U.S. patent application number 09/927792 was filed with the patent office on 2003-02-13 for system and method for actuating a subterranean valve to terminate a reverse cementing operation.
Invention is credited to Owens, Steven C..
Application Number | 20030029611 09/927792 |
Document ID | / |
Family ID | 25455260 |
Filed Date | 2003-02-13 |
United States Patent
Application |
20030029611 |
Kind Code |
A1 |
Owens, Steven C. |
February 13, 2003 |
System and method for actuating a subterranean valve to terminate a
reverse cementing operation
Abstract
A system and method for closing a subterranean valve (22) to
terminate a reverse cementing operation is disclosed. The system
comprises an interrogator (44) operably associated with the valve
(22) that detects at least one detectable member (52) that is
associated with an interface (50) between a first fluid (48) and a
cement composition (54) that is pumped through an annulus (26)
between a pipe string (20) and a wellbore (18). The detectable
member (50) is detectable by the interrogator (44) when the
detectable member (50) comes within communicative proximity with
the interrogator (44). Once the interrogator (44) detects the
detectable member (50), the interrogator (44) sends a signal
indicating it is time to close the valve (22), thereby terminating
the cementing process and allowing the cement (54) to set in the
annulus (26) into a hard, substantially impermeable mass.
Inventors: |
Owens, Steven C.;
(Woodlands, TX) |
Correspondence
Address: |
PAUL I. HERMAN
HALLIBURTON ENERGY SERVICES, INC.
P.O. Box 819052
Dallas
TX
75381-9052
US
|
Family ID: |
25455260 |
Appl. No.: |
09/927792 |
Filed: |
August 10, 2001 |
Current U.S.
Class: |
166/250.03 ;
166/292; 166/316; 166/373 |
Current CPC
Class: |
E21B 47/13 20200501;
E21B 34/10 20130101; E21B 33/14 20130101 |
Class at
Publication: |
166/250.03 ;
166/292; 166/373; 166/316 |
International
Class: |
E21B 034/06 |
Claims
What is claimed is:
1. A system for actuating an actuatable device in a subterranean
zone penetrated by a wellbore comprising: at least one interrogator
operably associated with the actuatable device; and at least one
detectable member disposed within a fluid, the detectable member
being detectable by the interrogator when the detectable member
comes in communicative proximity with the interrogator causing the
interrogator to send a signal to actuate the actuatable device.
2. The system as recited in claim 1 wherein the interrogator
comprises an oscillator that produces a magnetic field.
3. The system as recited in claim 1 wherein the interrogator
comprises a radio-frequency transmitter circuit that produces a
radio-frequency signal.
4. The system as recited in claim 1 wherein the interrogator
comprises a gamma ray detector that detects gamma rays.
5. The system as recited in claim 1 wherein the detectable member
comprises a resonant circuit.
6. The system as recited in claim 1 wherein the detectable member
comprises a radio-frequency modulator.
7. The system as recited in claim 1 wherein the detectable member
comprises a gamma ray source.
8. The system as recited in claim 1 wherein the fluid comprises an
interface fluid between a drilling fluid and a cement composition
and wherein the detectable member is disposed within the interface
fluid.
9. The system as recited in claim 1 wherein the fluid comprises a
mud-cement interface and wherein the detectable member is disposed
proximate the mud-cement interface.
10. A system for closing a subterranean valve to terminate a
reverse cementing operation comprising: at least one interrogator
operably associated with the valve; an interface between a first
fluid and a cement composition that is pumped through an annulus
between a pipe string and a wellbore; and at least one detectable
member associated with the interface, the detectable member being
detectable by the interrogator when the detectable member comes in
communicative proximity with the interrogator causing the
interrogator to send a signal to close the valve.
11. The system as recited in claim 10 wherein the interrogator
comprises an oscillator that produces a magnetic field and wherein
the detectable member comprises a resonant circuit.
12. The system as recited in claim 10 wherein the interrogator
comprises a radio-frequency transmitter circuit that produces a
radio-frequency signal and wherein the detectable member comprises
a radio-frequency modulator.
13. The system as recited in claim 10 wherein the interrogator
comprises a gamma ray detector that detects gamma rays and wherein
the detectable member comprises a gamma ray source.
14. The system as recited in claim 10 wherein the interface further
comprises an interface fluid between the first fluid and the cement
composition and wherein the detectable member is disposed within
the interface fluid.
15. The system as recited in claim 10 wherein the interface further
comprises a mud-cement interface and wherein the detectable member
is disposed proximate the mud-cement interface.
16. A system for closing a subterranean valve to terminate a
reverse cementing operation comprising: at least one interrogator
that produces a balanced magnetic field, the interrogator operably
associated with the valve; an interface between a first fluid and a
cement composition that is pumped through an annulus between a pipe
string and a wellbore; and at least one detectable member
associated with the interface, the detectable member unbalancing
the magnetic field when the detectable member comes in
communicative proximity with the interrogator causing the
interrogator to send a signal to close the valve.
17. The system as recited in claim 16 wherein the interface further
comprises an interface fluid between the first fluid and the cement
composition and wherein the detectable member is disposed within
the interface fluid.
