U.S. patent application number 14/668058 was filed with the patent office on 2015-10-01 for drill rig and methods for directional drilling.
The applicant listed for this patent is TREVI S.P.A.. Invention is credited to MARCO ANGELICI.
Application Number | 20150275583 14/668058 |
Document ID | / |
Family ID | 50693904 |
Filed Date | 2015-10-01 |
United States Patent
Application |
20150275583 |
Kind Code |
A1 |
ANGELICI; MARCO |
October 1, 2015 |
DRILL RIG AND METHODS FOR DIRECTIONAL DRILLING
Abstract
A device for measuring inclination is suspended to a cable
passing through a duct formed in the rods of the drill string. A
mechanism for winding and unwinding the cable allows to raise and
drop the measuring device within the lowermost rod, engaging it
with or disengaging from a mule shoe. This is performed without the
need to unscrew the rods and open the string. A valve element may
close the duct through which the cable passes. In one embodiment,
directional drilling is performed supplying low pressure fluid
through tubular rods having a single duct. In another embodiment,
high pressure fluids are supplied through rods having two or more
coaxial ducts.
Inventors: |
ANGELICI; MARCO; (PERUGIA,
IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TREVI S.P.A. |
Cesena |
|
IT |
|
|
Family ID: |
50693904 |
Appl. No.: |
14/668058 |
Filed: |
March 25, 2015 |
Current U.S.
Class: |
175/45 |
Current CPC
Class: |
E21B 47/024 20130101;
E21B 23/12 20200501; E21B 7/02 20130101; E04G 23/0218 20130101;
E21B 7/06 20130101; E21B 3/02 20130101; E21B 23/14 20130101 |
International
Class: |
E21B 7/06 20060101
E21B007/06; E21B 7/02 20060101 E21B007/02; E21B 47/024 20060101
E21B047/024; E21B 3/02 20060101 E21B003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 2014 |
IT |
TO2014A000251 |
Claims
1. A drill rig for directional drilling, comprising: a
self-propelled vehicle (10); a drilling mast (11) carried by the
self-propelled vehicle; a top-drive rotary head (12), translatable
along an axis (x) parallel to the mast (11), the head having a
rotatable part (12c) rotationally drivable around said axis and
defining a through cavity (13), and a rotationally stationary part
(12a); a string of threadedly coupled tubular rods (14) having
respective axially extended communicating cavities (15) and
defining altogether at least one duct adapted to convey at least
one fluid to at least one bore (18) obtained in a bottom element of
the string, wherein the string comprises at least one upper tubular
rod (14a) lockable in the through cavity (13) of the rotatable part
(12c) of the rotary head; at least one fluid supplying device (23,
123, 124) idly mounted for rotation on a rod (14b) located below
the rotary head, for supplying at least one fluid through the duct
(15); a boring tool (16) mounted at the bottom of the string (14)
of rods; a device (40) for measuring inclination suspended by a
cable (22) passing through the duct (15) formed by the rods; a
winding and unwinding mechanism (31) for moving the cable (22); a
mule shoe assembly (17, 28), comprising a guiding surface (28)
integral to the device (40) and a key member (17) within a bottom
rod (14c) of the string, adapted to engage the guiding surface (28)
and guide the device in a desired orientation with respect to the
bottom rod (14c); at least one valve member (30), associated with
the duct (15), and mounted on the string above said at least one
fluid supplying head and above the top-drive rotary head, the valve
member being capable of reaching a closure position closing the
duct and an open position opening the duct.
2. The drill rig of claim 1, wherein the valve member (30) is an
annular valve idly mounted for rotation about the axis (x) above an
upper end of a top rod (14a) of the string.
3. The drill rig of claim 2, wherein the annular valve (30) is
mounted on the upper end of the top rod (14a) through the
interposition of a swivel connector (19), the swivel connector
having an inner tubular element (19b) having a through axially
extending cavity (20) which is communicating and aligned axially
and rotationally integral with the inner cavity of the upper rod
(14a); an outer tubular element (19a) which is mounted rotationally
idle to the inner tubular element (19b) and is integral with the
annular valve (30).
4. The drill rig of claim 3, further comprising an anti-rotation
element (21) which engages a rotationally stationary part (12a) of
the rotary head (12) and the outer tubular element (19b) of the
swivel connector to maintain the outer tubular element (19b)
rotationally stationary.
5. The drill rig of claim 2, wherein the annular valve (30) is a
pneumatically operated pinch valve.
