Note: Descriptions are shown in the official language in which they were submitted.
2088324
METHOD AND APPARATUS FOR SECURING A WELL HEAD DRIVE
AGAINST UNINTENTIONAL ROTATION
This invention relates generally to pump drives, and has to do particularly
with a new design suitable for rotary pumps for oil wells.
BACKGROUND OF THE INVENTION
Decades ago, most oil wells were operated by a downhole pump at or close
to the bottom of a well, the pump being of a conventional reciprocating kind
actuated by a rod string which in turn was reciprocated vertically by a pump
jack.
Recently, however, many conventional reciprocating pumps have been
replaced by rotary-drive progressive cavity pumps. The rotary pumps are
particularly suited for the production of crude oil laden with sand and water.
With the introduction of the rotary pumps, a problem has arisen in
connection with preventing rotation of the drive with respect to the casing or
"pressure pipe" extending down the well.
In the field, it is common to guard against unexpected rotation of the drive
by connecting a link chain around the piping in order to hold the drive in
place. As
the threaded connections begin to loosen, the chain holds the drive from
rotational
movement. However, the chains sometimes break, primarily because the
tangential
operating position of the chain makes it subject to very high loads. If the
chain
breaks when operators are standing too close to the drive, the sudden spinning
of the
drive and the centrifugal flinging out of the chain can be very hazardous.
GENERAL DESCRIPTION OF THIS INVENTION
In view of the foregoing disadvantages of the use of chains on the currently-
used rotary pumps for oil wells, the aim of the present invention is to
provide a
construction which will ensure that the drive for a pump of the kind under
consideration cannot break free and begin rapid rotation.
More particularly, this invention provides, for use with the combination of a
pressure pipe extending down a drilled well, a rotationally driven pump at the
bottom of the well, and a surface-located drive for the pump, the drive
including a
prime mover and suitable means enabling the torque from the prime mover to be
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2
transmitted along a drive string consisting of threadably connected segments
extending down the pressure pipe, the combination further including a housing
member intended to be stationary, the housing member having a bore for
receiving
the drive string, the housing member in part defining a sealing means to
contain the
pressure in the pressure pipe,
a method of restraining rotation of the drive during pumping, the method
including:
a) providing an adaptor having a first end and a second end, the adaptor
having an open-ended longitudinal passage extending from one end to the
other end thereof, the longitudinal passage being capable of receiving the
drive string therethrough, and an open-ended transverse passage intersecting
the longitudinal passage, the adaptor having at said one end thereof first
means for securing the adaptor to the pressure pipe, the adaptor further
having at said other end thereof second means for securing the adaptor to
said housing member;
b) securing the adaptor to both the pressure pipe and the housing
member utilizing said first and second means, such that the drive string
passes through said longitudinal passage;
c) closing one end of said transverse passage; and
d) connecting the other end of the transverse passage to a discharge pipe
extending generally in the direction radially away from the adaptor,
whereby the discharge pipe acts to restrain the adaptor against rotation with
respect to the pressure pipe, in the event that said first means fails to so
restrain the adaptor.
Further, this invention provides, for use with the combination of a pressure
pipe extending down a drilled well, a rotationally driven pump at the bottom
of the
well, and a surface-located drive for the pump, the drive including a prime
mover
and suitable means enabling the torque from the prime mover to be transmitted
along a drive string consisting of threadably connected segments extending
down the
pressure pipe, the combination further including a housing member intended to
be
stationary, the housing member having a bore for receiving the drive string,
the
t.
~i w .
