SAFETY DEVICE
Technical field
The present invention relates to a downhole safety device for a downhole tool for
controlling a delivery of electricity from a power device to an electrical component
in the tool, comprising a first member comprising a plurality of conductors, and a
second member comprising a plurality of conductors. Furthermore, the invention
relates to a method for activating the safety device.
Background
When an electronic component, such as a relay, in a tool breaks down, there is a
risk that too much electrical power is transferred to the other components in the
tool. Many electrical components can withstand receiving too much power, and
electrical systems are often designed to turn off the power in cases like this.
However, when working downhole, communication to and from the tool as well as
communication within the tool can be difficult. Higher security is especially impor
tant in tools handling drilling units, explosives or cement to ensure that they do not
perform uncontrolled operations, such as explosives not being detonated, drilling
tools drilling in an uncontrolled direction or cement being ejected unintentionally,
thereby closing the well.
Description of the invention
It is an object of the present invention to wholly or partly overcome the above d is
advantages and drawbacks of the prior art. More specifically, it is an object to provide
a safety device for a downhole tool securing that operations are not performed
unintentionally so that e.g. a perforation switch is not activated if there is a failure
in the tool.
The above objects, together with numerous other objects, advantages, and features,
which will become evident from the below description, are accomplished by a
solution in accordance with the present invention by a downhole safety device for a
downhole tool for controlling a delivery of electricity from a power device to an
electrical component in the tool, comprising:
- a first member comprising a plurality of conductors, and
- a second member comprising a plurality of conductors, and
- a moving device for moving the first member in relation to the second member,
wherein the conductors of the first member are first and second conductors, and at
least two of the first conductors have a greater surface area than the second con
ductors, enabling the first conductors to transfer more power to the conductors of
the second member than the second conductors.
When the first conductors have a greater surface area than the second conductors,
the first conductors can be used to transfer power, and the second conductors can
be used to send a signal that the first conductors are in the right position. One
member is not moved in relation to the other member until there is a need for a
transfer of power to the electrical component.
Thus, contact between the first conductors of the first member and the conductors
of the second member is not initiated until it is confirmed that the second conduc
tors of the first member are in the right position. When the surface areas of the
second conductors are smaller, although large enough to send signals about the
position of the safety device, the first conductors can be positioned out of contact
until power is needed in the next electrical component. In this way, too much
power transferred to the safety device cannot unintentionally be transferred to the
next electrical component.
In one embodiment, the surface area may be a contact area in which contact with
another conductor is possible.
Moreover, the second conductors may verify if the first conductors are in or out of
electrical contact with the conductors of the second member.
Also, the first conductors may be electrically connected in a first electric circuit and
the second conductors may be electrically connected in a second electric circuit.
In addition, the moving device may be an electrical motor.
Further, a shaft may be connecting the first and the second member.
Said moving device may be arranged in connection with the shaft either inside the
first or second member or outside the first and the second members.
In an embodiment of the invention, the conductors of the second member may
have a surface area which is substantially the same as or larger than that of the
first conductors of the first member.
Moreover, the surface area of the first conductor may be at least 1.5 times the area
of the second conductor, preferably at least 2 times the area of the second conduc
tor.
In addition, the surface area of the first conductor may have a contact area of at
least 20 mm2, preferably at least 25 mm2 and more preferably at least 30 mm2.
Furthermore, the surface area of the second conductor may have a contact area of
less than 50% of a contact area of the first conductor, preferably less than 30% of
the contact area of the first conductor, and more preferably less than 15% of the
contact area of the first conductor.
In an embodiment, the safety device may have a first and a second position, and in
the first position, the first conductors of the first member are out of contact with
the conductors of the second member, and the second conductors are in electrical
contact with the conductors of the second member, and in a second position, the
first conductors of the first member are in contact with the conductors of the sec
ond member.
In addition, the safety device may have other positions between the first and the
second position.
In another embodiment, the conductors of the first or second member may be coil
springs.
Furthermore, the conductors of either the first or the second member may be coil
springs, and the conductors of the other member may be conductive rings or con
ductive bars.
Moreover, the structure may be made of a non-conductive material.
In addition, the first or second member may comprise circumferential or longit udi
nal grooves for receiving the conductors.
Also, the first member may be connected with the second member by means of a
threaded connection on a shaft, and when the shaft rotates in relation to the hous
ing, the first member and the second member move axially in relation to each
other.
Additionally, either the first or the second member may be a hollow structure and
the other member may be a body extending at least partly within that hollow st ruc
ture.
