FLUID DISPLACEMENT SYSTEM USING GEROTOR PUMP
A fluid displacement system for a fluid producing subterranean well includes a well extending from a surface to a subterranean fluid bearing formation, the formation being in fluid communication with the well; and a gerotor pump in the well for pumping fluid from the formation to the surface.
The invention relates to a system and method for pumping fluids from a subterranean well.
Subterranean wells are commonly used for producing fluids such as hydrocarbons and the like from deep underground formations bearing such fluids. In some instances these fluids are sufficiently free-flowing and under sufficient pressure that production through the well to the surface does not need to be assisted. In other instances, the fluids can have an extremely high viscosity, or formation pressure may be too low, or numerous other factors can lead to unsatisfactory flow rates from the well.
Various pumping methods have been used to increase flow from wells including sucker-rod pumps, progressing cavity pumps and electric submersible centrifugal pumps. In fact, each of these systems has issues when needed to operate on highly viscous hydrocarbons such as the heavy and extra heavy crude oils which are contained in the Orinoco Oil Belt.
The ability of centrifugal pumps to handle fluids is impaired by high viscosity. For surface applications where viscous fluids are to be pumped, centrifugal pumps or rotor-dynamical relatives are disregarded in favor of positive displacement pumps. Nevertheless, centrifugal impellers still have an advantage for downhole use. This advantage consists of the easiness to stack many impellers in a cylindrical housing that fits into oil production casing. This design produces a very long pump (30 ft or more) that must be driven by a powerful electric motor. Electric submersible pumps used in the Orinoco Oil Belt are equipped with motors whose power is in the range of 200 HP to 300 HP. A significant amount of power is wasted due to the low mechanical energy conversion capacity of centrifugal pumps. Thus, there is a need for a more efficient pumping device more suitable for handling viscous oils.
Sucker-rod pumps are preferred to produce medium to low flow rates (500 b/d or less). It is possible to achieve larger flow rates but at the expense of using cumbersome, visually unpleasant and expensive surface driving units such as giant walking beams and power cylinders with necessary hydraulic power units. Furthermore, clever as it is, converting rotational motion from prime motor to reciprocating motion to drive the downhole pump implies wasted energy due to incessant acceleration and deceleration of large mechanical parts such as rod strings and surface units.
Thus, the need remains for an improved approach to pumping these fluids. The present invention addresses this need.
SUMMARY OF THE INVENTIONIn accordance with the present invention, the forgoing need has been met. According to the invention, a fluid displacement system and method are provided for producing fluids from a subterranean well, and the system and method are based on the use of gerotor pumps which have been found to be particularly effective at pumping highly viscous hydrocarbons.
According to the invention, a fluid displacement system is provided for pumping fluids from a fluid producing subterranean well, which system comprises a well extending from a surface to a subterranean fluid bearing formation, the formation being in fluid communication with the well; and a gerotor pump in the well for pumping fluid from the formation to the surface. Details of the pump are also novel as discussed herein.
In further accordance with the invention, a method is provided for pumping a fluid from a well, which method comprises the steps of positioning a well from a surface to a subterranean formation; placing a gerotor pump in the well; and operating the gerotor pump to drive fluids from the subterranean well to the surface.
Other advantages and details will appear in the detailed description which follows.
A detailed description of preferred embodiments of the present inventions follows, with reference to the attached drawings, wherein:
The invention relates to a fluid displacement system and method which utilizes gerotor pumps to improve pumping flow rates of heavy and extra heavy crude oils from subterranean wells.
While useful with a variety of potential different applications, the present invention is particularly well suited for use in producing heavy and extra heavy crude oils such as the heavy crude oil contained in the Orinoco Oil Belt. A typical hydrocarbon from this belt has a viscosity of about 1,000 cP at reservoir temperature (130-140° F.), and this type of fluid is very difficult to pump utilizing conventional sucker-rod pumps, progressing cavity pumps and the like.
In accordance with the invention, a gerotor pump 10 is positioned down hole in well 1 and used to enhance flow of heavy and extra heavy crude oils from the wells in accordance with the present invention.
A gerotor is a positive displacement pumping unit. The name gerotor is derived from “generated rotor”. A gerotor typically consists of an inner and an outer rotor 16, 18 (
Ring 20 also serves as a journal bearing for outer rotor 18. Outer rotor 18 fits into eccentric ring 20 with the necessary space to allow sliding movement while preventing excessive fluid slippage or leakage.
In accordance with the invention, to enhance pumping volume and speed, gerotor sets 12 can be assembled in series such that fluid discharged from one gerotor set can then be acted upon by another gerotor set.
Still considering the embodiment of
It should be appreciated with consideration of the illustration of
The assembly illustrated in
Middle casing 32 has openings 33 to house multiple gerotor sets, and ports to feed fluid to and discharge pumped fluid from each gerotor set or stage.
