METHOD AND APPARATUS FOR USE IN SELECTIVELY FRACING A WELL
An apparatus for selectively fracing a well includes a tubular body having an exterior surface, and an interior surface that defines an interior bore. An annular flow area that has at least one fluid flow port extends radially through the tubular body to permit fluids from the interior bore to pass through the at least one fluid flow port into a surrounding earth formation. An external sealing sleeve selectively covers the annular flow area. There is a pressure actuated sleeve shifting mechanism, where increasing pressure tending to cause axial movement of the external sealing sleeve. The axial movement is resisted until a pre-selected pressure threshold is reached to permit movement of the external sealing sleeve to open the at least one fluid flow port.
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There is disclosed a method and apparatus for placing multiple fractures at spaced locations along a well bore.
BACKGROUNDU.S. Pat. No. 7,267,172 (Hofman) entitled “Cemented Open Hole Selective Fracing System” teaches selectively opening holes in production tubing of a hydrocarbon producing well by using sliding valves which can be selectively opened by a shifting tool. U.S. Pat. No. 7,096,954 (Weng et al.) entitled “Method and Apparatus for Placement of Multiple Fractures in Open Hole Wells” teaches using a plurality of burst disk assemblies, each having an independent burst pressure. The present method provides an alternative method of selectively opening holes in production tubing.
SUMMARYThere is provided an apparatus for use in selectively fracing a well. The apparatus comprises a tubular body having an exterior surface, and an interior surface that defines an interior bore. An annular flow area that has at least one fluid flow port extends radially through the tubular body from the interior surface to the exterior surface to permit fluids from the interior bore to pass through the at least one fluid flow port into a surrounding earth formation. An external sealing sleeve is detachably secured to the exterior surface of the tubular body to selectively cover the annular flow area and close the at least one fluid flow port. There is a pressure actuated sleeve shifting mechanism, with increasing pressure tending to cause axial movement of the external sealing sleeve. Axial movement is resisted until a pre-selected pressure threshold is reached to permit movement of the external sealing sleeve to open the at least one fluid flow port.
There is also provided a method for use in selectively fracing a well comprising the following steps: (a) providing a plurality of apparatus as described above; (b) deploying the apparatuses along a production tubing string in a well with packers being positioned between the apparatuses to isolate production areas, the pre-selected pressure threshold for each production area increasing from a toe of the well toward a heel of the well; (c) pumping fluids down the production tubing at pressures just sufficient to selectively shift the external sealing sleeve of the apparatus having a lowest shifting pressure to an open position without shifting the external sealing sleeve of others of the apparatus having higher shifting pressures; (d) continuing to pump fluids down the production tubing to pump fluids into the earth formation through the apparatus that has had its external sealing sleeve moved to the open position; (e) pumping balls down the production tubing until the balls seat on and close the at least one fluid flow port on the apparatus that has had its external sealing sleeve moved to the open position; (f) using fluid pressure to maintain the balls seated on the at least one fluid flow port while other of the external sealing sleeves in the production tubing are selectively moved to the open position; and (g) repeating steps (c), (d), (e) and (f) to selectively open the external sealing sleeve in apparatus in the production tubing in stages.
There is also provided an isolation tool for selectively applying pressure to an outer tubular body. The isolation tool comprises a tubular body carrying a first sealing element and a second sealing element. The tubular body has a fluid inlet and a fluid outlet. The tubular body is movable within the outer tubular body. A pressure cavity is defined by an outer surface of the tubular body, an inner surface of the outer tubular body, and the first and second sealing elements. The fluid outlet of the tubular body is in fluid communication with the pressure cavity. The first sealing element and the second sealing element permit fluid flow into the pressure cavity and sealing against fluid flow out of the pressure cavity.
These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein:
An apparatus for use in selectively fracing a well generally identified by reference numeral 10, will now be described with reference to
Referring to
Referring to
Preferably, external sealing sleeve 24 is detachably secured to exterior surface 14 of tubular body 12 by shear pins 46 in shear pin apertures 47. Exterior surface 14 of tubular body 12 has a circumferential shear pin groove 48 to accommodate shear pins 46. Shear pins 46 are designed to shear and permit external sealing sleeve 24 to move as pressure builds within annular flow area 18 and reaches a predetermined pressure threshold. In a preferred embodiment, the number of shear pins 46 is adjustable, which permits a user to select a pre-selected pressure threshold at which the external sealing sleeve 24 is able to move by using a greater number or fewer number of shear pins 46.