18. The system as recited in claim 16 wherein the interface further
comprises a mud-cement interface and wherein the detectable member
is disposed proximate the mud-cement interface.
19. A system for closing a subterranean valve to terminate a
reverse cementing operation comprising: an interrogator that
transmits an interrogating signal and receives a response signal,
the interrogator operably associated with the valve; an interface
between a first fluid and a cement composition that is pumped
through an annulus between a pipe string and a wellbore; and at
least one detectable member associated with the interface, the
detectable member transmitting the response signal in reply to the
interrogating signal when the detectable member comes in
communicative proximity with the interrogator causing the
interrogator to send a signal to close the valve.
20. The system as recited in claim 19 wherein the interrogating
signal and response signal are radio-frequency signals.
21. The system as recited in claim 19 wherein the interface further
comprises an interface fluid between the first fluid and the cement
composition and wherein the detectable member is disposed within
the interface fluid.
22. The system as recited in claim 19 wherein the interface further
comprises a mud-cement interface and wherein the detectable member
is disposed proximate the mud-cement interface.
23. A system for closing a subterranean valve to terminate a
reverse cementing operation comprising: at least one interrogator
that detects gamma rays, the interrogator operably associated with
the valve; an interface between a first fluid and a cement
composition that is pumped through an annulus between a pipe string
and a wellbore; and at least one detectable member associated with
the interface, the detectable member having a source that emits
gamma rays such that when the detectable member comes in
communicative proximity with the interrogator, the interrogator
sends a signal to close the valve.
24. The system as recited in claim 23 wherein the interface further
comprises an interface fluid between the first fluid and the cement
composition and wherein the detectable member is disposed within
the interface fluid.
25. The system as recited in claim 23 wherein the interface further
comprises a mud-cement interface and wherein the detectable member
is disposed proximate the mud-cement interface.
26. A method for actuating an actuatable device in a subterranean
zone penetrated by a wellbore comprising the steps of: operably
associating at least one interrogator with the actuatable device;
disposing at least one detectable member within a fluid; detecting
the detectable member with the interrogator when the detectable
member comes in communicative proximity with the interrogator; and
sending a signal from the interrogator to actuate the actuatable
device.
27. The method as recited in claim 26 wherein the step of detecting
the detectable member with the interrogator when the detectable
member comes in communicative proximity with the interrogator
further comprises producing a magnetic field with an oscillator in
the interrogator and unbalancing the magnetic field with a resonant
circuit in the detectable member.
28. The method as recited in claim 26 wherein the step of detecting
the detectable member with the interrogator when the detectable
member comes in communicative proximity with the interrogator
further comprises producing a radio-frequency signal with a
radio-frequency transmitter circuit in the interrogator, modulating
the radio-frequency signal with the detectable member and returning
the modulated radio-frequency signal to the interrogator.
29. The method as recited in claim 26 wherein the step of detecting
the detectable member with the interrogator when the detectable
member comes in communicative proximity with the interrogator
further comprises detecting gamma rays with a gamma ray detector in
the interrogator and emitting gamma rays from a gamma ray source in
the detectable member.
30. The method as recited in claim 26 wherein the step of disposing
at least one detectable member within a fluid further comprises
disposing the at least one detectable member within an interface
fluid between a drilling fluid and a cement composition.
31. The method as recited in claim 26 wherein the step of disposing
at least one detectable member within a fluid further comprises
disposing the at least one detectable member proximate a mud-cement
interface.
32. A method for closing a subterranean valve to terminate a
reverse cementing operation comprising the steps of: operably
associating at least one interrogator with the valve; disposing at
least one detectable member within an interface between a first
fluid and a cement composition; pumping the cement composition
through an annulus between a pipe string and a wellbore; detecting
the detectable member with the interrogator when the detectable
member comes in communicative proximity with the interrogator; and
sending a signal from the interrogator to close the valve.
33. The method as recited in claim 32 wherein the step of detecting
the detectable member with the interrogator when the detectable
member comes in communicative proximity with the interrogator
further comprises producing a magnetic field with an oscillator in
the interrogator and unbalancing the magnetic field with a resonant
circuit in the detectable member.
34. The method as recited in claim 32 wherein the step of detecting
the detectable member with the interrogator when the detectable
member comes in communicative proximity with the interrogator
further comprises producing a radio-frequency signal with a
radio-frequency transmitter circuit in the interrogator, modulating
the radio-frequency signal with the detectable member and returning
the modulated radio-frequency signal to the interrogator.
35. The method as recited in claim 32 wherein the step of detecting
the detectable member with the interrogator when the detectable
member comes in communicative proximity with the interrogator
further comprises detecting gamma rays with a gamma ray detector in
the interrogator and emitting gamma rays from a gamma ray source in
the detectable member.
36. The method as recited in claim 32 wherein the step of disposing
at least one detectable member within an interface between a first
fluid and a cement composition further comprises disposing the at
least one detectable member within an interface fluid between the
first fluid and the cement composition.