The safety device as described above may further comprise a housing comprising
the first and second members as well as conductive means, such as a cable or
cords, to be connected to a power device of the tool in one end of the housing and
to an operational unit of the tool, such as a drilling head, a perforation gun or a
cementing unit, in another end of the housing
The invention furthermore relates to a downhole tool comprising the safety device
as described above for controlling the passage of electricity to a perforation unit, a
drilling unit or a cementing unit.
Moreover, the invention relates to a method for activating the safety device as de
scribed above, the method comprising the steps of:
- arranging the first member in a first position in which the first conductors are out
of conductive contact with the conductors of the second member, and in which two
of the second conductors are in conductive contact with the conductors of the second
member,
- sending a signal to an operational unit through the second conductors and the
conductors of the second member,
- sending a signal from the operational unit through the second conductors and the
conductors of the second member,
- moving the first and second members in relation to each other from the first posi
tion to the second position, in which second position the first conductors are in con
ductive contact with the conductors of the second member and the two other sec
ond conductors are in conductive contact with the conductors of the second mem
ber,
- sending a signal to an operational unit through the second conductors and the
conductors of the second member,
- sending a signal from the operational unit through the second conductors and the
conductors of the second member, and
- transferring power to the operational unit.
Finally, the invention relates to another method for activating the safety device as
described above, the method comprising the steps of:
- arranging the first member in a first position in which the first conductors are out
of conductive contact with the conductors of the second member, and in which two
of the second conductors are in conductive contact with the conductors of the sec
ond member,
- sending a signal through the second conductors and the conductors to confirm the
first position of the safety device,
- sending a signal back to confirm the first position of the safety device,
- moving the first and second members in relation to each other from the first posi
tion to the second position, in which second position the first conductors are in con
ductive contact with the conductors of the second member and the two other second
conductors are in conductive contact with the conductors of the second mem
ber,
- sending a signal through the second conductors and the conductors to confirm the
second position of the safety device,
- sending a signal back confirming the second position of the safety device, and
- transferring power to the operational unit.
Brief description of the drawings
The invention and its many advantages will be described in more detail below with
reference to the accompanying schematic drawings, which for the purpose of illus
tration show some non-limiting embodiments and in which
Fig. 1 shows a safety device arranged in a downhole tool,
Fig. 2 shows a cross-sectional view of the safety device in an open position,
Fig. 3 shows a cross-sectional view of the safety device in a closed position, able to
transfer electrical power to an operational unit of the tool,
Fig. 4 shows a cross-sectional view of another embodiment of the safety device in
an open position,
Fig. 5 shows a cross-sectional view of the safety device of Fig. 4 in a closed posi
tion, able to transfer electrical power to an operational unit of the tool,
Fig. 6 shows a cross-sectional view of yet another embodiment of the safety device,
Fig. 7 shows a cross-sectional view of the hollow structure transverse to the view in
Fig. 6, and
Fig. 8 shows a cross-sectional view of yet another embodiment of the safety device,
and
Fig. 9 shows a cross-sectional view of the hollow structure transverse to the view in
Fig. 8.
All these figures are highly schematic and not necessarily to scale, and they show
only those parts which are necessary in order to elucidate the invention, other parts
being omitted or merely suggested.
Detailed description of the invention
The present invention relates to a safety device adapted for delivering electricity to
a downhole tool to ensure that an operational unit, such as a drilling head, perf ora
tion gun or cementing unit, is not unintentionally activated if an electronic device in
the downhole tool breaks down.
The downhole tool may comprise several safety devices arranged in series, in paral
lel or in different positions within the tool, however, in the following description, the
tool is described as having only one safety device 1, as shown in Fig. 1. When the
tool is connected to a perforation gun, the tool most often has at least two safety
devices in series so that a first safety device controls the power delivery to a sec
ond safety device which controls the power delivery to a perforation switch or d i
rectly to the perforating gun.
At its input side 12, the safety device is connected with a power device (not
shown), such as an electrical motor, in the downhole tool by means of conductive
means 14, such as cables or cords. At its output side 13, the safety device 1 is
electronically connected with the operational unit (not shown), such as a perfora
tion gun, also by means of a conductive means 15.
The safety device 1 comprises a housing 11 in which a first 3 and a second member
6 are arranged together with the conductive means 14, 15. In Fig. 1, the housing
11 and the downhole tool 2 is illustrated by a dotted line.
