U.S. patent application number 12/747553 was filed with the patent office on 2011-02-03 for device and method to reduce breakdown/fracture initiation pressure.
This patent application is currently assigned to SCHLUMBERGER TECHNOLOGY CORPORATION. Invention is credited to Jerry D. Campbell, Jorge E. Lopez De Cardenas, Desmond E. Rees, Jason Swaren.
Application Number | 20110024117 12/747553 |
Document ID | / |
Family ID | 40756140 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110024117 |
Kind Code |
A1 |
Lopez De Cardenas; Jorge E. ;
et al. |
February 3, 2011 |
DEVICE AND METHOD TO REDUCE BREAKDOWN/FRACTURE INITIATION
PRESSURE
Abstract
A slim perforating gun includes a plurality of shape charges; a
positioning device that orients the perforating gun in relation to
a down direction of a deviated well; the shaped charges being
positioned inside the perforating gun and aimed in predetermined
directions with respect to the down direction of the deviated well;
wherein a ratio of the outer diameter of the slim perforating gun
to the inner diameter of a casing used in connection with the slim
perforating gun is from 0.85 to 0.30.
Inventors: |
Lopez De Cardenas; Jorge E.;
(Sugar Land, TX) ; Swaren; Jason; (Sugar Land,
TX) ; Rees; Desmond E.; (Tyler, TX) ;
Campbell; Jerry D.; (Katy, TX) |
Correspondence
Address: |
SCHLUMBERGER RESERVOIR COMPLETIONS
14910 AIRLINE ROAD, Bldg. 14
ROSHARON
TX
77583
US
|
Assignee: |
SCHLUMBERGER TECHNOLOGY
CORPORATION
SUGAR LAND
TX
|
Family ID: |
40756140 |
Appl. No.: |
12/747553 |
Filed: |
December 12, 2008 |
PCT Filed: |
December 12, 2008 |
PCT NO: |
PCT/US08/86679 |
371 Date: |
October 19, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61012941 |
Dec 12, 2007 |
|
|
|
Current U.S.
Class: |
166/298 ;
166/55.2 |
Current CPC
Class: |
E21B 43/26 20130101;
E21B 43/117 20130101; E21B 43/119 20130101 |
Class at
Publication: |
166/298 ;
166/55.2 |
International
Class: |
E21B 43/11 20060101
E21B043/11 |
Claims
1. A slim perforating gun system, comprising: a plurality of shape
charges; a positioning device that orients the perforating gun in
relation to a down direction of a deviated well; the shape charges
being positioned inside the perforating gun and aimed in
predetermined directions with respect to the down direction of the
deviated well; wherein a ratio of the outer diameter of the slim
perforating gun to the inner diameter of a casing used in
connection with the slim perforating gun is from 0.85 to 0.30.
2. The slim perforating gun of claim 1, wherein the directions of
the shape charges are phased approximately 180 degrees.
3. The slim perforating gun of claim 1, wherein the directions of
the shape charges are phased approximately at 0, +/-60 degrees.
4. The slim perforating gun of claim 1, wherein the directions of
the shape charges are phased approximately at +/-90, +/-30
degrees.
5. The slim perforating gun of claim 1, wherein the positioning
device comprises at least one selected from the following: magnetic
device, centralizer springs, mechanical caliper devices, and
fins.
6. The slim perforating gun of claim 5, wherein the positioning
device positions the perforating gun with the shape charges
pointing in a direction perpendicular to a shortest path to the
casing.
7. The slim perforating gun of claim 1, comprising a swivel to
decouple torque from a cable.
8. The slim perforating gun of claim 1, wherein a ratio of the
outer diameter of the slim perforating gun to the inner diameter of
the casing used in connection with the slim perforating gun is from
0.80 to 0.40.
9. The slim perforating gun of claim 1, wherein a ratio of the
outer diameter of the slim perforating gun to the inner diameter of
the casing used in connection with the slim perforating gun is from
0.7 to 0.40.