6. The drill rig of claim 1, wherein the rods of the string have a
single central duct (15) and wherein the apparatus comprises a
single fluid supplying device (23), mounted below the rotary head,
for supplying a fluid through the single duct (15).
7. The drill rig of claim 1, wherein: the upper tubular rod (14a)
which is lockable to the rotatable part (12c) of the rotary head
has a single, axially extending through cavity; the string
comprises a plurality of tubular dual-passage rods (14b, 14c),
wherein each dual-passage rod comprises two coaxial tubes which
have a central, axially extending cavity communicating with the
through cavity of the upper tubular rod (14a) so as to define
altogether a first central duct (15) capable of conveying a fluid
to at least one bore (18) obtained in a bottom element of the
string; an axially extending annular cavity communicating with the
annular cavities of the other dual-passage rods so as to define
altogether a second peripheral duct (151) adapted to convey a fluid
to at least one bore (18a) obtained in a bottom element of the
string; two fluid supplying devices idly mounted for rotation on
one or two dual-passage rods mounted below the rotary head: a first
fluid supplying device (123) for supplying a fluid through the
peripheral duct (151), and a second fluid supplying device (124)
for supplying a fluid through the central duct (15); and wherein
the valve member (30a) is associated with the central duct (15) and
is mounted above the second fluid supplying device (124).
8. A method of performing directional drilling, comprising the
steps of: performing a directional drilling in a soil by means of
the drill rig of claim 1, supplying a drilling fluid in the duct
(15) through the fluid supplying device (23); interrupting the
supply of drilling fluid and stopping the motion of the rotary head
and the string of rods; bringing the at least one valve member (30,
30a) into open position; without unscrewing the rods to open the
string, lowering the inclination measuring device (40) into the
duct (15), bringing the mule shoe assembly (17, 28) to an engaged
condition so as to orient the inclination measuring device (40) in
a desired orientation with respect to the bottom rod (14c) of the
string; measuring the inclination of the bottom rod by means of the
device (40); lifting the device (40) by means of the cable (22) so
as to disengage the mule shoe assembly and rotationally release the
device (40) from the string; optionally, performing maneuvers to
correct the inclination of the string; bringing the at least one
valve member (30, 30a) into the closed position; resuming drilling
and supplying drilling fluid through the duct (15).
9. The method of claim 8, wherein the step of bringing the valve
member (30, 30a) into the closed position is preceded by the step
of completely removing the measuring device (40) from the string of
rods, pulling the device (40) upward by rewinding the cable (22),
without unscrewing the rods of the string.
10. The method of claim 8, wherein the step of bringing the valve
member (30) into the closed position is performed by hermetically
closing the valve member (30) around the cable (22), and the
subsequent step of resuming the drilling is performed keeping the
measuring device (40) suspended to the cable (22) inside the duct
(15), simultaneously keeping the valve member element (30)
rotationally stationary.
11. A method of performing directional drilling, comprising the
steps of: performing a directional drilling in a soil by means of
the drill rig according to claim 7, supplying a drilling fluid in
the second peripheral duct (151) through the second fluid supplying
device (124); interrupting the supply of drilling fluid and
stopping the movements of the rotary head and the rod string;
bringing the valve member (30a) into the open position; without
unscrewing the rods to open the string, lowering the inclination
measuring tool (40) into the first central duct (15), bringing the
mule shoe assembly to an engaged condition so as to orient the
measuring device in a desired orientation with respect to the
bottom rod (14c) of the string; measuring the inclination of the
bottom rod by means of the device (40); lifting the device (40) via
the cable (22) so as to disengage the mule shoe assembly and
rotationally release the device from the string; optionally,
performing maneuvers to correct the inclination of the string;
resuming the drilling and the supply of drilling fluid in the
second duct (151) through the second fluid supplying device (124);
upon completion of the drilling, completely removing the device
(40) from the rod string, pulling the device upward by rewinding
the cable (22), without unscrewing the rods of the string; bringing
the valve member (30a) into the closed position so as to close the
first central duct (15); lifting the string of rods while supplying
a consolidating fluid in the first central duct (15) through the
first fluid supplying device (123).
Description
TECHNICAL FIELD
[0001] The present invention pertains to the field of civil
engineering and relates to a drill rig and methods for performing
directional drilling in the ground. The drilling operations are
aimed, particularly but not exclusively, at executing jet grouting
consolidations.
