Note: Descriptions are shown in the official language in which they were submitted.
CA 02706712 2010-05-25
WO 2009/066097 PCT/GB2008/051035
COMPLETION ARRANGEMENT
The present invention relates to a completion arrangement and
particularly, to a completion arrangement for a hydrocarbon (e.g. oil or
gas) and/or an injection (e.g. water or gas) well.
When an oil/gas well is drilled, extraction equipment is inserted into an
oil/gas reservoir from which oil/gas will be produced to the surface. A bore
is drilled into the oil/gas reservoir and production tubing is introduced into
the bore. The oil/gas well has then to be "completed", which entails
running a completion section into the well to enable extraction of
hydrocarbons from the reservoir for transfer to the surface via the
production tubing. It is generally desired that the completion section is
ideally located at, or extends into, the bottom (or total depth) of the well.
A number of "completion" devices exist, for example, "openhole
completions", i.e. where a packer is provided on tubing above an
"openhole" (an openhole being an uncased portion of a well bore), or
"inflow control devices", i.e. a tubing section provided with devices to
control flow of fluid from the reservoir to the interior of the tubing section
in
a producing well and control flow of fluid from the tubing section to the
reservoir in an injection well.
In current completion techniques, when the completion is "run-in" to the
well, it is the weight of the completion string that urges the completion to
the end of the well.
However, such techniques are problematic in that the completion may get
stuck due to entrained rock and debris accumulated at the head of the
completion. Additionally, there may be "burrs" in the openhole section of
the well caused by the drilling process, and the completion may also
become stuck when it encounters these "burrs".
1
CA 02706712 2010-05-25
WO 2009/066097 PCT/GB2008/051035
Under the current techniques, if the completion becomes stuck as
described above, then remedial actions (such as "jarring" the completion
string) are taken to free the completion in an attempt to insert the
completion section further into the well bore. Unfortunately, these remedial
actions are not always successful, which leads to the well being completed
as is or side-tracked. The problem of the completion becoming stuck is a
particular problem in long horizontal wells.
WO 2008/043985 describes drilling a lower completion into a pre-drilled
wellbore with casing liner. A casing liner is a tubular section that
conventionally is `pushed' into the pre-drilled hole to total depth. Once to
total depth, the casing liner is cemented into place by pumping cement into
the space between the reservoir rock and the casing liner (tubular section).
The cement is required for structural integrity and to hold the casing liner
in
place. In order for hydrocarbons to reach the production tubing to flow to
the surface, it is necessary that the casing liner be perforated using
perforating charges to connect the production tubing space to the reservoir
rock.
The present invention seeks to provide for a completion arrangement
having advantages over known such completions.
According to an aspect of the present invention, there is provided a
completion arrangement for a hydrocarbon well bore comprising: a
completion section arranged to be coupled to production tubing, and
having means to allow hydrocarbons to pass therein from reservoir rock in
which the well bore is formed, said means also arranged to serve as
flushing portals, whereby drilling fluid introduced into said production
tubing is arranged to flow via said means into a space between said
production tubing and said well bore and circulate in said space; the said
arrangement further including impacting formations, drivingly moveable
relative to the well bore, wherein one, or both, of said drilling fluid
circulating in said space and said impacting formations are arranged to
remove obstructing material and formations from the well bore, for return
2
CA 02706712 2010-05-25
WO 2009/066097 PCT/GB2008/051035
to surface by way of said space, during insertion of the completion
arrangement into the well bore.
An advantage of the present invention is that debris around the completion
arrangement during an insertion process can be removed by: (i) flushing
drilling fluid through said means which, during production, are arranged to
allow hydrocarbons to pass into the production tubing from reservoir rock
in which the well bore is formed, but which, during the insertion process,
allow drilling fluid to enter a space around the production tubing; and (ii)
driving the impacting formations. Thus, with the above two features, the
completion section is less likely to become stuck when being "run-in" to the
well.