10. The slim perforating gun of claim 1, wherein a ratio of the
outer diameter of the slim perforating gun to the inner diameter of
the casing used in connection with the slim perforating gun is from
0.6 to 0.4.
11. A method of perforating a subterranean hydrocarbon well, the
method comprising: determining an azimuth for at least a portion of
a deviated well; placing a slim perforating gun in the well and
using a positioning device to locate the perforating gun proximate
to a casing in the deviated well in down direction; positioning a
plurality of shape charges in the slim perforating gun in
predetermined directions with respect to the down direction;
wherein an outer diameter of the slim perforating gun and an inner
diameter of a casing used in connection with the slim perforating
gun has a ratio from 0.85 to 0.30.
12. The method of claim 11, comprising positioning the shape
charges so that the directions of the shape charges are phased
approximately 180 degrees.
13. The method of claim 11, comprising positioning the shape
charges so that the directions of the shape charges are phased
approximately at 0, +/-60 degrees.
14. The method of claim 11, comprising positioning the shape
charges so that the directions of the shape charges are phased
approximately at +/-90, +/-30 degrees.
15. The method of claim 11, wherein the positioning device
comprises at least one selected from the following: magnetic
device, centralizer springs, mechanical caliper devices, and
fins.
16. The method of claim 15, comprising using the positioning device
to position the perforating gun with the shape charges pointing in
a direction perpendicular to a shortest path to the casing.
17. The method of claim 11, wherein the azimuth of the well is
substantially in a direction of minimal horizontal stress.
18. The method of claim 11, wherein a ratio of the outer diameter
of the slim perforating gun to the inner diameter of the casing
used in connection with the slim perforating gun is from 0.80 to
0.40.
18. The method of claim 11, wherein a ratio of the outer diameter
of the slim perforating gun to the inner diameter of the casing
used in connection with the slim perforating gun is from 0.6 to
0.40.
20. A method for treating multiple intervals of one or more
subterranean formations intersected by a cased wellbore, said
method comprising: a) using a perforating device to perforate at
least one interval of said one or more subterranean formations; b)
pumping a treating fluid into the perforations created in said at
least one interval by said perforating device without removing said
perforating device from said wellbore; c) deploying one or more
diversion agents in said wellbore to removably block further fluid
flow into said perforations; and d) repeating at least steps a)
through b) for at least one more interval of said one or more
subterranean formations; wherein at some time after step a) and
before removably blocking fluid flow into said perforations, said
perforating device is moved to a position above said at least one
interval perforated in step a); wherein the perforating device
comprises a slim perforating gun, comprising: a plurality of shape
charges; a positioning device that orients the perforating gun in
relation to a down direction of a deviated well; the shape charges
being positioned inside the perforating gun and aimed in
predetermined directions with respect to the down direction of the
deviated well; wherein a ratio of the outer diameter of the slim
perforating gun to the inner diameter of a casing used in
connection with the slim perforating gun is from 0.85 to 0.30.
Description
RELATED APPLICATION
[0001] This present application claims the benefit of the filing
date of U.S. Provisional Patent Application No. 61/012,941, filed
Dec. 12, 2007 incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] The present application relates to perforating, and more
particularly, orienting a direction of perforating charges for a
slim perforating gun in a deviated well.
BACKGROUND
[0003] Subterranean fluids are desirable for extraction. These
fluids are often water, oil, or natural gas. Alternatively, it is
often desired to inject fluids and gases into subterranean regions
for various reasons that are known in the art.
[0004] To access subterranean regions, wells are created.
Generally, in the hydrocarbon industry, wells are drilled from
surface into formation. Those wells are cased with a metal casing.
In order to access the formation surrounding the casing from within
the casing in order to retrieve formation fluids (oil/water/natural
gas), perforations are creating through the casing.