BACKGROUND ART
[0002] With soil perforations known as "directional drillings",
deviations are checked at certain phases of the drilling.
Corrections are consequently made either to keep the axis of the
drilling within certain limits of deviation from the desired
theoretical axis, or to keep a given trajectory of the drilling
according to design requirements.
[0003] In order to detect the inclination during a drilling step, a
known method provides for mounting a device for detecting
inclination fixedly secured to the bottom of the drill string. A
number of electrical connections have to be made as new drill pipes
are added, to extend a conductor line from the device up to a power
supply on ground surface. Unless special shock absorbers are used,
this method does not preserve the device from shocks and vibrations
transmitted from the drill.
[0004] Another known system (FIG. 1) provides that a tool 40 for
measuring inclination is periodically introduced and lowered
through the hollow rods of a drill string 14. Inclination is
typically measured every 3-6 meters as the drilling proceeds.
According to established practice in oilfield applications, the
device for measuring inclination may be of the gyroscopic type, or
of the electromagnetic accelerometer, usually including a compass
associated with an inclinometer. A known method of this type uses a
winch to lower the inclination measuring device 40 within the rods.
The measuring device is suspended by a steel cable 22 containing an
insulated electrical conductor. Whenever the inclination is to be
measured, the drilling must be stopped, the drill string must be
opened by unscrewing the rods, and the measuring device must be
introduced through the inner cavity of the rods. A device known in
the field as a "mule shoe" allows to orient the measuring device
according to a known direction, which coincides with the direction
of the lowermost element of the drill string (usually built in
non-magnetic steel) and the drilling bit integral with it.
[0005] In other instances, where real-time inclination data are not
required, the device may be lowered by means of a standard cable
without an electrical conductor, and the inclination data may be
downloaded from a buffer of the device after it has been brought
back up to the surface. However, the above method is unsuitable if
inclination data are needed in real time, for example, to promptly
correct the direction of the drilling.
[0006] A typical conventional method, regardless of the type of
instrumentation used, involves a sequence of operating steps
comprising:
a) interrupting the supply of the drilling fluid and stopping the
drilling; b) opening of the drill string, by unscrewing the rods;
c) lowering the measuring device until the "mule shoe" is engaged;
d) measuring the inclination by orienting the string through a
clamp, since the rotary in this step is not connected to the
string; measurement of the inclination may be performed at 4
different angular positions spaced 90.degree. from each other; e)
retrieving the measuring device back up to surface; f) closing the
drill string by re-screwing the rods.
[0007] For the cases requiring the inclination to be corrected,
step f) must be followed by a subsequent step in which a deviated
bore section is drilled, thereby correcting the inclination of the
borehole. Then, before resuming drilling, it is necessary to repeat
the sequence of steps a) to f).
[0008] U.S. Pat. No. 3,718,194 (to Hering et al.) discloses an
apparatus for orienting a borehole device in a borehole within the
context of drilling oil wells. An orienting tool is positioned in a
drill pipe and provided with a conductor cable to the surface. An
instrument in the tool provides a measurement for indicating the
orientation (the so-called "high side") of the tool in the
wellbore. Instrument measurements are transmitted by the conductor
cable to the surface for surface read-out. A surface indicator
provides the readout in a manner which is indicative of degrees of
rotation of a reference on the tool to the right or left of the
high side of the hole. The tool may then be rotated and subsequent
readings taken to determine the position of the tool until the bit
is oriented, whereupon drilling proceeds. Such readings can be
taken continuously throughout the drilling operation.
[0009] U.S. Pat. No. 2,207,505 (to Bremner et al.) discloses a mule
shoe tool for orienting a drill pipe in the bore of an oil
well.
SUMMARY OF THE INVENTION
[0010] The present invention aims at speeding up a directional
drilling, eliminating some of the steps mentioned herein above.
Another object of the invention is to keep the inclination
measuring device within the string during the drilling while
preserving the device from vibrations and shocks transmitted from
the drill string.
[0011] The above and other objects and advantages, which will be
better understood from the ensuing description, are achieved
according to the invention by methods defined in the appended
claims. According to another aspect, the invention provides drill
rigs for implementing these methods.
[0012] In brief, a device for measuring inclination is suspended to
a cable passing through a duct formed by the cavity of the rods of
the drill string. A mechanism for winding and unwinding the cable
allows to raise and drop the measuring device within the lowermost
rod, engaging it with or disengaging from the mule shoe. This is
performed without the need to unscrew the rods and open the string.
