DOWNHOLE PUNCH COMPONENT
Field of the Invention
The present invention relates to a downhole punch or valve for insertion into a
wall of a casing. Furthermore, the invention relates to a downhole tool for
inserting a downhole punch or valve into a wall of a casing, to a downhole system
comprising the downhole tool and a driving unit as well as to a downhole method
for insertion of a downhole punch or valve into a casing downhole.
Background Art
During production, it may be expedient to change the openings through which oil
fluid can enter the casing, thus sealing the existing openings, and create new
openings. However, such operations may be very difficult to perform in muddy
fluid where visibility is low and the casing is narrow.
One type of opening may be a valve to be inserted at another position in the
casing when the oil production zone is sealed off. Thus, there is a need for a
simple solution for inserting new valves in the wall of a casing.
Summary of the Invention
It is an object of the present invention to wholly or partly overcome the above
disadvantages and drawbacks of the prior art. More specifically, it is an object to
provide an improved simple solution for inserting a downhole valve, and thus for
a valve which can easily be inserted into the wall of a casing.
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 punch for
insertion into a wall of a casing, comprising:
- a body having a first end and a second end and a through-bore forming an
inner face of the body and an outer face of the body,
wherein the first end comprises at least one cutting edge at least forming a
leading tip or a leading edge for punching an opening in the casing, and a
component is arranged in the through-bore.
In an embodiment, the component may be a valve, a sensor, an emitter, a
receiver, a probe or a communication device arranged in the through-bore.
By having a valve or a sensor in the through-bore, the punching tool can be
punched into the casing without clearance so that the punching tool is fastened
to the casing, and thus the valve or sensor is fastened in the casing.
Further, the body in cross-section may have a periphery and the cutting edge
may be arranged in the periphery.
Moreover, the valve may be an inflow control valve, a gas lift valve, a throttle or
a pressure control valve.
Also, the sensor may be a temperature sensor, pressure sensor, resistivity
sensor, electromagnetic sensor, acoustic sensor, capacitance sensor, or a density
sensor.
Additionally, the component may be a seismic transceiver or a detonation charge.
The cutting edge may be arranged as an extension of the outer face.
Furthermore, the cutting edge may extend from the inner face to the outer face.
Said cutting edge may have a meander shape.
Also, the body in cross-section may have a circumference and the cutting edge
may extend partly or fully around the circumference.
The present invention further relates to a downhole valve for insertion into a wall
of a casing, comprising:
- a housing having a first end and a second end as well as an inner face and an
outer face,
wherein the first end of the housing comprises at least one cutting edge at least
forming a leading tip or a leading edge for punching an opening in the casing.
In an embodiment, the housing in cross-section may have a periphery and the
cutting edge may be arranged in the periphery.
In one embodiment, the housing may have an inlet at the first end and an outlet
at the second end.
Furthermore, the housing may comprise a valve means for restricting the flow
from the inlet to the outlet.
The valve may have an axial extension and an axial direction from the inlet to the
outlet.
Moreover, the valve means may comprise a diaphragm.
Additionally, the valve means may comprise a spring acting on a piston.
The aforementioned cutting edge may be arranged as an extension of the outer
face.
Also, the cutting edge may extend from the inner face to the outer face.
In addition, the cutting edge may be arranged at an angle in relation to a radial
extension from the inner face to the outer face.
Further, the cutting edge may have a meander shape.
Moreover, the housing in cross-section may have a circumference, and the
cutting edge may extend partly or fully around the circumference.
The wall of the housing may be made of a metal, such as cemented carbide,
tungsten-carbide cobalt, hard metal or widia.
Further, the valve may be an inflow control valve, a gas lift valve, a throttle or a
pressure control valve.
Also, the outer face of the housing may be provided with a thread.
The present invention furthermore relates to a downhole tool for inserting a
downhole valve or the downhole punching device as described above into a wall
of a casing, comprising:
- at least one downhole valve, and
- a moving means for moving the valve to penetrate the wall of the casing.
In one embodiment, the casing may have an axial extension, and the tool may
move the valve so that the axial extension of the valve is transverse to the axial
extension of the casing.
In addition, the downhole tool may further comprise a holder for holding the
valve.
The holder may comprise a contact surface.
