U.S. patent application number 13/896107 was filed with the patent office on 2013-12-05 for pumpable seat assembly and use for well completion.
This patent application is currently assigned to Encana Corporation. The applicant listed for this patent is Encana Corporation. Invention is credited to ARMIN JAHANGIRI, SAM TSCHETTER.
Application Number | 20130319668 13/896107 |
Document ID | / |
Family ID | 49626706 |
Filed Date | 2013-12-05 |
United States Patent
Application |
20130319668 |
Kind Code |
A1 |
TSCHETTER; SAM ; et
al. |
December 5, 2013 |
PUMPABLE SEAT ASSEMBLY AND USE FOR WELL COMPLETION
Abstract
An assembly and process for fracturing, stimulating and
producing a wellbore having a plurality of oil or gas producing
zones is provided comprising introducing into the well the pumpable
seat assembly comprising a generally cylindrical tube having an
outer diameter and an inner diameter with an upper end forming a
ball seat; setting the pumpable seat assembly below an oil or gas
producing zone to be produced; introducing a dissolvable ball into
the well, said dissolvable ball having a sufficiently large enough
outer circumference so that it can sit on the ball seat and
temporarily restrict a flow of fluids to the portion of the
wellbore located below the pumpable seat assembly; and fracturing
the oil and gas producing zone to stimulate oil or gas production;
whereby the biodegradable ball is configured to dissolve within a
predetermined period of time so that when it dissolves any oil or
gas produced from zones below the pumpable seat assembly can flow
through the cylindrical tube.
Inventors: |
TSCHETTER; SAM; (Calgary,
CA) ; JAHANGIRI; ARMIN; (Calgary, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Encana Corporation |
Calgary |
|
CA |
|
|
Assignee: |
Encana Corporation
Calgary
CA
|
Family ID: |
49626706 |
Appl. No.: |
13/896107 |
Filed: |
May 16, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61648415 |
May 17, 2012 |
|
|
|
Current U.S.
Class: |
166/281 ;
166/193 |
Current CPC
Class: |
E21B 43/26 20130101;
E21B 43/261 20130101; E21B 33/12 20130101 |
Class at
Publication: |
166/281 ;
166/193 |
International
Class: |
E21B 43/26 20060101
E21B043/26; E21B 33/12 20060101 E21B033/12 |
Claims
1. A process for fracturing, stimulating and producing a wellbore
having a plurality of oil or gas producing zones, comprising:
introducing into the well a pumpable seat assembly comprising a
generally cylindrical tube having an outer diameter and an inner
diameter with an upper end forming a ball seat; setting the
pumpable seat assembly below an oil or gas producing zone to be
produced; introducing a dissolvable ball into the well, said
dissolvable ball having a sufficiently large enough outer
circumference so that it can sit on the ball seat and temporarily
restrict a flow of fluids to the portion of the wellbore located
below the pumpable seat assembly; and fracturing the oil and gas
producing zone to stimulate oil or gas production; whereby the
biodegradable ball is configured to dissolve within a predetermined
period of time so that when it dissolves any oil or gas produced
from zones below the pumpable seat assembly can flow through the
cylindrical tube.
2. The process as claimed in claim 1, wherein the inner diameter of
the generally cylindrical tube is about 1 inch.
3. The process as claimed in claim 1, wherein the inner diameter of
the generally cylindrical tube is about 2 inches or greater.
4. The process as claimed in claim 1, wherein the inner diameter is
sufficiently large so that oil or gas can freely flow
therethrough.
5. The assembly as claimed in claim 1, wherein the inner diameter
of the generally cylindrical tube is between about 1 inch and 2
inches.
6. The process as claimed in claim 1, further comprising pumping a
second pumpable seat assembly comprising a generally cylindrical
tube having an outer diameter and an inner diameter with an upper
end forming a ball seat, setting the second pumpable seat assembly
below a second oil or gas producing zone to be produced, and
introducing a second dissolvable ball into the well to restrict the
flow from the previously formed oil and gas producing zone.
7. A pumpable seat assembly for temporarily sealing a well casing,
comprising: a generally cylindrical tube having an outer diameter
and an inner diameter with an upper end forming a ball seat; a
upper slip assembly and a lower slip assembly mounted on such
cylindrical tube and adapted to selectively engage the well casing
to anchor the pumpable seat assembly; an elastomeric packing
element mounted on said cylindrical tube between the upper slip
assembly and the lower slip assembly; and a dissolvable ball having
a sufficiently large enough outer circumference so that it can sit
on the ball seat and temporarily restrict a flow of fluids to the
portion of the wellbore located below the pumpable seat
assembly.
8. The assembly as claimed in claim 7, wherein the inner diameter
of the generally cylindrical tube is about 1 inch.
