Note: Descriptions are shown in the official language in which they were submitted.
METHODS AND SYSTEMS OF CREATING PRESSURE PULSES FOR PULSE
TELEMETRY FOR MWD TOOLS USING A DIRECT DRIVE HYDRAULIC RAM
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Application
Serial No.
62/782,667 filed December 20, 2018 titled "Magnetic Positioned Sensing Smart
Hydraulic
Cylinder."
BACKGROUND
[0002] Hydrocarbon drilling operations utilize information relating to
parameters and
conditions downhole during drilling. Such information may comprise
characteristics of the
earth formations surrounding the borehole, along with data relating to the
size and
direction of the borehole itself. The collection of information relating to
conditions
downhole is termed "logging."
[0003] In the early hydrocarbon prospecting, drilling operations and logging
operations
where separate and distinct operations. Logging a well required removing or
"tripping"
the drilling assembly to insert a wireline logging tool to collect the data.
As drilling
technology advanced, aspects of logging tools became part of the drill string,
and
specifically the bottom hole assembly (SHA), such that data could be collected
contemporaneously with the drilling processing.
[0004] Systems for measuring conditions downhole, such as the movement and
position
of the drilling assembly, have come to be known as "measuring-while-
drilling"techniques,
or "MWD''. Similar techniques, concentrating more on the measurement of
formation
parameters, have come to be known as "logging-while-drilling" techniques, or
"LVVD". The
terms MWD and LWD often are used interchangeably. For purpose of this
disclosure, the
term MWD will be used with the understanding that this term may encompass both
the
collection of formation parameters and the collection of information relating
to the
movement and position of the drilling assembly.
[0005] In MWD systems, sensors in the drill string measure drilling parameters
and in
some cases formation characteristics. While drilling is in progress, data from
these
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sensors is continuously or intermittently transmitted to a surface detector by
some form
of telemetry. Most MWD systems use the drilling fluid (or mud) in the drill
string as the
information carrier, and are thus referred to as mud-pulse telemetry systems.
In positive-
pulse systems, a valve or other form of flow restrictor creates pressure
pulses in the fluid
flow by adjusting the size of a constriction in the drill string (e.g.,
positive-pressure
system). In negative-pulse systems, a valve creates pressure pulses by
releasing fluid
from the interior of the drill string to the annulus, bypassing the drilling
bit (e.g., negative-
pulse systems). In both system types, the pressure pulses propagate at the
speed of
sound through the drilling fluid to the surface, where they are detected by
various types
of transducers.
[0006] Some related art positive-pulse systems create the positive pulse by
actuating a
pilot valve, and the pilot valve in turn actuates a main poppet valve to cause
a temporary
flow restriction and/or blockage and thus an increased pressure pulse. Such
systems
have reliability issues in that particles in the drilling fluid tend to
accumulate in and around
the pilot valve, which degrades performance of the pilot valve. Eventually the
particle
accumulation in and around the pilot valve disables the pilot valve, and thus
disables the
ability to create pulses.
SUMMARY
[0007] One example embodiment is a method of creating pressure pulses within a
drill
string during drilling operations, the method comprising moving a poppet of a
pulser
system within a measuring while drilling (MWD) tool. Moving of the poppet may
include:
activating, by a motor controller, an electric motor and thereby turning a
motor shaft;
turning a threaded shaft by rotation of the motor shaft; translating a ball
screw nut along
the threaded shaft responsive to turning the threaded shaft, the ball screw
nut telescoped
over the threaded shaft, and the ball screw nut rigidly coupled to a linear
positioner;
translating a piston rod within a cylinder housing by the linear positioner
responsive to
translating the ball screw nut; and thereby moving the poppet coupled to the
piston rod,
the movement of the poppet relative to a valve seat; counting, by the motor
controller
during the activating, pulses from a sensor that senses full or partial
rotations of the motor
shaft, the counting creates a pulse count value; and ceasing activation of the
electric
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motor when the pulse count value meets or exceeds a set point pulse count
value
proportional to a predetermined travel distance of the poppet.
[0008] Another example embodiment is a pulser system for a measuring-while-
drilling
(MWD) tool, the pulser system comprising a poppet assembly, a linear actuator
assembly,
and an electric drive assembly. The poppet assembly may comprise: a poppet; a
piston
rod defining a first end and a second end, the first end coupled to the
poppet; and a
cylinder housing defining an internal diameter, the second end of the piston
rod
telescoped within the internal diameter of the cylinder housing, and the
cylinder housing
and second end of the piston rod form a first seal. The linear actuator
assembly may
comprise: a barrel defining an inside diameter, a first end, and a second end,
the first end
of the barrel coupled to the cylinder housing; hydraulic fluid within the
inside diameter of
the barrel between the first seal and a second seal on the second end of the
barrel; a
linear positioner defining a first end and a second end, the first end of the
linear positioner
coupled to the second end of the piston rod, and the linear positioner
submerged in the
hydraulic fluid; a ball screw nut coupled to the second end of the linear
positioner and
submerged in the hydraulic fluid; a threaded shaft submerged in the hydraulic
fluid, the
threaded shaft threaded through the ball screw nut; and an electric motor
defining a motor
shaft and stator windings submerged in the hydraulic fluid, the motor shaft
coupled to a
connection end of the threaded shaft. The electric drive assembly may
comprise: a motor
controller electrically coupled to the stator windings; and the motor
controller configured
to move the poppet relative to the electric motor by selectively activating
the motor shaft
to turn in either a first direction or a second direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] For a detailed description of example embodiments, reference will now
be made
to the accompanying drawings (not necessarily to scale) in which:
[0010] Figure 1 shows a well during drilling operation in accordance with at
least some
embodiments;
[0011] Figure 2 shows a side elevation view of a pulser system in accordance
with at
least some embodiments;
[0012] Figure 3 shows an exploded perspective view of a poppet assembly in
accordance with at least some embodiments;
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[0013] Figure 4 shows an exploded perspective view of a first portion of a he
linear
actuation assembly, in accordance with at least some embodiments;
[0014] Figure 5 shows a cross-sectional view of an actuation barrel in
accordance with
at least some embodiments;
[0015] Figure 6 shows a side elevation, exploded, and partial cross-sectional
view of a
second portion of the linear actuation assembly, in accordance with at least
some
embodiments;
[0016] Figure 7 shows an exploded perspective view of a second portion of the
linear
actuation assembly, in accordance with at least some embodiments;
[0017] Figure 8 shows a disassembled side elevation view of an electric drive
assembly
in accordance with at least some embodiments; and
[0018] Figure 9 shows a method of creating pressure pulses within a drill
string during
drilling operations, in accordance with at least some embodiments.
