U.S. patent application number 10/817870 was filed with the patent office on 2005-10-06 for vibration-dampening drill collar.
Invention is credited to Clark, Brent Alexander.
Application Number | 20050217898 10/817870 |
Document ID | / |
Family ID | 32968325 |
Filed Date | 2005-10-06 |
United States Patent
Application |
20050217898 |
Kind Code |
A1 |
Clark, Brent Alexander |
October 6, 2005 |
Vibration-dampening drill collar
Abstract
A drill collar primarily for use with measurement-while-drilling
and logging-while-drilling sensors, the drill collar composed of a
non-magnetic nickel alloy, and having three or four elongate nitral
elastomer ribs parallel the longitudinal axis and mounted on the
inner surface of the drill collar, defining a central aperture for
receiving the down-hole sensor and inter-rib apertures for
receiving drilling fluid. This novel drill collar is especially
useful in rough or underbalanced drilling applications, protecting
the sensor and enhancing measurement accuracy by dampening
flow-based harmonic vibrations, absorbing vibration from lateral
tool movement, and stabilizing/centralizing the sensor within the
central aperture. Also, the novel drill collar allows the operator
to run lower fluid rates while drilling, minimizing formation
damage from fluid invasion.
Inventors: |
Clark, Brent Alexander;
(Calgary, CA) |
Correspondence
Address: |
GOWLING LAFLEUR HENDERSON LLP
SUITE 1400, 700 2ND ST. SW
CALGARY
AB
T2P 4V5
CA
|
Family ID: |
32968325 |
Appl. No.: |
10/817870 |
Filed: |
April 6, 2004 |
Current U.S.
Class: |
175/56 |
Current CPC
Class: |
E21B 17/16 20130101;
E21B 17/07 20130101; E21B 47/017 20200501 |
Class at
Publication: |
175/056 |
International
Class: |
E21B 007/24 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 1, 2004 |
CA |
2,462,987 |
Claims
Embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A drill collar for use with a down-hole tool, the drill collar
comprising: a hollow, cylindrical sleeve having a longitudinal axis
and an inner surface facing towards the longitudinal axis; and a
plurality of elongate ribs parallel the longitudinal axis and
mounted on the inner surface in spaced-apart arrangement, defining
thereby a central aperture within the sleeve for receiving the
down-hole tool and inter-rib apertures for receiving drilling
fluid.
2. The drill collar of claim 1 wherein the down-hole tool is a
sensor used in measurement-while-drilling and/or
logging-while-drilling applications.
3. The drill collar of claim 1 wherein the sleeve is composed of a
non-magnetic material.
4. The drill collar of claim 3 wherein the non-magnetic material is
a nickel alloy.
5. The drill collar of claim 1 wherein the sleeve further comprises
a box end and a pin end at opposed ends of the sleeve.
6. The drill collar of claim 1 wherein the elongate ribs are
composed of an elastomeric material.
7. The drill collar of claim 6 wherein the elastomeric material is
a nitral elastomer.
8. The drill collar of claim 1 wherein the elongate ribs are
equally spaced around the inner surface.
9. The drill collar of claim 1 wherein there are four elongate
ribs.
10. The drill collar of claim 1 wherein the elongate ribs extend
along substantially the entire length of the sleeve.
11. A vibration-dampening apparatus for use with a down-hole tool
used in measurement-while-drilling and/or logging-while-drilling
applications, the vibration-dampening apparatus comprising: a drill
collar comprising a hollow, cylindrical sleeve having a
longitudinal axis and an inner surface facing towards the
longitudinal axis; and a plurality of elongate ribs parallel the
longitudinal axis and mounted on the inner surface of the drill
collar in spaced-apart arrangement, defining thereby a central
aperture within the drill collar for receiving the down-hole tool
and inter-rib apertures for receiving drilling fluid.
12. The vibration-dampening apparatus of claim 11 wherein the drill
collar is composed of a non-magnetic material.