In this particular invention the lower completion can be set into the
openhole section without cementing. Once the well is put into production,
the hydrocarbon from the reservoir rock is drawn into the space created by
the openhole packers. The hydrocarbon then flows from the space,
through nozzles in the flow restrictors into the production tubing and then
on to the surface. If this particular arrangement was to be cemented, then
connection between the production tubing and the reservoir will be
required via perforating charges. However, in the present invention,
cementing is not required and the stability of the openhole section is
maintained by the strength of the reservoir rock.
As mentioned, cementing is not required for this invention since the type of
lower completion serves a different purpose - this is an openhole
completion with openhole packers and flow restrictors.
The invention is further advantageous in that it enhances completion
deployment and allows longer completions to be run, thereby providing
completion capabilities for extended reach applications.
The impacting formations are operable to crush, cut, abrade, scrape,
pound or grind material and formations in the well bore.
3
CA 02706712 2010-05-25
WO 2009/066097 PCT/GB2008/051035
Also, said means to allow hydrocarbons to pass therein from reservoir rock
in which the well bore is formed may comprise flow restrictors having at
least one nozzle.
Preferably, said impacting formations comprise a drill bit or ream-in shoe.
Conveniently, said impacting formations are operable by rotating said
production tubing, to which said impacting formations are coupled via said
completion section.
If required, the completion arrangement further comprises a motor coupled
between said completion section and said impacting formations and
arranged to control operation of said impacting formations.
Further, said motor comprises a mud motor operable by means of drilling
fluid supplied thereto through said production tubing and completion
section.
Preferably, said drilling fluid further serves to lubricate said impacting
formations.
According to another aspect of the present invention, there is provided
production tubing for a hydrocarbon well, comprising a completion
arrangement as described above.
According to a further aspect of the present invention, there is provided a
method of completing a hydrocarbon well bore, comprising the steps of: (i)
inserting a completion arrangement into said well bore, the completion
arrangement comprising a completion section having means for allowing
hydrocarbons to pass therein from reservoir rock in which the well bore is
formed and impacting formations, and the said means also arranged to
serve as flushing portals whereby drilling fluid introduced into completion
section via production tubing is arranged to flow via said means into a
space between said completion arrangement and said well bore and
4
CA 02706712 2010-05-25
WO 2009/066097 PCT/GB2008/051035
circulate in said space ; and (ii) introducing drilling fluid into said
completion arrangement for flow via said means into said space and/or
driving said impacting formations so as to move relative to the well bore to
remove obstructing material and formations from the well bore during
insertion of the completion arrangement into the well bore.
Preferably, said driving step comprises rotating said production tubing to
drive said impacting formations.
If required, the method further comprises the step of: locating, between
said completion section and said impacting formations, a motor; and
wherein said driving step comprises activating said motor by means of fluid
pumped to said motor via production tubing coupled to said completion
section such that said motor can operate said impacting formations.
The present invention is described further hereinafter, by way of example
only, with reference to the accompanying drawings in which:
Fig. 1 illustrates a cross-sectional side view of an oil/gas well or an
injection well;
Fig. 2 illustrates a cross-sectional side view of the well of Fig. 1 into
which
the present invention is being introduced;
Fig. 3 illustrates a cross-section side view of the well of Fig. 1 with the
present invention located partially along the well length;
Fig. 4 illustrates a cross-section side view of the well of Fig. 1 with a
particular arrangement of the present invention located partially along the
well length;
Fig. 5 illustrates a cross-section side view of the well of Fig. 1 with the
present invention located at total depth; and
5
CA 02706712 2010-05-25
WO 2009/066097 PCT/GB2008/051035
Fig. 6 illustrates a cross-section side view of the well of Fig. 1 with an
alternative arrangement of the present invention being introduced to the
well.
As mentioned, Fig. 1 illustrates an oil/gas well or injection well 10. The
well
comprises a well bore 12 which extends from the surface 14 to oil/gas
bearing rock 16. Part of the well bore 12 is lined with a production casing
18 to support the walls of the well bore 12 and prevent collapse of the well
bore 12. The part of the well bore 12 which extends into the oil/gas bearing
10 rock 16 comprises a so-called openhole section 20 which is not lined with
production casing.