DEFINITIONS
[0019] Various terms are used to refer to particular system components.
Different
companies may refer to a component by different names ¨ this document does not
intend
to distinguish between components that differ in name but not function. In the
following
discussion and in the claims, the terms "including" and "comprising" are used
in an open-
ended fashion, and thus should be interpreted to mean "including, but not
limited to... ."
Also, the term "couple" or "couples" is intended to mean either an indirect or
direct
connection. Thus, if a first device couples to a second device, that
connection may be
through a direct connection or through an indirect connection via other
devices and
connections.
[0020] "About" in relation to recited quantity means the recited quantity
within +1- 5%
(five percent).
[0021] "Bore," such as a through-bore or counter-bore, and as it relates to
internal
volumes of various components of a pulser system, shall not speak to the
creation method
of any such bore. Thus a bore may be made by boring (e.g., with a bit), and
the bore may
also be creating by casting the bore, or any other creation method.
[0022] "Poppet" in relation to a system for creating pressure pulses within a
drill string
shall mean a valve member moveable relative to a valve seat, where position of
the valve
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member relative to the valve seat controls a majority of flow of drilling
fluid within a drill
string. A pilot valve that controls less than a majority of flow of drilling
fluid, and is used
to control position of another valve member, shall not be considered a poppet
for
purposes of this specification and claims.
DETAILED DESCRIPTION
[0023] The following discussion is directed to various embodiments of the
invention.
Although one or more of these embodiments may be preferred, the embodiments
disclosed should not be interpreted, or otherwise used, as limiting the scope
of the
disclosure, including the claims. In addition, one skilled in the art will
understand that the
following description has broad application, and the discussion of any
embodiment is
meant only to be exemplary of that embodiment, and not intended to intimate
that the
scope of the disclosure, including the claims, is limited to that embodiment.
[0024] Example embodiments are directed to measuring-while-drilling (MWD)
tools, and
more particularly pulser systems that create pressure pulses in the drilling
fluid within the
drill string. More particularly, example embodiments are directed to a pulser
system as
part of a measuring-while-drilling (MWD) tool that controls position of a
poppet relative to
a valve seat by a direct drive system, thus omitting the pilot valve and its
related problems.
More particularly still, example embodiments are directed to a pulser system
where an
electric motor, submerged in hydraulic fluid within the pulser system, turns a
drive shaft.
By controlling direction of rotation of the drive shaft of the motor, and
number of rotations
of the drive shaft, the position of the poppet of the pulser system is
controlled to create
positive-pressure pulses for mud-pulse telemetry. The specification first
turns to a drilling
system to orient the reader.
[0025] Figure 1 shows a well during drilling operation in accordance with at
least some
embodiments. A drilling platform 102 includes a derrick 104 associated with a
hoist 106.
Drilling of hydrocarbon boreholes is carried out by a string of drill pipes
connected
together by "tool joints" 107 so as to form a drill string 108. In the example
system, the
hoist 106 suspends a top drive 110 that is used to rotate the drill string 108
as the drill
string 108 is being lowered into the borehole. In other cases, the drill
string 108 may be
turned by drive unit on the floor of the drilling platform 102. Connected to
the lower end
of the drill string 108 is a drill bit 114. Drilling is accomplished by
rotating the drill bit 114,
CA 3040707 2019-04-18
either by the top drive 110 rotating the drill string 108, a downhole motor
(not specifically
shown) rotating the drill bit 114, or both. Drilling fluid is pumped by mud
pump 116 through
stand pipe 120, goose neck 124, top drive 110, and down through the drill
string 108 at
high pressures and volumes to emerge through nozzles or jets in the drill bit
114. The
drilling fluid then travels back up the borehole via the annulus 126 formed
between the
exterior of the drill string 108 and the borehole wall 128, through a blowout
preventer (not
specifically shown), and into a mud pit 130 on the surface. On the surface,
the drilling
fluid is cleaned and then circulated again by mud pump 116. The drilling fluid
is used to
cool the drill bit 114, to carry cuttings to the surface, and to balance the
hydrostatic
pressure in the rock formations.
[0026] In boreholes employing mud-pulse telemetry for MWD, downhole tools 134
collect data regarding the formation properties and/or various drilling
parameters. The
downhole tools 134 are coupled to a pulser system 132 that transmits the data
to the
surface. Pulser system 134 modulates a flow resistance of drilling fluid
within drill
string 108 to generate pressure pulses that propagate to the surface at
designated pulse
widths. Transducers, such as transducers 136, 138, and 140, convert the
pressure pulses
into electrical signals for a signal digitizer 142 (e.g., an analog-to-digital
converter). While
three transducers 136, 138, and 140 are illustrated, a greater number of
transducers, or
fewer transducers (e.g., one transducer), may be used. The digitizer 142
supplies a digital
form of the pressure pulses to a computer 144 or some other form of a data
processing
device. Computer 144 operates in accordance with software (which may be stored
on a
computer-readable storage medium) to process and decode the received pulses.
The
resulting telemetry data may be further analyzed and processed by computer 144
or other
computer to generate a display of useful information. For example, a driller
could employ
computer system 144 to obtain and monitor the bottom hole assembly (BHA)
position and
orientation information, drilling parameters, and formation properties (e.g.,
natural
gamma).
[0027] Pulser system 132 in example systems generates positive-pressure pulses
within the drill string 108. Ideally, each and every positive-pressure pulse
created
downhole would propagate toward the surface and be easily detected by a
transducer.
However, drilling fluid pressure fluctuates and contains noise from several
sources (e.g.,
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bit noise, torque noise, and mud pump noise). Bit noise is created by
vibration of the drill
bit during the drilling operation. As the drill bit moves and vibrates, the
drilling fluid exiting
nozzles or jets in the drill bit can be partially or momentarily restricted,
creating a high
frequency noise in the pressure pulses. Torque noise is generated downhole by
the action
of the drill bit sticking in a formation, causing the drill string to torque
up. The subsequent
release of the drill bit relieves the torque on the drill string and generates
a low frequency,
high amplitude pressure surge. Finally, the mud pump 116 creates cyclic noise
as the
positive-displacement elements (e.g., pistons) within the pump force the
drilling fluid into
the drill string. Some drilling systems contain a dampener 152 to reduce noise
associated
with these and other noise sources.