Moreover, the moving means may comprise a piston punching the valve through
the casing.
Furthermore, the moving means may screw the valve through the casing.
In addition, the moving means may rotate the valve so that the valve drills itself
through the casing.
The downhole tool may further comprise a magazine comprising several valves to
be inserted into the wall of the casing.
Additionally, the downhole tool may further comprise a stop means for controlling
the moving means so that the valve penetrates the wall of the casing and the
second end face is aligned with an inner face of the wall of the casing.
The present invention furthermore relates to a downhole system comprising the
downhole tool and a driving unit, such as a downhole tractor, for moving the tool
forward in the casing.
Finally, the present invention relates to a downhole method for insertion of a
downhole unit, such as a punch or a downhole valve as described above, into a
casing downhole, comprising the steps of:
- arranging the unit outside a predetermined position in the casing,
- punching a hole in the casing by means of the cutting edge of the unit,
- leaving the unit in the casing.
This method may further comprise the steps of arranging a second unit at the
predetermined position, and pushing the second unit into the hole and replacing
the former unit.
Also, the second unit may have a larger outer diameter than the former 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
illustration show some non-limiting embodiments and in which
Fig. 1 shows a downhole valve,
Fig. 2 shows another embodiment of the valve,
Fig. 3 shows a downhole tool in a casing,
Fig. 4 shows a partly cross-sectional view of part of another embodiment of the
downhole tool,
Fig. 5 shows a partly cross-sectional view of part of yet another embodiment of
the downhole tool,
Fig. 6 shows a partly cross-sectional view of part of yet another embodiment of
the tool,
Fig. 7 shows a downhole punch,
Fig. 8 shows another embodiment of the downhole punch, and
Fig. 9 shows the downhole tool in a casing.
All the 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
Fig. 1 shows a downhole valve 1 for insertion into a wall 2 of a casing 3 in a well
in order to let formation fluid into the casing. The valve 1 comprises a housing 4
having a first end 5 and a second end 6. The housing 4 has a cutting edge 9
arranged at the first end 5 of the housing. The housing 4 comprises an inner face
7 and an outer face 8, and in Fig. 1, the cutting edge 9 is arranged as an
extension of the outer face 8 so that the outer face 8 terminates in the cutting
edge at the first end. The cutting edge 9 has a meander shape when seen from
the side. The cutting edge 9 curves up and down forming at least one leading tip
being three tips enabling the valve 1 to cut itself into the wall 2 of the casing 3
when being punched into the casing wall.
The housing 4 has an inlet at the first end 5 of the housing 4 and an outlet at the
second end 6 of the housing 4. Inside the housing 4, the valve 1 comprises a
valve means 10 providing a valve function and restricting free flow from the inlet
to the outlet in an axial direction of the valve 1.
The valve means 10 comprises a diaphragm, a throttle, a spring acting on a
piston or similar means providing controlled flow restriction in the axial direction
of the valve 1. Thus, the valve 1 may be any kind of valve, such as a flow control
valve, a gas lift valve, a throttle or a pressure controlled valve.
As shown in Fig. 2, the valve 1 has two cutting edges 9 which extend from the
inner face 7 to the outer face 8, and between the cutting edges, a first end face
of the first end 5 of the housing 4 inclines, causing the cutting edges 9 to form a
tip of the housing 4. When the valve is punched into the casing wall 2 by pushing
the valve from a second 38 end face of the second end 6 of the housing 4, the
cutting edges 9 cut through the wall. Each cutting edge 9 extends along the
radius from the inner face 7 to the outer face 8. In another embodiment, the
cutting edge 9 is arranged at an angle in relation to a radial extension from the
inner face 7 to the outer face 8.
When seen in cross-section, as in Fig. 1, the housing 4 has a circumference, and
the cutting edge 9 extends fully around the circumference. In Fig. 2, the cutting
edge 9 forms only part of the circumference.
In order to be able to cut itself into the casing 3 when used as a punch, the
housing wall is made of a metal, such as cemented carbide, tungsten-carbide
cobalt, hard metal or widia.