A valve element may close the duct through which the cable passes.
Two embodiments are provided. One embodiment is particularly
suitable for the execution of directional drilling with the supply
of low pressure fluid with tubular rods having a single duct. A
second embodiment is specific for directional drilling with the
supply of high pressure fluids and rods having two or more coaxial
ducts.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] A few preferred but not limiting embodiments of the methods
and drill rig according to the invention will now be described;
reference is made to the accompanying drawings, in which:
[0014] FIG. 1 is a schematic view of a step of measuring the
inclination of a drilling according to the prior art;
[0015] FIG. 2 is a schematic elevation view of a drill rig for
executing perforations intended for jet grouting consolidations
with detection of the borehole inclination, according to an
embodiment of the invention;
[0016] FIGS. 3A, 3B and 3C are schematic views in vertical cross
section, to an enlarged scale, of part of the drill rig of FIG. 2,
in three different operational positions;
[0017] FIGS. 4A and 4B are elevation views, as viewed from to two
different angles, of a device for measuring inclination with a
"mule shoe" guide for its angular orientation;
[0018] FIG. 5 is a partial view of the vertical section, further
enlarged scale, of the lower part of the string of rods shown in
FIGS. 3A-3C;
[0019] FIG. 6 is a schematic cross-sectional view to enlarged view
of a head the supply of fluid in the apparatus of FIGS. 3A-3C;
[0020] FIG. 7 is an enlarged view of a detail of FIG. 3A; and
[0021] FIGS. 8 and 9 are schematic elevational views, in two
different operational conditions, of an apparatus according to a
further embodiment of the invention.
DETAILED DESCRIPTION
[0022] Referring to FIG. 2, a self-propelled vehicle 10 carries a
drilling mast 11, in this example illustrated in an upright or
vertical position. Slidably mounted along the mast 11 is a
top-drive rotary head 12. The rotary head serves to impart rotation
and sliding movement (push-pull) to a string 14 of hollow rods for
carrying out soil perforation or drilling. The rotary head may be
driven by an associated hydraulic motor gear 12b. A boring tool 16
is fixed at the bottom end of the string 14 of rods.
[0023] The general structure of a drilling mast and of the
actuating means of a rotary head are to be considered generally
known. Consequently, the present description will describe in
detail only those elements of specific importance and interest for
the purposes of implementing of the invention. For the construction
of the parts and elements not shown in detail, such as the motor
assembly for driving the rotary head and the drive systems of the
boring tool, reference may be made to any apparatus of known
design. In the description and in the drawings, two different
embodiments of the method are illustrated, which differ mainly in
the level of pressure of the fluid supplied to the string.
[0024] FIGS. 2, 3A-C, 5-7 show an arrangement which is suitable for
operation with a boring tool 16 operating with a drilling fluid at
low pressure, for example air-powered hammers or non-percussive
bits able to work with water pressures not exceeding 50 bars,
approximately. FIGS. 8 and 9 depict an apparatus suitable for
working with a boring tool operatively associated with a high
pressure fluid, for example an in-the-hole hammer powered by high
pressure water or rotation bits such as tricone rock bits, three
(or four) blade drag bits and the like. As an alternative,
asymmetric non-rotating thrust directional bits may be used, or
directional active tools, such as "mud motors". The type of boring
tool may vary depending on the applications.
[0025] For an operational mode with the use of air or low pressure
drilling fluid, the string 14 may comprise a set of tubular hollow
rods 14a-14c which define a central longitudinal axis x and each
have an axially extending inner cavity 15, preferably a cylindrical
cavity coaxial to the longitudinal axis x. As understood here,
terms and expressions indicating positions and orientations, such
as "longitudinal", "axial" or "radial" should be interpreted with
reference to the longitudinal axis x. In the prevailing mode of
use, the x axis is vertical; however, the method is applicable also
for perforations inclined with respect to a vertical direction.
[0026] When the rods are joined, in a manner known per se, the
inner cavities 15 of the rods are axially aligned and
interconnected so as to form together a duct through which a
drilling fluid can be conveyed, such as water or air or a grout
consolidating mixture, according to requirements. The example of
FIGS. 3A-3C shows three rods 14a, 14b, 14c. It is understood that
the total number of rods used may be greater than three, depending
on the depth of the work of consolidation to be carried out.
[0027] The lowermost or bottom hollow rod 14c has one or more
bottom nozzles 18a, in this example, two in number, communicating
with the internal cavity 15, for discharge of drilling fluid. The
boring tool 16 is integral with the lower end of the lowermost
hollow rod 14c.