[0028] Figure 2 shows a side elevation view of a pulser system 132 in
accordance with
at least some embodiments. In particular, the example pulser system 132 may be
conceptually, though necessarily physically, divided into a poppet assembly
200, a linear
actuation assembly 202, and an electrical drive assembly 204. The example
embodiments discussed are part of retrievable MWD tool, meaning that the
various
components of the pulser system 132 shown in Figure 2, along with downhole
tools 134
(Figure 1), may be placed into the drill string and removed from the drill
string without the
need of removing the drill string from the borehole. Thus, in example
embodiments the
pulser system 132 may be telescoped within an internal diameter of the drill
string at the
surface and lowered into place. The poppet assembly 200 includes mule shoe 206
that
couples to a landing sub (not specifically shown). The mule shoe 206 holds the
pulser
assembly 132 in a desired orientation within the drill string (e.g., centered
within the drill
string). One or more standoffs, such as standoff 208 associated with the
electrical drive
assembly 204, may likewise help hold the pulser system 132 in the desired
orientation
within the drill string. While the example pulser system 132 is thus held at
opposite ends
(e.g., by the mule shoe 206 on one end and the standoff 208 on the other end),
additional
standoffs may be included at any suitable location along the outside diameter
of the pulser
system 132. In yet still other embodiments, the pulser system 132 may be
included as
part of a non-retrievable MWD system, such that retrieving the MWD system
requires
tripping the entire drill string.
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[0029] Whether part of a retrievable or non-retrievable MWD tool, the example
pulser
system 132 defines an outside diameter. In particular, the poppet assembly 200
defines
an outside diameter 210, and the linear actuator 202 and electrical drive
assembly 204
define a second outside diameter 212. In example systems, the outside
diameters 210
and 212 are smaller than an inside diameter of drill pipe within which the
pulser
system 132 is placed such that drilling fluid flows in the annulus between the
outside
diameter of the pulser systems 132 and an inside diameter of the drill pipe.
More
particularly, in use drilling fluid flows past the electrical drive assembly
204, then the linear
actuator assembly 202, then through apertures 214 of the mule shoe 206. More
particularly, mule shoe 206 has a landing zone 216 and a flow zone 218. The
landing
zone 216 seals against an inside diameter of the landing sub. Drilling fluid
thus flows
along the outside diameter of the mule shoe 206 in the flow zone 218, and then
into the
mule shoe 206 through one or more apertures 214. As will be discussed in
greater detail
below, a poppet within the poppet assembly 200 is selectively moved in
relation to a valve
seat within the poppet assembly to cause selective restrictions of the flow of
drilling fluid,
and thus pressure pulses that then propagate toward the surface (to the right
in Figure
2).
[0030] Figure 3 shows an exploded perspective view of a poppet assembly 200 in
accordance with at least some embodiments. In particular, visible in Figure 3
is the mule
shoe 206, a cylinder housing 300, a hydraulic ram or piston rod 302, and a
poppet 304.
The mule shoe 206 includes a circular outside diameter that includes the
landing zone
216 and apertures 214. The landing zone 214 defines a plurality of annular
channels that
circumscribe the mule shoe 206 and which, in use, house respective seals
(e.g.,
polymeric 0-rings). The example mule shoe 206 has three oblong-shaped
apertures 214,
but the apertures may have any suitable shape and number so long apertures
enable the
drilling fluid to flow from outside the mule shoe 206 to the internal volume
306. Visible
through the apertures 214 is the valve seat 308. In some example embodiments
the valve
seat 308 is defined by a shoulder region between a larger internal diameter
(e.g., at the
location of the apertures 214) and a smaller internal diameter at the distal
end 310 of the
mule shoe 206 (e.g., at the location of the landing zone 218). In some cases
the poppet
(discussed more below) does not actually contact or seal against the valve
seat 308;
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rather, the physical relationship between the valve seat 308 and the poppet
define a
cross-sectional area through which drilling fluid passes. Larger cross-
sectional areas
result in lower resistance to drilling fluid flow, and smaller cross-sectional
areas result in
higher resistance to drilling fluid flow.
[0031] The example poppet assembly 200 further comprises the cylinder housing
300.
As shown by Figure 3, the cylinder housing 300 telescopes within an internal
diameter of
the mule shoe 206. The example cylinder housing 300 defines a distal end 312
and a
proximal end 314. Medially disposed along the cylinder housing 300 is a
rotational
alignment feature 316. The
rotational alignment feature 316 interacts with a
corresponding feature on an inside diameter of the mule shoe 206 to
rotationally align the
cylinder housing 300 (and in some cases the balance of the pulser system)
relative to the
mule shoe 206. Further the rotational alignment feature 316 may also hold the
cylinder
housing 300 (and in some cases the balance of the pulser system) against
rotation
relative to the drill string (not shown). That is, torque loads generated
within the pulser
system (e.g., such as by an electric motor, discussed more below) may exert a
rotational
force, but the rotational alignment feature 316 may hold the system against
rotation. In
the example system the rotational alignment feature 316 is in the form an
increased
diameter portion in shape of a tear drop, with the point of the tear drop
"pointing" toward
the distal end 312, and with the bulbous portion of the tear drop meeting on
the opposite
side the cylinder housing 300 from the point. Other rotational alignment
features may be
used.
[0032] The cylinder housing 300 further comprises a plurality of annular
channels 318
circumscribing the outside diameter of the cylinder housing 300, the annular
channels 318
closer to the proximal end 314. The annular channels 318 may facilitate
connection and
sealing to a barrel (discussed more below) of the linear actuation assembly
202. The
cylinder housing 300 further defines an inside diameter 320. In some example
embodiments the inside diameter 320 of the cylinder housing 300 is uniform
over the
entire length. As will be discussed more below, the inside diameter 320 works
in
conjunction with the piston rod 302 to form a seal that seals hydraulic fluid
within the
pulser system.