37. The method as recited in claim 32 wherein the step of disposing
at least one detectable member within an interface between a first
fluid and a cement composition further comprises disposing the at
least one detectable member proximate a mud-cement interface.
38. A method for closing a subterranean valve to terminate a
reverse cementing operation comprising the steps of: operably
associating at least one interrogator with the valve; producing a
balanced magnetic field with the interrogator; disposing at least
one detectable member within an interface between a first fluid and
a cement composition; pumping the cement composition through an
annulus between a pipe string and a wellbore; unbalancing the
magnet field by bringing the detectable member within communicative
proximity of the interrogator; detecting the detectable member with
the interrogator; and sending a signal from the interrogator to
close the valve.
39. The method as recited in claim 38 wherein the step of disposing
at least one detectable member within an interface between a first
fluid and a cement composition further comprises disposing the at
least one detectable member within an interface fluid between the
first fluid and the cement composition.
40. The method as recited in claim 38 wherein the step of disposing
at least one detectable member within an interface between a first
fluid and a cement composition further comprises disposing the at
least one detectable member proximate a mud-cement interface.
41. A method for closing a subterranean valve to terminate a
reverse cementing operation comprising the steps of: operably
associating at least one interrogator with the valve; transmitting
a interrogating signal from the interrogator; disposing at least
one detectable member within an interface between a first fluid and
a cement composition; pumping the cement composition through an
annulus between a pipe string and a wellbore; transmitting a reply
signal from the detectable member in response to the interrogating
signal when the detectable member is within communicative proximity
of the interrogator; receiving the reply signal with the
interrogator, thereby detecting the detectable member; and sending
a signal from the interrogator to close the valve.
42. The method as recited in claim 41 wherein the step of
transmitting an interrogating signal from the interrogator further
comprises transmitting a radio-frequency interrogating signal and
wherein the step of transmitting a reply signal from the detectable
member in response to the interrogating signal further comprises
modulating the radio-frequency interrogating signal and
transmitting the modulated radio-frequency interrogating signal as
the reply signal.
43. The method as recited in claim 41 wherein the step of disposing
at least one detectable member within an interface between a first
fluid and a cement composition further comprises disposing the at
least one detectable member within an interface fluid between the
first fluid and the cement composition.
44. The method as recited in claim 41 wherein the step of disposing
at least one detectable member within an interface between a first
fluid and a cement composition further comprises disposing the at
least one detectable member proximate a mud-cement interface.
45. A method for closing a subterranean valve to terminate a
reverse cementing operation comprising the steps of: operably
associating at least one interrogator with the valve; disposing at
least one detectable member within an interface between a first
fluid and a cement composition; pumping the cement composition
through an annulus between a pipe string and a wellbore; emitting
gamma rays from a source in the detectable member; detecting the
gamma rays from the detectable member with a gamma ray detector in
the interrogator when the detectable member comes within
communicative proximity of the interrogator; and sending a signal
from the interrogator to close the valve.
46. The method as recited in claim 45 wherein the step of disposing
at least one detectable member within an interface between a first
fluid and a cement composition further comprises disposing the at
least one detectable member within an interface fluid between the
first fluid and the cement composition.
47. The method as recited in claim 45 wherein the step of disposing
at least one detectable member within an interface between a first
fluid and a cement composition further comprises disposing the at
least one detectable member proximate a mud-cement interface.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates, in general, to controlling
the actuation of a subterranean valve and, in particular, to a
system and method for actuating a subterranean valve upon
confirmation that cement has reached the far end of the annulus
between the casing and the wellbore during a reverse cementing
operation.
BACKGROUND OF THE INVENTION
[0002] Without limiting the scope of the present invention, its
background will be described with reference to cementing a string
of casing within a wellbore as an example.
[0003] In primary cementing operations carried out in oil and gas
wells, a hydraulic cement composition is disposed between the walls
of the wellbore and the exterior of a pipe string, such as a casing
string, that is positioned within the wellbore. The cement
composition is permitted to set in the annulus thereby forming an
annular sheath of hardened substantially impermeable cement
therein. The cement sheath physically supports and positions the
pipe in the wellbore and bonds the pipe to the walls of the
wellbore whereby the undesirable migration of fluids between zones
or formations penetrated by the wellbore is prevented.
[0004] One method of primary cementing involves pumping the cement
composition down through the casing and then up through the
annulus. In this method, the volume of cement required to fill the
annulus must be calculated. Once the calculated volume of cement
has been pumped into the casing, a cement plug is placed in the
casing. A drilling mud is then pumped behind the cement plug such
that the cement is forced into and up the annulus from the far end
of the casing string to the surface or other desired depth. When
the cement plug reaches a float shoe disposed proximate the far end
of the casing, the cement should have filled the entire volume of
the annulus. At this point, the cement is allowed to dry in the
annulus into the hard, substantially impermeable mass.
[0005] It has been found, however, that due to the high pressure at
which the cement must be pumped, at a pressure above the
hydrostatic pressure of the cement column in the annulus plus the
friction pressure of the system, fluid from the cement composition
may leak off into a low pressure zone traversed by the wellbore.