9. The assembly as claimed in claim 7, wherein the inner diameter
of the generally cylindrical tube is about 2 inches or greater.
10. The assembly as claimed in claim 7, wherein the inner diameter
of the generally cylindrical tube is between about 1 inch and two
inches.
11. The process as claimed in claim 7, wherein the inner diameter
is sufficiently large so that oil or gas can freely flow
therethrough.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to the field of
vertical and horizontal well completion, and, more particularly, to
a process for fracturing, stimulating and producing a wellbore
without having to mill out and remove fracturing/bridge plugs and
to a pumpable seat assembly for use with said process.
BACKGROUND OF THE INVENTION
[0002] Oil and gas well are drilled to a depth in order to
intersect a series of formations or zones which produce
hydrocarbons. Often the drilled wells are cased with steel casing
pipe and cemented to secure the casing in place. Hence, it is
necessary to create a flow path from these cased producing zones to
the surface of the wellbore. This is generally accomplished by
stimulation processes such as fracturing using water, various
chemicals and/or proppants. However, the steel and cement barrier
needs to be first perforated with shaped explosive charges prior to
fracturing the surrounding oil or gas reservoir.
[0003] Depending on the number of producing zones in a particular
reservoir, usually several elevation levels and/or lateral
intervals will need to be fractured. Thus, it is common in the
industry to use a temporary well completion plug which is generally
set in the bore of the steel well casing with a setting tool just
below the level or interval where the perforation of the steel and
cement barrier and fracturing occurs. It is understood that these
bridge or "frac plugs" can also be pumped down the well on an
electric wireline, either by itself or in combination with the
perforating gun assemblies. When the barrier is perforated, "frac
fluids" and/or sand are pumped down to the perforations and into
the reservoir to stimulate movement of the oil or gas. Use of the
temporary plug prevents contamination of the already fractured
levels below.
[0004] Interval isolation and fracturing or stimulation can be
performed on both vertical and horizontal wells with multiple
planned intervals, often with multiple intervals and sometimes
greater than 25 intervals per well at varying depths including
sometimes greater than 6000 Meters Below Kelly Bushing (MKB).
Bridge/frac plug technology for interval isolation for frac
stimulation purposes is proven, effective, predictable and
repeatable.
[0005] Unfortunately, once all of the zones have been stimulated,
these temporary plugs may prevent the flow of oil or gas to the
surface. Thus, traditionally, these plugs need to be milled or
drilled out using a drill bit using jointed pipe or coiled tubing.
However, there are operational risks associated with this process
and, further, this is a time consuming and costly procedure.
Furthermore, it has been found that frac plugs having even a
minimal amount of steel are difficult to drill during removal and
can damage the drill bit.
[0006] Coil tubing or jointed pipe intervention to mill out and
remove the plugs on extended reach wells, e.g. lateral length
exceeding 2500 m, is extremely costly, unpredictable and sometimes
impossible due to metal to metal friction encountered sliding in
the casing, creating what is known as coil tubing lock-up. In some
cases, frac plugs that are not reachable due to friction lock up
issues are left in the well (i.e., not milled out) and intervals
left behind these frac plugs are expected to flow through a 3/4
inch hole in the center of the frac plugs. Flow can sometimes be
restricted by the number of frac plugs which were not accessible
for mill-out due to the friction lock encountered. In some cases
operations are exposed to such risks as sticking the coil tubing or
bottom-hole assembly (BHA) in the well, resulting in fishing
operations for pipe recovery. Fishing operations can cost an
operating company millions of dollars depending on difficulty and
risk, in extreme cases wellbore have been lost due to fishing
operations and associated costs.
[0007] Accordingly, there is a need in the art for a well
completion process and plug which will allow the plug to behave
like a frac plug for a temporary period of time and then allow the
flow of gas and or oil from the reservoir up to the well head
without the need for drilling the plug out.
SUMMARY OF THE INVENTION
[0008] The present invention relates generally to a process and
apparatus for multiple interval isolation of a horizontal or
vertical well, where intervention such as drilling out frac plugs
is not necessary for well completions. Generally, a frac plug is
provided, which is a seat and slip assembly that would be
applicable to more than 80% of vertical and horizontal completions
activity within the industry and that can be configured to fit all
casing sizes and casing weights. In one embodiment, the pumpable
seat assembly would be deployed or pumped on electric wireline down
the well by itself or in combination with the perforating guns to a
desired depth within the well. A standard setting tool would set
the pumpable seat assembly in the casing and the wireline would
then log on depth the guns and perforate the interval at desired
depth and pull to surface.