13. The vibration-dampening apparatus of claim 12 wherein the
non-magnetic material is a nickel alloy.
14. The vibration-dampening apparatus of claim 11 wherein the drill
collar further comprises a box end and a pin end at opposed ends
thereof.
15. The vibration-dampening apparatus of claim 11 wherein the
elongate ribs are composed of an elastomeric material.
16. The vibration-dampening apparatus of claim 15 wherein the
elastomeric material is a nitral elastomer.
17. The vibration-dampening apparatus of claim 11 wherein the
elongate ribs are equally spaced around the inner surface.
18. The vibration-dampening apparatus of claim 11 wherein there are
four elongate ribs.
19. The vibration-dampening apparatus of claim 11 wherein the
elongate ribs extend along substantially the entire length of the
sleeve.
20. A drill collar for use with a measurement-while-drilling and/or
logging-while-drilling sensor, the drill collar comprising: a
hollow, cylindrical sleeve having a longitudinal axis, an inner
surface facing towards the longitudinal axis, and a box end and a
pin end at opposed ends of the sleeve, the sleeve composed of a
non-magnetic nickel alloy; and four elongate ribs parallel the
longitudinal axis and mounted on the inner surface in spaced-apart
arrangement, defining thereby a central aperture within the sleeve
for receiving the sensor and inter-rib apertures for receiving
drilling fluid, the elongate ribs extending along substantially the
entire length of the sleeve and composed of a nitral elastomer.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to apparatus for
protecting down-hole tools such as sensors during drilling, and
more particularly to apparatus for protecting down-hole sensors
from the effects of vibration produced when drilling a well.
BACKGROUND OF THE INVENTION
[0002] In typical drilling systems utilized in the oil and gas
industries, a rig is established at a desirable location, the rig
comprising a rotatable drill string (consisting of drill pipe
sections and heavier drill collars, the latter fitting around the
lower drill pipe) and a drill bit at the down-hole end. During
drilling, this rotatable component of the rig is rotated from the
surface, causing the drill bit to cut into the downwardly adjacent
rock formations, with the weight of the drill collar assisting in
driving the drill bit downward into contact with the underlying
rock. Drill collars also act as conduits for the drilling fluids
used to lubricate the drill bit and carry cuttings back to the
surface. Mud motors and turbines are sometimes employed down-hole
to aid the drill bit rotation.
[0003] At various points during drilling, specialized measurement
and telemetry tools can be employed to assess conditions in the
rock formations adjacent the wellbore. Methods well known in the
art include measurement-while-drilling (MWD) and
logging-while-drilling (LWD), which methods employ a diverse and
evolving range of sensors. These sensors are usually located in the
drill string near the drill bit, with the derived data from such
sources as resistivity, gravity, magnetic and nuclear magnetic
resonance measurements being stored in down-hole memory or
transmitted to the surface.
[0004] While such sensors provide highly useful information about
the down-hole drilling environment, vibration due to the drilling
process can damage the sensors. An axial load is applied to the
drill bit during drilling into underlying formations, and this
produces vibrations in the overlying drill string, and vibration
can occur due to drill string rotation in deviated or directional
wellbores. Also, drilling fluid flow around the tool can initiate
harmonic vibrations and side-to-side "slapping" of the tool ensues.
While most of these sensors are sufficiently robust to address the
vibrations of normal drilling conditions, a variety of attempts
have been made to counter the potentially damaging vibrations.
[0005] U.S. Pat. No. 4,522,271 to Bodine et al., for example,
teaches a sonic damper unit which is placed directly above a drill
collar string to damp out unwanted complex wave vibrations of the
string both longitudinal and lateral in vibration mode, the damper
unit comprising a tubular section filled with small pieces of
material capable of motion in a random pattern and thereby
responding to the frequency content to damp out unwanted
vibrational energy. In another example, U.S. Pat. No. 6,429,653 to
Kruspe et al. discloses a method and apparatus for protecting a
sensor from impact and abrasion, including a drill collar having a
section of electrically non-conductive material, the sensor being
located inside the drill collar within the section of electrically
non-conductive material. Kruspe et al. alternatively disclose
placing the sensor in a removable probe fitted with protective
stabilizers. A variety of other shock absorbing devices are also
known in the art, such as mechanical stabilizing projections
mounted on the tool.