Fig. 2 illustrates the same oil/gas well 10, but with extraction equipment
partially introduced into the well in a "running-in" process, i.e. the process
whereby extraction equipment is delivered to the oil/gas producing region
of the well. This equipment comprises production tubing 22 which is
located within the production casing 18 and which is formed of a series of
tubing sections connected together by means of couplers 24 arranged to
couple adjacent sections of tubing sections together. The extraction
equipment further comprises a completion section 26 coupled to an end of
the production tubing 22 and which is arranged, upon well completion, to
reside in the portion of the well bore 18 (i.e. the openhole section 20)
extending into the oil/gas bearing rock 16. The completion section 26 is
arranged such that fluid can permeate from the surrounding oil/gas bearing
rock into an interior section of the completion section 26 such that the fluid
can be transferred to the surface 14 via the production tubing 22. Vice
versa for an injection well: the injected fluid is pumped from surface into
the production tubing 22 and permeates through the completion section 26
into the reservoir rock 16.
In addition to the production tubing 22 and the completion section 26, the
illustrated embodiment of the completion arrangement of the invention
includes a drill bit 28 coupled to an end of the completion section 26
remote from the end coupled to the production tubing 22. The drill bit 28 is
6
CA 02706712 2010-05-25
WO 2009/066097 PCT/GB2008/051035
located at the "front" face of the completion section 26, i.e. the face of the
completion section 26 which is foremost with respect to its direction of
travel into the openhole section 20.
Fig. 3 illustrates the same oil/gas well 10 as Figs. 1 and 2. The features
illustrated in Fig. 3 which correspond to features already described in
relation to Figs. 1 and 2 are denoted by like reference numerals.
The illustration of Fig. 3 differs from that of Fig. 2 in that the production
tubing 22 extends further into the well bore 12. In Fig. 2, the completion
section 26 and drill bit 28 are located within the production casing 18 of the
lined section of the well bore 12. However, in Fig. 3, the completion section
26 and drill bit 28 have been inserted further so as to extend into the
openhole section 20 of the well bore 12.
The completion section 26 preferably comprises a number of different
combinations of extraction devices, valves, sensors, measurements,
mechanical and swellable packers etc. In a particular arrangement as
illustrated in Fig. 4, which shows a detailed view of the completion section
26 to illustrate the features thereof, the completion section 26 is made up
of openhole swellable packers 200 (for openhole compartmentalisation)
and Inflow Control devices ("flow restrictors" 202) which serve two
purposes: (i) during the "running in" procedure, drilling fluid 204 is pumped
from surface down to the drill bit 28 (or ream-in shoe) to circulate and
lubricate the completion section 26 during deployment; and (ii) during a
production phase, hydrocarbons can enter the completion section 26 from
reservoir rock surrounding the completion section 26, via the flow
restrictors 202 and pass therefrom to the surface via production tubing 22
attached to the completion section 26. Since the flow restrictor 202 is
-10 formed with a plurality of nozzles 206 arranged to allow drilling fluid
204 to
be injected through the production tubing 22 into a space 208 (which may
be annular) around production tubing 22, this aids in a lubricating process
to ease the passage of the completion section 26 into the well bore.
Should the lubrication process fail, or be inadequate to remove debris, etc.
7
CA 02706712 2010-05-25
WO 2009/066097 PCT/GB2008/051035
and the completion section 26 becomes stuck, the completion section 26
can be rotated by means of surface control (or by a downhole mud motor -
see Fig. 5 and the description relating thereto). However the rotational
capability is secondary to the fact that drilling fluid is being flushed
across
the entire completion section 26, rather than merely at the drill bit 28. By
efficiently flushing and lubricating across the entire lower completion, this
may reduce the need to rotate the drill bit 28. Debris is carried along the
space 208 to surface and since the flow restrictors 200 are passing fluid
from the production tubing 22 into the space 208, this aids in the flushing
process.
The illustrations of Figs. 2, 3 and 4 are merely schematic "snapshots" of
the process of introducing extraction equipment into the well, and the
progress of the extraction equipment on its route to the position as
illustrated in Fig. 5.
