VENTURI SIPHON ATOMIZATION LIQUID LIFT APPARATUS AND METHOD

Abstract

A method and apparatus for increasing the production of a hydrocarbon well by removal of accumulated formation fluid from the bottom of the well. The apparatus includes a body positionable down hole and a sealing assembly, with a converging-diverging nozzle installed axially within a through bore extending through the body at a position below the sealing assembly. A fluid lift passage extends from the accumulated formation fluid through the body and into the throat of the nozzle. The entrance into the throat of the nozzle includes inwardly tapered shoulder portion position below the opening of the fluid lift passage into the throat. The apparatus creates a low-pressure zone within and lifts the accumulated formation fluid into the throat where it is atomized by a high velocity flowing production gas. The atomized fluid is carried to the surface of the well by the production gas where it is then separated from the gas. The method includes the installation of an apparatus within the well.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/743,691, filed Mar. 23, 2005, the entire of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to an apparatus and a method for removing formation fluids from the bottom section of hydrocarbon producing wells. More specifically, an apparatus which uses the natural flow of gases to enhance the production of hydrocarbons, such as gas, from a subsurface wellbore.

BACKGROUND OF THE INVENTION

It is common for a gas well to produce liquids in addition to gas. These liquids, typically termed as formation fluid, may include water, oil, and condensate. The accumulation of formation fluid in the well can effect the flow characteristics of the well resulting in low production or no production at all.

There exists several methods of removing or recovering the formation fluid from the well to simulate further production. A first method removes formation fluid from the well bottom by lifting it to the surface using various pumps. A second method aims at maintaining gas velocity at or above a critical velocity for production by continually reducing the diameter of the production tubing. A third method uses plungers which reciprocate in with in the well between the bottom where formation fluid is capture by the plunger and the where the captured fluid is unloaded. Another method includes artificial lift where a pressurized fluid is injected into the well to increase gas velocity.

Despite the above and other methods and devices, a need still exists for an improved formation fluid lift and gas production device which utilizes only the flow of produced gas to lift and atomize formation fluid for entrapment with produced gas to be carried to the well surface.

SUMMARY OF THE INVENTION

The apparatus of the present invention operates by using the natural flow of well gases to remove accumulated formation fluid within a well to increase production of the well and to avoid the use of artificial gas injection. In accordance with one aspect of the invention, there is provided an apparatus for reducing the level of formation fluid at the bottom of a gas producing well including a narrowed throat section in which a production gas flow from the well creates a low pressure zone having a pressure less than the formation gas pressure. At least one conduit provides a flow path from the formation fluid accumulated within the well to the low pressure zone.

The apparatus includes a body or mandrel run into a well casing using conventional methods, or can be placed into a tubular and run into a well along with the tubular. The apparatus includes a sealing element which seals against the well casing or tubular dividing the well casing or tubular into the top side region and the bottom side region. The body includes a nozzle which creates a sufficient pressure difference between the bottom side region and the top side region to provide for the lifting of formation fluid contained within the bottom side region, to cause the atomization of the formation fluid into small droplets which are carried to the surface of the well by produced gas.

In general, in one aspect, an apparatus for lifting fluid from a well using the natural flow of well gases is provided. The apparatus includes a body being of dimension permitting the body to be lowered into a well casing, the body having a top section, a lower section and an outer wall. The body having an axial bore extending longitudinally therethrough from a bottom side surface to a top side surface. The axial bore defining a converging-diverging nozzle having a throat section intermediate to and fluidically coupling the converging and diverging sections of the nozzle. A sealing element positionable between the outer wall of the body and the inner of the wall casing and sealing divides the well casing into a top side region and a bottom side region. The body having at least one aperture extending therethrough at a position below the sealing element connecting together the bottom side region to the throat section. The nozzle having a tapered shoulder extending inwardly into the throat section and reducing the cross sectional area of the throat section in a direction from the bottom side surface to the top side surface. A tube having a first end connected to the at least one aperture and a second end extendable into a column of formation fluid within the bottom side region.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a diagrammatic view of a venturi siphon atomization liquid lift apparatus constructed in accordance with the principles of the present invention positioned in a well bore about a bottom hole location;

FIG. 2 is an enlarge cross sectional diagrammatic view of the venturi siphon atomization liquid lift apparatus showing an internal converging-diverging nozzle configuration; and

FIG. 3 is an enlarge cross sectional diagrammatic view of the converging-diverging nozzle showing an inwardly tapering portion.