[0005] The perforations are generally created with a perforating
gun that uses charges to fire matter through the casing and into
the formation to further assist in the flow of formation fluids
into the casing annulus.
[0006] In connection with that activity, many issues arise. Some of
those issues are described and addressed in the present
application.
SUMMARY
[0007] According to one of the embodiments, a slim perforating gun
comprises a plurality of shape charges; a positioning device that
orients the perforating gun in relation to a down direction of a
deviated well; the shaped charges being positioned inside the
perforating gun and aimed in predetermined directions with respect
to the down direction of the deviated well; wherein a ratio of the
outer diameter of the slim perforating gun to the inner diameter of
a casing used in connection with the slim perforating gun is from
0.85 to 0.30.
[0008] The summary relates to at least one embodiment and is not
meant in any way to limit the interpreted scope of any inventive
aspects of this application or the scope of any claims recited
herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic of a perforating gun.
[0010] FIG. 2 is schematic showing a slim gun having a shot
interval of 60 degrees.
[0011] FIG. 3 is a schematic showing a slim gun having a shot
interval of 180 degrees.
DETAILED DESCRIPTION
[0012] In the following description, numerous details are set forth
to provide an understanding of embodiments described herein.
However, it will be understood by those skilled in the art that the
presently claimed subject matter may be practiced without many of
these details and that numerous variations or modifications from
the described embodiments may be possible.
[0013] In the specification and appended claims: the terms
"connect", "connection", "connected", "in connection with", and
"connecting" are used to mean "in direct connection with" or "in
connection with via another element"; and the term "set" is used to
mean "one element" or "more than one element". As used herein, the
terms "uphole", "downhole", "up" and "down", "upper" and "lower",
"upwardly" and downwardly", "upstream" and "downstream"; "above"
and "below"; and other like terms indicating relative positions
above or below a given point or element are used in this
description to more clearly described some embodiments of the
invention. However, when applied to equipment and methods for use
in wells that are deviated or horizontal, such terms may refer to a
left to right, right to left, or other relationship as
appropriate.
[0014] Multiple-stage fracturing relates to completion of a well
and includes running in the hole with a string of multiple wireline
guns that are fired one by one selectively at each stage, leaving
the guns in the well while the fracture is being pumped. Diversion
between zones is obtained by pumping a set of ball sealers from the
surface to plug the perforations of each zone. At the time that the
ball sealers plug the perforations of the zone being treated,
another gun in the string is fired at the next zone to be
fractured. The operation is repeated for each zone saving valuable
time as compared with conventional ways of completing these type of
wells (i.e., set a bridge plug, perforate, remove guns from the
well, frac, move to the next zone and repeat for each zone, and at
the end drill the bridge plugs). That process and accompanying
equipment is readily understandable in the art and therefore
excluded from the drawings herein.
[0015] According to an embodiment in the present application, since
the multi-stage treatment method requires leaving the guns in the
well as the fracture is being pumped, it has been found that it is
beneficial to use small diameter guns (slim guns), e.g., to avoid
excessive tension on the wireline cable and to allow sufficient
clearance between the guns and the inside diameter of the
casing.
[0016] However, use of the slim guns results in undesirable issues.
For example, a slim gun tends to produce perforations of
significantly different sizes. Also, due to the size of slim guns
and various factors, excessive breakdown pressure has been observed
in many cases.
[0017] Accordingly, the present application relates to equipment
and methods for orienting slim perforating guns and charges in such
a way to avoid undesired differences in size of the perforations,
perforating in relation to the Preferred Fracture Plane (PFP) with
regard to the direction of minimal horizontal stress in the
formation, and avoiding high fracturing breakdown pressure when a
slim gun is used to perforate an interval in a well that needs to
be fractured.
