U.S. patent application number 12/476859 was filed with the patent office on 2010-12-02 for permeability flow balancing within integral screen joints.
This patent application is currently assigned to BAKER HUGHES INCORPORATED. Invention is credited to MICHAEL H. JOHNSON, NAMHYO KIM.
Application Number | 20100300675 12/476859 |
Document ID | / |
Family ID | 43218901 |
Filed Date | 2010-12-02 |
United States Patent
Application |
20100300675 |
Kind Code |
A1 |
JOHNSON; MICHAEL H. ; et
al. |
December 2, 2010 |
PERMEABILITY FLOW BALANCING WITHIN INTEGRAL SCREEN JOINTS
Abstract
A thermally assisted downhole system including a tubular
configured to be disposed within an open hole borehole, the tubular
being intended to be exposed to a heated fluid; a plurality of open
hole anchors spaced along the tubular and engagable with the open
hole, the anchors restricting longitudinal thermal growth of the
tubular when engaged with the open hole.
Inventors: |
JOHNSON; MICHAEL H.; (KATY,
TX) ; KIM; NAMHYO; (HOUSTON, TX) |
Correspondence
Address: |
CANTOR COLBURN LLP
20 Church Street, 22nd Floor
Hartford
CT
06103
US
|
Assignee: |
BAKER HUGHES INCORPORATED
HOUSTON
TX
|
Family ID: |
43218901 |
Appl. No.: |
12/476859 |
Filed: |
June 2, 2009 |
Current U.S.
Class: |
166/57 |
Current CPC
Class: |
E21B 43/2406
20130101 |
Class at
Publication: |
166/57 |
International
Class: |
E21B 43/24 20060101
E21B043/24; E21B 36/00 20060101 E21B036/00 |
Claims
1. A thermally assisted downhole system comprising: a tubular
configured to be disposed within an open hole borehole, the tubular
being intended to be exposed to a heated fluid; and a plurality of
open hole anchors spaced along the tubular and engagable with the
open hole, the anchors restricting longitudinal thermal growth of
the tubular when engaged with the open hole.
2. A thermally assisted downhole system as claimed in claim 1
further including one or more baffles disposed along the
longitudinal extent of the tubular, the baffles being of sufficient
size and thermal resistance to withstand and divert applied heated
fluid.
3. A thermally assisted downhole system as claimed in claim 1
wherein the plurality of open hole anchors are spaced evenly.
4. A thermally assisted downhole system as claimed in claim 1
wherein the open hole anchors are spaced unevenly.
5. A thermally assisted downhole system as claimed in claim 1
wherein the space between each of the plurality of open hole
anchors is selected to prevent movement of a liner relative to the
wellbore during temperature or pressure changes.
6. A thermally assisted downhole system as claimed in claim 1
further including one or more baffles disposed along the
longitudinal extent of the tubular, the baffles being of sufficient
size and thermal resistance to withstand and divert applied heated
fluid.
7. A thermally assisted downhole system as claimed in claim 1
wherein the one or more baffles are a plurality of baffles spaced
evenly along the tubular.
8. A thermally assisted downhole system as claimed in claim 1
wherein the one or more baffles are a plurality of baffles spaced
unevenly along the tubular.
9. A thermally assisted downhole system as claimed in claim 1
wherein the one or more baffles are a plurality of baffles spaced
as dictated by formation condition.
10. A thermally assisted downhole system comprising: a tubular
within an open hole borehole, the tubular being exposed to a heated
fluid; and a plurality of open hole anchors spaced along the
tubular and engaged with the open hole, the anchors restricting
longitudinal thermal growth of the tubular.
11. A thermally assisted downhole system as claimed in claim 10
further including one or more baffles disposed along the
longitudinal extent of the tubular, the baffles being of sufficient
size and thermal resistance to withstand and divert applied heated
fluid.
12. A thermally assisted downhole system as claimed in claim 2
wherein the thermally assisted downhole system is a SAGD system.
Description
BACKGROUND
[0001] Viscous hydrocarbon recovery is a segment of the overall
hydrocarbon recovery industry that is increasingly important from
the standpoint of global hydrocarbon reserves and associated
product cost. In view hereof, there is increasing pressure to
develop new technologies capable of producing viscous reserves
economically and efficiently. Steam Assisted Gravity Drainage
(SAGD) is one technology that is being used and explored with good
results in some wellbore systems. Other wellbore systems however
where there is a significant horizontal or near horizontal length
of the wellbore system present profile challenges both for heat
distribution and for production. In some cases, similar issues
arise even in vertical systems.
[0002] Both inflow and outflow profiles (e.g. production and
stimulation) are desired to be as uniform as possible relative to
the particular borehole. This should enhance efficiency as well as
avoid early water breakthrough. Breakthrough is clearly inefficient
as hydrocarbon material is likely to be left in situ rather than
being produced. Profiles are important in all well types but it
will be understood that the more viscous the target material the
greater the difficulty in maintaining a uniform profile.
