METHOD AND APPARATUS FOR TREATING A WELL
A tool for forming an obstruction in the production casing of an oil or gas well includes a sleeve adapted to be secured to the casing and having an annular abutting surface that captures a body or a cage having a solid body within the casing thereby forming an obstruction. The tool may be secured within the well either by an expandable sleeve or a collet having resilient fingers. The tool may be used as a plug to prevent flow through the production casing of the well in a well treatment process such as fracing. A process for treating a well using the tool is also presented.
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This is a Continuation-in-Part of application Ser. No. 13/605,298 filed on Sep. 6, 2012.
BACKGROUND OF INVENTION1. Field of the Invention
The invention disclosed and claimed in this application relates to the treatment of oil and/or gas wells. One example of such treatment is commonly referred to as fracturing the formulation around an oil or gas well. Fluid with certain chemical additives and a proppant are injected into the formation surrounding either a vertical or horizontal well to form cracks or passageways in the formation to stimulate the production of the well.
2. Description of Related Art
Currently there are several techniques utilized to stimulate producing of a well by fracing. Typically a packer or plug is utilized to isolate a particular portion of the well and the fracing fluid is injected into the isolated portion under high pressure. Once a given portion of the well is treated in this manner, a second zone uphole of the first zone is isolated by a second packer or plug that cuts off flow to the downhole portion of the well that has been treated.
U.S. Pat. No. 7,322,417 discloses a plurality of vertically spaced production layers 1 and a plurality of valves 14. A ball is captured on a valve seat 94 which will cause an increase in pressure to open valve 14. This allows fracturing fluids to enter the annular region that surrounds the valve. The balls may be formed of a dissolvable or frangible material, which allows the ball to be dissolved or eroded to open up communication upstream through the casing.
U.S. Pat. No. 7,134,505 discloses a similar system in which a plurality of spaced apart packers 20 a-n and a plurality of valve bodies 26 c-n that capture balls of varying diameters to selectively open ports 16 c-e to allow fracturing fluids to flow into the isolated zones.
Stage frac methods include the use of pump down bridge plugs, perforating guns, and sliding sleeves. The current pump down method requires a drill out phase after frac with coiled tubing or jointed pipe. This is an expensive and time consuming process which involves additional risk of the coil tubing getting stuck in the wellbore. This time and operational risk is a significant impact item on the overall economics of oil and gas projects.
Sliding sleeves require that their exact position needs to be known as the casing is run into the well. The number of frac initiation points is limited and the cost is significant for each sleeve. Sleeves may malfunction either during opening or closing. Higher risk comes from incomplete frac distribution and limited reservoir drainage.
BRIEF SUMMARY OF THE INVENTIONThe present invention overcomes the difficulties with the prior art as described above by using proven concepts and a simplified approach. An expansible valve seat or stop member that can be run on wireline (pump-down, tractor, tubing or coiled tubing) is positioned at predetermined locations along the production casing and is expanded for example by a shaped charge or with a mandrel extrusion process. A disintegrating or dissolvable ball can be dropped in the valve seat to isolate a portion of the well to allow for fracturing of the isolated portions of the well. The seat may be made of the same material as the ball so that the drill out step is completely eliminated. Alternately, the valve seat may be mechanically captured by the production casing.
The ball and valve seat become the frac plug that would normally be pumped down in a conventional horizontal pump-down process.
The production casing can be perforated as in the pump down method and fracing can be initiated once the ball seals on the valve seat. A dart may be used in lieu of a ball. Balls, darts, seats or sleeves may be soluble, dissolvable or frangible.
As described below, the invention of this application is directed to a novel process of fracturing a plurality of zones in the formation surrounding a horizontal or vertical well without the use of multiple bridge plugs or frac plugs that require drill out after the fracturing process is complete prior to the production stage.
This is accomplished in the following manner. After the well has been drilled (81) and the production casing has been fully positioned (82), an expansible sleeve such as shown in
Expansible sleeve 10 may be precisely positioned within the production casing by any suitable known technique such as a line counter or collar locator. Once positioned within the desired location of the production casing, the cord is detonated (84) causing the sleeve to expand outwardly against the inner surface of the casing (21). In so doing, the sleeve forms a seat 12 as shown in
Once the tube 11 and seat have been set in place, the production casing and cement (if present) in the first frac zone can be perforated (85) in the conventional way by a perforating gun on the same tool-string as the expansible sleeve. At this point the tool-string can be removed, and the fracing process can be initiated by pumping down (86) a ball or dart to rest against seat 12. This will prevent the fracing fluid from flowing downhole and will cause the fracing fluid under pressure (87) to enter the formation surrounding the perforations in the production casing and thus commence the fracing process.