[0028] In the illustrated example, just above the bottom nozzle 18a
there are provided radially oriented side nozzles 18b, which open
on an outer side surface of the bottom rod. Schematically
designated 18c is a valve element which, under fluid pressures in
excess of a predetermined value, moves so as to occlude the bottom
nozzle 18a and simultaneously open the side nozzles 18b to perform
a jet grouting injection. In other embodiments, the side nozzles
18b can be made in a cylindrical element called a "monitor" which
is mounted immediately above of the boring tool. It should be
understood that this specific use is not intended to limiting and
that the method may also be implemented with different jet grouting
technologies.
[0029] In a manner known per se, the inner cavity 15 of the bottom
14c of the rod provides an internal projection 17 (FIG. 5),
radially protruding towards the inside of the cavity and defining a
predetermined angular position with respect to the central
longitudinal axis x of the string 14.
[0030] The rotary head 12 has an axially extending through cavity
13 and is lockable to the uppermost or top hollow rod 14a. An upper
end 141a of the rod 14a projects above the top of the through
cavity 13 of the rotary head and supports a swivel connector
19.
[0031] The swivel connector 19 (FIG. 7) comprises two coaxial
tubular elements 19a, 19b, rotatable relative to one another by
means of a rolling bearing 19c. The outer tubular member 19a of the
swivel connector is idly mounted for rotation about the uppermost
rod 14a and can be kept rotationally stationary with respect to the
x axis. This may be achieved, for example, by means of a bracket or
arm or other anti-rotation means 21 which engages an outer,
rotationally fixed portion 12a of the rotary head 12 and the swivel
connector 19. Designated at 12c is rotatable portion of the rotary
head 12. The inner tubular member 19b of the swivel connector 19
has an axially extending inner through cavity 20. This cavity is
axially aligned and communicating with the inner cavity of the rod
14a and therefore with the duct 15 formed by the communicating
cavities of the joined rods of the string.
[0032] A cable 22, to which a device (or instrument) 40 for
measuring inclination is suspended, passes through the duct formed
by the through cavities of the rods 15 and the cavity 20 passing
through the swivel connector 19.
[0033] The internal cavity 20 passing through the swivel connector
19 may be occluded by an annular valve 30, preferably a
pneumatically operated pinch valve mounted on the outer, stationary
element 19a of the swivel connector 19. The annular valve 30 is
mounted idly mounted for rotation about the axis x above an upper
end of a top rod 14a of the string and above the top-drive rotary
head.
[0034] The annular valve 30 may comprise a flexible body,
preferably made of rubber, which can be closed by radially
tightening or clamping it around the cable 22. The annular valve 30
may be controlled in opening and closing in different ways (for
example electrically, pneumatically, hydraulically, or manually),
so as to open or seal the passage of the cable 22 and the duct
formed by the rods and the swivel connector 19.
[0035] The device or instrument 40 for measuring inclination is
mounted on a guiding element 29, per se known in the drilling field
as "mule shoe". The guiding element provides a guide 28 for example
in the form of a flared groove, downwardly widening and upwardly
tapering. As the device 40 is lowered into the drill string, the
lower and wider part of the guiding groove 28 meets the inner
projection 17 in the cavity of the lowermost rod and guides the
device 40 downwards, at the same time orienting it in a
predetermined angular position with respect to the x-axis, the
device reaches a stable position in which the inner projection 17
abuts against the upper end 27 of the guiding groove 28.
[0036] According to an embodiment (not shown), the guiding element
29 may be provided with a switch or other switching device (such as
a sensor) that closes an electrical circuit (not shown) when the
measuring device 40 reaches the correct angular position with
respect to the lowermost rod. This way an operator may be sure that
the inclination has been detected correctly.
[0037] The device 40 may include a tracking or guiding sensor or
probe for measuring inclination, for example a Paratrack.RTM. or
TrueTrack device. The measuring device 40 may incorporate an
inclinometer and a compass, such as a triaxial magnetometer,
already used in the field of directional drilling. The selection of
the particular device for measuring inclination is not to be
considered limiting as regards the implementation of the present
method.
[0038] The inner cavities 15 of the rods of the string have an
internal diameter sufficient to ensure easy handling of the
measuring device 40 within the string. For example, the inner
cavities 15 may have an internal diameter between 30 and 100 mm
wide.
