U.S. patent application number 14/623092 was filed with the patent office on 2015-06-11 for bit for drilling wells and associated drilling method.
The applicant listed for this patent is TOTAL S.A.. Invention is credited to Robert Delwiche, Beno t Deschamps, Sebastian Desmette, Abdelhakim Hahati, Matthieu Naegel.
Application Number | 20150159439 14/623092 |
Document ID | / |
Family ID | 38596984 |
Filed Date | 2015-06-11 |
United States Patent
Application |
20150159439 |
Kind Code |
A1 |
Hahati; Abdelhakim ; et
al. |
June 11, 2015 |
BIT FOR DRILLING WELLS AND ASSOCIATED DRILLING METHOD
Abstract
A bit for drilling wells has a front face with radial blades
having cutting elements distributed around the front face. A space
for forming a core is situated at the center of the front face. A
cavity is provided for evacuating the core towards a periphery of
the bit. At least a portion of the cavity is situated between
adjacent blades. The cavity is delimited by two lateral surfaces
and a clearance surface set back with respect to the front face,
and the cavity is open in a direction opposite the clearance
surface. The bit may be used in methods for drilling wells and
makes it possible to rapidly drill wells of great depth in all
types of rock without the risk of clogging.
Inventors: |
Hahati; Abdelhakim;
(Evere-Bruxelles, BE) ; Desmette; Sebastian;
(Thieusies, BE) ; Deschamps; Beno t; (Gottignies,
BE) ; Delwiche; Robert; (Uccle, BE) ; Naegel;
Matthieu; (Strasbourg, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOTAL S.A. |
Courbevoie |
|
FR |
|
|
Family ID: |
38596984 |
Appl. No.: |
14/623092 |
Filed: |
February 16, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12596995 |
Oct 22, 2009 |
8960335 |
|
|
PCT/IB2008/002299 |
Apr 22, 2008 |
|
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14623092 |
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Current U.S.
Class: |
175/58 ; 175/403;
175/404 |
Current CPC
Class: |
E21B 10/485 20130101;
E21B 25/10 20130101; E21B 10/02 20130101; E21B 25/005 20130101;
E21B 10/55 20130101 |
International
Class: |
E21B 10/02 20060101
E21B010/02; E21B 25/10 20060101 E21B025/10; E21B 25/00 20060101
E21B025/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 23, 2007 |
FR |
07/02919 |
Claims
1. A bit for drilling wells, comprising: a front face; a plurality
of radial blades provided with cutting elements, the blades being
distributed around the front face; a space for forming a core, the
space being situated at the center of the front face; and a cavity
for evacuating the core towards a periphery of the bit, the cavity
being situated between two adjacent of the blades and preventing
any clogging inside the bit.
2. A bit according to claim 1, wherein the radial blades are
arranged on an external annular crown of the front face.
3. A bit according to claim 1, wherein a majority of the cavity is
situated between two adjacent blades, wherein the cavity is
delimited by two lateral surfaces and a clearance surface, and
wherein the clearance surface is set back with respect to the front
face.
4. A bit according to claim 1, further comprising drilling mud feed
channels, wherein each of the channels opens onto the front face,
and wherein one of the channels opens into the cavity and is
suitable for facilitating the evacuation of the core towards the
periphery of the bit.
5. A bit according to claim 1, wherein the clearance surface is
suitable for evacuating the core simultaneously towards the
periphery and towards the rear of the bit.
6. A bit according to claim 1, further comprising a device for
breaking up the core.
7. A bit according to claim 6, wherein the breaking device is
situated in the cavity close to the center of the bit.
8. A bit according to claim 7, wherein the breaking device is a tip
made of an abrasion-resistant material.
9. A bit according to claim 8, wherein the tip is inclined with
respect to the axis of the bit.
10. A bit according to claim 1, wherein the dimensions of the
cavity are suitable for forming cylindrical cores the length of
which is equal to at least twice their diameter.
11. A bit according to claim 1, further comprising an element for
radially cutting the core.
12. A method for drilling wells, comprising: providing a bit for
drilling wells, comprising: a front face; a plurality of radial
blades provided with cutting elements, the blades being distributed
around the front face; a space for forming a core, the space being
situated at the center of the front face; and a cavity for
evacuating the core towards a periphery of the bit, the cavity
being situated between two adjacent of the blades and preventing
any clogging inside the bit; forming a core at the center of the
bit; evacuating the core up through the drilling well to the ground
surface; and recovering the core.