[0018] FIG. 1 shows a schematic of a slim perforating gun 300. The
perforating gun 300 is supported by a member 104, preferably a
wireline, slickline, coiled tubing, or production tubing. The
perforating gun 300 includes a body 301 that is normally tubular or
cylindrical and made from metal. Within the body 301 are shaped
charges 302 that are connected by a detonating cord 303. Shaped
charges 302 have a case, a liner, explosives between the case and
the liner, and a detonator. The shaped charges are activated by the
detonating cord 303.
[0019] FIGS. 2 and 3 are schematics showing an axial view of firing
of a slim perforating gun. A slim perforating gun 201 is located
inside a deviated well casing 202. In FIG. 2, the slim perforating
gun 201 is on the lower part of the casing 202 due to gravity and
deviation of the well. Cement 203 surrounds the casing 202.
Formation 204 surrounds the cement 203. FIG. 2 shows a
configuration of the perforating gun 201 where the shaped charges
are at approximately 60 degree intervals from one another. Given
that spacing, the distances for the shots from the different
charges are significantly different.
[0020] FIG. 3 shows a schematic where like numbers correspond to
like parts shown in FIG. 2. In FIG. 3, the angular spacing of the
shaped charges is 180 degrees, and that direction is substantially
parallel to the tangent of the casing that the gun 201 is most
near. Accordingly, the distances of each shot to the casing are
substantially equal thereby encouraging the perforations to have a
same or similar size.
[0021] Some embodiments addressed in this application generally
relate to a well construction method comprising drilling a slightly
deviated well, anywhere from 5 to 45 degrees, but preferably around
15 degrees and close or in the direction of the minimum horizontal
stress in the formation. Having the wells drilled with that
deviation and azimuth allows the use of gravity to position and
orient the gun with shape charges phased at 180 degree with shots
in the direction of the preferred fracture plane (PFP). If the well
is drilled, for example, in the direction of the minimum horizontal
stress, then, as described herein, the gun can be oriented to have
the perforations perpendicular to the radius of the gun 201 in the
gun to casing point of contact as shown in FIG. 3. An advantage of
using that method with a slim gun having 180 degree phasing is that
the entrance hole (EH) on both phases tends to be very uniform and
symmetrical.
[0022] Looking particularly at the slim gun 201, in the context of
the present application, a slim gun 201 is a perforating gun having
a maximum outer diameter that is less than a recommended API
diameter for a particular casing size. According to some
embodiments, a slim gun 201 can have a ratio between the maximum
outer diameter of the slim gun 201 and the inside diameter of the
casing 202 of about 0.85 to 0.35, and is preferably between about
0.8 to 0.4.
[0023] Some embodiments described herein generally relate to a
design and use of slightly deviated wells in a predetermined
direction relative to the preferential PFP with the use of oriented
perforating, aided by gravity, to align the perforations with the
PFP. Also, some embodiments relate to gun charge phasing and
positioning devices to assure both a relatively uniform exit hole
diameter in the casing and alignment of the perforations with the
PFP or within or close to 30 degree phasing of the PFP.
[0024] A well construction method for the purpose of increasing the
efficiency and effectiveness of a hydraulic fracture includes a
design and construction of (slightly) deviated wells with a known
azimuth with respect to the PFP, and the positioning of guns
against the low (down) side of the casing, and orienting the
perforations in relation to the azimuth of the well. A primary use
of that method is to shoot a slim gun with 180 degree phasing in
the direction of the PFP.
[0025] Another aspect relates to the design and use of shot phasing
in slim guns 201 in such as way as to assure that the perforations
are approximately within 30 degrees from the PFP, regardless of the
relative orientation of the gun 201 with respect to the PFP while,
for slim guns, shooting only in directions where the perforations
have a small clearance between the gun and the casing, e.g.
shooting with a phasing of 0, +60/-60 degree (tri-phase) in the
direction of a hemisphere of the gun in contact with the casing,
with a phasing of +/-90, +/-30 degree (quad-phase), or with a
phasing of 180 degrees positioned as shown in FIG. 3.