In Fig. 1, the first member 3 is a hollow structure in which the second member 6 in
the form of a body 6 is arranged. In one end 16 of the safety device 1, the body 6
is connected with the hollow structure 3 by means of a threaded connection 10 so
that movement of either the hollow structure 3 or the body 6 in relation to the
other results in the hollow structure and the body moving axially in relation to each
other. In order to move the first member 3 in relation to the second member 6, the
safety device 1 comprises a moving device 3 1 which may be arranged inside the
body as shown in Fig. 2 or outside the housing in the end of a shaft 32 as shown in
Fig. 4. The moving device 3 1 may rotate the shaft threadingly connecting the first
and second members and thus move the first member in relation to the second
member. The moving device 3 1 may be an electrical motor.
The first 3 and second members 6 comprise a plurality of conductors 4, 7 or con
tacts. The first member 3 has five conductors 4; two first conductors 8 and three
second conductors 9, all in the form of circumferential contact rings. The second
member 6 comprises four circumferential grooves comprising four equally sized
conductors 7 in the form of conductive coil springs. The first conductors 8 have a
greater surface area than the second conductors 9 and are therefore able to t rans
fer more power to the conductors 7 of the second member 6 than the second con
ductors 9 are. The second conductors 9 are dimensioned to transfer enough power
to signal the position of the first 3 and second members 6 in relation to one another
within the safety device 1. The first conductors 8 are electrically connected, forming
part of a first electric circuit and the second conductors 9 are electrically connected,
forming part of a second electric circuit.
In a first position, a first and second of the three second conductors 9 are arranged
outside two conductors 7 of the second member 6 of the second electric circuit and
the first conductors 8 are out of electrical contact with two other conductors 7 of
the second member of the first electric circuit. In order to confirm this first position
in which the first conductors 8 are out of electrical contact with two other conductors
7 of the second member of the first circuit and in which it is thus not possible
to transfer electric power to an operational tool, the second electric circuit of the
two second conductors 9 and the two conductors 7 of the second member 6 is
tested to see if the electric circuit is connected. In a second position, the second
and third of the three second conductors 9 are arranged outside two conductors 7
of the second member 6 of the second circuit and the first conductors 8 are a r
ranged outside the other two conductors 7 of the second member 6 forming part of
the first circuit. In this second position, the first electric circuit is connected and
power can be transferred to the operational tool. The second position is confirmed
by confirming that the second and third of the three second conductors 9 are elec
trically connected with the two conductors 7 of the second member forming part of
the second circuit. In the first position, electricity cannot be transferred uninten
tionally to an operational unit even though high power was unintentionally connected
due to the fact that the small surface conductors cannot transfer the high
power between the first and the second members.
The area in which the first conductors 8 are in conductive contact with the conduc
tors of the second member 6 can be smaller than the surface area of the first conductors,
especially if the conductors of one of the members 3, 6 are coil springs.
The conductors 4 of the first member 3 are connected to the power device of the
downhole tool 2. The two first conductors are connected with the operational unit of
the tool 2, and the three second conductors may be connected to a control device
of the tool, able to give signal to move the first 3 and second members 6 in relation
to one another. Thus, the three second conductors are not connected to the opera
tional unit as they are only used for determining or verifying the position of the
safety device 1.
In Fig. 2, the first conductors 8 are in their first position arranged so that they are
not conductively connected to any conductors 7 of the second member 6. In this
position, signals can be sent down to the safety device 1 without being passed on
to the operational tool. In the event that an electronic device, such as a relay,
breaks down and too much power is sent to the safety device 1, the second conductors
are unable to transfer that power further on to the operational unit of the
downhole tool 2.
In Fig. 3, the safety device 1 is shown in its second position in which the first con
ductors 8 are in contact with two of the four conductors 7 of the second member 6.
Two of the three second conductors 9 are now connected with the two other con
ductors 7 of the second member 6. In this position, the tool 2 can transfer a high
amount of power to and from the operational unit through the two first conductors
When the safety device 1 has two positions and two differently sized conductors on
one side of the conductive connection, high power cannot unintentionally be t rans
ferred to the operational tool. Before entering the well or borehole, the safety de
vice 1 is arranged in its first and open position so that power cannot be transferred
to the operational unit. When signals sent to the safety device 1 confirm that the
safety device is functional and that the operational unit is in place, the safety de
vice changes its position, and power can now be transferred to the operational tool.
In another embodiment, the safety device may have other positions between the
first and the second position in which neither the first 8 nor the second 9 conductors
of the first member 3 are in contact with the conductors 7 of the second mem
ber 6.
In some embodiments, the second conductors 9 are also connected to the opera
tional tool, but since the contact area is not large enough, only signalling power can
be transferred to the operational tool. In this way, the condition of the operational
unit can be determined or confirmed before transmitting high power to the tool.