[0009] In one aspect, a dissolvable ball is supplied which would be
dropped by the service provider into the well from surface and then
pumped downhole until the dissolvable ball lands on the pumpable
seat assembly and provides isolation from the previous interval for
frac stimulation purposes. The process can then be repeated a
multiple number of times in the same wellbore using additional
pumpable seat assemblies and dissolvable balls. Once the frac or
stimulation services are completed, the dissolvable ball will
dissolve and the well can be flowed on production, or equipped with
production tubing, all without any wellbore intervention.
[0010] In one aspect, the pumpable seat assembly has an inner
diameter that is greater than about 1 inch. In one embodiment, the
assembly has an inner diameter of about 2 inches and larger. By
having a larger inner diameter than conventional frac plugs, once
the dissolvable ball has dissolved, the flow would not be
restricted.
[0011] In one aspect, the invention comprises a process for
fracturing, stimulating and producing a wellbore having a plurality
of oil or gas producing zones, comprising: [0012] introducing into
the well a pumpable seat assembly comprising a generally
cylindrical tube having an outer diameter and an inner diameter
with an upper end forming a ball seat; [0013] setting the pumpable
seat assembly below an oil or gas producing zone to be produced;
[0014] introducing a dissolvable ball into the well, said
dissolvable ball having a sufficiently large enough outer
circumference so that it can sit on the ball seat and temporarily
restrict a flow of fluids to the portion of the wellbore located
below the pumpable seat assembly; [0015] fracturing the oil and gas
producing zone to stimulate oil or gas production; whereby the
biodegradable ball is configured to dissolve within a predetermined
period of time so that when it dissolves any oil or gas produced
from zones below the pumpable seat assembly can flow through the
cylindrical tube.
[0016] In one embodiment, the inner diameter of the cylindrical
tube is sufficient to allow relatively unrestricted flow of oil or
gas there through. In one embodiment, the inner diameter is greater
than about 1 inch. In one embodiment, the inner diameter is about 2
inches and larger.
[0017] In another aspect, the pumpable seat assembly is provided
for temporarily sealing a well casing, the pumpable seat assembly
comprising: [0018] a generally cylindrical tube having an outer
diameter and an inner diameter with an upper end forming a ball
seat; [0019] a upper slip assembly and a lower slip assembly
mounted on such cylindrical tube and adapted to selectively engage
the well casing to anchor the pumpable seat assembly; [0020] an
elastomeric packing element mounted on said cylindrical tube
between the upper slip assembly and the lower slip assembly; and
[0021] a dissolvable ball having a sufficiently large enough outer
circumference so that it can sit on the ball seat and temporarily
restrict a flow of fluids to the portion of the wellbore located
below the pumpable seat assembly.
[0022] In one embodiment, the inner diameter of the cylindrical
tube is greater than 1/4 inches. In another embodiment, the inner
diameter of the cylindrical tube is greater than 1 inch. In another
embodiment, the inner diameter of the cylindrical tube is greater
than 2 inches. In one embodiment, the cylindrical tube has at least
one flow port located at a lower end of the cylindrical tube.
[0023] Additional aspects and advantages of the present invention
will be apparent in view of the description, which follows. It
should be understood, however, that the detailed description and
the specific examples, while indicating preferred embodiments of
the invention, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the
invention will become apparent to those skilled in the art from
this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The invention will now be described by way of an exemplary
embodiment with reference to the accompanying simplified,
diagrammatic, not-to-scale drawings:
[0025] FIG. 1 is a cross-sectional view of an exemplary embodiment
of the pumpable seat assembly.
[0026] FIG. 2 is a partial cross-sectional perspective of a
plurality of pumpable seat assemblies set within a length of well
casings.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0027] The detailed description set forth below in connection with
the appended drawings is intended as a description of various
embodiments of the present invention and is not intended to
represent the only embodiments contemplated by the inventor. The
detailed description includes specific details for the purpose of
providing a comprehensive understanding of the present invention.
However, it will be apparent to those skilled in the art that the
present invention may be practised without these specific
details.
[0028] The present invention relates generally to a process for
fracturing, stimulating and producing a wellbore without having to
mill out and remove fracturing/bridge plugs and to a pumpable seat
assembly for use therein.
[0029] FIG. 1 shows one embodiment of a pumpable seat assembly (10)
useful in the present invention, which assembly (10) is shown being
set within a wellbore casing (12). Pumpable seat assembly (10)
comprises a generally cylindrical tube (14) having an upper end
(15) and a lower end (17). Situated near the first end (15) of
cylindrical tube (14) is an upper slip assembly (18) and situated
near the lower end (17) of cylindrical tube (14) is a lower slip
assembly (22). Both the upper and lower slip assemblies generally
include a plurality of serrations (23) which engage the casing (12)
and prevent longitudinal movement of the slips (18) and (22) once
set.
