BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates a method and apparatus for isolating and controlling fluid flow within a zone of a subterranean formation.

2. Description of Related Art

In hydrocarbon production, it is frequently desirable to select which zone of the wellbore is to be opened for production from time to time for use in fracturing or the like. One method of isolating a zone is to provide valves within each zone which may be selectably opened to provide access to one or more of the zones as desired by a user. One conventional type of valve which may be utilized in such situations is a sleeve valve having an outer pipe with a plurality of ports therethrough which may be selectably covered or uncovered by a sliding sleeve within the pipe.

One current difficulty with sleeve valves is that the sleeve and string has a significant weight such that during run in, the weight of the string may cause it to rest along and drag on the bottom of the well bore or liner. Such weight causes significant friction thereby impeding run in or potentially damaging the string or valves.

Another difficulty is that some current valves may require a tool to be run into the valve to mechanically open the valve for operation. This can be a time consuming process.

SUMMARY OF THE INVENTION

According to a first embodiment of the present invention there is disclosed an apparatus for displacing a sleeve within a downhole tool. The apparatus comprises an outer mandrel, and a sleeve extending between first and second ends slidably located within the outer mandrel wherein the sleeve and mandrel form first, second and third annular chambers therebetween. The first annular chamber is in fluidic communication with an interior of the sleeve. The second annular chamber is in fluidic communication with an exterior of the mandrel. The third annular chamber is substantially sealed. The second chamber may be in fluidic communication with the interior of the sleeve by ports extending radially through the sleeve. The first chamber may be in fluidic communication with the exterior of the mandrel by ports extending radially through the mandrel. The sleeve may be longitudinally secured within the mandrel by a shear pin. The apparatus may include a plurality of valve ports extending through said mandrel operable to be covered or uncovered by displacement of the sleeve.

According to a further embodiment of the present invention there is disclosed a method for opening a valve within a downhole tool. The method comprises, providing a sleeve within the mandrel operable to cover a plurality of valve openings forming first, second and third annular chambers between the mandrel and the sleeve. The method further comprises pressurizing the second chamber through bores extending through the sleeve fluidically connecting the second chamber and the interior of the sleeve so as to displace the sleeve towards a first end of the outer mandrel. The method further comprise releasing the pressure within the second chamber so as to permit a vacuum within a third sealed chamber and a pressure from an exterior of the mandrel to pressurize a first chamber to draw the sleeve towards a second end of the outer mandrel thereby uncovering the valve openings.

Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate embodiments of the invention wherein similar characters of reference denote corresponding parts in each view, Figure 1 is a cross-sectional view of a wellbore having a plurality of flow control valves according to a first embodiment of the present invention located therealong.

Figure 2 is a perspective view of an apparatus for selectably isolating a subterranean formation according to a first embodiment of the present invention.

Figure 3 is a cross sectional view of the apparatus of Figure 2 as taken along the line 2-2 at a first or run in position.

Figure 4 is a cross sectional view of the apparatus of Figure 2 as taken along the line 2-2 at a second or release position.

Figure 5 is a cross sectional view of the apparatus of Figure 2 as taken along the line 2-2 at a third or open position.

Figure 6 is a detailed cross sectional view of a portion of the apparatus of

Figure 2 as indicated in Figure 3 at A.

DETAILED DESCRIPTION

Referring to Figure 1 , a wellbore 10 is drilled into the ground 8 to a production zone 6 by known methods. The production zone 6 may contain a horizontally extending hydrocarbon bearing rock formation or may span a plurality of hydrocarbon bearing rock formations such that the wellbore 10 has a path designed to cross or intersect each formation. As illustrated in Figure 1 , the wellbore includes a vertical section 12 having a valve assembly or Christmas tree 14 at a top end thereof and a bottom or production section 16 which may be horizontal or angularly oriented relative to the horizontal located within the production zone 6. After the wellbore 10 is drilled the production tubing 20 of the hydrocarbon well is formed of a plurality of alternating liner or casing 22 sections and an apparatus 24 for selectably permitting fluid flow between the interior of the liner and the formation. The valve bodies 24 are adapted to control fluid flow from the surrounding formation proximate to that valve body and may be located at predetermined locations to correspond to a desired production zone within the wellbore. In operation, between 8 and 100 valve bodies may be utilized within a wellbore although it will be appreciated that other quantities may be useful as well. Turning now to Figure 2, a perspective view of one apparatus 24 is illustrated. The apparatus 24 comprises a substantially elongate cylindrical outer casing or mandrel 26 extending between first and second ends 28 and 30, respectively and having a central passage 31 therethrough. The outer casing

26 may be formed of a central portion 32 and top and bottom caps, 34 and 36, respectively. The top cap 34 includes internal threading 38 (illustrated in Figure 3) for connection to adjacent casing sections while the bottom cap includes outer threading 40 for connection to adjacent casing sections. The central portion 32 includes a plurality of ports 42 therethrough which may be of any conventionally known type. The outer casing 26 further includes a downstream oriented first annular casing ridge, 44, and second and third upstream oriented annular casing ridges, 46 and 48, respectively on an inner surface thereof. As illustrated, the first upstream annular ridge may be angled inwardly towards the central axis of the valve body 24.