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3
housing member in part defining a sealing means to contain the pressure in the
pressure pipe,
an adaptor comprising:
a) a first end and a second end,
b) an open-ended longitudinal passage extending from one end to the
other end of the adaptor, the longitudinal passage being capable of receiving
the drive string therethrough,
c) an open-ended transverse passage intersecting the longitudinal
passage,
d) first means at said first end for securing the adaptor to the pressure
pipe, and second means at said second end for securing the adaptor to said
housing member, such that said drive string passes through said longitudinal
passage,
e) a closure member for closing one end of said transverse passage;
wherein the other end of the transverse passage is adapted for connection to a
discharge pipe extending generally in the direction radially away from the
adaptor,
whereby the discharge pipe acts to restrain the adaptor against rotation with
respect
to the pressure pipe, in the event that said first means fails to so restrain
the adaptor.
Lastly, this invention provides, in combination:
a pressure pipe extending down a drilled well,
a rotationally driven pump at the bottom of the well,
a drive string consisting of threadably connected segments extending down
the pressure pipe,
a surface-located drive for the pump, the drive including a prime mover and
suitable means enabling the torque from the prime mover to be transmitted
along
said drive string,
a housing member intended to be stationary and having a bore for receiving
the drive string, the housing member in part defining a sealing means to
contain
pressure in the pressure pipe, and
an adaptor which includes:
a) a first end and a second end,
B
4 2098 324
b) an open-ended longitudinal passage extending from one end to the other
end of the adaptor, the longitudinal passage being capable of receiving the
drive
string therethrough,
c) an open-ended transverse passage intersecting the longitudinal passage,
d) first means at said first end for securing the adaptor to the pressure
pipe,
and second means at said second end for securing the adaptor to said housing
member, such that said drive string passes through said longitudinal passage,
e) a closure member for closing one end of said transverse passage;
whereby the other end of the transverse passage is adapted for connection to
a discharge pipe extending generally in the direction radially away from the
adaptor,
whereby the discharge pipe acts to restrain the adaptor against rotation with
respect
to the pressure pipe, in the event that said first means fails to so restrain
the adaptor.
GENERAL DESCRIPTION OF THE DRAWINGS
Two embodiments of this invention are illustrated in the accompanying
drawings, in which like numerals denote like parts throughout the several
views,
and in which:
Figure 1 is a longitudinal axial section through a portion of a rotary drive
apparatus for a down-hole oil well pump, showing one embodiment of the
invention;
Figure 2 is a view similar to that of Figure 1, showing a second embodiment
of the invention; and
Figure 3 is a longitudinal sectional view of the second embodiment of this
invention, shown to a larger scale.
DETAILED DESCRIPTION OF THE DRAWINGS
Attention is first directed to Figure 1, which at the left shows the top end
of
a pressure pipe 10 (illustrated schematically). The pressure pipe 10 extends
down a
drilled well 12, in known manner. At the top, the pressure pipe is closed by
an
annular wall 14, which supports a frusto-conical nipple 16 which has an
external
pipe thread (tapering thread) 18.
At far left in Figure 1 a rotationally driven pump 20 is schematically
illustrated.
B
4a
Driving torque for operating the pump 20 is conveyed down the well by a
drive string 22 typically consisting of threadably connected tubular or solid
segments extending down the pressure pipe 10.
~o~s~~~
In accordance with this invention, the nipple 16 is threadably interlocked
either directly to an adaptor 24 (known in the art as a Flow "T" adaptor), or
indirectly to the adaptor 24 through an intermediate blow-out prevention
fitting
(not shown). The latter fitting is needed where oil under natural pressure
would
5 otherwise seek to escape from the well.
The adaptor 24 has a first end 26 and a second end 28, and an open-ended
longitudinal passage 30 extending from one end to the other end of the adaptor
24.
It will be noted that the passage 30 is large enough to receive the drive
string 22
without contacting the same, thus leaving an annular space around the drive
string
22 inside the adaptor 24, along which oil, or a mixture containing oil, can
pass.
The adaptor 24 also defines an open-ended transverse passage 32 which
intersects (and thus communicates with) the longitudinal passage 30.
At the first end 26 of the adaptor 24, first means are provided for securing
the adaptor 24 to the pressure pipe 10. In the embodiment specifically
illustrated
in Figure 1, this first means is constituted by the combination of the
exteriorly
threaded nipple 16 and an internally threaded recess 34 which constitutes one
end
of the longitudinal passage 30.