When such leak off occurs, the remainder of the cement composition
near this low pressure zone flash freezes and sets at that location
in the annulus. Once this occurs, additional cement cannot be
pumped past this location and all the cement in the system sets.
Thereafter, remedial cementing operations, commonly referred to as
squeeze cementing, must be used to place cement in the remainder of
the annulus. In addition, a large mass of cement that was intended
to be placed in the annulus must now be drilled out of the
casing.
[0006] Accordingly, prior art attempts have been made to avoid the
problems associated with fluid leak off into low pressure zones
during cementing operations. One method of avoiding such problems
is called reverse cementing wherein the cement composition is
pumped directly into the annulus. Using this approach, the pressure
required to pump the cement to the far end of the annulus is much
lower than that required in conventional cementing operations.
Thus, the likelihood of flash freezing the cement in the annulus
before the entire annulus is filled with cement is significantly
reduced.
[0007] It has been found, however, that with reverse cementing it
is necessary to identify when the cement begins to enter the far
end of the casing such that the cement pumps may be shut off.
Continuing to pump cement into the annulus after cement has reached
the far end forces cement into the casing, which in turn may
necessitate a drill out operation.
[0008] One method of identifying when the cement has reached the
far end of the annulus involves running a neutron density tool down
the casing on an electric line. The neutron density tool monitors
the density out to a predetermined depth into the formation. When
the cement begins to replace the drilling mud in the annulus
adjacent to the neutron density tool, the neutron density tool
senses the change in density and reports to the surface that it is
time to stop pumping additional cement into the annulus. Another
method of identifying when the cement has reached the far end of
the annulus involves running a resistivity tool and a wireless
telemetry system down the casing on a wireline. The resistivity
tool monitors the resistivity of the fluid in the casing such that
when the cement begins to replace the drilling mud in the casing, a
wireless signal is sent to the surface indicating it is time to
stop pumping additional cement into the annulus.
[0009] It has been found, however, that use of such retrievable
tool systems is prohibitively expensive. In fact, numerous neutron
density tools and resistivity tools have been ruined during such
operations as a result of the cement entering the far end of the
casing and contacting these tools.
[0010] Therefore, a need has arisen for a system and method for
cementing the annulus between the wellbore and the casing that does
not require pumping the cement at pressures that allow for leak off
into low pressure zones. A need has also arisen for such a system
and method that identify when to stop pumping additional cement
into the wellbore. Further, a need has arisen for such a system and
method that do not require the use of expensive equipment including
tools that must be retrieved from the well once the cementing
operation is complete.
SUMMARY OF THE INVENTION
[0011] The present invention disclosed herein comprise a system and
method for cementing the annulus between the wellbore and the
casing that does not require pumping the cement at pressures that
allow for leak off into low pressure zones. The system and method
of the present invention identify when to stop pumping additional
cement into the wellbore and do not require the use of expensive
equipment including tools that must be retrieved from the well once
the cementing operation is complete.
[0012] Broadly stated, the system of the present invention
comprises at least one interrogator that is operably associated
with an actuatable device disposed within a wellbore and at least
one detectable member disposed within a fluid. The detectable
member is detectable by the interrogator when the detectable member
comes in communicative proximity with the interrogator causing the
interrogator to send a signal to actuate the actuatable device.
[0013] The system of the present invention may be specifically used
for closing a subterranean valve to terminate a reverse cementing
operation. This system comprises at least one interrogator operably
associated with the valve, an interface between a first fluid and a
cement composition that is pumped through an annulus between a pipe
string and a wellbore and at least one detectable member associated
with the interface that is detectable by the interrogator when the
detectable member comes in communicative proximity with the
interrogator causing the interrogator to send a signal the close
the valve.
[0014] In one embodiment, the interrogator is an oscillator that
produces a magnetic field and the detectable member is a resonant
circuit. In another embodiment, the interrogator comprises a
radio-frequency transmitter circuit that produces a radio-frequency
signal and the detectable member is a radio-frequency modulator
that modulates the radio-frequency signal and returns the modulated
radio-frequency signal to the interrogator. In yet another
embodiment of the present invention, the interrogator is a gamma
ray detector and the detectable member is a gamma ray source.
[0015] In one embodiment of the present invention, the interface is
an interface fluid between the first fluid and the cement
composition and the detectable member is disposed within the
interface fluid. In another embodiment, the interface is a
mud-cement interface and the detectable member is disposed
proximate the mud-cement interface.
[0016] Broadly stated, the method of the present invention involves
the steps of operably associating at least one interrogator with
the actuatable device, disposing at least one detectable member
within a fluid, detecting the detectable member with the
interrogator when the detectable member comes in communicative
proximity with the interrogator and sending a signal from the
interrogator to actuate the actuatable device.
[0017] The method of the present invention may be specifically used
for closing a subterranean valve to terminate a reverse cementing
operation. In this case, the method involves the steps of operably
associating at least one interrogator with the valve, disposing at
least one detectable member within an interface between a first
fluid and a cement composition, pumping the cement composition
through an annulus between a pipe string and a wellbore, detecting
the detectable member with the interrogator when the detectable
member comes in communicative proximity with the interrogator and
sending a signal from the interrogator to close the valve.