Fig. 7 shows a downhole punch 101 for insertion into a wall 2 of a casing 3 in a
well in order to let formation fluid into the casing or to sense formation and/or
fluid properties. The downhole punch 101 comprises a body 104 having a
through-bore in which a valve 111 or a sensor 112 is arranged. The body has a
first end 105 and a second end 106, and in the first end the body 104 has a
cutting edge 109. The body 104 comprises an inner face 107 and an outer face
108, and in Fig. 7, the cutting edge 109 is arranged as an extension of the outer
face 108 so that the outer face 108 terminates in the cutting edge at the first
end. Thus, the first end has at least one leading tip 114 being three leading tips
114 in Fig. 7 or a leading edge 115 being two leading edges as shown in Fig. 8
leading in the punching process and thus being the first part of the punch to
contact the casing when the punch is being punched into the casing. The leading
tips form part of the cutting edge 109. The cutting edge 109 has a meander
shape when seen from the side. The cutting edge 109 curves up and down and
forms the three tips enabling the punch 101 to cut itself into the wall 2 of the
casing 3 when being punched into the casing wall.
The body 104 has an inlet at the first end 105 of the body 104 and an outlet at
the second end 106 of the body 104. Inside the body 4, the downhole punch 101
comprises a valve 111 restricting free flow from the inlet to the outlet in an axial
direction of the downhole punch 101. In another embodiment, the body of Fig. 7
comprises a sensor.
The valve comprises a diaphragm, a throttle, a spring acting on a piston or
similar means providing controlled flow restriction in the axial direction of the
valve 1. Thus, the valve 1 may be any kind of valve, such as a flow control valve,
a gas lift valve, a throttle or a pressure controlled valve.
As shown in Fig. 8, the downhole punch 101 has two cutting edges 9 which
extend from the inner face 107 to the outer face 108, and between the cutting
edges, a first end face of the first end 105 of the body 104 inclines, causing the
cutting edges 109 to form a tip of the body 104, the tip being a leading tip or
front tip and being the first part of the punch to contact the casing. When the
downhole punch 101 is punched into the casing wall 2 by pushing the downhole
punch 101 from a second 38 end face of the second end 106 of the body 104, the
cutting edges 109 cut through the wall. Each cutting edge 109 extends along the
radius from the inner face 107 to the outer face 108.
In another embodiment, the cutting edge 109 is arranged at an angle in relation
to a radial extension from the inner face 107 to the outer face 108.
When seen in cross-section, the body 104 has a circumference. The cutting edge
109 of Fig. 7 extends fully around the circumference. In Fig. 8, the cutting edge
109 forms only part of part of the circumference.
The cutting edge 9 may be part of a bit welded or embedded into the first end 5
of the housing 4 or the body 104.
In another embodiment, the outer face 8 of the housing 4 or the body 104 is
provided with a thread, and the valve 1 or the punch 101 is screwed into the wall
2 of the casing 3. Hereby, the valve 1 or the punch 101 is mechanically secured
into the wall of the casing 3 and can withstand direct pressure acting on the first
end 5.
The valve 1 or the punch 101 is inserted in the casing 3 by means of a downhole
tool 100 comprising a moving means 12 for moving the valve 1 or the punch 101
so that it penetrates the wall 2 of the casing 3, as shown in Figs. 3 and 9,
respectively. The moving means 12 provides a movement transverse to the
longitudinal extension of the tool 100 and the axial extension of the casing 3.
As shown in Fig. 4, the moving means 12 comprises a holder 11 for holding the
valve 1 or the punch 101. The moving means 12 furthermore comprises a piston
13 which is activated by a cylinder 14 and which moves the holder 11 holding the
valve 1 or the punch 101 through an opening 15 in the tool 100. The opening 15
is sealed by a blocking plate made of e.g. glass breaking when the moving means
12 punches the valve 1 or the punch 101 into the casing wall 2.
When the moving means 12 moves the valve 1 or the punch 101 towards the
wall 2 of the casing 3, a contact surface of the holder 11 abuts the inner face 39
of the casing 3, providing a backstop and a measure of how far the moving
means 12 has to punch and/or rotate into the casing wall in order for the second
end 6 of the valve 1 to be aligned with the inner face 7 of the casing 3. This
serves to ensure that the valve 1 or the punch 101 does not extend into the
casing 3, thereby decreasing the inner diameter of the casing 3.