13. A method for drilling wells according to claim 12, further
comprising analyzing the petrophysical properties of the core.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/596,995, filed Oct. 22, 2009, which is the
National Stage under 35 USC .sctn.371 of PCT/IB2008/002299, filed
Apr. 22, 2008, which claims priority to French Patent Application
No. 07/02919, filed Apr. 23, 2007. Each of the foregoing
applications is incorporated herein by reference in its entirety as
if set forth in full.
TECHNICAL FIELD
[0002] The present invention relates to a bit for drilling wells,
and in particular cylindrical wells of great depth such as mine
shafts, oil or gas wells. The present invention also relates to a
method for drilling wells using the bit.
BACKGROUND
[0003] The bit is a drilling tool intended to be installed at the
end of a drill pipe string for drilling wells into a reservoir. By
reservoir, is meant rock which is sufficiently porous and permeable
to be able to contain fluids (water, oil, gas). These fluids can
optionally accumulate to form a deposit.
[0004] A drill pipe string is supported by a metal derrick and is
rotated by a rotary table. The drilling mud, a specific mixture of
clay, water and chemical products is continuously injected into the
inside of the drill pipes then emerges via the bit and returns to
the surface via annular space contained between the drill pipes and
the walls of the well. The circulation of the drilling mud cools
the bit and allows the cuttings to be evacuated. At the surface,
the drilling mud is filtered and reinjected. Analysis of the
cuttings provides invaluable information on the nature and
composition of the rocks cut through.
[0005] Thirty years ago, the drilling of a well of great depth
could take several months. Also, in order to accelerate the
drilling speed, bits have been proposed that do not drill at the
centre of wells. In fact, the circumferential linear speed of the
bit decreases from the periphery of the bit towards its centre and
is zero at the centre of the bit. Thus, by not drilling the centre
of the wells, the bits have gained efficiency. However, this type
of bit produces a core in its centre, which must be broken up or
evacuated.
[0006] Various types of bits which do not drill the centre of wells
are known.
[0007] In particular, a bit is known from document U.S. Pat. No.
2,931,630 comprising an array in the surface of which a plurality
of diamonds is mounted. This bit comprises moreover a cavity for
receiving a core, the core being periodically broken off and
evacuated by moving towards the outside and above the bit. The
array in which the plurality of diamonds is mounted makes it
possible to drill through hard and very hard rocks. However, if the
bit encounters soft rock, the spaces situated between the diamonds
become clogged and the tool can no longer drill. Now, during the
drilling of wells of great depth, different types of geological
formations are passed through by the bit and it is highly probable
that soft rock will be encountered. This type of tool is therefore
not suitable for drilling wells of great depth.
[0008] Bits provided with a chamber for crushing the core formed
are known from the documents FR-A-2 141 510 and FR-A-2 197 325.
However, if the bit encounters soft rock, the crushing chamber
becomes clogged. The bit provided with a crushing chamber must then
be brought out so that the bit can be cleaned, which leads to a
significant loss of time.
[0009] From the document BE-A-1 014 561 a bit is also known,
provided with a means or a device suitable for destroying the core
in a progressive or continuous fashion or periodically, this means
or this device being situated in the central zone of the body of
the bit. In one embodiment, the means for destroying the core is
the side wall of the central zone of the body of the bit. The core
is then broken periodically under the effect of transmitted
mechanical vibrations. However, if the bit encounters soft rock,
the central zone of the bit becomes clogged. It must then be
brought out to be cleaned, which leads to a considerable loss of
time.
SUMMARY
[0010] The purpose of the invention is therefore to propose a bit
which makes it possible to rapidly drill wells of great depth in
all types of rocks without the risk of clogging.
[0011] This purpose is achieved by a bit for drilling wells
comprising: [0012] a front face [0013] a plurality of radial blades
provided with cutting elements, the blades being distributed around
the front face, [0014] a space for forming a core, the space being
situated at the centre of the front face, and [0015] a cavity for
evacuating the core towards the periphery of the bit, the cavity
being situated between two adjacent blades.
[0016] According to another feature, the cavity is delimited by two
lateral surfaces and a clearance surface, the clearance surface
being set back with respect to the front face.
[0017] According to another feature, the clearance surface is
suitable for evacuating the core simultaneously towards the
periphery and towards the rear of the bit.
[0018] According to another feature, the bit further comprises a
device for breaking up the core.
[0019] According to another feature, the breaking device is
situated in the cavity close to the centre of the bit.
[0020] According to another feature, the breaking device is a tip
made of an abrasion-resistant material.
[0021] According to another feature, the tip is inclined with
respect to the axis of the bit.
[0022] According to another feature, the dimensions of the cavity
are suitable for forming cylindrical cores the length of which is
equal to at least twice their diameter.