[0003] Another issue in conjunction with SAGD systems is that the
heat of steam injected to facilitate hydrocarbon recovery is
sufficient to damage downhole components due to thermal expansion
of the components. This can increase expenses to operators and
reduce recovery of target fluids. Since viscous hydrocarbon
reserves are likely to become only more important as other
resources become depleted, configurations and methods that improve
recovery of viscous hydrocarbons from earth formations will
continue to be well received by the art.
SUMMARY
[0004] A thermally assisted downhole system including a tubular
configured to be disposed within an open hole borehole, the tubular
being intended to be exposed to a heated fluid; and a plurality of
open hole anchors spaced along the tubular and engagable with the
open hole, the anchors restricting longitudinal thermal growth of
the tubular when engaged with the open hole.
[0005] A thermally assisted downhole system including a tubular
within an open hole borehole, the tubular being exposed to a heated
fluid; and a plurality of open hole anchors spaced along the
tubular and engaged with the open hole, the anchors restricting
longitudinal thermal growth of the tubular.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Referring now to the drawings wherein like elements are
numbered alike in the several figures:
[0007] FIG. 1 is a schematic view of a wellbore system in a viscous
hydrocarbon reservoir;
[0008] FIG. 2 is a chart illustrating a change in fluid profile
over a length of the borehole with and without permeability
control.
DETAILED DESCRIPTION
[0009] Referring to FIG. 1, the reader will recognize a schematic
illustration of a portion of a SAGD wellbore system 10 configured
with a pair of boreholes 12 and 14. Generally, borehole 12 is the
steam injection borehole and borehole 14 is the hydrocarbon
recovery borehole but the disclosure should not be understood as
limiting the possibilities to such. The discussion herein however
will address the boreholes as illustrated. Steam injected in
borehole 12 heats the surrounding formation 16 thereby reducing the
viscosity of the stored hydrocarbons and facilitating gravity
drainage of those hydrocarbons. Horizontal or other highly deviated
well structures like those depicted tend to have greater fluid
movement into and to of the formation at a heel 18 of the borehole
than at a toe 20 of the borehole due simply to fluid dynamics. An
issue associated with this property is that the toe 20 will suffer
reduced steam application from that desired while heel 18 will
experience more steam application than that desired, for example.
The change in the rate of fluid movement is relatively linear
(declining flow) when querying the system at intervals with
increasing distance from the heel 18 toward the toe 20. The same is
true for production fluid movement whereby the heel 28 of the
production borehole 14 will pass more of the target hydrocarbon
fluid than the toe 30 of the production borehole 14. This is due
primarily to permeability versus pressure drop along the length of
the borehole 12 or 14. The system 10 as illustrated alleviates this
issue as well as others noted above.
[0010] According to the teaching herein, one or more of the
boreholes (represented by just two boreholes 12 and 14 for
simplicity in illustration) is configured with one or more
permeability control devices 32 that are each configured
differently with respect to permeability or pressure drop in flow
direction in or out of the tubular. The devices 32 nearest the heel
18 or 28 will have the least permeability while permeability will
increase in each device 32 sequentially toward the toe 20 and 30.
The permeability of the device 32 closest to toe 20 or 30 will be
the greatest. This will tend to balance outflow of injected fluid
and inflow of production fluid over the length of the borehole 12
and 14 because the natural pressure drop of the system is opposite
that created by the configuration of permeability devices as
described. Permeability and/or pressure drop devices 32 usable in
this configuration include inflow control devices such as product
family number H48688 commercially available from Baker Oil Tools,
Houston Tex., beaded matrix flow control configurations such as
those disclosed in U.S. Ser. Nos. 61/052,919, 11/875,584 and
12/144,730, 12/144,406 and 12/171,707 the disclosures of which are
incorporated herein by reference, or other similar devices.
Adjustment of pressure drop across individual permeability devices
is possible in accordance with the teaching hereof such that the
desired permeability over the length of the borehole 12 or 14 as
described herein is achievable. Referring to FIG. 2, a chart of the
flow of fluid over the length of borehole 12 is shown without
permeability control and with permeability control. The
representation is stark with regard to the profile improvement with
permeability control.
[0011] In order to determine the appropriate amount of permeability
for particular sections of the borehole 12 or 14, one needs to
determine the pressure in the formation over the length of the
horizontal borehole. Formation pressure can be determined/measured
in a number of known ways. Pressure at the heel of the borehole and
pressure at the toe should also be determined/measured. This can be
determined in known ways. Once both formation pressure and
pressures at locations within the borehole have been ascertained,
the change in pressure (.DELTA.P) across the completion can be
determined for each location where pressure within the completion
has been or is tested. Mathematically this is expressed as .DELTA.P
location=P formation-P location where the locations may be the
heel, the toe or any other point of interest.