In order to move the valve 1 or the punch 101 to penetrate the casing wall 2, the
moving means 12 comprises a piston 13 punching or pushing the valve 1 or the
punch 101 through the casing 3.
As shown in Figs. 5 and 9, the tool 100 comprises two moving means 12 each
moving a valve 1 or the punch 101 to penetrate the casing wall 2. The tool 100
comprises an electrical motor 26 for driving a pump 27 providing hydraulic power
to the moving means 12, enabling the valve 1 to penetrate the casing wall 2. The
moving means 12 may also be driven directly by the motor 26 without the use of
hydraulics.
In another embodiment, the tool 100 comprises a magazine 20 holding several
valves or punches ready to be inserted into the holder 11, as shown in Fig. 6.
When one valve or punch is inserted in a position in the casing 3, the tool 100
moves and the holder 11 is loaded with a second valve or second punch from the
magazine 20, and when the tool reaches a new position, the second valve or
second punch is ready to be inserted into the casing wall 2.
While moving the valve 1 to penetrate the casing wall 2, the moving means 12
may also screw the valve 1 through the casing 3.
In another embodiment, the moving means 12 rotates the valve 1 so that the
valve 1 drills itself through the casing 3.
The holder 11 acts as a stop means for controlling the moving means 12 to
ensure that the valve 1 or punch 101 penetrates the wall 2 of the casing 3 and
the second end face is aligned with an inner face 7 of the wall 2 of the casing 3.
The tool 100 may also have a separate stop means if the holder 11 is not
designed to abut the inner face of the casing 3.
The downhole punch or downhole valve may be replaced by arranging a second
downhole punch or downhole valve at the position of the former punch or valve
which it is to replace, and pushing the second punch or valve into the hole and
replacing the former unit. The second punch or valve may have a slightly larger
outer diameter than the former punch or valve in order that the second punch or
valve can be properly fastened.
In order to fasten the downhole punch or downhole valve, it is designed having
no clearance and will consequently fasten itself by means of friction. The hole
punched in the casing does not have to have an inner diameter as large as the
outer diameter of the punch or valve as the cutting edge merely needs to make a
hole in the casing in order to gain contact with fluid in the annulus surrounding
the casing.
The downhole tool 100 may be connected with a driving unit 22, such as a
downhole tractor, for moving the tool forward in the casing 3. The downhole tool
100 and the driving unit 22 together form a downhole system. The driving unit
comprises four projectable and retractable wheel arms 3 1 each connected with a
wheel 30.
By fluid or well fluid is meant any kind of fluid that may be present in oil or gas
wells downhole, such as natural gas, oil, oil mud, crude oil, water, etc. By gas is
meant any kind of gas composition present in a well, completion, or open hole,
and by oil is meant any kind of oil composition, such as crude oil, an oilcontaining
fluid, etc. Gas, oil, and water fluids may thus all comprise other
elements or substances than gas, oil, and/or water, respectively.
By a casing is meant any kind of pipe, tubing, tubular, liner, string etc. used
downhole in relation to oil or natural gas production.
In the event that the tool is not submergible all the way into the casing 3, a
downhole tractor can be used to push the tool all the way into position in the
well. A downhole tractor is any kind of driving tool capable of pushing or pulling
tools in a well downhole, such as a Well Tractor®.
Although the invention has been described above in connection with preferred
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 punch (1, 100) for insertion into a wall (2) of a casing (3),
comprising:
- a body (104) having a first end (5, 105) and a second end (6, 106) and a
through-bore forming an inner face (7, 107) of the body and an outer face (8,
108) of the body,
wherein the first end comprises at least one cutting edge (9, 109) at least
forming a leading tip (32, 114) or a leading edge (33,115) for punching an
opening in the casing, and a component is arranged in the through-bore.
2. A downhole punch according to claim 1, wherein the component is a valve,
a sensor, an emitter, a receiver, a probe or a communication device arranged in
the through-bore.
3. A downhole punch according to claim 2, wherein the valve is an inflow
control valve, a gas lift valve, a throttle or a pressure control valve.
4. A downhole punch according to claim 2, wherein the sensor is a
temperature sensor, pressure sensor, resistivity sensor, electromagnetic sensor,
acoustic sensor, capacitance sensor or density sensor.