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[0033] The cylinder housing 300, which may alternatively be referred to as a
hydraulic
housing, has a dual purpose. The cylinder housing 300 is used to orient the
tool in the
mule shoe 206 as well as being the main cylinder through which the piston rod
302
protrudes. External fluid (e.g., drilling fluid) pressure is applied on the
poppet 304 that is
mounted on the distal end of the piston rod 302. Through the piston rod any
vibration,
tension, and pressure caused by the drilling fluid are applied on the sealing
mechanism
between the piston rod 302 and the cylinder housing, which makes the cylinder
housing
300 an important and vulnerable part of the whole system. Thus, in example
embodiments the cylinder housing 300 is engineered to provide reduced
friction, high
quality sealing methods, and robust design to withstand the vibration,
tension, and
pressure of the drilling fluid. For strength and durability the cylinder
housing 300 may be
built from a strengthened stainless steel alloy, such as NITRONIC-brand
material
available from AK Steel of Wes Chester Township, Ohio. The piston rod 302 may
also be
made from the strengthened stainless steel alloy, such as NITRONIC-brand
materials.
[0034] In some example embodiments, to achieve suitable sealing and yet
maintain
reduced friction, the example system may further include rod wiper 330 and
seals 332
and 334. In example systems, the rod wiper 330 may be disposed at the distal
end 312
of the cylinder housing 300, and the seals 332 and 332 disposed along an
inside diameter
of the cylinder housing 300 at any suitable location, such as near the distal
end. The
various embodiments of the pulser system have an operating temperature between
0 C.
and 175 C., storage temperatures down to -40 C., and an operating pressure
range
between 0 and 20,000 PSI. Thus, in the example embodiments the rod wiper 330
may
comprise a scraper made out of ARLON() 1330 (manufactured by Greene Tweed of
Houston, Tex.) and include 566 FFKM 0-ring. The ARLON() 1330 lubricated PEEK
reduces friction. In the example system the scraper of rod wiper 330 is not
intended to
form a seal; rather, the scraper reduces or prevents particulates from
entering the
hydraulic fluid. The scraper profile helps reject drilling mud from the
internal hydraulic fluid
within the pulser system.
[0035] Seals 332 and 334 in example systems use an MSEO brand assembly
(manufactured by Greene Tweed) that has a scraper-style MSEO jacket made out
of
AVLONO 89 (manufactured by Greene Tweed), which is designed for a high dynamic
Date recue/Date Received 2020-08-20
application. The seals 332 and 334 have finger spring to energize the seal
legs. For this
is a high pressure, high cycle application, backup rings are included to
reduce or prevent
extrusion of the elastomer through the extrusion gap. A solid anti-extrusion
ring (back up
ring) made of ARLON 1000 resists extrusion into the extrusion gap. A hat ring
may be
included to reduce damage to the MSE legs, and the hat ring may be made from
ARLON 1260 (also manufactured by Greene Tweed).
[0036] Still referring to Figure 3, the example poppet assembly 200 further
comprises
the piston rod 302. The piston rod 302 defines a distal end 322, a proximal
end 324, and
a medially disposed sealing region 326. In the example embodiments shown, the
sealing
region 326 is a region having an axial length L of uniform outside diameter.
The sealing
region 326 works in conjunction with the inside diameter of the cylinder
housing 300 to
form the seal to retain hydraulic fluid within the pulser system, while still
enabling the
piston rod 302 to move axially within the cylinder housing 300. In other
cases, either the
piston rod 302, the inside diameter 320 of the cylinder housing 300, or both,
may comprise
annular channels within which seals (e.g., polymeric 0 rings) may be placed to
assist with
the sealing process. In order to reduce friction between the piston rod 302
and the
cylinder housing 300, the piston rod 302 may be high velocity oxygen fuel
(HVOF) coated.
Such an HVOF coating not only reduces frictions, but also increases life of
the piston rod
302. The piston rod 302 and cylinder housing 300 thus form an engineered seal
gland
that improves durability and maintains insulation from, for example, ambient
deep sea
level pressure conditions and high temperature of about 200 Celcius. The
proximal end
324 defines a connector 328 designed and constructed to mechanically couple to
a linear
positioner (discussed more below). The distal end 322 is designed and
constructed to
couple to the poppet 304. In example embodiments, the poppet 304 telescopes
over the
distal end 322 of the piston rod 302, and couples to the piston rod 302 in any
suitable
fashion. The specification now turns to the example linear actuation assembly
204.
[0037] Figure 4 shows an exploded perspective view of a first portion of the
linear
actuation assembly 202, in accordance with at least some embodiments. In
particular, the
portion of the actuation assembly 202 shown comprises actuation barrel 400,
membrane
support member 402, membrane 404, linear positioner 406, and transition member
408.
Each will be addressed in turn. The actuation barrel 400 defines a distal end
410, a
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proximal end 412, and an interior volume 414. The distal end 410 is designed
and
constructed to telescope over, couple to, and seal to the proximal end 314
(Figure 3) of
the cylinder housing 300 (Figure 3). Example internal components of the
actuation
barrel 400 are discussed in great detail below. The membrane support member
402
defines a distal end 416, a proximal end 418, and a medially disposed annular
trough 420.
The annular trough 420 is defined between a seal region 422 (near the distal
end 416)
and a seal region 424 (near the proximal end 418). The annular trough 420
includes a
plurality of apertures 426 that fluidly couple the annular trough 420 to an
internal volume
428 of the membrane support member 402 for purposes of pressure compensation
of the
pulser system. The membrane 404, in example cases a sleeve of polymeric
material
(e.g., Viton), telescopes over the membrane support member 402, and resides
within the
annular trough 420 between the seal region 422 and seal region 424. When the
pulser
system is assembly and filled with hydraulic fluid, the region between the
outside surface
of the annular trough 420 and an inside surface of the membrane 404 is exposed
to the
hydraulic fluid. Drilling fluid enters through aperture 430 through the
actuation barrel 400,
and equalizes pressure as between the drilling fluid within the drill string
and the hydraulic
fluid within the pulser system. The example system can provide pressure
equalization
for pressures of up to about 20,000 PSIA.
[0038] The linear actuation assembly 200 further comprises the linear
positioner 406.