[0012] A flow profile whether into or out of the completion is
dictated by the .DELTA.P at each location and the pressure inside
the completion is dictated by the head of pressure associated with
the column of fluid extending to the surface. The longer the
column, the higher the pressure. It follows, then, that greater
resistance to inflow will occur at the toe of the borehole than at
the heel of the completion. In accordance with the teaching hereof
permeability control is distributed such that pressure drop at a
toe of the borehole is in the range of about 25% to less than 1%
whereas pressure drop at the heel of the borehole is about 30% or
more. In one embodiment the pressure drop at the heel is less than
45% and at the toe less than about 25%. Permeability control
devices distributed between the heel and the toe will in some
embodiments have individual pressure drop values between the
percentage pressure drop at the toe and the percentage pressure
drop at the heel. Moreover, in some embodiments the distribution of
pressure drops among the permeability devices is linear while in
other embodiments the distribution may follow a curve or may be
discontinuous to promote inflow of fluid from areas of the
formation having larger volumes of desirable liberatable fluid and
reduced inflow of fluid from areas of the formation having smaller
volumes of desirable liberatable fluid.
[0013] Referring back to FIG. 1, a tubing string 40 and 50 are
illustrated in boreholes 12 and 14 respectively. Open hole anchors
42, such as Baker Oil Tools WBAnchor.TM. may be employed in the
borehole to anchor the tubing 40. This is helpful in that the
tubing 40 experiences a significant change in thermal load and
hence a significant amount of thermal expansion during well
operations. Unchecked, the thermal expansion can cause damage to
other downhole structures or to the tubing string 40 itself thereby
affecting efficiency and production of the well system. In order to
overcome this problem, one or more open hole anchors 42 are used to
ensure that the tubing string 40 is restrained from excessive
movement. Because the total length of mobile tubing string is
reduced by the interposition of open hole anchor(s) 42, excess
extension cannot occur. In one embodiment, three open hole anchors
42, as illustrated, are employed and are spaced by about 90 to 120
ft from one another but could in some particular applications be
positioned more closely and even every 30 feet (at each pipe
joint). The spacing interval is also applicable to longer runs with
each open hole anchor being spaced about 90-120 ft from the next.
Moreover, the exact spacing amount between anchors is not limited
to that noted in this illustrated embodiment but rather can be any
distance that will have the desired effect of reducing thermal
expansion related wellbore damage. In addition the spacing can be
even or uneven as desired. The determination of distance between
anchors must take into account. The anchor length, pattern, or the
number of anchor points per foot in order to adjust the anchoring
effect to optimize performance based on formation type and
formation strength tubular dimensions and material.
[0014] Finally in one embodiment, the tubing string 40, 50 or both
is configured with one or more baffles 60. Baffles 60 are effective
in both deterring loss of steam to formation cracks such as that
illustrated in FIG. 1 as numeral 62 and in causing produced fluid
to migrate through the intended permeability device 32. More
specifically, and taking the functions one at a time, the injector
borehole, such as 12, is provided with one or more baffles 60. The
baffles may be of any material having the ability to withstand the
temperature at which the particular steam is injected into the
formation. In one embodiment, a metal deformable seal such as one
commercially known as a z-seal and available from Baker Oil Tools,
Houston Tex., may be employed. And while metal deformable seals are
normally intended to create a high pressure high temperature seal
against a metal casing within which the seal is deployed, for the
purposes taught in this disclosure, it is not necessary for the
metal deformable seal to create an actual seal. That stated
however, there is also no prohibition to the creation of a seal but
rather then focus is upon the ability of the configuration to
direct steam flow with relatively minimal leakage. In the event
that an actual seal is created with the open hole formation, the
intent to minimize leakage will of course be met. In the event that
a seal is not created but substantially all of the steam applied to
a particular region of the wellbore is delivered to that portion of
the formation then the baffle will have done its job and achieved
this portion of the intent of this disclosure. With respect to
production, the baffles are also of use in that the drawdown of
individual portions of the well can be balanced better with the
baffles so that fluids from a particular area are delivered to the
borehole in that area and fluids from other areas do not migrate in
the annulus to the same section of the borehole but rather will
enter at their respective locations. This ensures that profile
control is maintained and also that where breakthrough does occur,
a particular section of the borehole can be bridged and the rest
will still produce target fluid as opposed to breakthrough fluid
since annular flow will be inhibited by the baffles. In one
embodiment baffles are placed about 100 ft or 3 liner joints apart
but as noted with respect to the open hole anchors, this distance
is not fixed but may be varied to fit the particular needs of the
well at issue. The distance between baffles may be even or may be
uneven and in some cases the baffles will be distributed as
dictated by formation condition such that for example cracks in the
formation will be taken into account so that a baffle will be
positioned on each side of the crack when considered along the
length of the tubular.
[0015] While preferred embodiments have been shown and described,
various modifications and substitutions may be made thereto without
departing from the spirit and scope of the invention. Accordingly,
it is to be understood that the present invention has been
described by way of illustration and not limitation.
* * * * *