At the second end 28 of the adaptor 24 there is provided a flange 36 which
is intended to cooperate with a further flange 38 which is at the bottom of a
housing member 40 which in part defines a sealing means 42 intended to contain
the pressure within the pressure pipe 10, but which does not lie at the focus
of the
present invention. It is therefore not necessary to describe the sealing means
42
in any greater detail.
To briefly describe the remainder of the apparatus shown in Figure l, the
housing member 40 is secured with suitable fasteners to a portion 44 of a
frame.
The housing member 40 and the portion 44 define an internal recess within
which
a sleeve 46 is mounted for rotation. To the right of the sleeve 46 in Figure 1
there is illustrated a packing member 48 which cooperates with a nut 50 to
compress packing 52 around the drive string 22, and thus provide a positive
seal.
The packing member 48 is threadably engaged with the sleeve 46 at the location
54.
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6
The top end of the drive string 22 is threaded into a further nut member 56
which is shaped to define a ring 58 by which the entire drive string 22 can be
raised upwardly and lowered. The nut 50 and the nut member 56 both have
similarly shaped protuberances 60 which are linked together by a tail member
62.
The protuberances 60 are non-circular, as is the tail member 62, which means
that
(due to the force urging the nut member 56 toward the nut 50 arising from the
weight of the drive string 22), the nut 50 and nut member 56 will always
rotate
together.
The sleeve 46 is keyed to a pulley 61 which is rotated through an endless
belt 63, driven by a prime mover (motor M). This illustration is merely a
schematic representation.
Returning now to the adaptor 24, it is to be noted that the flanges 36 and
38 have matching bores 70 through which suitable fasteners (not shown) can be
inserted and tightened.
A closure member 72, in the form of a threaded plug or cap, constitutes
means by which one end of the transverse passage 32 can be closed and sealed
against the leakage of pressurized oil.
The other end of the transverse passage 32 is adapted to be connected to a
discharge pipe 76 extending generally in a radial direction away from the
adaptor
24. The discharge pipe ultimately delivers oil to one or more holding tanks,
and
is normally configured in such a way as to make it sturdy and able to resist
movement. Typically, the discharge pipe 76 (particularly in cold climates)
undergoes a bend downwardly, so that it can run underground for at least part
of
its length, thus protecting it from extreme cold.
It will thus be seen that the provision of the transverse passage 32 in the
adaptor 24, by allowing the connection of a radially directed discharged pipe
(76),
achieves considerable stability and resistance to torsional force.
The adaptor 24 is preferably a solid steel component of sufficient strength
to withstand all exceptional loads that occur in such installations.
Illustrated in the drawing is an annular groove 80 in the flange 36, and a
matching annular groove. 82 in the flange 38. An ,O-ring seal is intended to
be
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7
lodge within these matching grooves, thus ensuring that no pressurized oil
will
leak out between the flanges 36 and 38.
Attention is now directed to Figure 2, in which the adaptor 24a differs
from the adaptor 24 in Figure 1 only by providing, at the upper end of the
adaptor
24a, an internally threaded frusto-conical recess 84 which is identical to the
recess
r
34 at the other end. The provision of the threaded recess 84 in the Figure 2
embodiment provides flexibility in the use of the adaptor. The recess 84 is
not
utilized in the particular structure shown in the figures, but would 'allow a
threaded
connection to subsequent components, in the event that such use was desirable.
One of the reasons for providing the cap 72 for one end of the transverse
passage 32 is the need for a standard maintenance tool connection.
Figure 3 is an expanded illustration of the adaptor 24a.
While two embodiments of this invention have been illustrated in the
accompanying drawings and described hereinabove, it will be evident to those
skilled in the art that changes and modifications may be made therein, without
departing from the essence of this invention, as set forth in the appended
claims.