The same reference numerals refer to the same parts throughout the various figures.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and particularly to FIGS. 1-3, a preferred embodiment of the venturi siphon atomization liquid lift apparatus of the present invention is shown and generally designated by the reference numeral 10.

With reference to FIGS. 1-3, there is shown a diagrammatic partial view of a well casing 100 positioned within a borehole 120 drilled into a formation 125. The venturi siphon atomization liquid lift apparatus (VSALL) 10 is shown positioned within the casing 100 at a bottom hole location 110. It is important to note, the VSALL 10 can also be set within a tubular that is run into a well casing.

The VSALL 10 operates to increase gas production from the well by lifting accumulated formation fluid using only the transport velocity or energy of the gas being produced. The VSALL 10 depends upon basic laws of physics to lift the formation fluid to the surface.

In doing so, the VSALL 10 includes a body 12 of dimensions allowing the body to be run in and positioned at the bottom hole location 110 using conventional methods, such a wireline (not shown). The body 12 includes a top section 36, a lower section 38, and an outer wall 40. An axial bore 14 extends longitudinally through the entire length of the body 12 along a central axis thereof from a top side surface 16 to a bottom side surface 18. The body 12 makes a sealing contact with an interior surface 115 of the casing 110, thereby dividing the borehole into two regions, a top side region 130 and a bottom side region 140. The sealing contact is created by a sealing element 30 positioned around the circumference of the exterior surface of the body 12. The axial bore 14 establishes fluid communication between the top side region 130 and the bottom side region 140, thereby permitting fluid to cross from the bottom side region to the top side region by passing through the axial bore.

The axial bore 14 includes a nozzle 20 of a converging-diverging configuration. The nozzle 20 is orientated such that the converging section 22 is bottom side and the diverging section 24 is top side. The converging-diverging configuration of the nozzle 20 acts to increase the transport velocity or energy of a fluid flowing through the body 12 from the bottom side region 140 of the borehole 100 to the top side region 130.

The body 12 further includes at least one aperture 26 extending from the bottom side surface 18 to the throat 28 between the converging section 22 and diverging section 24 of the nozzle 20. The throat 28 comprises an elongated narrowed section between the exit of the converging section 22 and the entrance in to diverging section 24. Attached to and extending from each aperture 26 is a lift tube 29. The lift tube 29 extends from the aperture 26 in a direction into the bottom side region 140 and into formation fluid 150 that has accumulated within the borehole 120. The lift tube 29 may be various lengths, dimensions, cross sectional shape and may extend into the formation fluid 150 at various angles.

With reference to FIG. 3, at a lower stream end of the throat 28 just before the aperture 26 conjoins with the axial bore 14 at the throat, there is a narrowed section created by an inwardly protruding tapered shoulder 25. The shoulder 25 decreases the cross sectional area of the throat in a direction from the bottom side surface 18 to the top side surface 16. The tapered shoulder 25 is formed annularly around the inner wall of the throat 28 with the top of the shoulder being flush with the lower edge of the opening of the aperture 26 into the throat, and normal to the inner wall of the throat. The reduced cross sectional area of the throat 28 created by the tapered should 25 increases the transport velocity of gas as it flows across the tapered shoulder. The gas flowing with an increased transport velocity through the throat 28 and across the end of the aperture 26 creates a low pressure zone. This low pressure zone acts to siphon the formation fluid 150 up through the lift tube 29 and the aperture 26 into the throat 28. In the throat 28, formation fluid 150 flows across the top of the shoulder 25 into the narrowed cross sectional area. The formation fluid 150 is atomized by the high velocity gas into small droplets that are carried to the surface of the well by the gas.