BRIEF DESCRIPTION OF THE DRAWING
[0018] For a more complete understanding of the features and
advantages of the present invention, reference is now made to the
detailed description of the invention along with the accompanying
figures in which corresponding numerals in the different figures
refer to corresponding parts and in which:
[0019] FIG. 1 is a schematic illustration of an onshore oil or gas
drilling rig operating a system for actuating a subterranean valve
to terminate a reverse cementing operation of the present
invention;
[0020] FIG. 2 is schematic illustration of a system for actuating a
subterranean valve to terminate a reverse cementing operation of
the present invention prior to actuating the valve;
[0021] FIG. 3 is schematic illustration of a system for actuating a
subterranean valve to terminate a reverse cementing operation of
the present invention following the actuation of the valve;
[0022] FIG. 4 is a block diagram of one embodiment of a system for
actuating a subterranean valve to terminate a reverse cementing
operation of the present invention;
[0023] FIG. 5 is a block diagram of another embodiment of a system
for actuating a subterranean valve to terminate a reverse cementing
operation of the present invention;
[0024] FIG. 6 is a block diagram of another embodiment of a system
for actuating a subterranean valve to terminate a reverse cementing
operation of the present invention;
[0025] FIG. 7 is a flowchart detailing a method for actuating a
subterranean valve to terminate a reverse cementing operation of
the present invention;
[0026] FIG. 8 is schematic illustration of a system for actuating a
subterranean valve to terminate a reverse cementing operation of
the present invention prior to actuating the valve; and
[0027] FIG. 9 is schematic illustration of a system for actuating a
subterranean valve to terminate a reverse cementing operation of
the present invention following the actuation of the valve.
DETAILED DESCRIPTION OF THE INVENTION
[0028] While the making and using of various embodiments of the
present invention are discussed in detail below, it should be
appreciated that the present invention provides many applicable
inventive concepts which can be embodied in a wide variety of
specific contexts. The specific embodiments discussed herein are
merely illustrative of specific ways to make and use the invention,
and do not limit the scope of the invention.
[0029] The present invention provides systems and methods for
actuating a subterranean valve. Even though the systems and methods
are described as being useful in actuating valves during reverse
cementing, it should be understood by one skilled in the art that
the systems and methods described herein are equally well-suited
for actuating valves during other well operations and actuating
downhole equipment other than valves.
[0030] Referring to FIG. 1, an onshore oil or gas drilling rig
operating a system for actuating a subterranean valve to terminate
a reverse cementing operation of the present invention is
schematically illustrated and generally designated 10. Rig 12 is
centered over a subterranean oil or gas formation 14 located below
the earth's surface 16. A wellbore 18 extends through the various
earth strata including formation 14. Wellbore 18 is lined with a
casing string 20. Casing 20 has a valve 22 that is disposed
proximate the far end of casing 20. Valve 22 is used to selectively
permit and prevent the flow of fluids therethrough. For example,
during a reverse cementing operation, valve 22 remains open as
drilling fluids 24 is forced from annulus 26 into the far end of
casing 20 when cement 28 is pumped, via cement pump 30, into the
near end of annulus 26. When the leading edge of cement 28 reaches
the far end of casing 20, valve 22 is closed to prevent cement 28
from traveling within casing 20. Thereafter, cement 28 is allowed
to set in annulus 26 to form a hard, substantially impermeable mass
which physically supports and positions casing 20 in wellbore 18
and bonds casing 20 to the walls of wellbore 18.
[0031] Rig 12 includes a work deck 32 that supports a derrick 34.
Derrick 34 supports a hoisting apparatus 36 for raising and
lowering pipe strings such as casing 20. Pump 30 on work deck 32 is
of conventional construction and is of the type capable of pumping
a variety of fluids into the well. Pump 30 includes a pressure
measurement device that provides a pressure reading at the pump
discharge.
[0032] Referring now to FIG. 2, therein is depicted an enlarged
view of a system for actuating a subterranean valve to terminate a
reverse cementing operation of the present invention that is
schematically illustrated and generally designated 40. The far end
of wellbore 18 is shown with casing 20 disposed therein. Valve 22
is positioned within casing 20 and is in the open position in FIG.
2. Valve 22 may be of any suitable construction that is known in
the art such as ball valves, sleeve valves or the like. Valve 22
may be operated mechanically, electrically, electro-mechanically,
hydraulically or by other suitable means.
[0033] Valve 22 has an actuator 42 for operating valve 22 between
the open and closed positions. Coupled to actuator 42 is a pair of
interrogators 44, 46. Interrogators 44, 46 are used to send a
signal to actuator 42 when it is time to operate valve 22. In the
illustrated configuration, interrogators 44, 46 are used to send a
signal to actuator 42 when it is time to operate valve 22 from the
open position to the closed position. It should be noted, however,
by those skilled in the art the interrogators 44, 46 could
alternatively be used to operate valve 22 from the closed position
to the open position or could be used to operate other types of
actuatable devices. In addition, even though FIG. 2 depicts two
interrogators 44, 46, it should become apparent to those skilled in
the art that other numbers of interrogators, either a greater
number or a lesser number, may be used to signal actuator 42 to
operate without departing from the principles of the present
invention.
