Note: Descriptions are shown in the official language in which they were submitted.
CA 02913214 2015-11-20
WO 2015/013136
PCT/US2014/047242
LIVE WELL STAGED INSTALLATION OF WET CONNECTED ESP
AND RELATED METHOD
Inventors: Steven K. Tetzlaff; Dan L. Adams; Dewayne May;
Walter R. Dinkins and Steven W. Pyron
FIELD OF THE INVENTION
[0001] The field of the invention is installation of electric
submersible
pumps and more particularly, devices that enable subassembly installation to
fit into a lubricator for live well deployment.
BACKGROUND OF THE INVENTION
[0002] Electric submersible pumps (ESP) are used to increase bottom hole
pressure to deliver produced fluids to a well surface. These pumps are
multistage centrifugal pumps with the number of stages determined by the
depth of the ESP and the properties of the pumped fluids and the well
configuration. As wells get deeper, with improved drilling technologies, the
number of stages needed to achieve desired production has necessarily
increased. The additional horsepower to drive the added stages and obtain
higher discharge pressures, also by necessity, increased the length of the
motor
associated with the ESP.
[0003] In order to deploy ESPs in live wells utilizing wire line, the
pump
assembly has to pass through a lubricator. A lubricator is mounted on the well
head at the surface. There are installations where the lubricator length is
limited by the derrick height. Other installations may limit the lubricator
length based on safety concerns or policy. Lubricator assemblies contain
valves at opposed ends that can be sequentially operated to introduce the ESP
components into the live well, such as with a wireline or slickline, when the
bottom valve is opened and the wireline or slickline is delivered through a
sealed connection near the top of the lubricator. Another more recent
development is to mate a wet connect device on the lower end of the ESP
assembly with the other half of the connection that is connected to a cable,
run
alongside the tubing that will convey the pumped fluids to the surface. This
type of power / instrumentation connection has also added to the overall
length
of the assembly. Since there is a finite limit to the height of the lubricator
supported in the derrick, or limited for safety reasons, it has become a
problem
1
CA 02913214 2015-11-20
WO 2015/013136
PCT/US2014/047242
to get extended length, higher horsepower, ESP assemblies inserted into live
wells.
[0004] It should be noted that coiled tubing, continuous rod and jointed
rod or tubing could also be utilized to deploy these ESP systems with and
without lubricator type equipment. While the lubricator type applications
allow these installs on live wells, the same equipment can be used on wells
that have been pressure equalized / neutralized or killed.
[0005] The present invention addresses this problem with a solution that
allows the overall ESP assembly to be broken down into subassemblies that
will fit in a lubricator for staged deployment and final system assembly, at
the
downhole fixture located at or near the bottom of the production tubing. This
downhole fixture being the socket portion of the wet connection device. Once
run into the well, these staged subassemblies function as though the entire
assembly was put together at the surface, as could be done before when the
assemblies had smaller motors and fewer stages.
[0006] Those skilled in the art will better appreciate the various
aspects of
the invention from a review of the detailed description of the preferred
embodiment and the associated drawings while understanding that the full
scope of the invention is to be determined by the appended claims.
SUMMARY OF THE INVENTION
[0007] An ESP assembly is broken down into subassemblies to fit within a
lubricator where a safe working length is required for live well deployment. A
lifting device has a shaft transmission feature and associated housing
rotational lock for use at the top of the first subassembly which is left in
position for engagement of the next assembly. The subassemblies can be
delivered on wireline or slickline. A wet connect can be at the lower end of
the
initial subassembly to connect to a cable run alongside the production tubing.
The ESP subassemblies all are deployed and interconnected in the live well
and function as they would if assembled at the surface. The ability to break
down the assembly and run it in segments lets the components fit through a
length limited lubricator for live well deployment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of the lift device to run in the
first
subassembly into production tubing;
2
CA 02913214 2015-11-20
WO 2015/013136
PCT/US2014/047242
[0009] FIG. 2 shows the production tubing in cased hole, in section,
illustrating the wet connect and screen at the lower end of the production
tubing;
[0010] FIG. 3 illustrates the first subassembly to be run into the
production
tubing with the other half of the wet connect at its lower end;
[0011] FIG. 4 is a section view of the lift sub used at the top of the
assembly in FIG. 2 to run it into the production tubing to mate with the wet
connect at the lower end of the production tubing;
[0012] FIG. 5 is the next subassembly to be run into the production
tubing
and includes the pump and lower end shaft extension to mate into the lift sub
shown in FIG. 4 that is left in the production tubing;
[0013] FIG. 6 is the last subassembly that includes a seal assembly for
the
production tubing;
[0014] FIG. 7 is an anchor mounted above the seal assembly of FIG. 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0015] Referring to FIG. 2, a borehole is shown with casing 10 although
an open hole is an alternative. Production tubing 12 is run into the casing 10
and supports at its lower end a half 14 of a wet connection of a type known in
the art. A cable for power and communication between the surface and the wet
connect 14 is schematically illustrated. The assembly in FIG. 2 has the other
half of the wet connect 20 at its lower end and is referred to as the socket
portion of the wet connect. When the halves 14 and 20 make electrical contact
such a condition is sensed at the surface through the cable 16. The assembly
is
retained by the lift device 26 that is shown in more detail in FIGS. 1 and 4.
As
shown in FIG. 1 there is a lift profile 28 where a slickline or wireline can
be
releasably attached in a manner known in the art. Apart from that there are
anti-rotation lugs 32 in the housing 30 that are engaged by splines 34 shown
at
the lower end of FIG. 5 on the crossover assembly 35. Once crossover
assembly 35 is landed onto lift device 26, axial load from the pump, 46 is
transferred from 4-3, through 35, 26 and ultimately to the thrust bearing
inside
24.