Even though high power is sent while the safety device 1 is in its first position, the
contact area between the first conductors 9 of the first member 3 and the conduc
tors 7 of the second member 6 is not large enough to transmit the power, and the
power transmitted to the operational unit is automatically reduced to less than sig
nalling power.
Figs. 4 and 5 show another embodiment of the safety device 1. The four conductors
7 of the second member 6 are in the form of conductive rings, and the conductors 4
of the first member 3 are coil springs.
By having coil springs or Bal seals (sold by Bal Seal Engineering) on one side of the
conductive connection, the elastic spring is able to compensate for a thermal ex
pansion of the first and second members and for inaccuracies in the manufacturing
of the first 3 and second members 6 as the elastic spring can be more or less com
pressed inside the grooves.
The conductors can also be arranged in axial groves in the first and/or second
members, as shown in Figs. 6 and 7. As shown, the first member 3 comprises two
first conductors 8 and three second conductors 9 axially arranged in the form of
conductive bars having different widths and thus different circumferential exten
sions. Fig. 7 shows a cross-sectional view of the safety device transverse to that of
Fig. 6, in which conductive bars are also axially arranged so that a rotational
movement of the first 3 and/or the second member 6 in relation to one another re
sults in a change of position from a first position to a second position, or vice versa.
The safety device 1 may also have a third position in which neither the first 8 nor
the second 9 conductors of the first member 3 are in contact with the conductors of
the second member 6.
The surface area of the first conductor 8 is at least 1.5 times the surface area of the
second conductor 9, preferably at least 2 times the area of the second conductor 9.
In order to transfer power to an operational tool such as a perforation unit, a con
tact area of the surface area of the first conductor 8 of the first member 3, which is
the area in contact with the conductor of the second member 6, is at least 20 mm2,
preferably at least 25 mm2, and more preferably at least 30 mm2. When t ransfer
ring higher power, e.g. during a drilling process, the surface area may have to be
increased.
The contact area of the second conductor 9 is less than 50% of a contact area of
the first conductor 8, preferably less than 30% of the contact area of the first con
ductor, and more preferably less than 15% of the contact area of the first conductor.
The first member 3 is shown connected with the second member 6 by means of a
threaded connection 10, however, this connection may be any connection suitable
for generating a rotational or axial movement of the first 3 and second members 6
in relation to each other.
The first 3 and second members 6 comprise axial or circumferential grooves in
which the conductors are arranged. The conductors may also be casted or moulded
together with the first 3 and/or the second member 6.
The first 3 and/or the second member 6 is made of a non-conductive material, such
as ceramics, plastic, composite, fibre glass or similar material.
The first member 3 is shown as a solid body and the second member 6 as a hollow
structure, which in another embodiment could be vice versa as shown in Figs. 8 and
9. The first 3 and second members 6 may have any suitable shape, such as a hol
low element, a partly hollow element, a frame structure, a solid cylinder or even a
square cross-sectional shape if the movement from the first to the second position
is only axial.
When activating the safety device 1, the first member 3 is arranged in a first position
in which the first conductors 8 are out of conductive contact with the conduc
tors 7 of the second member 6, and in which two of the second conductors 9 are in
conductive contact with the conductors 7 of the second member 6. In one embodi
ment, a signal is sent to an operational unit or a switch through the second conduc
tors 9 and the conductors 7 of the second member 6 to confirm that the tool or
switch is functioning, and another signal is sent back as confirmation. When the op
erational unit is in the right position for performing the operation, the first 3 and
second members 6 are moved in relation to each other from the first position to the
second position by means of the moving device 31, in which second position the
first conductors 8 are in conductive contact with the conductors 7 of the second
member 6 and the two of the second conductors 9 are in conductive contact with
the conductors 7 of the second member 6 of the second electric circuit. Subse
quently, a signal is sent through the second conductors 9 and the conductors 7 of
the second member 6 to confirm the second position, and another signal is sent
back. Finally, power is transferred to the operational tool.
By contact area is meant the area in which the surface area of the first conductor of
one member is in contact with the conductor of the other member.
By a casing is meant all types of pipes, tubings, tubulars, etc. used downhole in relation
to oil or natural gas production.
In the event that the tools are not submergible all the way into the casing 4, a
downhole tractor can be used to push the tools all the way into position in the well.
A downhole tractor is any type of driving tool capable of pushing or pulling tools in
a well, such as a Well Tractor®.
Although the invention has been described in the above in connection with pre
ferred embodiments of the invention, it will be evident for a person skilled in the art
that several modifications are conceivable without departing from the invention as
defined by the following claims.