[0026] A preferred perforation pattern for hydraulic fracturing is
180 degrees in the direction of the PFP, that is, in the direction
of the maximum horizontal stress as shown in FIG. 3. That
perforation pattern maximizes the chances of having all
perforations connected to the PFP, minimizes tortuosity and reduces
break down and treating pressure.
[0027] FIG. 2 illustrates a 2'' gun shot in 51/2'' casing and a
corresponding variation on the entrance hole size in the casing
varying from 0.11'' to 0.5''. As alluded to earlier, the hole size
variation presents two issues: 1) since the pressure drop of a
liquid being pumped through a hole in the casing is given by
Equation 1 (shown below) the difference in pressure drop between
the largest and smallest hole could be relatively large, e.g. above
460% for the instance; and 2) the smaller holes would be too small
to adequately pump proppant through them (the recommended
guidelines is to have a hole size of at least 6 times the diameter
of the proppant).
Ppf=(2.93*Q.sup.2*SG)/(EH.sup.4*N.sup.2) (Perforation Friction
Pressure) Equation 1
[0028] To address some of the issues mentioned above, the present
application describes using slim guns 201 with a phasing so that
shots are placed in directions where the perforations would have
relatively small clearance, typically less than 0.5'' due to the
eccentricity of the gun with respect to the inside diameter (ID) of
the casing 202. Typically these directions are within the
hemisphere defined by a diameter of the gun 201 perpendicular to
the gun-to-casing point of contact as shown in FIG. 3. Furthermore,
to assure that the perforations are approximately within 30 degrees
of the PFP the perforations could be within 60 degrees as
illustrated in FIG. 2. Typical shot phasing that meets the criteria
mentioned above (gun-casing clearance of less than 0.5'' and
assurance of having some perforations within 30 degrees of the PFP)
are 0, +/-60 degrees as shown on FIG. 2 or +/-90, +/-30 degrees.
The desired shot phasing can be achieved with several shot
arrangements for example:
[0029] For the 0, +/-60 degree phasing shown in FIG. 2:
[0030] 0, 60, 0, -60, 0, 60 . . .
[0031] or
[0032] 0, 60, -60, 0, 60 . . .
[0033] For the +/-90, +/-30 degree phasing:
[0034] -90, -30, 30, 90, 30, -30, -90, -30 . . .
[0035] or
[0036] -90, -30, 30, 90, -90, -30, 30, 90 . . .
[0037] Many other similar arrangements are possible, including
leaving empty shots in conventional 60 degree phased guns.
[0038] To aid creating uniform exit hole size, the perforating guns
may have some standoff, typically within 0.5'' or zero. Also, in
some cases, combining different shape charges in different phasing
can be used to aid creating a uniform exit hole size in the
casing.
[0039] Alternatively, a phasing of 180 degrees positioned as shown
in FIG. 3 can also be used in vertical wells to increase the
chances of being closer to the PFP and thus reduce breakdown
pressure. The advantage of that phasing is that because of the
symmetry of the shots, it encourages very uniform exit hole,
regardless of the gun standoff or type of shaped charge. Uniform
exit hole size is very much desired to encourage good action of the
ball sealers and adequate diversion in connection with multi-stage
fracturing.
[0040] Furthermore, to facilitate and provide that the shots are
directed in the correct direction, embodiments described herein can
use a combination of positioning devices such as weights, magnetic
positioning devices (MPDS), centralizer springs, gyroscopes,
mechanical caliper devices (MCDs), or fins to position the gun
string with the perforations pointing in the direction of the
hemisphere with less water clearance. In addition, swivel devices
can be used to decouple the torque produced by the wireline cable
and preventing that way the rotation of the gun string keeping it
correctly positioned with the shots in the direction of the desired
hemisphere.
[0041] The embodiments and examples described herein are exemplary
and are not meant to limit the scope of any claims recited
herein.
* * * * *