External sealing sleeve 24 is moved by applying pressure to a pressure actuated sleeve shifting mechanism. For example, as shown in
It will be understood that other pressure actuated sleeve shifting mechanisms may be used, including different release mechanisms. For example, sleeve 24 may be biased to the shifted, open position, and a pressure increase may release a catch that allows sleeve 24 to shift.
Operation:Referring to
Once tubing string 53 is positioned with packers 55 set, fluids are pumped down tubing string 53 at pressures just sufficient to selectively shift external sealing sleeve 24 of apparatus 10 having the lowest pre-determined shifting pressure to an open position as shown in
The operation steps above are based on using differential pressures to open selected sealing sleeves 24. It has been found that in some circumstances, the flow ports 20 closest to the wellhead may become washed out by the abrasives, and become unusable. It will be understood other methods may also be employed, and may be preferable in some circumstances. For example, referring to
Isolation tool
In the example described above, an isolation tool 70 is used to apply pressure to a specific portion of outer tubular member, or tubing string 53. It will be understood that this particular tool may be used for other tools aside from a sealing sleeve 24. For example, the isolated pressure may be used to open various types of pressure-actuated openings, such as rupture discs, removable plugs, shifting sleeves, etc. as are known in the art.
Referring to
In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.
The following claims are to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, and what can be obviously substituted. Those skilled in the art will appreciate that various adaptations and modifications of the described embodiments can be configured without departing from the scope of the claims. The illustrated embodiments have been set forth only as examples and should not be taken as limiting the invention. It is to be understood that, within the scope of the following claims, the invention may be practiced other than as specifically illustrated and described.
Claims
1. An apparatus for use in selectively fracing a well, comprising:
- a tubular body having an exterior surface, and an interior surface that defines an interior bore;
- an annular flow area having at least one fluid flow port extending radially through the tubular body from the interior surface to the exterior surface to permit fluids from the interior bore to pass through the at least one fluid flow port into a surrounding earth formation;
- an external sealing sleeve detachably secured to the exterior surface of the tubular body to selectively cover the annular flow area and close the at least one fluid flow port;
- a pressure actuated sleeve shifting mechanism, where increasing pressure tending to cause axial movement of the external sealing sleeve, such axial movement being resisted until a pre-selected pressure threshold is reached to permit movement of the external sealing sleeve to open the at least one fluid flow port.
2. The apparatus of claim 1, wherein the pressure actuated sleeve shifting mechanism is a fluid cavity formed between the external sealing sleeve and the exterior surface of the tubular body, the fluid cavity being asymmetrical to provide an asymmetrical pressure distribution so that increasing pressure within the fluid cavity tends to cause axial movement of the external sealing sleeve.
3. The apparatus of claim 1, wherein the pressure actuated sleeve shifting mechanism is an inclined plane in fluid pressure communication with at least one fluid flow port.
4. The apparatus of claim 1, wherein the external sleeve has a first end with a first internal diameter that engages a first sealing area on the exterior surface of the tubular body on a first side of the annular flow area and the external sleeve has a second end with a second internal diameter that engages a second sealing area on the exterior surface of the tubular body on a second side of the annular flow area.
5. The apparatus of claim 4, wherein the first sealing area has a first seal groove in which is positioned a first O-ring seal and the second sealing area has a second seal groove in which is positioned a second O-ring seal.
6. The apparatus of claim 1, wherein a locking engagement is provided between the external sealing sleeve and the exterior surface of the tubular body to lock the external sealing sleeve in the open position.
7. The apparatus of claim 6, wherein several resilient fingers are carried by the external sealing sleeve and the exterior surface of the tubular body has an engagement profile that the resilient fingers engage to maintain the external sealing sleeve in the open position.
8. The apparatus of claim 1, wherein the external sealing sleeve is detachably secured to the exterior surface of the tubular body by shear pins.
9. The apparatus of claim 8, wherein one selects the pre-selected pressure threshold at which the external sealing sleeve moves by using a greater number or fewer number of shear pins.
10. The apparatus of claim 8, wherein the exterior surface of the tubular body has a circumferential shear pin groove to accommodate the shear pins.