The linear positioner 406 defines a rod 432 and a coupler 434. The rod defines
a distal
end 436 designed and constructed to couple to the connector 328 (Figure 3) of
the piston
rod 302 (Figure 3). In the example embodiment shown the rod 432 defines axial
grooves 438 and 440. In particular, axial groove 438 is disposed on an outside
surface
of the rod 432, and the axial groove 438 runs along the outside surface of the
rod 432
parallel to the central axis 442 of the linear positioner 406. The axial
groove 438 may
take any suitable cross-sectional shape (the cross-section perpendicular to
the central
axis 442), such as square, rectangular, triangular, and the like. While in
some cases a
single axial groove may be used, in the example shown the linear positioner
406 includes
a second axial groove 440. Axial groove 440 runs along the outside surface of
the rod
432 parallel to the central axis 442 of the linear positioner 406, and also
parallel to the
axial groove 438. The axial groove 440 may take any suitable cross-sectional
shape (the
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cross-section perpendicular to the central axis 442), such as square,
rectangular,
triangular, and the like, and axial groove 440 need not have the same cross-
sectional
shape as axial groove 438. In some cases the rod 432 includes four axial
grooves of any
suitable cross-sectional shape. The rod 432 not only holds the linear
positioner 406
against rotation, but also provides a path for hydraulic fluid with the linear
actuation
assembly to be displaced during movement of the linear positioner 406.
Moreover, the
axial grooves enable fluid displacement as the pressure is equalized by way of
the
membrane support member 402 and membrane 404.
[0039] The linear position 406 further comprises the coupler 434. Coupler 434
defines
an outside diameter 444 greater than an outside diameter 446 of the rod 432.
The coupler
434 defines an internal volume 448 defined by an inside diameter (e.g., a
blind bore, not
visible in Figure 4). The internal volume 448 defines a region within which a
threaded
shaft (discussed more below) extends and retracts as the pulser system moves
the
poppet relative to the valve seat. In particular, the coupler 434 couples to a
ball screw
nut such that, as the ball screw nut translates along the threaded shaft, the
ball screw nut
moves the linear positioner 406. During retraction of the poppet away from the
valve seat
(or, alternatively, toward an electric motor), the ball screw nut moves
proximally on the
threaded shaft, and thus a distal portion of the threaded shaft telescopes
into the internal
volume 448 of the coupler 434. Oppositely, during extension of the poppet
toward the
valve seat (or, alternatively, away from the electric motor), the ball screw
nut move distally
on the threaded shaft, and the threaded shaft thus retracts from the internal
volume 448
of the coupler 434.
[0040] Still referring to Figure 4, the first portion of the linear actuation
assembly 202
further comprises the transition member 408. The transition member 408 defines
a distal
end 450 and a proximal end 452. The distal end 450 defines a distal seal
region 454
designed and constructed to couple to and seal within the proximal end 412 of
the
actuation barrel 400. The transition member 408 further defines an annular
ridge 456
that circumscribes a central axis of the transition member 408. The annular
ridge 456
thus defines a distal shoulder region 458 and a proximal shoulder region 460.
When
assembled, the actuation barrel 400 abuts the distal shoulder region 458. In
example
systems, an outside diameter of the actuation barrel 400 and an outside
diameter of the
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CA 3040707 2019-04-18
annular ridge 456 are about the same. Just proximal of the annular ridge 456
resides
another seal region 462 which, as is discussed more below, couples to and
seals against
a mechanical barrel of the second portion of the linear actuation assembly
202.
[0041] The transition member 402 further defines a translation region 464
proximal to
the seal region 462. In example embodiments the translation region 464 defines
an
outside diameter smaller than the outside diameter of the annular ridge 456
(and smaller
than an inside diameter of the mechanical barrel discussed more below). The
translation
region 464 also defines an internal volume 466 by way of an inside diameter.
In example
embodiments, the inside diameter of the translation region 464 is slightly
larger than an
outside diameter 444 of the coupler 434 of the linear positioner 406. As shown
in
Figure 4, when assembled the linear positioner 406 telescopes through the
transition
member 408, and the coupler 434 resides within the translation region 464.
Cutout 468
enables access to the coupler 434 for assembly and disassembly (e.g., access
to set
screws that couple the coupler 434 to the ball screw nut discussed more
below).
[0042] Figure 5 shows a cross-sectional view of the actuation barrel 400 in
accordance
with at least some embodiments. In particular, Figure 5 shows the distal end
410 and the
proximal end 412 of the actuation barrel 400. The actuation barrel 400 defines
the interior
volume 414 between the distal end 410 and the proximal end 412. In particular,
the
interior volume 414 includes through-bore 500. The through-bore 500 in example
embodiments includes a first tab 502 that extends from an internal diameter of
the
through-bore 500 toward the central axis 508. The example through-bore 500
further
comprises a second tab 504 that also extends from the internal diameter of the
through-
bore 500 toward the central axis 508. In some cases, and as shown, the tabs
502 and 504
are disposed at 180 radial degrees apart (e.g., on opposite sides of the
internal diameter
of the through-bore 500). Other arrangements of the tabs 502 and 504 are
possible. In
example embodiments, the tabs 502 and 504 define a cross-sectional shape that
is
complementary to the axial grooves 438 and 440 (Figure 4) of the linear
positioner 406.
When assembled, the tabs 502 and 504 reside within the axial grooves 438 and
440, and
thus serve an example purpose of the enabling translation of the linear
positioner 406
relative the central axis 508, and also holding the linear positioner 406
against rotational
about the central axis 508.
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[0043] The internal diameter of the distal end 410 of the actuation barrel 400
defines an
example set of counter bores (e.g., counter bores 510, 512, and 514). A
shoulder region
is defined between counter bores 514 and 512. An annular groove 516 is defined
between counter bores 512 and 510. The counter bores 510, 512, and 514, along
with
annular groove 516, are designed and constructed to mate with and seal against
the
proximal end 314 (Figure 3) of the cylinder housing 300 (Figure 3). The
internal diameter
414 of the actuation barrel 400 further defines another example set of counter
bores (e.g.,
counter bores 518, 520, and 522. While three counter bores are defined in the
example
system, and single counter bore (e.g., counter bore 522) may be used to lead
to the
through-bore 500. Counter bore 522 defines a region 524 within which the
membrane
support member 402 (Figure 4) and membrane 404 (Figure 4) reside when the
linear
actuation assembly is assembled. In particular, the seals 422 and 424 (Figure
4) of the
membrane support member 402 seal against the inside diameter of the counter
bore 522.
Aperture 526 provides for fluid communication with drilling fluid for pressure
compensation. Finally, the proximal end 412 of the example actuation barrel
400 defines
various features (e.g., annular groove 528 and shoulder 530) designed and
constructed
to mate with and seal to the distal end 450 of the transition member 408.