[0023] According to another feature, the bit further comprises
drilling mud feed channels, each of the channels opening onto the
front face.
[0024] According to another feature, one of the channels opens into
the cavity and is suitable for facilitating the evacuation of the
core towards the periphery of the bit.
[0025] According to another feature, the bit further comprises an
element for radially cutting the core.
[0026] Another purpose of the invention is to provide a method for
drilling wells using the bit described above, comprising the steps
consisting of forming a core at the centre of the bit; evacuating
the core up through the drilling well to the ground surface;
recovering the core.
[0027] According to another feature, the drilling method further
comprises a step of analyzing the petrophysical properties of the
core.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Other characteristics and advantages of the invention will
become apparent on reading the following detailed description of
the embodiments of the invention, given by way of example only and
with reference to the drawings, which show:
[0029] FIG. 1, a perspective view of a bit (PDC tool) according to
the invention,
[0030] FIG. 2, a longitudinal cross-section view of a bit
(impregnated tool) according to the invention,
[0031] FIG. 3, a front view of a bit (PDC tool) according to the
invention,
[0032] FIG. 4, a side view of a cutting element,
[0033] FIG. 5, a longitudinal cross-section view of the front face
of the bit.
DETAILED DESCRIPTION OF THE INVENTION
[0034] A bit according to the invention comprises a front face. The
bit also comprises a plurality of radial blades provided with
cutting elements, the blades being distributed around the front
face. The blades, provided with cutting elements, make it possible
to drill, by shearing, in all types of rocks, thus avoiding
clogging of the blades. A space situated at the centre of the front
face allows the formation of a core at the centre of the bit. The
formation of a core at the centre of the bit makes rapid drilling
possible. A cavity situated between two adjacent blades of the bit
allows the core to be evacuated towards the periphery of the bit.
Thus, the evacuation of the core prevents any clogging inside the
bit. The bit according to the invention therefore allows the rapid
drilling of wells of great depth in all types of rocks without the
risk of clogging.
[0035] Identical reference numbers in the different figures
represent identical or similar elements.
[0036] FIG. 1 represents a perspective view of a bit according to
the invention. The bit comprises a body 12 having a rotational
symmetry about an axis 13. The bit is suitable for mounting on a
drill pipe string and being rotationally driven by different types
of motor, on the surface or bottom, for example a motor with a
spiral shaft (for example of Moineau type) or a turbine.
[0037] The front of the bit is defined as the part of the bit which
is orientated towards the bottom of the well and the rear of the
bit as the part of the bit which is orientated towards the outside
of the well, i.e. in the case of vertical drilling, the earth's
surface.
[0038] Moreover, the inside of the bit is defined as the part of
the bit situated close to the axis 13 and the outside of the bit as
the part of the bit situated close to the periphery of the bit.
[0039] The body 12 of the bit comprises a front face 1, which is
preferably rounded so as to facilitate the penetration of the bit
into the rocks as well as to provide the tool with satisfactory
stability. The front face 1 is provided with a plurality of blades
2, for example 4, 6 or 8 blades, or even many more, for example 36.
The harder the rocks to be drilled, the higher the number of
blades.
[0040] The blades 2 are arranged in a substantially radial fashion,
as can be seen in particular in FIG. 3. The blades extend along the
outside wall of the body 12. The blades 2 project with respect to
the front face 1 and to the outside wall of the body 12. Each blade
2 comprises a plurality of cutting elements 3 arranged alongside
each other along the blade. The cutting element of a blade which is
closest to the centre of the tool is called the inside cutting
element of a blade. And the cutting element of a blade which is
closest to the periphery of the tool is called the outside cutting
element. Each cutting element 3 has a substantially cylindrical
shape. The cutting elements 3 are mounted in the blades 2.
[0041] Each cutting element 3 is composed of material based on
various metals including, for example, tungsten carbide (WC).
[0042] In a first embodiment, the metal-based material, with or
without tungsten carbide, is impregnated with synthetic diamond, or
even natural diamond, grains of varying sizes, ranging for example
from 0.2 mm to 2 mm. A tool provided with cutting elements
according to this first embodiment is called an "impregnated
tool".
[0043] In a second embodiment, illustrated in particular in FIG. 4,
a layer of polycrystalline diamond compact, PDC, 32 is situated on
the face of a stud 31 made of case-hardened tungsten carbide. This
layer of PDC comprises a small quantity of metal so as to ensure
its shock-resistance. A tool provided with cutting elements
according to this second embodiment is called a "PDC tool".
[0044] The cutting elements of the impregnated tools and PDC tools
are very hard and thus make it possible to drill rocks of variable
hardness and in particular very hard rocks. The cutting elements
are suitable for breaking rocks by shearing, which also makes them
suitable for drilling in soft rocks.
