CA2471681A1

CA2471681A1 - Pump for agitating reservoir

Info

Publication number: CA2471681A1
Application number: CA002471681A
Authority: CA
Inventors: Brennon Cote
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-06-18
Filing date: 2004-06-18
Publication date: 2005-12-18
Also published as: CA2510240A1; US20060016591A1

Description

APPARATUS FOR AGITATING RESERVOIR WHILE PUMPING
This invention is in the field of pumping equipment and in particular pumping equipment for agitating the reservoir being pum~d.
BACKGROUND
In cxrtain oil producing areas considerable sand, waxer and like impurities are presem in the producing formation in addition to the desired oil. 1n such formations the sand can settle out of the reservoir, aad block the flow of production fluid from the formation into the well casing. In addition the sand can settle on down hole tools, anchors, tubing, pumps and the like and jam them in the well casing such that same cannot be removed.
Petroleum pt~oduction fluid is also generally mixed with gas. Where gas concentrations are significant, pump performance can be reducxd because the pump periodically draws gas instead of liquid, and then the pump heats because theca is a lack of lubrication.
Present pumps simply pump the fluid from the reservoir at a desired rate, and are located at an elevation in the reservoir such that the production fluid enters the well fast enough to prevent the re~roir from being drawn down below the pump intake. Sand present in the produ~ion fluid at the intake is pumped to the surface, however sand concenarations at lower levels of the reservoir are typically higher than at the pump intake.
Eventually the sand in the lower levels settles to the bottom of the reservoir and stays there.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a pump apparatus that overcomes problems in the prior art. 8 is a further object of the present invention to provide such a pump apparatus that agitates the fluid in the reservoir by re~ir~culating a portion of the pumped fluid back into the reservoir. The re-circulated fluid agitates the fluid in the reservoir such that sand is continually mixed into the fluid and pumped to the surface rather than settling out and remaining in the reservoir. The agitation also promotes gas breakout, where the gas separates from the liquid and rises out of the reservoir, reducing the problems associated with gas in the production fluid.
The apparatus comprises a port in the output ooru~uit of a down-hole pump. ~Y
located just about the pump output. A circulat'rag cxmduit is ,connected to the port such that pumped fluid can either pass up the output conduit to the surface, or into the circulating conduit. The circulating conduit extends downward from the top of the pump to a location in the reservoir outside the pump, and a circulating nozzle is attached at the lower end of the circulating conduit that restricts flow through the circulating conduit.
The circulating nozzle is sized to suit the pomp capacity, depth of well, type and viscosity of production fluid, and desired rate of flow fmm the reservoir to the surface. The flow through the circulating conduit plus the flow to the surface equal the pump output.
Rotating pumps are known whereby the speed of rotation can be varied to vary the P~P~B ~. For example a 100 liters per second (l/acc) pump may pump 100 I/sec at 1000 pounds per square inch (psi) at maximum speed. Prrssure at the pump output down-hole is a factor of the volume being pumped to surface, and the distance to surface.
Where it is desired to pump 50 1/sx to the surface, the pressure at the reservoir depth c~dd be for example 500 psi, and the speed of the pump oo adtieve this can be calculated.

Adding the circxilating conduit and nozzle of the invention, the pump speed will be increased such that the pump output down-hole is raised for example to 60 1/sec. It is desired to still maintain the flow of 50 Usec to the surfa~oe, so the pressure at the pump output will remain at 500 psi, but the circulating nozzle will have a size that allows 10 l/sec to flow through the circulating conduit and circulating nozzle and back into the reservoir at that pressure of 500 psi. The pump still raises 50 llsec to the surface, but also is re-circulating 10 l/sec though the circulating nozzle into the reservoir to agitate the reservoir.
in a given well it might be found that 10 l/sec provides satisfactory agitation and sufficient mixing of the sand with the fluid, as in the above example. The pump efficiency is reduced somewhat since it is pumping 60 Vsec but only 501/sec is getting to the surface,, but this could be seen as an acceptable expense far agitating the reservoir.
If it is then decided to increase the production rate of the well in the above example such that men fluid is pumped to surface, typically the pump speed would be increased.
However the increased flow from the pump output will increase the pressure in the output conduit and at the port, such that flow through the circulating ~nduit and nozzle will increase. For example increasing the pump to 70 Usec might increase the pressure and thus the flow through the circulating oanduit and nozzle to 15 1/sec, with only 55 Usec getting to the surface. Thus one half of the increased output would be reaching surface, and the pump efficiency losses could be unacceptable.
If 10 1/sec through the circulating nozzle provides adequate agitation, the increase to 15/Isec may not provide sufficient benefits to overcome the loss of pump efficiency. As the pump speed is increased to 801/sec, the pressure at the pump output might increase such that the flow through the cirarlating nozzle increases to 22 llsec, such that only 3 llsec of the 101/sec increased pump output is reaching the surface.
Where it is desired in the above example to increase the flow to surface from 50 to 60 Uses, it will generally be desirable to raise the pump and change the circulating nozzle to one with a smaller passageway, such that at the increased pressure present when the flow to the surface is 60 Usec, flow through the nozzle is maintained at 10 Usec, and pump output is 70 Usec.
The proper circulating nozzte size can be calculated for a production fluid with given characteristics, pumped from a given depth at a given flow to surface. The cineulating nozzle can be located at virtually any level in the reservoir. Where it is desired to agitate the reservoir to suspend sand in the production fluid so same is pumped to the surface, the circulating nozzle will generally be located below the pump intake. Where it is desired to agitate the reservoir to release gas from the production fluid the circulating nozzle will likely be located above the pump intake so that the agitated fluid is nearer the top of the production fluid so that the gas more readily escapes the fluid.
It is contemplated that the fluid passing through the circulating conduit and nozzle could also be used to drive a centrifuge that would aid in separating the gas from the liquid in the production fluid DE~~RIPTIQN 4F THE DRAWINGS:
While the invention is claimed in the concluding portions hereof, preferred embodiments are provided in the accompanying detailed description which may be best understood in conjunction with the accompanying diagrams where like parts in each of the several diagrams are labeled with like numbers, and where:
Fig. l is a schematic side view of an embodiment of the invention;
S
Fig. 2 is a schematic cross-sectional side view of a port adapter for attachment to the pump output, and the connected circulating conduit and circulating nozzle;
Fig. 3 is a schematic cross-sectional side view of a circulaEing nozzle for use with the invention.
DET n.FD DESCIZiP'1_'ION OF T1EI1'; IL-t.LISTRA_TED EIyIgODIMGNTS:
Fig. 1 schematically illustrates a conventional pump 2. The illustrated pump 2 for example comprises a fixed stator and a rotating rotor mounted inside a housing. The pump capacity varies as the rotor speed increases or decreases.
The pump Z pushes production fluid from the reservoir up through the output conduit b connected to the pump output at the top of the pump 2. As illustrated in Fig.