[0039] The cable 22 may be a steel cable. Optionally, the cable 22
may contain in its interior an insulated electrical cable (e.g. of
a Camesa cable or the like). Alternatively, the cable 22 may be an
electric cable reinforced on its outside.
[0040] Schematically designated 23 in FIG. 6 is a fluid supplying
head (or top swivel, or rotary air/water swivel), in this example
mounted on an intermediate rod element 14b of the string. The head
23, known per se, supplies a drilling fluid (air, water, polymer
additives, bentonite, grout mixtures) that is introduced in the
central cavity 15 through one or more lateral inlet openings 24
formed in the rod element 14b. The supplying head 23 is idly
mounted for rotation on rod element 14b through one or more rolling
bearings 23a.
[0041] A tubular body 26, containing a swivel valve member 30a able
to withstand high pressures (e.g. in the order of 300-500 bars),
may be mounted in the drill string above the fluid supplying head
23 in order to selectively occlude the central duct 15.
[0042] The drill rig comprises a winch 31 (FIG. 2) or another
winding and unwinding mechanism for moving the cable 22 and the
measuring device 40. In the illustrated example, the winch 31 is
positioned immediately behind the mast 11.
[0043] FIG. 3A shows an arrangement for measuring inclination of
the drilled borehole. The measuring device 40 is located in the
lowest position reached within the bottom rod 14a. In this
position, the device 40 is oriented in an angular position
determined by engagement of the guiding element 29 with the
internal projection 17.
[0044] During a drilling step (FIG. 3B), the measuring device 40
can be held within the string of rods, either in a condition where
the mule shoe is engaged, or suspended from the cable 22 in a
raised position above the internal projection 17. When suspended,
the measuring device 40 is not integral with the bottom rod 14c,
and therefore is not negatively affected by vibrations and shocks
transmitted by the boring tool 16 to the bottom rod of the string.
It is convenient to perform drilling with the measuring device 40
engaged in the mule shoe because this mode allows to obtain
inclination data in real time. It will be understood that this
operating mode is only applicable when the boring tool is not a
percussive tool.
[0045] The annular valve 30 is kept closed around the cable 22
during the steps of drilling and/or injecting fluid through the
drill string, to prevent the escape of fluid from the top of the
string, particularly from the top of the duct formed by the
communicating cavities of the rods. When the drill string is
rotated integrally with the rotary head, the valve 30 is kept
rotationally stationary due to the swivel connection 19, which is
idly mounted for rotation on the rotary head 12. The measuring
device 40, suspended from the cable 22, is rotationally stationary
with respect to the rotating string. As a result of the tightening
of the annular valve 30 on the cable 22, the measuring device 40 is
vertically or axially constrained to the annular valve 30, and
follows the movements of axial translation of the rotary head 12
along the mast 11.
[0046] When the inclination of the drilled borehole is to be
measured, a sequence of operating steps may be as follows. [0047]
The supply of drilling fluid is interrupted and the drilling is
stopped. [0048] Without needing to unscrew the rods to open the
string, the inclination measuring device 40 may be let down to
lowest position it may reach inside the bottom rod 14c until the
device 40 engages the internal protrusion 17. Advantageously, the
device 40 is already present in suspended condition within the
string. By engaging the internal projection 17, the guiding element
29 (FIG. 3A) orientates the measuring tool 40 in a given angular
position. [0049] The inclination of bottom rod 14c is measured by
the device 40. The inclination may be advantageously measured
without releasing the rods from the rotary head. The methods of
measuring the inclination are not limiting. For example,
measurements may be taken in 4 different angular positions spaced
90.degree. from one another, in accordance with the methods
disclosed in patent publication US 2013/020129 A1, incorporated
herein by reference in its entirety. [0050] After measuring the
inclination, the device 40 may be raised again so as to disengage
it from the internal projection 17 release it rotationally from the
string 14. The measuring device may be fully recovered, i.e. pulled
out of the string without opening it. Alternatively, the device 40
may be kept suspended within the string (FIG. 3B).
[0051] The drilling operations may then be resumed or steps may be
followed to correct the inclination of the borehole. To correct the
inclination, the measuring device 40 is preferably suspended within
the string to protect it from the vibrations generated by the
downhole boring tool. Maneuvers for correcting inclination are
known in the art, and therefore will not be described herein.