[0045] The body 12 and the blades 2 of the bit are for example made
of steel or infiltrated WC. They are preferably made of steel as
this material is more resistant than infiltrated WC. Steel
therefore allows more varied geometries of the bit, making it
easier to adapt to the ground to be drilled.
[0046] Moreover, the blades 2 are arranged on an external annular
crown of the front face 1. A space 4 is thus situated approximately
at the centre of the front face 1. This space 4 is situated
approximately at the intersection of the planes of the blades. This
space is delimited by the inside cutting elements of each blade.
When the bit is driven into the rock while rotating, a
substantially cylindrical core 10 is formed in this space 4.
[0047] Moreover, the bit comprises an evacuation cavity 5 situated
between two adjacent blades 2. This evacuation cavity 5 is suitable
for evacuating the core towards the periphery of the tool. The
evacuation cavity 5 is delimited by two lateral surfaces 6 and a
clearance surface 7. The lateral surfaces are substantially
parallel, even merged, with the lateral surfaces of the two blades
adjacent to the cavity. The angle between the adjacent blades,
between which the cavity is formed, is for example comprised
between 45.degree. and 90.degree.. This angle is a function of the
diameter of the tool and that of the core formed. The clearance
surface 7 is set back with respect to the front face 1. The
clearance surface can be seen particularly well in FIG. 2. The
clearance surface 7 extends from the space 4 to the periphery of
the bit. The base of the space 4 is situated in the cavity 5. The
clearance surface 7 rises towards the rear of the bit, and extends
along the tool guard. Thus, the clearance surface 7 allows the core
10 to be guided simultaneously towards the periphery of the bit
(which is facilitated by centrifugal force) and towards the rear of
the bit (which is facilitated by the forward movement of the tool
and by the drilling mud) in order to evacuate it into the well.
Once the core is evacuated from the cavity 5, it rises with the
drilling mud to the earth's surface.
[0048] Moreover, the bit comprises a breaking device 11, suitable
for causing the core to break by shearing. The breaking device 11
is situated on the clearance surface 7 of the cavity 5, close to
the centre of the bit. The breaking device 11 is for example fixed
onto this clearance surface 7, for example by crimping. During the
formation of the core, the length/diameter ratio of the core
increases. The longer the core becomes, the more the latter
weakens. Therefore a small lateral pressure is sufficient to cause
it to break. The breaking device 11 can therefore be any device
which is capable of producing such a lateral pressure. The breaking
of the core occurs when the core attains a length which is
determined by the depth of the space 4 (namely the distance between
the front of the blades 2 and the evacuation cavity 5 at the centre
of the bit) and the positioning of the breaking device 11 with
respect to the axis 13 of the bit.
[0049] The breaking device is for example made of an
abrasion-resistant material, for example a metal-based material,
with or without tungsten carbide, diamond impregnated, or of PDC,
or also of ceramic or of a carbide-based material. The breaking
device 11 is for example in the form of a tip. The tip is arranged
according to an axis which is inclined with respect to the axis 13
of the bit, as can be seen in particular in FIG. 2. The angle
between the plane of the tip and the axis of the bit is for example
comprised between 10.degree. and 15.degree..
[0050] The dimensions of the core 10 are limited by the geometry of
the bit, and in particular by the geometry of the space 4 and the
cavity 5.
[0051] Moreover, the bit comprises channels 8, 9, which can be seen
in particular in FIG. 3, which are suitable for conveying drilling
mud, the drilling mud making it possible to cool the bit down and
to raise the rock cuttings up through the well to the earth's
surface.
[0052] The drilling mud also makes it possible to raise the cores
formed in the bit up to the earth's surface.
[0053] Economic investments in the oil industry mean that it must
be possible to realistically describe the geological structure of
wells and reservoirs, for example by having access to the
petrophysical properties (porosity, permeability, etc.) of the
rocks constituting the wells and the reservoirs. These properties
are not uniform in any reservoir, but depend on the geological
structures which constitute it. This results in reservoir
heterogeneity. Knowledge of the reservoir involves the
determination of such heterogeneities. The characterization of
wells and reservoirs makes it possible to offer assistance in
deciding on the evolution of development of the deposit and more
generally, it makes it possible to provide assistance as regards
the exploitation of the deposit and the drilling of wasteland.
[0054] In the case of wells of great depth (typically 5-6 km), the
pressures and temperatures at the bottom of wells are such that it
is impossible to carry out standard characterizations such as
standard loggings or corings. In fact, the electronics used for
loggings is not resistant to high pressures (7800 bar or more) and
high temperatures (150.degree. C. or more). In addition, the
standard coring is very restricting as it assumes that the core
obtained is raised to the surface every 10 to 40 m of drilling.