5. A downhole punch according to any of the preceding claims, wherein the
cutting edge is arranged as an extension of the outer face.
6. A downhole punch according to any of the preceding claims, wherein the
cutting edge extends from the inner face to the outer face.
7. A downhole punch according to any of the preceding claims, wherein the
cutting edge has a meander shape.
8. A downhole punch according to any of the preceding claims, wherein the
body in cross-section has a circumference and the cutting edge extends partly or
fully around the circumference.
9. A downhole valve (1) for insertion into a wall (2) of a casing (3),
comprising:
- a housing (4) having a first end (5) and a second end (6) as well as an inner
face (7) and an outer face (8),
wherein the first end of the housing comprises at least one cutting edge (9) at
least forming a leading tip (32) or a leading edge (33) for punching an opening in
the casing.
10. A downhole valve according to claim 9, wherein the cutting edge is
arranged as an extension of the outer face.
11. A downhole valve according to claim 9 or 10, wherein the cutting edge
extends from the inner face to the outer face.
12. A downhole valve according to any of claims 9-11, wherein the cutting edge
has a meander shape.
13. A downhole valve according to any of claims 9-12, wherein the housing in
cross-section has a circumference and the cutting edge extends partly or fully
around the circumference.
14. A downhole valve according to any of claims 9-13, wherein the valve is an
inflow control valve, a gas lift valve, a throttle or a pressure control valve.
15. A downhole tool (100) for inserting a downhole valve according to any of
claims 9-14 or the downhole punching device according to any of claims 1-8 into
a wall of a casing, comprising:
- at least one downhole valve, and
- a moving means (12) for moving the valve to penetrate the wall of the casing.
16. A downhole tool according to any of the preceding claims, further
comprising a holder (11) for holding the valve.
17. A downhole tool according to claim 8, wherein the holder comprises a
contact surface.
18. A downhole tool according to any of claims 7-9, wherein the moving means
(12) comprises a piston (13) punching the valve through the casing.
19. A downhole tool according to any of claims 7-9, wherein the moving means
(12) screws the valve through the casing.
20. A downhole tool according to any of claims 7-9, wherein the moving means
(12) rotates the valve so that the valve drills itself through the casing.
21. A downhole tool according to any of claims 7-12, further comprising a
magazine (20) comprising several valves to be inserted into the wall of the
casing.
22. A downhole tool according to any of the preceding claims, further
comprising a stop means for controlling the moving means (12) so that the valve
penetrates the wall of the casing and a second end face (38) of the second end of
the housing is aligned with an inner face (39) of the wall of the casing.
23. A downhole system comprising the downhole tool according to any of claims
15-22 and a driving unit (22), such as a downhole tractor, for moving the tool
forward in the casing.
24. A downhole method for insertion of a downhole unit, such as a punch
according to any of claims 1-8 or a downhole valve according to any of the claims
9-14 into a casing downhole, comprising the steps of:- arranging the unit outside
a predetermined position in the casing,
- punching a hole in the casing by means of the cutting edge of the unit,
- leaving the unit in the casing.
25. A method according to claim 24, further comprising the steps of arranging a
second unit at the predetermined position, and pushing the second unit into the
hole and replacing the former unit.
26. A method according to claim 25, wherein the second unit has a larger outer
diameter than the former unit.

International application No.
INTERNATIONAL SEARCH REPORT PCT/ EP20 11/07 1039
Box No. II Observations where certain claims were found unsearchable (Continuation of item 2 of first sheet)
This international search report has not been established in respect of certain claims under Article (2)(a) for the following reasons:
□ Claims Nos.:
because they relate to subject matter not required to be searched by this Authority, namely:
□ Claims Nos.:
because they relate to parts of the international application that do not comply with the prescribed requirements to such
an extent that no meaningful international search can be carried out, specifically:
□ Claims Nos.:
because they are dependent claims and are not drafted in accordance with the second and third sentences of Rule 6.4(a).
Box No. Ill Observations where unity of invention is lacking (Continuation of item 3 of first sheet)
This International Searching Authority found multiple inventions in this international application, as follows:
see addi tional sheet
1. 1 As all required additional search fees were timely paid by the applicant, this international search report covers all searchable
' claims.
2. I I As all searchable claims could be searched without effort justifying an additional fees, this Authority did not invite payment of
additional fees.