Suffice it to mention that inclination correction usually provides
a further sinking or penetration of the boring tool for a short
length, of the order of some tens of inches, without setting the
string in rotation, so as to deviate appropriately the direction of
the drilling, depending on the measured values of inclination. In
this step, the device 40 may remain engaged in the mule shoe.
[0052] The annular valve 30 may be closed to seal the top of the
string when the measuring device has been pulled out of the string.
During rotation of the string, if the measuring device 40 has not
been completely removed, the annular valve 30 is locked in the
closed position around the cable 22, ensuring hydraulic seal.
[0053] It will be appreciated that the present method allows to
measure the inclination of the drilling without the need to unscrew
the rods in order to open the string and introduce the inclination
measuring device in the string, and without having to re-screw the
rods once the inclination has been measured and the measuring
device has been withdrawn from the string.
[0054] It will also be appreciated that, due to the above described
arrangement, it is possible to supply pressurized fluid in order to
perform the drilling without the need to remove the measuring
device from the string, and, unless a percussive boring tool is
used, without disengaging the mule shoe.
[0055] The mechanism 31 for winding and unwinding of the cable 22
may be equipped with automatic devices that facilitate the
operator's work. The rig may be equipped with a control system that
stores the depth reached by the measuring device 40.
[0056] The control system may be set to automatically slow down the
winch before the measuring device reaches a preset depth where it
has been programmed to measure the inclination. Advantageously, the
control system can be set to cause the measuring device 40 to raise
automatically up to a predetermined level just before the drilling
restarts, in order to protect the device from the vibrations
induced by the boring tool.
[0057] FIG. 3C shows the arrangement of the apparatus during a jet
grouting step. Once the drilling is completed, and after the
measuring device has been extracted out of the string 40, the duct
15 can be occluded or sealed tightly above the fluid supplying head
by rotating the rotatable valve element 30a in the closed position
(FIG. 3C). Then, the string may begin to raise and perform a jet
grouting injection in the lift mode, using the fluid supplying head
23 to pump pressurized grout (for example at 300-500 bars) through
the central duct 15. The valve element 18c, which is activated
automatically due to the pressure, will occlude the bottom holes
18a and force the fluid to exit from the radially oriented side
nozzles 18b.
[0058] Referring now to FIGS. 8 and 9, there is illustrated an
embodiment of a method of performing directional drilling with a
drill rig working with a high pressure fluid. The drill rig
comprises a top-drive rotary head 12 similar to that described with
reference to FIGS. 2 and 3A-3C, lockable to a drill string 14. The
string includes a tubular top rod 14a, in this example with a
single passage or through cavity 15, and a number of dual passage
rods 14b, 14c (two in number in the illustrated example).
[0059] Fixed to the bottom rod 14c is a boring tool 161 capable of
operating with a drilling fluid supplied at high pressure. The
boring tool 161 may for example be a an in-the-hole hammer powered
by high pressure water (known as "Wassara.TM.") or a rotating bit
(a tricone, or a three blade drag bit) or an asymmetric directional
bit (or "slant face bit") to be supplied with fluid at high
pressure.
[0060] The top rod 14a is lockable in the passage 13 of the
rotating part 12c of the rotary head in a manner similar to that
described in relation to FIGS. 2 and 3A-3C, except for the fact
that for the execution of soil consolidation with fluids at high
pressure, an annular valve of the type indicated at 30 in FIGS.
3A-3C is not used.
[0061] The dual passage rods 14b, 14c each comprise two coaxial
pipes: an inner pipe 141b, 141c, with an internal diameter
sufficient to ensure the passage of a device 40 for measuring
inclination, and an outer pipe 142b, 142c. Each inner pipe has a
central cavity 15. The central cavities 15 of the rods are axially
aligned and interconnected so as to form together a first central
(or more internal) duct through which a fluid can be conveyed, in
this example a grout consolidating mixture.
[0062] An annular gap forming a second duct 151 is defined between
the outer pipes 142b, 142c and inner pipes 141b, 141c is defined
the peripheral (or external), through which drilling fluids can be
made to pass, typically water or air. These fluids are then
injected out of the string through one or more bottom nozzles 18a
provided in the boring tool 161. The drilling fluids may be
introduced into the peripheral duct 151 through a supplying head
123 idly mounted for rotation about the outer pipe 142b, for
example by means of one or more rolling bearings (not shown)
similarly to the fluid supplying head 23 shown in FIG. 6. The fluid
supplying head 123 is arranged below the rotary head 12, in
proximity to and in fluid communication with one or more inlet
lateral openings 123a formed in the outer pipe 142b.
