 10 is fragmented.
[0038] FIG. 6 is an embodiment of an assembly of the present
invention including an isolation member 10, an isolation member
seat 44 secured within a well casing 62 to isolate a first portion
70 of the well casing 62 from a second portion 71 of the well
casing 62 upon activation to engage the isolation member 10 with
the isolation member seat 44. The isolation member 10 of the
assembly of FIG. 6 is captured within a cage 87 through which well
fluids (not shown) may flow without separating the isolation member
10 from the isolation member seat 44 to which the cage 87 is
attached. It will be understood that the isolation member 10 is of
the same type as discussed above, that is, it includes an interior
chamber to receive components that will enable the isolation member
10 to be fragmented by an explosive charge after use in effecting a
seal within the well casing 62.
[0039] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, components and/or groups, but do not
preclude the presence or addition of one or more other features,
integers, steps, operations, elements, components, and/or groups
thereof. The terms "preferably," "preferred," "prefer,"
"optionally," "may," and similar terms are used to indicate that an
item, condition or step being referred to is an optional (not
required) feature of the invention.
[0040] The corresponding structures, materials, acts, and
equivalents of all means or steps plus function elements in the
claims below are intended to include any structure, material, or
act for performing the function in combination with other claimed
elements as specifically claimed. The description of the present
invention has been presented for purposes of illustration and
description, but it is not intended to be exhaustive or limited to
the invention in the form disclosed. Many modifications and
variations will be apparent to those of ordinary skill in the art
without departing from the scope and spirit of the invention. The
embodiment was chosen and described in order to best explain the
principles of the invention and the practical application, and to
enable others of ordinary skill in the art to understand the
invention for various embodiments with various modifications as are
suited to the particular use contemplated.
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