[0030] An elastomeric packer element (20) is mounted on the
cylindrical tube (14) between the upper slip ((18) and the lower
slip (22). The packing element (20) is adapted to be deformed into
sealing engagement with the casing (12) upon compression of setting
components (not shown). Although the packing element (60) is shown
and described as being one-piece it is to be understood that a
packing element having multiple members is contemplated under the
present invention. In either case, the packing element (20) is
adapted to provide a fluid-tight seal between the cylindrical tube
(14) and the casing (12).
[0031] The lower end (17) of the cylindrical tube (14) can further
comprise one or more flow ports (24). The flow ports (24)
facilitate the flow of oil or gas from the region below the
pumpable seat assembly (10) through the cylindrical tube (14) to
the wellhead (not shown). The upper end (15) further comprises a
time-dissolvable ball (28), which ball (28) is sized to generally
sit into and cover the seat (16) formed in the upper portion (15)
of the cylindrical tube (14) to prevent the flow of fluids such as
those used for fracturing, stimulating and the like from flowing
through the cylindrical tube (14) to the formation below the
pumpable seat assembly (10). The ball (28), however, is dissolvable
within a predetermined passage of time to then allow the flow of
oil and gas from the formation below to the surface. Thus, the
dissolvable ball (28) functions to temporarily restrict the flow
through the cylindrical tube (14) until it is desirable to do so.
The inner diameter (ID) of the cylindrical tube must be large
enough so that unrestricted flow can occur therethrough. In one
embodiment, the ID is about 2 inches but can be larger, depending
upon the ID of the varying casings and the tools are run in
therein.
[0032] An example of biodegradable balls that may be used in the
present invention is BioBalls soluble ball sealers available from
Santrol of Texas. It is understood that other oil field service
providers can also supply dissolvable products. Generally,
dissolvable balls can include biodegradable balls that can degrade
over a period of hours or days when exposed to a set of
predetermined environmental conditions. For example, the
environmental conditions can include normal wellbore operating
conditions of temperature and pressure at a particular depth or
elevation in the wellbore, as well as the normal chemistry for
drilling mud or pumping/frac fluids used during completion
operations.
[0033] FIG. 2 shows an embodiment of a well completion process of
the present invention using a plurality of pumpable seat assemblies
(10) of the present invention. In FIG. 2, a horizontal portion of a
well is shown which has been cased in with casing (12), such as
steel pipe casing. The casing (12) may be cemented in place in the
well. The horizontal well portion in FIG. 2 comprises five separate
producing zones, zone A, zone B, zone C, zone D and zone E. The end
of the casing (12) is shown as element (130). The first zone to be
fractured/stimulated would be the zone closest to the casing end
(130), namely, zone A. A perforating apparatus (not shown) can be
used to form perforations 132 in the casing (12) and
fracing/stimulating fluids can then be pumped down to complete the
fracing/stimulating process.
[0034] The next producing zone to be
perforated/fractured/stimulated would now be zone B. However, it is
desirable that any fracing/stimulating fluids that are used to
stimulate zone B do not reach zone A in order to prevent
re-stimulating or re-fracturing an already stimulated/fractured
zone/interval. Thus, pumpable seat assembly (10a) is pumped
downhole and set just below zone B but above zone A. Dissolvable
ball (28a) is then pumped down to cover the open seat of pumpable
seat assembly (10a). This will then prevent any (racing/stimulating
fluid from reaching zone A. After zone B is stimulated, the next
zone to be perforated/fractured/stimulated is zone C, using a
second pumpable seat assembly (10b) which is pumped down the
wellbore casing (12) followed by a second dissolvable ball (28b).
After zone C is stimulated, zone D is the next producing zone to be
perforated/fractured/stimulated using pumpable seat assembly (10c)
and dissolvable ball (10c). Finally, pumpable seat assembly (10d)
and dissolvable ball (10d) is used when zone E is
perforated/fractured/stimulated.
[0035] From the foregoing description, one skilled in the art can
easily ascertain the essential characteristics of this invention,
and without departing from the spirit and scope thereof, can make
various changes and modifications of the invention to adapt it to
various usages and conditions. Thus, the present invention is not
intended to be limited to the embodiments shown herein, but is to
be accorded the full scope consistent with the claims, wherein
reference to an element in the singular, such as by use of the
article "a" or "an" is not intended to mean "one and only one"
unless specifically so stated, but rather "one or more". All
structural and functional equivalents to the elements of the
various embodiments described throughout the disclosure that are
known or later come to be known to those of ordinary skill in the
art are intended to be encompassed by the elements of the claims.
Moreover, nothing disclosed herein is intended to be dedicated to
the public regardless of whether such disclosure is explicitly
recited in the claims.
* * * * *