[0063] A consolidating mixture, such as a grout mixture, can be
introduced into the central duct 15 within the inner pipes 141b,
141c by a fluid supplying head 124. The head 124 is idly mounted
for rotation about the outer pipe 142b, similarly to the fluid
supplying head 123. The fluid supplying head 124 is mounted just
below the rotary head 12, and provides fluid communication between
an external fluid source (not shown) and the central duct 15 within
the inner pipe 151.
[0064] In proximity to and in fluid communication with one or more
inlet side openings 124a formed in the outer pipe 142b and with
inlet side openings 124c formed in the inner pipe 141b. The grout
is injected out of the string through one or more side nozzles 18b.
The side nozzles 18b can be formed in a monitor mounted immediately
above of the boring tool.
[0065] The fluid supplying heads 123 and 124 may be conveniently
mounted on a same dual passage rod, as in the example illustrated.
In other embodiments (not shown), the two fluid supplying heads may
be mounted on two distinct rods.
[0066] In the embodiment illustrated in FIGS. 8 and 9, the head 124
for supplying the consolidating mixture is located above or
upstream of the head 123 for supplying drilling fluids.
[0067] According to an alternative embodiment (not shown), the two
fluid supplying heads 123 and 124 may be constructed as a single
unit.
[0068] The swivel connector 19, visible in FIGS. 8 and 9, may be
omitted.
[0069] A tubular body 26 containing a rotatable valve member 30a,
capable of withstanding high pressures (e.g. in the order of
300-500 bars), may be mounted in the drill string above the fluid
supplying head 124 to occlude the central duct 15 when this is
required.
[0070] The device 40 for measuring inclination may be introduced
into the string during any operational step, for example even
during the drilling. The device 40, suspended from a cable 22 in a
manner similar to that described with reference to FIGS. 2, 3A-C,
may be lowered into the central duct 15 until it reaches an inward
projection 17 protruding in the central cavity 15 of the bottom rod
14c to provide angular orientation of the inclination measuring
device 40.
[0071] FIG. 8 illustrates an operating condition in which the
measuring device 40 is suspended in the central cavity 15 and
detached from the bottom rod, in order to preserve the device 40
from vibrations coming from the boring tool. The central duct 15
has a diameter (for example between 30 and 100 mm wide) sufficient
to ensure easy handling of the device 40 within the string. The
rotatable valve member 30a is rotated into a position in which it
leaves the central duct 15 open and allows the passage of the cable
22.
[0072] During a drilling step, the tool 40 may be left inside the
string in the suspended and raised condition shown in FIG. 8. In
this event, the mule shoe allows a quick connection of the
measuring device 40 to the bottom rod in order to immediately
achieve inclination data just after a step of correcting the
inclination has been completed.
[0073] When grout has to be injected as the string moves upwards,
after the borehole has been drilled, the measuring device 40 must
be completely removed from the string, The central duct 15 must be
temporarily occluded to prevent the fluid from reaching the top of
the string (FIG. 9). During the injection step, the rotatable valve
member 30a is rotated to close the central duct 15 above the fluid
supplying head 124. Then, the consolidating mixture is supplied
into the central duct 15 through the fluid supplying head 124.
[0074] The second, peripheral duct or cavity 151 may be used to
inject pressurized air, as typically occurs in a dual-fluid jet
process. The central duct 15 may be provided with an automatic
valve, shown schematically at 18c, configured for moving under the
action of pressures in excess of 200-300 bars and putting the
central duct 15 in fluid communication with the side nozzles 18b,
typically made in a monitor.
[0075] Preferably, the peripheral duct 151 can communicate with
both the nozzles of the bottom of the boring tool and the side
nozzles in the monitor.
[0076] It will be appreciated that the embodiment shown in FIGS. 8
and 9 allows to perform, with a same single rig, both the
directional drilling and the following jet grouting operations. The
central duct 15 is advantageously exploited also for guiding and
protecting the inclination measuring device 40 (FIG. 8) while high
pressure drilling fluids are injected through the peripheral duct
151.
[0077] It will also be appreciated that the cable 22 provides a
continuous and perfectly insulated power line which allows power to
be supplied and data collected by the device 40 to be transmitted
even when considerable depths are reached. This allows to dispose
of sealed electrical contacts and quick connection electric
contacts between the rods, which usually increase the electric
resistance and cause electric dispersion, leading to malfunction of
the equipment.
* * * * *