[0006] However, existing means to dampen drill string vibrations or
provide shock absorption suffer from numerous disadvantages,
including high manufacturing cost, failures of inherently
unreliable "point-contact" mechanical shock absorbers (such as
belly springs), and the requirement for a significant drilling
fluid throughflow to support certain stabilization devices (which
can result in formation damage from fluid invasion). Also, in rough
or underbalanced drilling environments, conditions are such that
excessive vibration can defeat currently known tool protection
means.
[0007] What is therefore required is a means for addressing the
problem of down-hole vibration (from the drill bit as well as
harmonic vibration) and resultant tool damage, the means being
relatively inexpensive to manufacture, preferably more reliable
than point-contact mechanical stabilizers and capable of effective
use in rough or underbalanced environments, and not requiring
reliance on significant fluid flow to support the stabilization of
the down hole tool.
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention, therefore, to
provide a simple apparatus effective in dampening down-hole
vibration in the tool-housing region of a drill string, even in
rough or underbalanced drilling environments, while not requiring
significant fluid flow for its utility.
[0009] According to a first broad aspect of the present invention,
there is provided a drill collar for use with a down-hole tool, the
drill collar comprising: a hollow, cylindrical sleeve having a
longitudinal axis and an inner surface facing towards the
longitudinal axis; and a plurality of elongate ribs parallel to the
longitudinal axis and mounted on the inner surface in spaced-apart
arrangement, defining thereby a central aperture within the sleeve
for receiving the down-hole tool and inter-rib apertures for
receiving drilling fluid.
[0010] According to a second broad aspect of the present invention,
there is provided a vibration-dampening apparatus for use with a
down-hole tool used in measurement-while-drilling and/or
logging-while-drilling applications, the vibration-dampening
apparatus comprising: a drill collar comprising a hollow,
cylindrical sleeve having a longitudinal axis and an inner surface
facing towards the longitudinal axis; and a plurality of elongate
ribs parallel the longitudinal axis and mounted on the inner
surface of the drill collar in spaced-apart arrangement, defining
thereby a central aperture within the drill collar for receiving
the down hole tool and inter-rib apertures for receiving drilling
fluid.
[0011] According to a third broad aspect of the present invention,
there is provided a drill collar for use with a
measurement-while-drilling and/or logging-while-drilling sensor,
the drill collar comprising: a hollow, cylindrical sleeve having a
longitudinal axis, an inner surface facing towards the longitudinal
axis, and a box end and a pin end at opposed ends of the sleeve,
the sleeve composed of a non-magnetic nickel alloy; and four
elongate ribs parallel to the longitudinal axis and mounted on the
inner surface in spaced-apart arrangement, defining thereby a
central aperture within the sleeve for receiving the sensor and
inter-rib apertures for receiving drilling fluid, the elongate ribs
extending along substantially the entire length of the sleeve and
composed of a nitral elastomer.
[0012] In exemplary embodiments of the present invention, the
down-hole tool is a sensor used in measurement-while-drilling
and/or logging-while-drilling applications. The sleeve is
preferably composed of a non-magnetic material, and most preferably
a nickel alloy, and the sleeve preferably but not necessarily
comprises a box end and a pin end at opposed ends of the sleeve,
while double box end or double pin end connections may be used in
some preferred embodiments. The elongate ribs are preferably
composed of an elastomeric material, most preferably a nitral
elastomer. The ribs are preferably three or four in number,
depending primarily on sleeve dimensions, the ribs preferably
equally spaced around the inner surface of the sleeve and
preferably but not necessarily extending along substantially the
entire length of the sleeve.