[0044] Figure 6 shows a side elevation, exploded, and partial cross-sectional
view of a
second portion of the linear actuation assembly, in accordance with at least
some
embodiments. In particular, visible in cross-section is the transition member
408 including
the proximal end 452 and the translation region 464 defining the internal
volume 466.
The example internal volume 466 is defined by a counter bore 600 that extends
from the
distal end 452 and ends at a shoulder 602. Also visible in the cross-sectional
view of the
transition member 408 is the cutout 468. The cutout 468 defines a distal end
604 that
terminates proximally of the shoulder 602, and a proximal end 606 including
tabs 608 that
protrude toward each other. As will be discussed more below, in some cases the
tabs 608
play a role in holding a proximal grommet in place.
[0045] The next example element in the exploded view is a distal grommet 610.
The
distal grommet 610 is a tube or sleeve of polymeric material (e.g., Viton)
that acts as a
bumper or stop for the coupler 434 of the linear positioner 406. In
particular, the distal
grommet 610 defines an outside diameter slightly smaller than an inside
diameter of the
CA 3040707 2019-04-18
counter bore 600, and internal aperture (shown in dashed lines). During
assembly, the
distal grommet 610 is telescoped within the counter bore 600 until the distal
grommet 610
abuts the shoulder 602. The rod 432 of the linear positioner 406 is telescoped
through
the aperture through the distal grommet 610.
During translation of the linear
positioner 406 toward the distal end of the MWD tool (or, equivalently, away
from the
electric motor), a shoulder 611 defined between the rod 432 and coupler 434 of
the linear
positioner 406 may contact the distal grommet 610 in some situations. The
distal
grommet 610, being mode of a polymeric material, has a certain amount of
compressibility
to enable a motor controller in the electric drive assembly (discussed more
below) to
sense increasing torque provided by the electric motor, and stop the electric
motor before
damage occurs to the electric motor or other intervening components (e.g., an
optional
gear box). In particular, the distal grommet 610 can prevent the linear
positioner from
bottoming down when the linear positioner in the "zero" position. In case of
obstruction
in the rod travel, the motor controller can reset itself to zero position and
continue the
programmed cycle. The distal grommet 610 can dampen the backlash so that the
unit
can easily reset at a desired "zero" position.
[0046] Still referring to Figure 6, a portion of the linear positioner 406 is
shown, including
the rod 432 and coupler 434. To the right of the linear positioner 406 is a
ball screw nut
612 threaded over a threaded shaft 614. The example threaded shaft 614 defines
two
threaded regions, including a first pitch zone 616 and a second pitch zone
618. The
thread pitch, and other aspects of the threads, in the first pitch zone 616
are designed
and constructed to work in conjunction with the ball bearings in the ball
screw nut 612.
The threads in the second pitch zone 618 have a smaller pitch (e.g., smaller
distance
between adjacent crests of the threads measured parallel to the central axis
of the
threaded shaft 614). The second pitch zone 618 is designed and constructed to
threadingly couple to a bearing assembly (discussed more below). The ball
screw nut
612 defines external threads 620 designed and constructed to mate with
internal threads
of the coupler 434 (the internal threads not visible in Figure 6). Moreover,
the ball screw
nut 612 defines an aperture through which the threaded shaft 614 (particularly
the first
pitch zone 616) may protrude depending on the axial position of the ball screw
nut 612
along the threaded shaft 614. Assuming the device is assembled, in the
relative
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CA 3040707 2019-04-18
orientation of the ball screw nut 612 and the threaded shaft 614 shown, the
poppet 304
(Figure 3) would be in its closest position to the valve seat 308 (Figure 3).
When the
poppet 304 is withdrawn from its closest position to the valve seat 308, a
portion of the
first pitch zone 616 extends through the ball screw nut 612 into an internal
volume 448 of
the coupler 434.
[0047] Still referring to Figure 6, the next example element is a proximal
grommet 622.
The proximal grommet 622 is a tube or sleeve of polymeric material that acts
as a bumper
or stop for the coupler 434 of the linear positioner 406 similar to the distal
grommet 610,
but at the opposite end of the counter bore 600 of the translation region 464.
In particular,
the proximal grommet 622 defines an outside diameter slightly smaller than an
inside
diameter of the counter bore 600, and internal aperture (shown in dashed
lines). During
assembly, the proximal grommet 610 is telescoped within the counter bore 600
and
resides at the proximal end 452 of the translation region 464. In some cases,
the proximal
grommet 622 has features on an outside diameter that interacts with the tabs
608 to retain
the proximal grommet 622 within the internal volume 466 of the translation
region 464.
Other mechanisms may be used, in addition to, or in place of, the tabs 608 to
retain the
proximal grommet 622 (e.g., fasteners). The threaded shaft 614 is telescoped
through
the aperture through the proximal grommet 622. During translation of the
linear
positioner 406 away from the distal end of the MWD tool (or, equivalently,
toward the
electric motor), a shoulder 624 defined between ball screw nut 612 and the
first pitch zone
616 of the threaded shaft 614 may contact the proximal grommet 622 in some
situations.
The proximal grommet 622, much like the distal grommet 610, has a certain
amount of
compressibility to enable a motor controller in the electric drive assembly to
sense
increasing torque provided by the electric motor, and stop the electric motor
before
damage occurs to the electric motor or other intervening components (e.g.,
optional gear
box).
[0048] The next example component is a bearing assembly 624 that couples to
the
second pitch zone 618 of the threaded shaft 614. As the name implies, the
bearing
assembly 624 holds the threaded shaft 614 centered within a mechanical barrel
(not
shown in Figure 6). Any suitable bearing assembly may be used, such as a low
friction
ceramic bearing.
17
CA 3040707 2019-04-18
[0049] Still referring to Figure 6, the next example component is a flex
coupler 626. The
flex coupler 626 couples to the proximal end of the threaded shaft 614. In the
example
system, the threaded shaft 614 defines a proximal zone 628 defining a flat
surface 630.
The proximal zone 628 telescopes into the flex coupler 626, and couples by any
suitable
mechanism (e.g., a set screw through the flex coupler that seats against the
flat
surface 630). However, any suitable coupling system may be used. In example
embodiments, the flex coupler 626 dampens shock loads across the coupler, such
as by
having a polymeric component between two rigid components. Any suitable flex
coupler
may be used, and in other cases a coupler that does not have a shock reducing
component may also be used.