Claims
1. A downhole safety device (1) for a downhole tool (2) for controlling a delivery
of electricity from a power device to an electrical component in the tool, comprising:
- a first member (3) comprising a plurality of conductors (4),
- a second member (6) comprising a plurality of conductors (7), and
- a moving device (31) for moving the first member in relation to the second mem
ber,
wherein the conductors of the first member are first (8) and second (9) conductors,
and at least two of the first conductors have a greater surface area than the second
conductors, enabling the first conductors to transfer more power to the conductors
of the second member than the second conductors.
2. A downhole safety device according to claim 1, wherein the conductors of the
second member have a surface area which is substantially the same as or larger
than that of the first conductors of the first member.
3. A downhole safety device according to claim 1 or 2, wherein the surface area
of the first conductor is at least 1.5 times the area of the second conductor, pref
erably at least 2 times the area of the second conductor.
4. A downhole safety device according to claim 3, wherein the surface area of the
first conductor has a contact area of at least 20 mm2, preferably at least 25 mm2
and more preferably at least 30 mm2.
5. A downhole safety device according to any of the preceding claims, wherein
the surface area of the second conductor has a contact area of less than 50% of a
contact area of the first conductor, preferably less than 30% of the contact area of
the first conductor, and more preferably less than 15% of the contact area of the
first conductor.
6. A downhole safety device according to any of the preceding claims, wherein
the safety device has a first and a second position, and
- in the first position, the first conductors of the first member are out of contact
with the conductors of the second member, and the second conductors are in elec
trical contact with the conductors of the second member, and
- in a second position, the first conductors of the first member are in contact with
the conductors of the second member.
7. A downhole safety device according to any of the preceding claims, wherein
the conductors of the first or second member are coil springs.
8. A downhole safety device according to any of the preceding claims, wherein
the conductors of either the first or the second member are coil springs, and the
conductors of the other member are conductive rings or conductive bars.
9. A downhole safety device according to any of the preceding claims, wherein
the first or second member comprises circumferential or longitudinal grooves for re
ceiving the conductors.
10. A downhole safety device according to any of the preceding claims, wherein
the first member is connected with the second member by means of a threaded
connection (10) on a shaft (32), and when the shaft rotates in relation to the hous
ing, the first member and the second member move axially in relation to each
other.
11. A downhole safety device according to any of the preceding claims, wherein ei
ther the first or the second member is a hollow structure and the other member is a
body extending at least partly within that hollow structure.
12. A downhole safety device according to any of the preceding claims, further
comprising a housing comprising the first and second members as well as conduc
tive means, such as a cable or cords, to be connected to a power device of the tool
in one end of the housing and to an operational unit of the tool, such as a drilling
head, a perforation gun or a cementing unit, in another end of the housing
13. A downhole tool (2) comprising the safety device of claims 1-12 for controlling
the passage of electricity to a perforation unit, a drilling unit or a cementing unit.
14. A method for activating the safety device according to any of claims 1-12, the
method comprising the steps of:
- arranging the first member in a first position in which the first conductors are out
of conductive contact with the conductors of the second member, and in which two
of the second conductors are in conductive contact with the conductors of the sec
ond member,
- sending a signal to an operational unit through the second conductors and the
conductors of the second member,
- sending a signal from the operational unit through the second conductors and the
conductors of the second member,
- moving the first and second members in relation to each other from the first posi
tion to the second position, in which second position the first conductors are in con
ductive contact with the conductors of the second member and the two other second
conductors are in conductive contact with the conductors of the second mem
ber,
- sending a signal to an operational unit through the second conductors and the
conductors of the second member,
- sending a signal from the operational unit through the second conductors and the
conductors of the second member, and
- transferring power to the operational unit.
15. A method for activating the safety device according to any of claims 1-12, the
method comprising the steps of:
- arranging the first member in a first position in which the first conductors are out
of conductive contact with the conductors of the second member, and in which two
of the second conductors are in conductive contact with the conductors of the sec
ond member,
- sending a signal through the second conductors and the conductors to confirm the
first position of the safety device,
- sending a signal back to confirm the first position of the safety device,
- moving the first and second members in relation to each other from the first posi
tion to the second position, in which second position the first conductors are in con
ductive contact with the conductors of the second member and the two other second
conductors are in conductive contact with the conductors of the second mem
ber,
- sending a signal through the second conductors and the conductors to confirm the
second position of the safety device,
- sending a signal back confirming the second position of the safety device, and
- transferring power to the operational unit.