Turning now to Figure 3, the apparatus 24 includes a sleeve 50 slidably located within the outer casing 26. At the initial or run in position the sleeve 50 covers the ports 42. The sleeve extends between first and second ends, 52 and 54, respectively and includes a first upwardly oriented annular sleeve ridge 54 and second and third downwardly oriented annular sleeve ridges, 58 and 60, respectively on an outer surface thereof.

As illustrated in Figures 3 through 5, the first casing ridge 44 and the first annular ridge 56 form a first annular chamber 62 therebetween. Similarly, the second casing ridge 46 and second sleeve ridge 58 form a second annular chamber 64 therebetween and the third casing ridge 48 and third sleeve ridge 60 form a third annular chamber 66 therebetween. The first annular chamber 62 is in fluidic communication with an exterior of the outer casing 26 through casing ports 68 while the second annular chamber 64 is in fluidic communication with the central passage 31 of the apparatus through sleeve ports 70. The third annular chamber 66 is sealed at a pressure substantially corresponding to atmospheric pressure. Seals 72, as are commonly known isolate the first, second and third chambers from each other.

With reference to Figure 4, the casing 26 includes an annular groove 80 therearound having an inwardly biased ring 82 located therein. The sleeve 50 includes a shoulder 84 located upstream of the ring 82 sized to engage upon the ring in the run in position to prevent retraction of the sleeve 50 as illustrated in Figure 3 and a release groove 86 downstream of the shoulder 84 as illustrated in greater detail in Figure 6. The casing 26 also includes a plurality of shear pins 88 extending to the sleeve 50 to retain the sleeve 50 at the initial or run in position. Optionally, the sleeve 50 may also include other means for being engaged upon by a tool or the like as are commonly known.

In operation, the apparatus 24 is located in line in a tool or working string as illustrated in Figure 1. During run in or while the valve is being positioned, the sleeve is at an initial position as illustrated in Figure 3. In such position the shear pins 88 retain the sleeve at the initial position such that the sleeve covers the ports 42. In such a position the central passage 31 is isolated from the wellbore or exterior of the valve such that the pressure within the valve and tool string may be controlled to prevent or minimize contact of the valve on the bottom of the well bore. Once the valves 24 are located at their desired location, the production tubing 20 may be pressurized to fill the second annular chamber 64 through the sleeve ports 70. This increased pressure within the second annular chamber 64 will not be balanced against any other pressure in the apparatus 24 and when this pressure reaches a desired level the shear pins 88 will be sheared permitting the sleeve to retract to the second or release position as illustrated in Figure 4. It will be appreciated that the desired release pressure may be selected as desired by the user by the selection of the shear pins such as between 2 to 4 times the well bore pressure, by way of non-limiting example.

Turning now to Figure 4, after the shear pins 88 have been sheared, the sleeve 50 is pushed upstream by the pressure within the second annular chamber 64. The ring 82 is retained in its position relative to the casing 26 until it is permitted to retract into the release groove as illustrated in Figure 4 at which point it will then be disengaged from the annular grove 80. Thereafter, the pressure within the production tubing 20 may be decreased thereby releasing the pressure within the second annular chamber 64. Once the pressure within well bore enters the first annular chamber 62 through the casing ports 68. The pressure within the first annular chamber 62 forces the sleeve 50 in a downward direction until the ports 42 are uncovered as illustrated in Figure 5. Additionally, the third annular chamber 66 which is sealed at atmospheric pressure also draws the sleeve 50 in a downward direction due to the vacuum within this chamber relative to the wellbore. It will be appreciated that in such operation, all the valves within a well bore may be opened at the same time and at a common pressure. Optionally, a tension spring may be provided in place of the third annular chamber to provide an additional drawing force to the sleeve 50 in a downward direction.

While specific embodiments of the invention have been described and illustrated, such embodiments should be considered illustrative of the invention only and not as limiting the invention as construed in accordance with the accompanying claims.