[0055] Also, it is particularly useful to be able to continuously
raise to the surface the cores formed by the bit according to the
invention in order to be able to carry out the characterizations of
the wells at the surface. It is also advantageous for the cores to
be of a length which is sufficiently great to be able to extract a
maximum amount of information on the geological structure of the
well.
[0056] In order that the core 10 is raised to the surface as intact
as possible, it is necessary that the breaking device 11 does not
crush it, but shears it.
[0057] It has been observed that the core is sheared and not
crushed when the length/diameter ratio is at minimum equal to 2.
The dimensions of the evacuation cavity 5 must therefore be at
least equal to the greatest dimension of the core, i.e. its
length.
[0058] The cores obtained by the bit according to the invention
have a length of the order of 10 to 100 mm.
[0059] In the case where the rocks to be drilled are hard, the bit
comprises a higher number of blades than in the case where the
rocks to be drilled are softer. The outside diameter of the bit is
for example 21.59 cm (8.5'') for a bit with 8 blades, 15.24 cm
(6'') for a bit with 6 blades and 66.04 cm (26'') for a tool with
36 blades.
[0060] For a bit with 8 blades with a diameter of 21.59 cm, cores
of length 35 mm and diameter 15 mm have been obtained.
[0061] For a bit with 6 blades with a diameter of 15.24 cm, cores
of length 30 mm and diameter 10 mm have been obtained.
[0062] The maximum diameter that can be envisaged for a core is
approximately equal to one-third of the outside diameter of the
bit. In order to be able to exploit the cores satisfactorily, it is
desirable for the diameter of the core to be at minimum equal to 5
mm.
[0063] Moreover, the presence of a core at the centre of the bit
has a stabilizing effect on the bit. The greater the diameter of
the cores, the more stable the bit during drilling.
[0064] Moreover, the cylindrical shape of the core makes it
possible to provide a directional reference, the axis of the core
corresponding to the axis of the well drilled.
[0065] The core 10 is sheared by the breaking device 11 of the bit,
then evacuated in cavity 5 towards the periphery of the bit then
raised up through the well to the earth's surface with the drilling
mud.
[0066] The bit comprises for example a number of channels 8, 9
supplying drilling mud, equal to the number of blades. The channels
8, 9 open out onto the front face 1 of the bit.
[0067] One of the channels 9 opens into the cavity 5 close to the
centre of the bit and the breaking device 11. This channel 9
facilitates the evacuation of the core in the cavity along the
clearance surface 7 towards the periphery of the bit. During its
evacuation via the cavity, the core is thus steeped in the drilling
mud. This reduces the risk of the core knocking against the lateral
walls 6 or the clearance surface of the cavity is reduced. The core
is therefore less likely to break up.
[0068] The orifices of the other channels 8 are arranged
substantially around an axial crown, as can be seen in particular
in FIG. 3.
[0069] Another embodiment is illustrated in particular in FIG. 5,
which represents a longitudinal cross-section view of the front
face of the bit. FIG. 5 shows the cutting elements 3 mounted on a
blade. Inside the bit, along the axis 13, a core 10 is represented
in the process of being created in the space 4. According to FIG.
5, the dimensions of the space 4 are increased. This allows higher
drilling speeds to be achieved. Moreover, the bit comprises a
component 14 for radially cutting the core. The component 14 can be
situated at the centre of the bit. The component can be arranged
laterally with respect to the space 4. This component is presented,
for example, according to the cutting element 3 described above.
The component 14 is for example mounted in the bit, the rotation of
the bit making it possible to reduce the diameter of the core by
cutting the core with the component 14. The reduction in the
diameter of the core makes it possible not only to raise the core
to the surface more easily, but also to raise the core without
damaging it. Therefore, it is possible to increase the size of the
space 4, and thus guarantee rapid drilling, while keeping a core
intact. By way of example, it is possible to use a bit with 6
blades (6'') having a space 4 with a 20 mm diameter. Starting with
a core diameter of 20 mm, the component 14 makes it possible to
obtain a core of 8 mm.
[0070] The invention also relates to a method for drilling wells
using the bit according to the invention. The method comprises the
steps consisting of: [0071] forming a core at the centre of the
bit, [0072] evacuating the core up through the well to the ground
surface, [0073] recovering the core, for example in a sieve.
[0074] The drilling method also comprises the step consisting of
analyzing the petrophysical properties of the core.
[0075] The drilling method also comprises the step consisting of
analyzing the mechanical properties of the core.
* * * * *