[0013] This novel drill collar is especially useful in rough or
underbalanced drilling applications, supporting and centralizing
the sensor and enhancing measurement accuracy by dampening
flow-based harmonic vibrations, absorbing vibration from lateral
tool movement, and stabilizing/centralizing the sensor within the
central aperture. Also, the novel drill collar allows the operator
to run lower fluid rates while drilling, minimizing formation
damage from fluid invasion.
[0014] A detailed description of an exemplary embodiment of the
present invention is given in the following. It is to be
understood, however, that the invention is not to be construed as
limited to this embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In the accompanying drawings, which illustrate an exemplary
embodiment of the present invention:
[0016] FIG. 1 is a cut-away side elevation view of a drill collar
according to the present invention, showing the positioning of the
elongate ribs in relation to the longitudinal axis of the drill
collar;
[0017] FIG. 2A is a cross-sectional view of the drill collar of
FIG. 1 along line 2-2, illustrating the use of four elongate ribs;
and
[0018] FIG. 2B is a cross-sectional view similar to FIG. 2A but
illustrating the use of three elongate ribs.
DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT
[0019] Referring now in detail to the accompanying drawings, there
is illustrated an exemplary embodiment of a drill collar according
to the present invention generally referred to by the reference
numeral 2.
[0020] The exemplary drill collar 2 is for use with
measurement-while-drilling and/or logging-while-drilling sensors
(not shown) employing electro-magnetic transmission modes, the
drill collar 2 comprising a hollow, cylindrical sleeve 4 having a
longitudinal axis 6. The sleeve 4 has an inner surface 8 facing
towards the longitudinal axis 6, and a box end 16 and pin end 18 at
opposed ends of the sleeve 4 for connecting the drill collar 2 to
adjacent string sections (not shown) (although double box end or
double pin end connections may be used in some preferred
embodiments). In this exemplary embodiment, the sleeve 4 is
composed of a non-magnetic nickel alloy such as Monel.TM., although
other non-magnetic materials may be suitable in various contexts.
In exemplary embodiments, the drill collar 2 may be from 2 to 12
metres in length, depending on tool requirements, with an outside
sleeve 4 diameter accordingly ranging from 89 to 229 mm, and an
internal sleeve 4 diameter accordingly ranging from 57 to 82.55 mm.
Multiple collar sizes will be required to address different hole
sizes, flow rates, and MWD/LWD tool sizes. The following table
provides dimensions for a variety of drill collars 2 according to
the present invention, including preferred rib 10 numbers:
1 Minimum Maximum Sleeve Sleeve Outside Sleeve Internal Sleeve
Number of Length Length Diameter Diameter Elongate Ribs 2 metres
9.5 metres 89 mm 57 mm 3 or 4 2 metres 9.5 metres 95.25 mm 57 mm 3
or 4 2 metres 9.5 metres 121 mm 57 mm 4 3 metres 12 metres 159 mm
71.44 mm 4 3 metres 12 metres 165 mm 71.44 mm 4 3 metres 12 metres
171 mm 71.44 mm 4 3 metres 12 metres 177.8 mm 76.2 mm 4 or 5 3
metres 12 metres 190.5 mm 76.2 mm 4 or 5 3 metres 12 metres 203 mm
76.2 mm 5 3 metres 12 metres 229 mm 82.55 mm 5 or 6
[0021] Referring now to FIGS. 2A and 2B, the drill collar 2 is
provided with a plurality of elongate ribs 10. In FIG. 2A, there
are four ribs 10, spaced evenly apart on the inner surface 8 of the
sleeve 4. In FIG. 2B, there are three ribs 10, again spaced evenly
apart on the inner surface 8 of the sleeve 4. The required flow
area (determined by collar size and drilling flow requirements)
will determine the number and size of elongate ribs 10 required in
a given application, with six ribs 10 for the largest collar 2
lengths (see the above table). The elongate ribs 10 are permanently
attached to the inner surface 8 and are parallel the longitudinal
axis 6, thereby defining a central aperture 12 (best seen in FIGS.