[0034] Wellbore 18 is filled with various fluids. As illustrated,
the fluids include a drilling fluid 48, an interface fluid 50
including a plurality of detectable members 52 and a hydraulic
cement composition 28. Drilling fluid 48 may be any typical
drilling fluid such as a water-based or oil-based drilling fluid.
Importantly, drilling fluid 48 is used to contain subsurface
pressure. Accordingly, drilling fluid 48 is weighted with various
additives so that the hydrostatic pressure of drilling fluid 48 is
sufficient to contain subsurface pressure along the entire depth of
wellbore 18, thereby preventing blowouts.
[0035] Interface fluid 50 may be any suitably viscous fluid that is
capable of maintaining substantial separation between drilling
fluid 48 and cement composition 28. In addition, interface fluid 50
is capable of containing and transporting the plurality of
detectable members 52 from the surface to the far end of wellbore
18. For example, interface fluid may be a water-based or oil-based
fluid.
[0036] Cement composition 28 may be any typical hydraulic
cementitious material including those comprising calcium, aluminum,
silicon, oxygen and/or sulfur which set and harden by reaction with
water. Such hydraulic materials include Portland cements, pozzolana
cements, gypsum cements, high aluminum content cements, silica
cements and high alkalinity cements. Portland cements are generally
preferred for use in accordance with the present invention.
Portland cements of the types defined and described in API
Specification for Materials and Testing for Well Cements, API
Specification 10, 5th Edition, dated Jul. 1, 1990 of the American
Petroleum Institute are particularly suitable. Preferred API
Portland cements include classes A, B, C, G and H, with API class H
being the most preferred.
[0037] The water used in forming cement composition 28 can be from
any source provided it does not contain an excess of compounds that
adversely affect other components in cement composition 28.
Generally, water is present in a cement slurry composition of this
invention in an amount in the range of from about 25% to about 100%
by weight of hydraulic material therein and, more preferably, in an
amount in the range of from about 30% to about 75% by weight of
hydraulic material therein. In addition, various dispersing agents
can also be utilized in cement composition 28. The dispersing agent
functions to facilitate the dispersal of the solids in the water,
and allows the use of smaller amounts of water than is the case
without the dispersing agent.
[0038] The plurality of detectable members 52 are suspended in
interface layer 50 and circulate with interface layer 50 through
annulus 26 and into casing 20 toward valve 22 as cement composition
28 is pumped into annulus 26 at the surface. When one or more of
the detectable members 52 come within the communicative proximity
of one or both of the interrogators 44, 46, interrogators 44, 46
identify the presence of detectable members 52 and send a signal to
actuator 42 to close valve 22.
[0039] As detectable members 52 are associated with interface fluid
50, when detectable members 52 are detected, interface fluid 50 is
near valve 22. When interface fluid 50 is near valve 22, annulus 26
is entirely filled with cement 28. Thereafter, valve 22 is closed
which sends a pressure signal through the column of cement 28 in
annulus 26 indicating that the cement pumps at the surface should
be shut off. As best seen in FIG. 3, once detectable members 52 are
within the communicative proximity of interrogators 44, 46,
actuator 42 closes valve 22 which prevents cement 28 from entering
the portion of casing string 20 above valve 22.
[0040] The detailed operation of various embodiments of a system
for actuating a subterranean valve to terminate a reverse cementing
operation of the present invention will now be discussed. Referring
to FIG. 4, interrogator 60 and detectable member 62, which is
disposed within interface fluid 50 between drilling fluid 48 and
cement 28, are depicted in communicative proximity to one another.
Interrogator 60 is an electronic identification system that
utilizes a magnetic field modulation system to monitor for the
presence of detectable members 62. Interrogator 60 creates a
magnetic field 64 that becomes unbalanced or detuned when one or
more detectable member 62 pass through magnetic field 64.
[0041] Several different types of detectable members 62 are
suitable for use with interrogator 60. In one type, the functional
portion of detectable member 60 consists of either an antenna and
diode or an antenna and capacitors forming a resonant circuit. When
placed in electromagnetic field 64 generated by interrogator 60,
the antenna-diode marker generates harmonics of the interrogating
frequency in the receiving antenna. The resonant circuit marker
causes an increase in absorption of the transmitted signal so as to
reduce the signal in a receiving coil. The detection of the
harmonic or signal level change by interrogator 60 indicates the
presence of detectable member 62.
[0042] A second type of detectable member 60 includes a first
elongated element of high magnetic permeability ferromagnetic
material disposed adjacent to at least a second element of
ferromagnetic material having higher coercivity than the first
element. When subjected to an interrogation frequency of
electromagnetic radiation, detectable member 62 causes harmonics of
the interrogating frequency to be developed in the receiving coil
of interrogator 60. The detection of such harmonics by interrogator
60 indicates the presence of detectable member 62.
