Method and apparatus for treating a well

Abstract

A tool for forming a valve seat within a well that is capable of catching an obstruction will prevent flow of fluid downstream of the seat. The seat is formed by expanding a sleeve with a ring positioned around its periphery or as a subsequent step in the process. As the sleeve is expanded over the ring, the seat is formed. Once the seat is formed, an obstruction in the form of a ball or dart is dropped down to the seat. The sleeve acts as a stop for a secondary valve seat which catches the obstruction.

Claims

1. A tool for forming a valve seat within an oil and/or gas well capable of capturing an obstruction to thereby prevent flow of fluids downhole of the valve seat comprising: a. a sleeve formed of expansible material; b. a valve seat formed as part of the sleeve; and c. a ring member surrounding the sleeve; wherein the valve seat is formed by expanding the sleeve over the ring.

2. The tool for forming a valve seat as claimed in claim 1 further including a thin strip of no-slip metallic material impregnated on an outer surface of the sleeve.

3. The tool for forming a valve seat as claimed in claim 1 further including a cap closing a downhole portion of the sleeve so that the tool can be pumped down into the well to a predetermined location.

4. The tool for forming a valve seat as claimed in claim 1 further including an explosive charge positioned within the sleeve to expand the sleeve when the charge is detonated.

5. The tool for forming a seat as claimed in claim 4 further comprising a frangible mandrel supporting the explosive charge.

6. The tool for forming a seat as claimed in claim 4 wherein the explosive charge is detonation cord.

7. The tool as claimed in claim 2 wherein the thin strip of no-slip metallic material includes an elastomeric sealing agent.

8. The tool as claimed in claim 1 wherein the ring is positioned around the sleeve approximately at the midpoint of the sleeve.

9. The tool as claimed in claim 1 wherein the ring has an outer diameter approximately equal to the inner diameter of a production tubular within the well.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

(1) FIG. 1 is a flow diagram of the process according to an embodiment of the invention.

(2) FIG. 2 is a cross sectional view of expansible sleeve seat according to an embodiment of the invention.

(3) FIG. 3 is a cross-sectional view of the sleeve seat deployed within the casing with ball.

(4) FIG. 4 is a cross-sectional view of a second expansible sleeve seat with dart.

(5) FIG. 5 is a cross-sectional view of a third expansible sleeve seat with ball.

(6) FIG. 6 is a cross-sectional view of a fourth embodiment with an expansible sleeve and separate seat with dart.

DETAILED DESCRIPTION OF THE INVENTION

(7) 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.

(8) This is accomplished in the following manner. After the well has been drilled (51) and the casing has been fully positioned (52), an expansible sleeve such as shown in FIG. 2 is placed at the desired location within the casing (53). As shown in FIG. 2, the expansible sleeve 10 consists of a relatively thin walled cylindrical tube 11 formed of a high tensile strength material similar to that of the well casing 21. A ring of expansible material 12 may surround a portion of tube 11. A cap 15 is positioned over the downhole end 16 of the tube so that the expansible sleeve 10 may be pumped into the well. The outside diameter of the ring 12 is slightly less that the inside diameter of the casing. Detonation cord 14 is wound about a frangible mandrel 13 positioned within the tube and includes an electrical cord 17 for detonation. Another embodiment of this patent may employ the use of an extrusion process using a mandrel and sleeve to create the seat as shown in FIG. 5. The resultant sleeve or seat installed in the casing will be the same whether the installation process is expansive or extruded.

(9) Expansible sleeve 10 may be precisely positioned within the casing by any suitable known technique such as a line counter or collar locator. Once positioned within the desired location of the casing, the cord is detonated causing the sleeve to expand outwardly against the inner surface of the casing (54). In so doing, the sleeve forms a seat 12 as shown in FIG. 3 which is capable of catching and retaining a ball or dart as shown in FIG. 3 and FIG. 4 that is pumped down. The outer surface of tube 11 may be impregnated with a thin strip of no slip high strength metallic material.

(10) Once the tube 11 and seat have been set in place, the casing and cement (if present) in the first frac zone can be perforated (55) 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 (56) 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 (57) to enter the formation surrounding the perforations in the casing and thus commence the fracing process.

(11) Once the process is completed for the first zone, a second expansible sleeve can be placed (58) to isolate a second zone and the process can be repeated (59-62) for as many zones as desired as indicated in FIG. 1. The ball, dart, seat or sleeve may be made of a soluble, dissolvable, or frangible material such that it would not be necessary to drillout the sealing mechanism after fracturing. The ball, dart, seat or sleeve would shrink in size or completely dissolve so that the constituents went into solution or were flowed back with the frac load water.

(12) Another embodiment of the expansible sleeve is illustrated in FIG. 5. In this embodiment, a tubular member is shown in an unexpanded condition at 45. Chevron or swellable seals 43 are positioned about an uphole portion 44 of the sleeve 45. Sleeve portion 45 is expanded by a mandrel or shaped charge into the position indicated at 46 against the inner surface of the casing 21. In this embodiment the uphole portion 44 of the sleeve may have a beveled surface (47) against which ball 22 rests when a ball or dart is pumped down into the casing.

(13) An additional embodiment of the expansible sleeve is illustrated in FIG. 6. In this embodiment, a sleeve 11 is expanded in the casing 21 and used as a stop or no-go for a secondary conical seat 51 that is either simultaneously or subsequently placed on the no-go. The perforations are then added. A ball or dart 32 is then landed on the seat forming the sealing mechanism for the wellbore and the stage is frac'd. Secondary seat 51 may have an elastomeric annular seat 52 that engages a tapered portion 53 of the sleeve 11 to form a seal. This process can be repeated as many times as necessary to adequately stimulate the formation surrounding the wellbore. The ball, dart or seat in this embodiment may also be made of a soluble, dissolvable, or frangible material.

(14) 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 well casing so for example if the casing is 5½ inch casing, the sleeve may have an outside diameter of 4.5 inches.

(15) 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.