11. A method for use in selectively fracing a well, comprising:
- (a) providing a plurality of apparatus, each apparatus comprising: a tubular body having an exterior surface, and an interior surface that defines an interior bore; an annular flow area having at least one fluid flow port extending radially through the tubular body from the interior surface to the exterior surface to permit fluids from the interior bore to pass through the at least one fluid flow port into a surrounding earth formation; an external sealing sleeve detachably secured to the exterior surface of the tubular body to selectively cover the annular flow area and close the at least one fluid flow port; a pressure actuated sleeve shifting mechanism, where increasing pressure tending to cause axial movement of the external sealing sleeve, such axial movement being resisted until a pre-selected pressure threshold is reached to permit movement of the external sealing sleeve to open the at least one fluid flow port;
- (b) deploying the apparatuses along a production tubing string in a well with packers being positioned between the apparatuses to isolate production areas, the pre-selected pressure threshold for each production area increasing from a toe of the well toward a heel of the well;
- (c) selectively shifting an external sealing sleeve to an open position by applying fluid pressure to the pressure actuated sleeve shifting mechanism;
- (d) continuing to apply fluid pressure to pump fluids into the earth formation through the apparatus that has had its external sealing sleeve moved to the open position;
- (e) preventing additional flow through the apparatus that has had its external sealing sleeve moved to the open position;
- (f) repeating steps (c), (d), and (e) to selectively open the external sealing sleeve in apparatus in the production tubing in stages working toward a wellhead of the well from a remote end of the well.
12. The method of claim 11, wherein the pressure actuated sleeve shifting mechanism is a fluid cavity formed between the external sealing sleeve and the exterior surface of the tubular body, the fluid cavity being asymmetrical to provide an asymmetrical pressure distribution so that increasing pressure within the fluid cavity tends to cause axial movement of the external sealing sleeve.
13. The method of claim 11, wherein the pressure actuated sleeve shifting mechanism is an inclined plane in fluid pressure communication with at least one fluid flow port.
14. The method of claim 11, wherein selectively shifting the external sealing sleeve to the open position comprises using an isolation tool inserted into the tubular body, the isolation tool isolating fluid pressure to a desired portion of the interior surface of the tubular body.
15. The method of claim 11, wherein selectively shifting the external sealing sleve to the open position comprises pumping fluids down the production tubing at pressures just sufficient to selectively shift the external sealing sleeve of the apparatus having a lowest shifting pressure to an open position without shifting the external sealing sleeve of others of the apparatus having higher shifting pressures.
16. The method of claim 11, wherein preventing additional flow comprises:
- pumping balls down the production tubing until the balls seat on and close the at least one fluid flow port on the apparatus that has had its external sealing sleeve moved to the open position; and
- using fluid pressure to maintain the balls seated on the at least one fluid flow port while other of the external sealing sleeves in the production tubing are selectively moved to the open position.
17. In combination:
- a production tubing string having a plurality of apparatuses for use in selectively fracing a well and an isolation tool, each apparatus for use in selectively fracing a well comprising: a tubular body having an exterior surface, and an interior surface that defines an interior bore; an annular flow area having at least one fluid flow port extending radially through the tubular body from the interior surface to the exterior surface to permit fluids from the interior bore to pass through the at least one fluid flow port into a surrounding earth formation; an external sealing sleeve detachably secured to the exterior surface of the tubular body to selectively cover the annular flow area and close the at least one fluid flow port; and a pressure actuated sleeve shifting mechanism, where increasing pressure tending to cause axial movement of the external sealing sleeve, such axial movement being resisted until a pre-selected pressure threshold is reached to permit movement of the external sealing sleeve to open the at least one fluid flow port; and
- an isolation tool at least partially extended into the production tubing string, comprising: a tubular body having a fluid input in fluid communication with a fluid output; seals positioned on either side of the fluid output, the seals being adapted to seal against the interior surface of the tubular body such that fluid flowing from the output is isolated to a desired portion of the interior surface of the tubular body.
18. An isolation tool for selectively applying pressure to a pressure actuated opening of an outer tubular body, the isolation tool comprising:
- a tubular body carrying a first sealing element and a second sealing element, the tubular body having a fluid inlet and a fluid outlet, the tubular body being movable within the outer tubular body;
- a pressure cavity defined by an outer surface of the tubular body, the inner surface of the outer tubular body, and the first and second sealing elements, the fluid outlet of the tubular body being in fluid communication with the pressure cavity;
- the first sealing element and the second sealing element permitting fluid flow into the pressure cavity and sealing against fluid flow out of the pressure cavity.
19. The isolation tool of claim 18, further comprising an equalizing valve that is open when the isolation tool is being run into the outer tubular body and closes upon application of the fluid pressure within the pressure cavity.
Type: Application
Filed: Oct 14, 2009
Publication Date: Oct 21, 2010
Applicant: SOURCE ENERGY TOOL SERVICES INC. (Lloydminster)
Inventors: Don Turner (Lloydminster), Steve Winkler (Cochrane)
Application Number: 12/579,358
International Classification: E21B 43/26 (20060101);