[0043] When the detectable member 62 is exposed to a dc magnetic
field, the state of magnetization in the second element changes
and, depending upon the design of detectable member 62, either the
amplitude of the harmonics chosen for detection is significantly
reduced, or the amplitude of the even numbered harmonics is
significantly changed. Either of these changes can be readily
detected by interrogator 60.
[0044] In the illustrated embodiment, interrogator 60 includes an
oscillator 66 that applies a sinusoidal current to two
substantially identical electromagnetic field producing units 68.
Field producing units 68 may be of similarly constructed conducting
coils. The lines of the magnetic field produced by the coils are
indicated by lines 64.
[0045] Any perturbation in the fields produced by detectable member
62 is detected by a field detector unit 70. Detector unit 70 can be
a coil in which the time varying fields induce a voltage. It should
be noted that in the absence of a field perturbing object, such as
detectable member 62 when it is generally disposed in detectable
proximity of the field detector unit 70, the field is balanced.
[0046] The signals produced by detector unit 70 are amplified by an
amplifier 72. The output signal of amplifier 72 is filtered by a
filter 74. Filter 74 provides a means of eliminating any detected
spurious signals at frequencies differing from the electromagnetic
field frequency resulting from the interaction of detectable member
62 in field 64 and therefore provides a narrow ban signal of the
desired frequency. The output of filter 74 is amplified by an
amplifier 76 to provide a sufficient signal level to drive both
phase comparator 78 and amplitude comparator 80.
[0047] A portion of the output signal of amplifier 76 is applied to
the amplitude comparator circuit 80. When the output signal of
amplifier 76 is between predetermined values, a positive logic
signal is applied to detection logic circuits 82. Another portion
of the output of amplifier 76 is applied to phase comparator
circuit 78. The phase of the amplifier output signal is compared
with the phase of oscillator 66. When the phases of the two signals
differ by a predetermined value, a positive-logic signal is applied
to detection logic circuits 82. The simultaneous presence of the
amplitude-related and the phase-related logic signals are necessary
to activate the detection logic circuits 82. Upon application of
the proper positive logic signals to logic circuits 82, an activate
signal is applied to actuator 42. Valve actuator 42 triggers an
actuation event such as the closing of valve 22.
[0048] Referring next to FIG. 5, another embodiment a system for
actuating a subterranean valve to terminate a reverse cementing
operation of the present invention is depicted. An interrogator 90
and a detectable member 92, which is disposed within interface
fluid 50 between drilling fluid 48 and cement 28, are positioned
within communicative proximity of one another. Together,
interrogator 90 and detectable member 92 may, for example, form a
radio-frequency identification (RFID) system. Interrogator 90
comprises a power source 94, an interrogating signal generator 96
with a sending transducer or antenna 98. In addition, interrogator
90 also comprises an amplifier and demodulator 100 operably
connected to a signal receiving transducer or an antenna 102. In
the illustrated embodiment, the interrogating signal 104 and the
response signal 106 are typically radio-frequency (rf) signals
produced by an rf transmitter circuit.
[0049] Detectable member 92 comprises a signal receiving and
reflecting antenna 108 and a reflector modulator 110 for modulating
interrogating signal 104 received by the antenna 108 as well as for
reflecting the modulated signal, response signal 106, from antenna
108. As can be seen from FIG. 5, the power source 94 powers
interrogating signal generator 96 to send interrogating signal 104
from antenna 98. Preferably, power source 94 is four AA batteries.
Interrogating signal 104 from antenna 98 passes through the fluid
medium and is received by antenna 108 at detectable member 92.
Modulator 110 modulates the signal in accordance with information
desired and reflects the amplitude modulated signal, response
signal 106, from antenna 108 to antenna 102. Antenna 102 send the
signal to amplifier and demodulator 100 which processes the signal
to determine whether the response is from a detectable member 92.
Upon receipt of the proper response signal, amplifier and
demodulator 100 sends an activate signal to valve actuator 42.
Valve actuator 42 triggers an actuation event such as the closing
of valve 22.
[0050] It should be noted that interrogating signal 104 generated
by interrogator 90 need not be a continuous wave or constant in
amplitude and/or frequency. It may be appropriate in some
applications to generate an interrogating signal 104 that is
intermittent. This might be done for various reasons such as
conserving power. Many combinations and variations are possible as
will be readily recognizable to those skilled in the art.
[0051] Referring now to FIG. 6, another embodiment a system for
actuating a subterranean valve to terminate a reverse cementing
operation of the present invention is depicted. An interrogator 120
and a detectable member 122 are shown in communicative proximity to
one another. Interrogator 120 is a gamma ray detecting system that
detects gamma rays 124 originating close to interrogator 120 from
detectable member 122 that is a radioactive source, which is
disposed within interface fluid 50 between drilling fluid 48 and
cement 28. Detectable member 122 emits gamma rays 124 that travel
only a short distance before being scattered or absorbed.
