Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to a submersib1e pump assembly particularly
adapted for downho'le pumping of heavy crude oil and oil containing
particulate matter such as sand and other solids from the oil bearing
formation.
It re'lates especially to a means of varying the RPM of the
submersible pump so the pump li-fts the crude at a rate compatible with the
volume of crude produced by the oil bearing formation. It also relates
to a me~ns of heating the crude in the production tubing to make it less
viscous and easier to lift. A third aspect of this invention, the use of
endless tubing for production tube and for hydraulic power lines,
reduces the assembly installatlon and maintenance time significantly.
This invention uses a var-iable speed hydraulic motor to drive a
progressive cavity type pump such as the Moineau pump. The hydraulic
motor drive has two distinct advantages over the electric motor used in
the submersible pump assembly suggested in Canddian Patent No. 924,181
to Husky Oil. First, a variable speed control for a hydraulic motor
can vary motor speed infinitely to its upper limit by regulating the
quantity of power fluid entering the hydraulic lines. The submersible
pulnp assembly suggested in Canadian Patent No. 893,5~6 to Amoco
~0 Petro'leum Ltd~ which used a variable RPM electric motor control, has
only 30 percent variation in speed.
The infinite variability of the hydraulic motor is extremely
important when pumping crude oil of various densities and flow rates
as it enables one to reduce or increase the volume of crude produced to
a rate that is compatible with the flow capacity of the -formation.
Controlling -the pump rate avoids the problem of overproduction where
the pump, starved for oil~ runs dry and rapidly deteriorates. Moreover,
in wells having a large invasion of formation water, production
may be increased many -times until the maximum capacity of the pulllp
is reached.
The second advantage o-f a hydraulic motor is the dual functions
that can be served by the hydraulic power lines. As well as supr)lying
motive power, -they can be used to heat crude in the productiorl tubin~
by running lines insicle, or ad~iacent to, the production tubing.
Heretofore, it has been customary to lift heavy crude oil
by using a pump jack, sucker rod string and a reciprocating
type pump or a Moineau type pump which is rotated from the
surface by means of a sucker rod string. Both these methods
suffer the disadvantage of having no provisions to overcome
the viscosity of the crude (10 API to 12 API), thus causing
a much increased lifting pressure which, in turn, due to the
pressure, and sand in the crude, results in deterioration
of -the bottom hole pump assembly.
Unlike downhole heaters as suggested in Canadian Paten-t
No. 711,557 to Shell Oil Company, this heating process re~uires
almost no extra apparatus. A surface heat source heats the
fluid in the hydraulic input line. The heat is supplemented
wi.th f~r:iction heat created naturally within the hydraulic
lines. The hydraulic fluid can thus be heated to the optimum
temperature required to facilitate crude oil flow in the prod-
uction tubing. This process also heats the crude for the entire
lerlgth of the production tube whereas a downhole heater heats
the crwde only at the heater site -thus allowing the crude
to cool as i.t proceeds up the production tube.
The component of the pumping assembly which allows the
hydraulic input power line to be inserted into, or strapped
adjacent to, the production tube is -the use of the endless
tubing. Before any tubes are installed, the hydraulic inpu-t
power line is inserted into, or strapped adjacent to, the
production tubing. All three tubes--production tube, hydraulic
input power line and hydraulic return line--are attached -to
the well head. They can then be installed and extracted as
a single unit. At presen-t, 30-foot tubing lengths are used
for production tubing. Endless tubing can be installed in
abou-t one tenth -the time it -takes to install 30-foo-t lenghths
and with less equipment. Endless tubing requires the use of
a truck for ins-tallation whereas 30-Eoot leng-ths require the
use of a service rig.
i5~
--3--
This component of the invention is particularly important
to pumping heavy crude containing particulate matter such
as sand. Crude oil containing sand tends to wear out pumps
quickly requiring their frequent replacement. Since it takes
about one-tenth the time to pull out endless tubing as it
does to pull out 30-foot lengths each time the pump is re-
placed, endless tubing means a substantial savings to the
industry in bo-th time and equipment.
The crude oil in the production tubing can also be heated
where cold forma-tions are encountered by using a electrically
heated cable suspended inside the tubing. Electrical heating
wire can also be coiled around the tubing or in the case of
flexible tubing, it may be molded or woven into the rubber
sheath with the result that any temperture loss in the tubing
can be controlled.
Accordingly, it is the object of the present invention
to provide an improved submersible pump assembly for pumping
heavy crude oil and oil containing particulate matter such
as sand and other solids from the oil bearing formation.
It is a further object of the present invention to provide
a submersible pump assembly utilizing a progressive cavity
type pump which is driven at optimum and infinitely variable
RPM by a relatively inexpensive and readily available hydraulic
motor.
A further object is to heat the crude oil in the prod-
uction tubing with hydraulic fluid heated externally wi-th
surface line heaters and supplemented with friction heat creat-
ed naturally within the power lines.