As shown in
From a consideration of
Turning now to
Inlet and outlet connector sections 64, 64′ are also shown in
As discussed above, gerotor pump 10 in accordance with the present invention operates through rotation being imparted to shaft 14. Various available structures and methods could be used to impart rotation to shaft 14. One particularly preferred approach in accordance with the present invention is to use an electric submersible motor 80 (
Thus, in accordance with the present invention, the driver for the pump is advantageously an electric submersible motor, and it is desirable to position at least one of pump 10 and motor 80, and preferably both of these components, within well 1 at a depth D between 3,000 and 3,500 feet, and even greater than 10,000 feet as needed.
It should be appreciated that the present disclosure has been given in terms of a preferred embodiment. The scope of the invention is not to be viewed as being limited by this embodiment, but rather as being defined by the scope of the appended claims.
Claims
1. A fluid displacement system for a fluid producing subterranean well, comprising:
- a well extending from a surface to a subterranean fluid bearing formation, the formation being in fluid communication with the well; and
- a gerotor pump in the well for pumping fluid from the formation to the surface.
2. The apparatus of claim 1, wherein the gerotor pump is driven by an electric submersible motor.
3. The apparatus of claim 2, wherein at least one of the gerotor pump and the electric submersible motor is located in the well at a depth from the surface of at least 3,000 feet.
4. The apparatus of claim 1, wherein the gerotor pump comprises at least one set of inner and outer rotors rotatably engaged within a journal bearing.
5. The apparatus of claim 1, wherein the journal bearing defines an eccentric inner surface rotatably housing the outer rotor, and wherein the inner rotor engages the outer rotor such that the inner rotor is concentric with an outer cylindrical surface of the journal bearing.
6. The apparatus of claim 4, wherein the rotors are mounted in the journal bearing between disks having inlet and outlet ports for fluid to be compressed and discharged by the rotors, respectively.
7. The apparatus of claim 1, wherein the gerotor pump comprises a plurality of gerotor pumps each having at least one set of inner and outer rotors.
8. The apparatus of claim 7, wherein the plurality of gerotor pumps are communicated with each other in series.
9. The apparatus of claim 8, wherein the gerotor pumps are communicated in series through an intermediate cylinder having a port aligned with an outlet of a first gerotor pump and an inlet of a second gerotor pump.
10. The apparatus of claim 6, wherein the plurality of gerotor pumps are communicated in parallel.
11. The apparatus of claim 10, wherein the plurality of gerotor pumps are communicated in parallel through a middle casing.
12. The apparatus of claim 11, wherein the middle casing comprises a cylindrical member having a first opening at one end for receiving a first gerotor pump, a second opening at the other end for receiving a second gerotor pump, a central wall separating the first opening from the second opening, an inlet in the central wall aligned within an outlet of the first gerotor pump, the inlet leading through a passage to a radial outlet by passing the second gerotor pump, and a radial inlet defined in a wall surrounding the first opening which leads through a passage that bypasses the first gerotor pump and has an outlet aligned with an inlet of the second gerotor pump.
13. The apparatus of claim 12, wherein each of the first and second gerotor pumps comprises a pumping stage each having a plurality of gerotor assemblies communicated in series.
14. The apparatus of claim 12, further comprising an inlet bearing carrier and an outlet bearing carrier, wherein the inlet bearing carrier is mounted to the middle casing at the one end and has a first inlet aligned with the inlet of the first gerotor pump and a second inlet aligned with the radial inlet of the middle casing, and wherein the outlet bearing carrier is mounted to the middle casing at the other end and has a first outlet aligned with the radial outlet of the middle casing and a second outlet aligned with the outlet of the second gerotor pump.
15. The apparatus of claim 14, wherein the gerotor pumps are mounted on a shaft, and wherein the inlet bearing carrier and the outlet bearing carrier support bearings in which the shaft is rotatably mounted.
16. A method for pumping a fluid from a well, comprising the steps of:
- positioning a well from a surface to a subterranean formation;
- placing a gerotor pump in the well; and
- operating the gerotor pump to drive fluids from the subterranean well to the surface.
17. The method of claim 12, wherein the gerotor pump is driven by an electric submersible motor.
18. The method of claim 13, wherein at least one of the gerotor pump and the electric submersible motor is located in the well at a depth from the surface of at least 3,000 feet.
Type: Application
Filed: Sep 12, 2013
Publication Date: Mar 12, 2015
Inventors: Raimundo Pardo Vazquez (Los Teques), Sergio Arturo Caicedo Sandgren (Ahmadi), Alexandra del Carmen Araujo Anez (Los Teques)
Application Number: 14/024,765
International Classification: F04C 23/02 (20060101);