[0052] A variety of gamma-emitting tracer isotopes are suitable for
use within detectable member 122, including but not limited to
Gold.sup.198, Xenon.sup.133, Iodine.sup.131, Rubidium.sup.86,
Chromium.sup.51, Iron59, Antimony.sup.124, Stontium.sup.85,
Cobalt.sup.58, Iridium.sup.192, Scandium.sup.46, Zinc.sup.65,
Siler.sup.110, Cobalt.sup.57, Cobalt.sup.60 and Krypton.sup.85.
During the cementing treatment, detectable member 122 regularly
emits gamma rays 124, which move through the subterranean system in
a random direction for a distance of perhaps one meter, and in the
process are scattered and/or absorbed by the subterranean formation
and steel tubular elements such as casing 20. Since gamma rays 124
from detectable member 122 travel only a short distance before
being absorbed, the gamma rays 124 that impinge upon interrogator
120 will have originated from a location close to interrogator 120.
In this manner, interrogator 120 is able to detect when cement 28
has progressed to the far end of wellbore 18 proximate valve 22.
Once detection occurs, valve 22 may be closed and the pumping of
additional cement 28 is stopped before the interior of casing 20 is
cemented.
[0053] Interrogator 120 may be a conventional gamma detector
comprises, for example, a thallium activated sodium iodide crystal
126 coupled to a low noise photomultiplier 128 having appropriate
electronics associated therewith all of which is encased in lead
shielding. Upon detection of the proper gamma ray signal 124, an
activation signal is sent from photomultiplier 128 to valve
actuator 42 such that valve 22 may be closed.
[0054] Referring now to FIG. 7, a flowchart outlining the method
for actuating a subterranean valve to terminate a reverse cementing
operation of the present invention is depicted. At block 130, the
valve equipped with the interrogator and valve actuator is lowered
into the wellbore. The valve can be lowered with the casing string
as an attachment to the casing string or, the valve could
alternatively be lowered into the well after the casing string has
been put into place.
[0055] At block 132, detectable members are placed in the interface
fluid and the interface fluid is pumped into the annulus. At block
134, cement is pumped into the annulus. While cement is
continuously pumped into the annulus, at decision 136, the
interrogator is attempting to detect whether the detectable members
are proximate the valve. As long as no detectable members are
detected, the pumping of additional cement into the annulus
continues. When the interrogator detects the detectable member at
block 138, the interrogator sends a signal to the valve actuator at
block 140.
[0056] At block 142, the actuator closes the valve such that no
additional fluid may flow into the casing. This creates a pressure
signal that is detected at the hydraulic pump at block 144. The
cement pumping is discontinued at block 146. The cement in the
annulus is allowed to set and form a hard, substantially
impermeable mass which physically supports and positions the casing
in the wellbore and bonds the casing to the walls of the wellbore
in block 148.
[0057] Referring now to FIG. 8, therein is depicted an enlarged
view of a system for actuating a subterranean valve to terminate a
reverse cementing operation of the present invention that is
schematically illustrated and generally designated 150. The far end
of wellbore 18 is shown with casing 20 disposed therein. Valve 22
is positioned within casing 20 and is in the open positioned in
FIG. 8. Valve 22 has an actuator 42 for operating valve 22 between
the open and closed positions. Coupled to actuator 42 is a pair of
interrogators 44, 46. Interrogators 44, 46 are used to send a
signal to actuator 42 when it is time to operate valve 22. In the
illustrated configuration, interrogators 44, 46 are used to send a
signal to actuator 42 when it is time to operate valve 22 from the
open position to the closed position.
[0058] In the illustrated embodiment, wellbore 18 is filled with
two fluids, namely, drilling fluid 48 and hydraulic cement
composition 28 which form a mud-cement interface 152 therebetween.
A plurality of detectable members 52 are disposed proximate the
mud-cement interface 152 such that detectable members 52 circulate
through annulus 26 and into casing 20 toward valve 22 as cement
composition 28 is pumped into annulus 26 at the surface. When one
or more of the detectable members 52 come within the communicative
proximity of one or both of the interrogators 44, 46, interrogators
44, 46 identify the presence of detectable members 52 and send a
signal to actuator 42 to close valve 22.
[0059] As detectable members 52 are associated with mud-cement
interface 152, when detectable members 52 are detected, mud-cement
interface 152 is near valve 22. When mud-cement interface 152 is
near valve 22, annulus 26 is entirely filled with cement 28.
Thereafter, valve 22 is closed which sends a pressure signal
through the column of cement 28 in annulus 26 indicating that the
cement pumps at the surface should be shut off. As best seen in
FIG. 9, once detectable members 52 are within the communicative
proximity of interrogators 44, 46, actuator 42 closes valve 22
which prevents cement 28 from entering the portion of casing string
20 above valve 22.
[0060] While this invention has been described with a reference to
illustrative embodiments, this description is not intended to be
construed in a limiting sense. Various modifications and
combinations of the illustrative embodiments as well as other
embodiments of the invention, will be apparent to persons skilled
in the art upon reference to the description. It is, therefore,
intended that the appended claims encompass any such modifications
or embodiments.
* * * * *