[0050] In some cases the flex coupler 626 couples the threaded shaft 614
directly to a
motor shaft 632 of an electric motor 634. However, in other cases, and as
shown, a gear
box 636 resides between the threaded shaft 614 and the motor shaft 632. The
example
gear box 636 defines an output shaft 640 and an input shaft 630. The output
shaft 640
is coupled to the connection end (e.g., proximal zone 628) of the threaded
shaft 614. In
the example system, the connection between the output shaft 640 and the
threaded
shaft 614 is provided by the flex coupler 626. The input shaft 638 is coupled
to the motor
shaft 632. In the example system, the connection between the input shaft 638
and the
motor shaft 632 is provided another flex coupler 642. The gear box 636 is
configured
such that rotation of the input shaft rotates the output shaft according to a
gear ratio. An
embodiment of the gear box 636 can be a planetary gear box. Examples can have
a gear
ratio in a range of about 3.7:1 to about 4:1. Having an electric motor in an
approximate
range of 12,000 rpm can give a gear output rotation in a range of about 3,000
rpm. Thus,
one version can increase the output torque about four times while still
maintaining a duty
cycle of about 0.09 seconds, thereby enabling the piston rod 302 to create
pressure
pulses in the drilling fluid having durations of about 0.1 seconds.
[0051] Still referring to Figure 6, the next example component is the electric
motor 634.
The electric motor 634 defines the motor shaft 632 as well as stator windings
644 (visible
through cutout 646 to show the stator windings). In example embodiments the
electric
motor 634 is a brushless direct current (DC) electric motor comprising a
sensor 648 in
operational relationship to the motor shaft 632. The sensor 648 is configured
to sense
18
CA 3040707 2019-04-18
full or partial rotations of the motor shaft 632. The sensor 648 may be of any
suitable
type, such as a Hall-Effect sensor. The stator windings 644, as well as the
sensor 648,
are electrically coupled to the leads 650, and the leads 650 in turn are
electrically coupled
to an electric drive assembly (discussed more below). In example embodiments
the
electric motor 634 is a 480 Watt brushless DC electric motor with a speed
range of about
9,000 RPM to about 12,000 RPM, such as a model number SDSM300 available from
Standard Directional Services Ltd of Calgary, AB, Canada.
[0052] Figure 7 shows an exploded perspective view of a second portion of the
linear
actuation assembly, in accordance with at least some embodiments. In
particular, visible
in Figure 7 is a mechanical barrel 700 and a transition housing 702. The
mechanical
barrel 700 defines a distal end 704 and a proximal end 706. The distal end 704
is
designed and constructed to telescope over, couple to, and seal to the seal
region 462
(Figure 4) of the transition member 408 (Figure 4). The proximal end 706 is
designed
and constructed to telescope over, couple to, and seal to a seal region 710 of
the
transition housing 702. Thus, all the components shown in Figure 6 are
disposed within
an internal volume 708 of the mechanical barrel 700.
[0053] The transition housing 702 defines a distal end 712, a proximal end
714, and a
medial portion 716. The distal end 712 defines a motor coupler 718 designed
and
constructed to mechanically couple to a proximal end of the electric motor 634
(Figure 6).
For example, an outer housing of the electric motor 634 may be rigidly coupled
to the
motor coupler 718 by way of fasteners that telescope through apertures 720.
The
example motor coupler 718 defines an opening 722 such that the motor coupler
718
defines a "U" shape. The opening 722 is provided to enable placing the leads
650
(Figure 6) of the electric motor into the aperture 724 (to be passed through
to the electric
drive assembly 204 (Figure 2)). The medial portion 716 defines an outside
diameter that
is about the same as an outside diameter mechanical barrel 700, and may
include a fill
port 726 to aid in filling the linear actuation assembly 202 (Figure 2) with
hydraulic fluid.
The proximal end 714 of the transition housing 702 defines a plurality of
annular
channels 728 to enable coupling to and sealing against an electrical barrel
(discussed
more below).
19
CA 3040707 2019-04-18
[0054] In accordance with example embodiment, the linear actuation assembly
202,
from the seal created by the piston rod 302 (Figure 3) disposed within the
cylinder
housing 300 (Figure 3) to the seal created between an inside diameter of the
mechanical
barrel 700 (Figure 7) against the seal region 710 (Figure 7) is filled with
hydraulic fluid.
That is, all the components within the linear actuation assembly 202 are
submerged in
the hydraulic fluid, including the linear positioner 406 (Figure 4), the ball
screw nut 612
(Figure 6), the threaded shaft 614 (Figure 6), the bearing assembly 624, the
optional gear
box 636 (Figure 6), and the electric motor 634 (including the motor shaft 632
and stator
windings 644 (Figure 6)). Displacing all the air within the hydraulic oil of
the linear
actuation assembly 202 reduces the possibility of airlock. The hydraulic oil
serves to cool
and lubricate the various components, as well as assist in pressure
equalization when the
various components are disposed within a borehole, where ambient pressure can
be
20,000 PSI or more. In addition, a de-airing process can be applied using an
oil de-airing
machine for extracting air bubbles and dissolved air from the hydraulic fluid.
The oil de-
airing process can be beneficial in increasing the oil bulk factor and
subsequently
increasing its resistance to volume changes due to high pressure exposure at
extreme
depths and high temperatures. The hydraulic fluid may have several
characteristics, for
example: low moisture content to reduce corrosion, icing and thermal
expansion; low
carbon residue to reduce the tendency to form carbon deposits; low viscosity
index (e.g.,
under 10); in some cases ISO Grade 32 oil with viscosity index of 7; flash
point greater
than 150 degrees C.
[0055] Returning briefly to Figure 2. The specification to this point has
discussed
example embodiments of the poppet assembly 200 and linear actuation assembly
202.
The specification now turns to the electrical drive assembly 204.