The VSALL 10 further includes a collar stop 32 either attached to the body 12 or made integral therewith. Collar stops are well known in the industry as such the specific details of the collar stop is not shown or discussed. The collar stop 32 fixedly attaches the body 12 of the VSALL 10 to the casing 100 during run in using conventional methods. It is contemplated that a tubing stop or an “A” packoff or some other such fixing device could reasonably be used in place of the collar stop 32.

In use, it can now be understood, the VSALL 10 is run into the casing 100 to a desired depth such that the lift tubes 29 are at least partially submerged into accumulated formation fluid 150. Upon reaching the desired depth, the collar stop 32 is actuated fixing the body 12 of the VSALL 10 to the casing 100. Once the body 12 is fixedly attached to the casing 110, the borehole 120 is divided into two regions, a top side region 130 and a bottom side region 140. All produced gas is forced to flow through the axial bore 14 and across the nozzle 20. The converging-diverging configuration of the nozzle 20 reduces the cross sectional fluid flow area of the borehole 120 resulting in an increased casing pressure within the bottom side region 140. The increased casing pressure within the bottom side region 140 causes produced gas to flow with a higher velocity across the throat 28 of the nozzle 20, this is further enhanced by the tapered shoulder 25. The increased gas velocity across the tapered shoulder 25 and through throat 28 creates a low pressure within this region resulting in the siphoning of accumulated formation fluid 150 by the lift tubes 29 into the throat. At the throat 28, the gas is caused to expand rapidly as it enters the diverging section of the 24 of the nozzle 20. The expanding gas atomizes siphoned formation fluid 150 entering the throat 28 and carries the atomized formation fluid to the surface in tiny droplet form.

A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention.

Claims

1. An apparatus for increasing hydrocarbon production from a well, the apparatus comprising:

a body being of dimension permitting said body to be lowered into a well casing, said body having a top section, a lower section and an outer wall;

said body having an axial bore extending longitudinally therethrough from a bottom side surface to a top side surface;

said axial bore defining a converging-diverging nozzle having a throat section intermediate to and fluidically coupling the converging and diverging sections of said nozzle;

a sealing element positionable between said outer wall of said body and the inner of the wall casing sealing divides the well casing into a top side region and a bottom side region;

said body having at least one aperture extending therethrough at a position below said sealing element connecting together said bottom side region to said throat section;

said nozzle having a tapered shoulder extending inwardly into said throat section and reducing the cross sectional area of said throat section in a direction from said bottom side surface to said top side surface; and

a tube having a first end connected to said at least one aperture and a second end extendable into a column of formation fluid within said bottom side region.

2. The apparatus of claim 1, wherein said tapered shoulder gradually reduces the cross section of said throat section in a direction from said bottom side surface to said top side surface.

3. The apparatus of claim 2, wherein the top of said tapered should is flush with the bottom edge of the opening of said at least one aperture into said throat section.

4. The apparatus of claim 3, wherein said top of said tapered should is planer and is normal to the annular wall of said throat section.

5. The apparatus of claim 1, wherein said sealing element is attached to said body at said top section.

6. The apparatus of claim 1, further comprising:

a stop collar positioned between said outer wall and the inner wall of the well casing to affixed said body to the well casing.

7. The apparatus of claim 1, wherein said aperture extends through said body from said bottom side surface.

8. A method for increasing hydrocarbon production from a well having accumulated formation fluid, the method comprising the steps of:

positioning an apparatus down hole and forming a seal with the well to divide the well into a top side region and a bottom side region causing all produced hydrocarbons to flow through said apparatus from said bottom side region to said top side region;

increasing the velocity of produced hydrocarbons flowing within said apparatus;

creating a low pressure zone within said apparatus by said increased velocity of produced hydrocarbon;

delivering formation fluid from said bottom side region to said low pressure zone within said apparatus;

atomizing said formation fluid within said apparatus within said low pressure zone into small droplets by said increased velocity of produced hydrocarbon; and

lifting said small droplets upwardly to the surface of the well by said produced hydrocarbons.