A further object of the present invention is the provision
of a submersible pump assembly which uses endless tubing rather
than the commonly-used 30-foo-t lengths, thus reducing install-
ation and maintenance time of -the downhole assembly to about
one-tenth of that required for 30-foot lengths, as well as
substantially reducin~ -the equipment required to install the
endless tubing in relation -to the 30-foot lengths.
A still further object of the present invention is the provision of a
submersible pump assembly which may be lowered into the very confined space
of casing in a well bore and operated downhole to pump heavy crude oil or
oil containing particulate matter, such as sand, and which includes a progressive
cavity type pumping unit such as the Moineau~ whose speed is regulated by a
variable speed control for optimum variation of the RPM of the hydraulic
motor to its upward limit for driving the pump.
A further object of the present invention is the provision of a sub-
mersible pump assembly which is relatively inexpensive and lightweight,
which may be lowered into, raised out of, and operated downhole in the
confined spaces of well casing in a well bore, and which effectively and
efficiently pumps heavy crude oil including particulate matter,such as sand
and other formation solids.
Other and furth~r objects, features and advantages of the invention
will be apparent from the following description of presently-preferred
embodiments of the invention, given for the purpose of disclosure.
Figure 1 is an elevational view, in section, illustrating the
submersible pump assembly in place in well casing in a well bore with the
input hydraulic power line inside the production tubing and the hydraulic
return power line adjacent and attached to the production tubing.
Figure '~ is an elevational view, in section, illustrating submersible
pump assembly in place in well casins in a wellb~ire with the hydraulic
power lines adiacent and attached to the production tubing.
Referring to both drawings, the submersible motor assernbly is
generally indicated by the reference number 1 and is shown downhole in
the casing C of an oil well for pumping crude oil from the oil bear-ing
formation F. The submersible pump assembly 2 is secured at its upper
end to, and supported by, the tubing 3 extending through the well head
WH from the surface S, the production tubing 3 being connected to the
flow line FL for flowing oil pumped to suitable tanks or other destinations
as desired. Also, as shown, a flow metre FM is provided for determining
the rate offlow of oil in tubing 3 and into the flow line to destination.
A variable speed control 6 is disposed at the surface S and controls the
RPM of the hydraulic motor by controlling -the pressure flowing into the
hydraulic power lines driving the motor.
--5--
The casing C, perforations for permitting flow from the
formation F into the casing C, well head cap WH, the flow line
FL, Flow metre FM, variable speed control 6 are all conventional
and no detailed description thereof deemed necessary or given.
The pump assembly 2 of the present invention includes a
progressive cavity type pump 2 which is secured to and supported
by tubing 3, a hydraulic motor 1 connected to the lowermost
component of the pump assembly which drives the pump 2 through
hydraulic lines and a variable speed control 6 to provide a
wide range of flow, and therefore optimum RPM, to the pump 2
for the pumping operation desired for the crude oil being pumped.
The hydraulic power intake line 4 powering the hydraulic motor
and the hydraulic return line 5 impart their external and friction
heat to the crude being pumped up the tubing. A heat source
H at the surface supplements friction heat to raise the temp-
erature of the hydraulic fluid to the desired level. Endless
tubing is used for production tubing and hydraulic pressure
intake 4 and return 5 lines. The three tubes are attached to
a cap at the weLl head and are installed and extracted as a
~0 single unit.
The hydraulic motor, line heater, variable speed control
and endless tubing are all conventional and no detailed descrip-
tion is deemed necessary or given. Likewise, since any progress-
ive cavity type pump may be used as the pump, no more description
of the progressive cavity pump is given or deemed necessary.
~I.t~
.-6--
Supplementary Gisclosure
In addition to the process of heating'the fluid in the
production tubing, the hydraulic fluid could be passed through
a heat exchanger which is positioned near the pump intake to
'''~~ provide additional heati..ng of the crude oil. This heat exchanger
would be placed in series between the hydraulic line and the
hydraulic motor to further dissipate any residual heat remaining
in the input hydraulic fluid before entering or leaving the
hydraulic motor. This additional transfer of heat to the crude
oi.l would be beneficial in that addltional reduction of the
:1,0 viscosity of the crude oi.l through an i.ncrease in the temp-
erature will further reduce the required pumplng pressure.
Figure 3 is an enlaryed e.levationai vie~, in section,
lll.ustrating the submersible pump assembly in place in'the
wel.l casing in a well bore. This illustration'shows the position
of a heat exchanger 7 placed in series with the hydrau~ic power
in'cake line 3 and the hydraulic motor 1. The position of the
heat exchanger is placed in proximi,ty to the progressive cavity
pump's intake port ~ so as to transfer heat from the hydraulic
power intake line to the crude oil being drawn into the pump.
As the heat exchanger is of a conventional design no de-
tailed description is deemed necessary or given.
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