Once the process is completed for the first zone, a second expansible sleeve can be placed (88) to isolate a second zone and the process can be repeated (88-92) for as many zones as desired as indicated in
Another embodiment of the expansible sleeve is illustrated in
An additional embodiment of the expansible sleeve is illustrated in
A further embodiment of the invention can be described by reference to
A perforated disk 64 having perforations 63 closes one end of the cage as shown in
As in previous embodiments, the sleeve 11, cage member 62 and ball 66 may be made of a soluble, dissolvable or frangible material so that it would not be necessary to drill out the sealing mechanism after fracing.
Another embodiment of the invention is illustrated in
The expandable sleeve may be formed of steel for example J-55 or similar steel. The wall thickness may vary from approximately 0.095 inches to about 0.25 inches. The diameter of the sleeve is selected to be slightly smaller than that of the production casing so for example if the casing is 5 ½ inch casing, the sleeve may have an outside diameter of 4.5 inches.
A further embodiment of a tool suitable for use according to the invention is shown in
A cup shaped member 112 having seals 113 can be positioned on the uphole portion of ball or dart 106 to provide a seal. The internal surface of cup 112 is formed to conform to the spherical surface of ball or dart 106.
After the collet sleeve and valve seat have been positioned within the production casing and the casing has been perforated, a ball or dart can be run in or dropped to engage valve seat 125 to form a plug. At this point, the perforated zone of formation uphole of the plug can now be treated. As in other embodiments the collet sleeve, valve seat and dart or ball can be made of bio-degradable or dissolvable material.
Collet sleeve 127 and valve seat 125 may be run into the production casing separately or loosely attached to each other by an attachment mechanism, for example a shear pin, that can be disengaged by a suitable force applied to the valve seat such as fluid pressure.
As in the embodiment of
The embodiments of
Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.
Claims
1. A tool for forming an obstruction in production casing of an oil or gas well comprising:
- a sleeve adapted to be secured within the production casing;
- a cage member having an annular surface adapted to abut against a first end portion of the sleeve; and
- the cage member having a solid body that is axially movable to a first position blocking fluid flow through the tool in a first direction and movable to a second position permitting fluid flow through the tool in a direction opposite to the first direction.
2. The tool according to claim 1 wherein the cage member includes a hollow cylindrical portion having a diameter slightly less than that of the production casing and a hollow frustoconical portion extending downstream of the hollow cylindrical portion and terminating in an outlet.
3. The tool according to claim 1 wherein the cage member further includes a perforated disk closing one end of the hollow cylindrical portion of the cage member.
4. The tool according to claim 1 wherein the perforated disk includes an annular wall spacing the solid body from a planar flat portion of the disk.
5. A tool for forming an obstruction in the production casing of an oil or gas well comprising:
- an expandable sleeve adopted to be secured within the casing.
- a solid body having a frustonical shape and having a surface portion adapted to abut against an annular surface on the sleeve thereby forming an obstruction in the well.
6. A tool for forming an obstruction of an oil or gas well having production casing comprising:
- a sleeve having a passageway therethrough;
- a plurality of collet fingers on the sleeve adapted to engage a gap between adjacent production casing members; and
- a ball or dart adapted to seat on a surface of the sleeve to close the passageway.
7. A tool as claimed in claim 6 further including a cup-shaped member having an interior surface conforming to the exterior surface of the ball or dart and engaging an uphole surface of the ball or dart.
8. A tool as claimed in claim 6 wherein the sleeve includes a valve seat.
9. A method of treating a well having a production casing comprising:
- providing a production casing including a plurality of production casing members;
- securing a tool having a valve seat and a through passageway at a predetermined position within the production casing;
- perforating the production casing uphole of the tool;
- closing the through passageway in the tool; and
- pumping a treating fluid in the production casing and out through the perforations.
10. The method of claim 9 including:
- terminating the pumping of the treating fluid;
- positioning a second tool in the production casing upstream of the perforations in the production casing;
- perforating the production casing at a second location uphole of the second tool and resuming pumping of the treating fluid in the production casing and through perforations located in the second location.
11. The method of claim 9 wherein the tool includes a collet having a plurality of resilient fingers with tabs, the tabs adapted to be captured by a gap formed between adjacent production casing members.
12. The method of claim 9 wherein the tool includes a collet having a plurality of resilient fingers with tabs, the tabs adapted to be captured by a groove within a connection sub that connects two adjacent production casing members together.
Type: Application
Filed: Aug 30, 2013
Publication Date: Mar 6, 2014
Applicant: Texian Resources (Granbury, TX)
Inventor: Douglas N. Love (Granbury, TX)
Application Number: 14/015,618
International Classification: E21B 43/26 (20060101); E21B 34/06 (20060101);