2, a port adapter 8 is placed in the output conduit by threading it into the top of the pump 2 and then threading the output conduit 6 into the top of the port adapter 8. The port adapter 8 includes an elbow 10 extending from one side of the port adapter 8 and having an outside end oriented downward A circulating conduit 12 is threaded into the outside end of the elbow 10 and extends downward alongside the pump 2 to a location in the reservoir outside the pump 2. The circulating conduit 12 is securely fixed to the pump 2 with straps 18 or the like, and could also be secured to the anchor used conventionally to secure the pump 2 in a well casing.
The circulating conduit 12 must be socure so that it does not vibrate or shake loose aad be lost in the well. As indicated by the broken lines in Fig. 1, flee length of the circulating conduit 12 can be adjusted so that the circulating nozzle 14 is located at virtually any level of the reservoir, either above the pump intake 20, or below it in orda~
to suit the particular situation.
A circulating nozzle 14 is threaded onto the bottom end of the circxilating conduit 12.
Thus pumped fluid am either pass up the output conduit 6 to the surface, or into the circulating conduit 12. The circulating nozzle 14 restricts flow through the circulating conduit 12, such that, as indicated in Fig. 2, production fluid 36 flows both up the output conduit 6 and through the circulating conduit 12 and nozzle 14 in proportions that can be adjusted to suit the particular situation by varying the size of the orifice through the circulating nozzle 14.
By way of example, the pump 2 could have a capacity of 100 liters per second (Usec) such that the pump 2 can pump 100 Usec at 1000 pounds per square inch (psi) at maximum speed. Where it is desired to pump 50 Usec to the surface, and the pressure at the reservoir depth is 500 psi, the spoed of the pump 2 to achieve this can be calculated.
Adding the circulating conduit 12 and nozzle 14 of the invention, the pump speed will be increased from the 50 Usec rate such that the pump output is raisod for example to 60 Usec at a down-hole pressure of 500 psi, and the circulating nozzle will have a size that at a pressure of 500 psi allows 10 Usec to flow through the circulating conduit 12 and circulating nozzle 14 and back into the reservoir. The pump 2 still raises 50 Uses to the sutfaoe requiring a down-hole pressure of 500 psi, but also is ro-circulating 30 Usec though the circulating nozzle 14 into the reservoir to agitate the reservoir.

Fig. 3 illustrates a particular configuration of the circulating nozzle 14 that uses a venturi arrangement to inaease agitation of the production fluid in the reservoir. The primary orificx 30 has a diameter that is sized to allow the desit~ed flow through the nozzle conduit 14 as discussed above. The lower orifice 32 is much larger, creating a lower pressure area 34 as pressurized production fluid 36 flows from the primary orifice 30 into the lower orifive 32. The lower pressure area 34 will draw production Quid 36 from the reservoir through channels 38 and increase agitation of the reservoir by gating both a flow into the circulating nozzle 14 through the channels 38 and out of the circulating nozzle 14 through the lower orifice 32.
The foregoing is considered as illustrative only of the principles of the invention.
Further, since numerous changes and modifications will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all such suitable Changes or modifications in structure err operation which may be resorted to are intatded to fall within the scope of the claimed invention.