Turning now to Fig. 5 in detail, there is illustrated the same oil/gas well 10
as in Figs. 1 to 4. Again, features corresponding to those already
described are denoted by like reference numerals.
Here, the completion section 26 and drill bit 28 have reached total depth,
i.e. the maximum extent to which the bore has previously been drilled.
Once the completion section 26 and drill bit 28 have reached the total
depth, the well 10 is effectively "complete" and an oil/gas extraction
process can commence without limitation that might occur due to
incomplete insertion of the production tubing and completion section,
The lubrication process has been described above. Now the operation of
the drill bit 28 found in the illustrated embodiments of the invention will
now
be described in more detail.
As described above, in conventional processes where an oil/gas well is
"completed", the extraction equipment (including a completion section) is
introduced into the well bore, and it is the weight of the completion section
8
CA 02706712 2010-05-25
WO 2009/066097 PCT/GB2008/051035
and production tubing that urges the completion towards the end of the
well (i.e. total depth) and pulls the production tubing behind it. However,
and as mentioned above, the presence of "burrs" on the walls of the
openhole section of the well which were introduced by the drilling process,
or the accumulation of debris in front of the completion section, may cause
the completion section to become stuck. Remedial actions (e.g. "jarring")
are possible which can free the completion section for further insertion into
the well bore, but these are not always effective and the well may therefore
have to be completed without the completion section reaching total depth.
By providing a drill bit 28 at the head of the completion section 26, this
allows the completion section 26 to be drilled, or rather reamed into
position in the well bore should the lubrication process fail at some point to
ease passage of the completion section into the well. Thus, in the
illustrations of Figs. 3 to 5 where the completion section 26 and drill bit 28
are in the openhole section 20 of the well bore 12, the drill bit can be
operated to, for example, remove "burrs" from the walls of the openhole
section 20 and/or to remove debris from in front of the combined
drill/completion section for transfer to, and removal at, the surface 14. As
noted above, such process is secondary to the main process of providing
lubrication by way of drilling fluid 204 passing through nozzles 26 of the
flow restrictors 200. Thus, these features aid in the flushing process to
carry debris to surface and to efficiently lubricate the space during
deployment.
In a preferable arrangement, the drill bit 28 is rotated by rotating the
production tubing 22 at the surface 14 when the drill bit 28 has reached a
pre-detemined depth (e.g. when it has entered the openhole section 20).
By activating the drill bit, the openhole section 20 is drilled/reamed and
this
allows the completion section 26 to reach total depth without becoming
stuck.
Another arrangement of the present invention is illustrated in Fig. 6. The
same well 10 as illustrated in the previous figures is shown and reference
9
CA 02706712 2010-05-25
WO 2009/066097 PCT/GB2008/051035
numerals for like features remain the same. However, in the arrangement
of Fig. 6, a motor (preferably a mud motor 30 as illustrated) is provided
between the completion section 26 and drill bit 28.
The mud motor 30 is arranged to drive and control operation of the drill bit
28 and eliminates the requirement to rotate the production tubing 22 at
surface 14 to operate the drill bit 28.
It should be appreciated that the drill bit 28 and /or the motor 30 is
intended to remain in place once its final depth has been reached.
The mud motor 30 operates by means of fluid pumped from the surface
through the production tubing 22 (denoted by arrows A). This fluid
activates the mud motor 30 which, in turn, operates the drill bit 28. The
drill
bit 28 preferably comprises a number of nozzles 32 to allow the drilling
fluid to exit a face of the drill bit 28. After the drilling fluid has exited
through the nozzles 32, and through nozzles 206 in the flow restrictor 200,
it can lubricate the drill bit 28 and carry the debris from the face of the
drill
bit 28 back through the space between the production tubing 22 and the
walls of the openhoie section 20 and between the production tubing 22
and the production casing 28 to the surface 14 (this is indicated by arrows
B).
Advantages of the present invention have been described above although
the present invention is particularly advantageous when used in the
completion of horizontal wells.