[0056] Figure 8 shows a disassembled side elevation view of an electrical
drive
assembly 204 in accordance with at least some embodiments. In particular,
visible in
Figure 8 is the transition housing 702, an electrical barrel 800, a motor
controller 802, a
connector housing 804, and the standoff 208. The transition housing 702 again
defines
annular channels 728. The electrical barrel 800 defines a distal end 806, a
proximal end
808, and an internal volume 810. The distal end 806 is designed and
constructed to
telescope over, couple to, and seal to the annular channels 728 of the
transition housing
CA 3040707 2019-04-18
702. The proximal end 808 is designed and constructed to telescope over,
couple to, and
seal to a seal region 812 of the connector housing 804. When assembled, the
motor
controller 802 is disposed within the internal volume 810 of the electrical
barrel 800.
Finally, the example electrical drive assembly 204 comprises an
electrical/optical
connector 814 disposed at the proximal end of the connector housing 804. The
connector 814 enables the pulser system 132 (Figure 1) to couple to various
other
devices and systems, such as a battery barrel containing downhole batteries,
as well as
various measurement systems. The connector 814 may be a 10 pin rotary
connector.
The motor controller 802 may derive operational power through the connector
814 (e.g.,
from high power 28 Volt DC lithium battery cells (not shown)). Moreover, the
motor
controller may receive data over the connector 814, and based on the data
drive the
pulser system 132 to create pressure pulses in the drill string that propagate
to the
surface. The example motor controller 802 may take any suitable form depending
on the
characteristics of the electric motor 634 (Figure 6).
[0057] Referring simultaneously to Figure 3-8. Example embodiments thus
include
moving the poppet 304 of the pulser system 132 within a MVVD tool. The moving
of the
poppet may include activating, by the motor controller 802, the electric motor
634 and
thereby turning a motor shaft 632. The turning motor shaft 632 either
directly, or through
the optional gear box 636, turns the threaded shaft 614. Turning of the
threaded shaft
614 translates the ball screw nut 612 along the threaded shaft 614. The ball
screw nut
612 is rigidly coupled to the linear positioner 406, and more particularly the
coupler 434.
Translation of the ball screw nut 612 translates linear positioner 406, and
translation of
the linear positioner 406 in turn translates the piston rod 302 within the
cylinder housing
300. Thus, the poppet 304, coupled to the piston rod 302, moves relative to
the valve
seat 308. In a first rotational turning direction of the motor shaft 632, the
poppet 304 is
translated toward the valve seat 308, thus decreasing the cross-sectional flow
area for
drilling fluid within the drill string, and creating a positive pressure
pulse. In a second
rotational turning direction of the motor shaft 632 opposite the first
rotational turning
direction, the poppet 304 is translated away from the valve seat 308, thus
increasing the
cross-sectional flow area for drilling fluid within the drill string and
returning the pressure
within the drilling to pre-pulse pressure.
21
CA 3040707 2019-04-18
[0058] The linear actuation assembly 202 is filled with hydraulic fluid prior
to the pulser
system 132 being located within a borehole. Activating the electric motor 634
means the
activation takes place with the motor shaft (e.g., rotor) and stator (e.g.,
stator windings
644) of the electric motor 634, along with the ball screw nut 612, linear
positioner 406,
and other components all submerged in the hydraulic fluid and sealed with the
linear
actuation assembly 202.
[0059] In order to control position of the poppet 304 relative to the valve
seat 308, the
motor controller 802 counts, during the activation of the electric motor 634,
pulses from
the sensor 648 that senses full or partial rotations of the motor shaft 632,
the counting
creates a pulse count value. The motor controller 802 may cease activation of
the electric
motor 643 when the pulse count value meets or exceeds a set point pulse count
value
proportional to a predetermined travel distance of the poppet.
[0060] The example electric motor 634 and remaining components thus provide
the
energy to move the poppet 304 both toward and away from the valve seat 308. In
the
example embodiments, moving the poppet 304 toward the valve seat 308 is
without
mechanical assistance of a spring. Similarly, in some embodiments moving the
poppet 304 away from the valve seat 308 is without mechanical assistance of a
spring.
More particular, in example embodiment the poppet 304 is moved toward the
valve
seat 308 without a spring providing a force parallel to a central axis of the
threaded
shaft 614. Similarly, in some embodiments the poppet 304 is moved away from
the valve
seat 308 without a spring providing a force parallel to the central axis of
the threaded
shaft 614.
[0061] Figure 9 shows a method of creating pressure pulses within a drill
string during
drilling operations, in accordance with at least some embodiments. In
particular, the
method starts (block 900) and comprises moving a poppet of a pulser system
within a
measuring while drilling (MWD) tool (block 902). Moving the poppet may
comprise:
activating, by a motor controller, an electric motor and thereby turning a
motor shaft (block
904); turning a threaded shaft by rotation of the motor shaft (block 906);
translating a ball
screw nut along the threaded shaft responsive to turning the threaded shaft,
the ball screw
nut telescoped over the threaded shaft, and the ball screw nut rigidly coupled
to a linear
positioner (block 908); translating a piston rod within a cylinder housing by
the linear
22
CA 3040707 2019-04-18
positioner responsive to translating the ball screw nut (block 910); moving
the poppet
coupled to the piston rod, the movement of the poppet relative to a valve seat
(block 912);
counting, by the motor controller during the activating, electronic pulses
from a sensor
that senses full or partial rotations of the motor shaft, the counting creates
a count value
(block 914); and ceasing activation of the electric motor when the count value
meets or
exceeds a set point pulse value proportional to a predetermined travel
distance of the
poppet (block 916). Thereafter the method ends (block 918), likely to be
restarted to
move the poppet in an opposite direction.
[0062] The pulser system 132 in example embodiments may have a data rate of 10
pulses per second (PPS) (e.g., pulse durations of 0.1 second) in some cases.
In other
cases the pulser system 132 may have pulse durations of 0.250 seconds (4 PPS)
and/or
0.375 seconds. In some case the data rate and/or pulse duration may be
selectable by
way of messages transmitted from the surface. In some cases the selection may
be from
a set of four pulse duration modes (e.g., 0.8 second, 0.5 seconds, 0.375
seconds, and
0.250 seconds). The pulse amplitudes that the example system may create
include 50
PSI to 250 PSI, and in some cases about 100 PSI. Any suitable encoding scheme
may
used, such as pulse-position encoding, pulse amplitude encoding, and
combinations
thereof.
[0063] The above discussion is meant to be illustrative of the principles and
various
embodiments of the present invention. Numerous variations and modifications
will
become apparent to those skilled in the art once the above disclosure is fully
appreciated.
It is intended that the following claims be interpreted to embrace all such
variations and
modifications.
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