As only some of the required additional search fees were timely paid by the applicant, this international search report covers
' ' only those claims for which fees were paid, specifically claims Nos. :
I I No required additional search fees were timely paid by the applicant. Consequently, this international search report is
restricted to the invention first mentioned in the claims; it is covered by claims Nos.:
"see addi t i onal sheet(s) "
Remark on Protest The additional search fees were accompanied by the applicant's protest and, where applicable, the
' ' payment of a protest fee.
The additional search fees were accompanied by the applicant's protest but the applicable protest
' ' fee was not paid within the time limit specified in the invitation.
I INo protest accompanied the payment of additional search fees.
Form PCT/ISA/21 0 (continuation of first sheet (2)) (April 2005)
International Application No. PCTV EP2011/ 071039
FURTHER INFORMATION CONTINUED FROM PCT/ISA/ 210
Thi s Internati onal Searchi ng Authori t y found mul t i pl e (groups of)
i nventi ons i n thi s i nternati onal appl i cati on , as fol l ows :
1. cl aims : 1-18, 22-24
1. 1. cl aims : 1-5 , 8-10, 13-15 , 18, 24
A downhol e punch l i ke i n cl aim 1, wherei n (potenti al speci al
techni cal feature of cl aim 4) a sensor i s present for
vari ous measurements .
Techni cal probl em: how t o eval uate the regi on t o whi ch the
puncture provi des access .
1.2. cl aims : 16, 17
A downhol e punch l i ke i n cl aim 2, wherei n (potenti al speci al
techni cal feature of cl aim 16) further compri si ng a hol der
for hol di ng the val ve.
Techni cal probl em: how t o i ntegrate the val ve i n the tool .
1.3. cl aim: 22
A downhol e punch l i ke i n cl aim 2, wherei n (potenti al speci al
techni cal feature of cl aim 22) further compri si ng a stop
means for control l i ng the movi ng means so that the val ve
penetrates the wal l of the casi ng and a second end face of
the second end of the housi ng i s al i gned wi t h an i nner face
of the wal l of the casi ng.
Techni cal probl em: how t o preserve the i nternal through
di ameter of the casi ng.
1.4. cl aim: 23
A system l i ke i n cl aim 15 , wherei n (potenti al speci al
techni cal feature of cl aim 23) a dri vi ng uni t , such as a
downhol e tractor, for movi ng the tool forward i n the casi ng
i s present.
Techni cal probl em: how t o del i ver the punchi ng system at a
speci f i c l ocati on .
2. cl aims : 6, 7, 11 , 12
A downhol e punch l i ke i n cl aim 1, wherei n (potenti al speci al
techni cal feature of cl aim 6 respecti vely 7) the cutti ng
edge extends from the i nner face t o the outer face
respecti vely the cutti ng edge has a meander shape.
Techni cal probl em: how t o improve the punchi ng i ni t i ati on .
3. cl aims : 19 , 20
A downhol e punch l i ke i n cl aim 15 , wherei n (potenti al
International Application No. PCTV EP2011/ 071039
FURTHER INFORMATION CONTINUED FROM PCT/ISA/ 210
speci al techni cal feature of cl aim 19 respecti vely 20) the
movi ng means screws the val ve through the casi ng
respecti vely
the movi ng means rotates the val ve so that the val ve dri l l s
i tsel f through the casi ng.
Techni cal probl em: how t o reduce the punchi ng force.
4. cl aim: 21
A downhol e tool accordi ng t o cl aim 7, wherei n (potenti al
speci al techni cal feature of cl aim 21) further compri si ng a
magazi ne compri si ng several val ves t o be i nserted i nto the
wal l of the casi ng.
Techni cal probl em: how t o reduce the number of tri ps needed
t o compl ete the operati on .
5. cl aims : 25 , 26
A downhol e method accordi ng t o cl aim 24, wherei n (potenti al
speci al techni cal feature of cl aim 25) further compri si ng
the steps of arrangi ng a second uni t at the predetermi ned
posi t i on , and pushi ng the second uni t i nto the hol e and
repl aci ng the former uni t .
Techni cal probl em: how t o adapt the i nterface wi t h the
formati on for successi ve stages of the wel l bore operati ons .