2A and 2B) within the sleeve 4 for receiving the down-hole tool;
this central aperture 12 has a diameter of 44.5 to 47.63 mm
depending on tool clearance requirements. The positioning of the
elongate ribs 10 also results in inter-rib apertures 14, best seen
in FIGS. 2A and 2B, for receiving drilling fluid (not shown).
[0022] In the exemplary embodiment, the elongate ribs 10 extend
along substantially the entire length of the sleeve 4 and are
composed of a nitral elastomer; this is the same elastomer that is
used with some mud motor stators. Elastomeric material is known in
the art for its ability to absorb energy from vibration and impact
(for example, U.S. Pat. No. 6,102,142 to Besson et al.). The ribs
10 support the cylindrical tool along its entire length, not just
at contact points as is the case with current mechanical
stabilizers, so the tool does not start moving and causing harmonic
vibrations. The present invention accordingly does not require the
minimum fluid rates used in a multiphase flow in underbalanced
drilling applications to stabilize and protect the tool, which
therefore minimizes formation damage from fluid invasion. It has
been found, in fact, that only minor lubrication is required to
work this invention. Where a specific desired elastomer may swell
due to the presence of certain fluids, or experience possible
down-hole temperature limitations where hot hole conditions are
encountered, a special elastomer may be required.
[0023] In addition to being composed of a relatively inexpensive
material, the manufacturing process is relatively simple and akin
to known elastomer processes in mud motor contexts; the existing
process for building a mold for injecting mud motor stators can be
employed to inject the drill collars 2. A mold (not shown) will
incorporate three or more rib voids based on the required flow
data. The drill collar 2 is then prepared for the mold and a
bonding agent (not shown) is prepared and installed on the inner
surface 8 of the drill collar 2. The mold is then inserted into the
drill collar 2 and an elastomeric material is injected into the
drill collar 2 with the mold seated therein. The elastomeric
material then sets and adheres to the inner surface 8, and the mold
is removed, creating a set of elastomeric ribs 10 that run
substantially the entire length of the drill collar 2. When the
elongate ribs 10 wear down from prolonged use, the drill collar 2
can be provided with replacement ribs 10 using the same
process.
[0024] The present invention is especially useful in underbalanced
applications, and also with coalbed methane drilling. The
elastomeric fins 10 will both centralize the tool and dampen
vibration during the drilling process in single phase or multiphase
flow regimes. The result is a stable environment in which the
sensor can conduct measurements, with a significantly reduced risk
of tool damage due to vibration. Tool life and performance are
accordingly enhanced by use of the present invention.
[0025] A prototype according to the present invention was tested
for performance, and test drillings without a drill collar
according to the present invention were conducted for the sake of
comparison. The present invention was found to significantly
enhance the tool life. The test drillings were conducted with an
electromagnetic MWD tool in an underbalanced drilling medium, a
hole size of 61/4" (159 mm), and a drilling medium comprising 5
gallons/min. (20 litres/min.) fluid and 1300 cfm (36.8 cubic
metres/min.) gas. Two test runs were conducted without a drill
collar according to the present invention, g values were measured
up to 125.times.g (the force exerted by gravity), and catastrophic
tool failure occurred within a matter of minutes on both test runs.
In a test run conducted with a drill collar according to the
present invention, 9 values were measured at 2 to 4.times.g during
drilling, and there was no tool failure. During the test run of the
drill collar according to the present invention, the drilling fluid
was reduced near the bottom of the well, and even when running
"dry" the g values did not exceed 7.times.g. These results
accordingly indicate up to 18 to 31 times potential reduction in
vibration when utilizing the present invention.
[0026] While a particular embodiment of the present invention has
been described in the foregoing, it is to be understood that other
embodiments are possible within the scope of the invention and are
intended to be included herein. It will be clear to any person
skilled in the art that modifications of and adjustments to this
invention, not shown, are possible without departing from the
spirit of the invention as demonstrated through the exemplary
embodiment. The invention is therefore to be considered limited
solely by the scope of the appended claims.
* * * * *