[0016] Thus, in operation, the housing 30 does not rotate but the shaft
coupling assembly 36 turns. Assembly 36 is supported on bearings 38 and 40
and has a male end 42 with spline 44 to engage a pump shaft that is not shown
3
CA 02913214 2015-11-20
WO 2015/013136
PCT/US2014/047242
that extends out the lower end of the ESP 46 shown in FIG. 5. One or more
openings 48 are provided in housing 30 to allow solids or other debris to pass
out of the housing 30 when it is run in with the assembly shown in FIG. 3. The
remainder of the assembly in FIG. 3 is a lower portion of a motor module
module 22 that is rotationally locked at 50 to the remainder of the motor
assembly 22 and 24.
[0017] Item 24 is the seal section component. This component provides an
equalization function between the well bore pressures seen at depth and the
internal pressure of the ESP components 46, 58 and 60. In addition to
providing pressure equalization, the seal component 24 also handles axial
thrust to the ESP system created by the driven pump assembly 46 while the
system is energized. The seal component 24 also protects the motor 22, 24 and
connection plug 20 from well bore fluid contamination. It is important to note
that the assembly of FIG. 3 must all be part of the same staged installation
as
they are all serviced / filled with a synthetic type of dielectric oil.
[0018] The motor shaft extends From 22 through 24 to end 52 where an
end spline meshes into the female splined connection 54 shown in FIG. 1. The
pump shaft, not shown is a female end that slips over the male end shaft 42
with splines 44. In essence the lift device 26 serves as a coupling between
the
seal shaft at end 52, and the pump crossover 35 shaft to the pump intake shaft
not shown that passes through ports 66 to the shaft in pump 46 that is not
shown.
[0019] Once the assembly of FIG. 2 has been deployed into the production
tubing 12 of FIG. 1 and the wet connect portions 14 and 20 are
communicating the wireline or slickline or other conveyance supporting the
lift device 26 is released and the wireline or slickline is retrieved to the
surface
to allow the assembly of FIG. 5 to be picked up and run into a live well
through a lubricator that is not shown. In essence FIG. 5 is the ESP 46 that
has
a polished bore receptacle and an internal lifting profile not shown near its
upper end 56. The lifting profile allows running in the ESP 46 and the
crossover assembly 35 in one trip through the lubricator. The wireline or
slickline is again released so that another trip into the production tubing
can be
made with the sealing assembly 58, then anchor assembly 60 that can be run in
on a separate wire line run. Projections 62 positioned on the exterior and
4
CA 02913214 2015-11-20
WO 2015/013136
PCT/US2014/047242
adjacent interior polished bore receptacle act to centralize the assembly. The
anchor 60 holds the assembly shown in FIGS. 3-7 inside the production tubing
to keep the assembled components fixed against the wet connection 14 at
the lower end of the production tubing 10.
[0020] Those skilled in the art will appreciate the fact that the
problem of
limited length in a lubricator is addressed by the present invention that
breaks
down an overlong assembly into stages that are short enough to load into a
lubricator with a length limit of about 25 meters allowing the assembly to be
put together in the live well while still maintaining the safety systems that
are
there to prevent loss of well control. The first break location is at the
motor
drive shaft which is run in with the lift device 26 in a way that the motor
shaft
is already coupled to the lift device that is left in the hole after the first
trip to
deliver the assembly of FIG. 2. After making contact with the wet connect 14
already at the bottom of the production tubing 10 the conveyance such as
wireline or slickline is removed and the assembly of FIG. 5 including the ESP
46 is lifted and deployed. The pump shaft that is not shown connects to spline
44 on the lift sub shaft 42. The conveyance is again released leaving exposed
the polished bore receptacle on the top end 56 of the FIG. 5 assembly. The
seal assembly 58 can be run in with the anchor 60 or separately. A seal
assembly at the lower end of 58 registers with the polished bore receptacle
that
is not shown. Externally, the seal assembly 58 divides the suction and
discharge sides of the EPSP 46. Suction from the formation enters through
screen 64 shown in FIG. 1 and passes through inlets 66 shown in FIG. 5.
Discharge flow from the ESP 46 passes through the sealing assembly 58 and
the anchor 60 on up to the surface through the production tubing 12.
[0021] The problem that limits placement of ESP in a live well at depths
where the length of the ESP and motor exceed the lubricator length is solved
with the present invention. While the break locations in the ESP assembly can
be selected at different component connections doing the breaking up at the
connection of the motor shaft to the pump shaft allows more efficient use of
the available length in these limited length lubricators. The incorporation of
a
shaft connector in the lift sub also allows having the break in the assembly
at
the connection between the motor and pump shafts. The other components
above just push together and are finally anchored by anchor 60. As the
5
CA 02913214 2015-11-20
WO 2015/013136
PCT/US2014/047242
operating depth and pressure output demanded from ESPs increases the ability
to get the entire assembly into a live well will no longer be limited by
lubricator length can no longer be a limiting factor. Indeed in the deeper
applications where more pump stages and motor horsepower are required
would mean such assemblies could not be run into a live well without
significant risks of blowout. The method of the present invention allows the
safe downhole assembly in a live well of long ESPs that are wet connected in
the hole.
[0022] The above description is illustrative of the preferred embodiment
and many modifications may be made by those skilled in the art without
departing from the invention whose scope is to be determined from the literal
and equivalent scope of the claims below:
6
