# US 2013/0153220 A1 · Expandable seat assembly for isolating fracture zones in a well

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- Number: US 2013/0153220 A1
- Document ID: US20130153220A1
- Status: Published application
- Kind: A1
- Application number: 13/715,535
- Filed: 2012-12-14
- Published: 2013-06-20
- Earliest claimed: 2011-12-14
- Assignees: Utex Industries, Inc.
- Inventors: Derek L. Carter; Mark Henry Naedler
- Web page: https://patentgrep.com/patent/US20130153220A1

## CPC

- E21B 33/128: with a member expanded radially by axial pressure (E21B33/122, E21B33/124 take precedence)
- E21B 34/142: {unsupported or free-falling elements, e.g. balls, plugs, darts or pistons}
- E21B 43/26: by forming crevices or fractures
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

An expandable fracture ball seat assembly for use in wellbore zone fracturing operations functions to permit passage therethrough and exit therefrom of fracture ball plugs of only diameters less than a predetermined magnitude. In a representative form, the seat assembly includes a ring stack disposed within a tubular member and formed from a first expandable ring coaxially sandwiched between a setting ring and a second expandable ring. When an oversized fracture ball plug is forced into the seat assembly it axially compresses the ring stack and reduces the diameter of the first expandable ring and telescopes it into the second expandable ring, with the first expandable ring and the setting ring blocking passage through and exit from the seat. A reverse passage of a suitably large diameter fracture ball plug through the seat assembly axially returns the setting ring and first expandable ring to their original positions.

## Claims

### Claim 1

Wellbore fracturing apparatus comprising:
a tubular member; and
an annular fracture plug seat assembly coaxially carried within said tubular member, said annular fracture plug seat assembly being operative to permit axial passage therethrough and exit therefrom of fracture ball plugs only of diameters less than a predetermined magnitude, said annular fracture plug seat assembly including:
an expandable ring, and
expansion control structure, operative, in response to entry and forcible engagement of said annular fracture plug assembly by an axially moving fracture ball plug having a diameter equal to or greater than said predetermined magnitude, to axially displace said expandable ring within said tubular member and then utilize the axially displaced expandable ring to block the axially moving fracture ball from exiting said annular fracture plug seat assembly.

### Claim 2 (depends on 1)

The wellbore fracturing apparatus of claim 1 wherein:
said expansion control structure further includes a second ring structure coaxially disposed on a ball exit side of said expandable ring.

### Claim 3 (depends on 2)

The wellbore fracturing apparatus of claim 2 wherein:
the axially displaced expandable ring is telescoped within said second ring structure.

### Claim 4 (depends on 3)

The wellbore fracturing apparatus of claim 3 wherein:
said second ring structure is integrated with said tubular member and diametrically restricts the axially displaced expandable ring structure such that its internal diameter is insufficient to permit passage of the axially moving fracture ball plug therethrough.

### Claim 5 (depends on 3)

The wellbore fracturing apparatus of claim 3 wherein:
said expandable ring is a first expandable ring, and
said second ring structure is a second expandable ring.

### Claim 6 (depends on 5)

The wellbore fracturing apparatus of claim 5 wherein:
the axially displaced first expandable ring expands the second expandable ring, is diametrically restrained thereby, and has a central opening with a diameter insufficient to permit passage of the axially moving fracture ball plug therethrough.

### Claim 7 (depends on 6)

The wellbore fracturing apparatus of claim 6 wherein:
said tubular member restrains further expansion of the expanded second expandable ring.

### Claim 8 (depends on 1)

The wellbore fracturing apparatus of claim 1 wherein:
said expansion control structure further includes a setting ring coaxially disposed on a ball entry side of said expandable ring, said setting ring and said expandable ring being configured in manners such that both may be forcibly engaged by the axially moving fracture ball plug and axially displaced thereby relative to said tubular member in the direction of fracture ball plug travel until said expandable ring reaches a displaced limit position.

### Claim 9 (depends on 8)

The wellbore fracturing apparatus of claim 8 wherein:
said expandable ring and said setting ring are further configured in a manner such that when said expandable ring reaches said displaced limit position thereof, each of said expandable ring and said setting ring blocks exit of the axially moving fracture ball plug from said annular fracture plug seat assembly.

### Claim 10 (depends on 9)

The wellbore fracturing apparatus of claim 9 wherein:
when said expandable ring reaches said displaced limit position thereof, said setting ring contacts and blocks exit of the axially moving fracture ball plug along a first circular contact area, and said expandable ring contacts and blocks exit of the axially moving fracture ball plug along a second circular contact area having a diameter less than that of said first circular contact area.

### Claim 11 (depends on 1)

The wellbore fracturing apparatus of claim 1 wherein:
said expansion control structure further includes a setting ring member disposed on a fracture ball plug entry side of said expandable ring, and a second ring structure disposed on a fracture ball plug exit side of said expandable ring, said setting ring and said expandable ring, and said expandable ring and said second ring structure, having complementarily and slidingly engaged sloping surfaces that function, when said setting ring is forcibly moved toward the fracture ball plug exit end of said annular fracture plug seat assembly, to diametrically contract said expandable ring and move it into an inwardly telescoped relationship with said second ring structure.

### Claim 12 (depends on 11)

The wellbore fracturing apparatus of claim 11 wherein:
said expandable ring is a first expandable ring,
said second ring structure is a second expandable ring, and
said first expandable ring, when inwardly telescoped into said second expandable ring, expands said second expandable ring and is itself restricted therein against diametrical expansion.

### Claim 13 (depends on 12)

The wellbore fracturing apparatus of claim 12 wherein:
with said first expandable ring inwardly telescoped into said second expandable ring, said first expandable ring, said second expandable ring, and said setting ring may be returned to their original positions within said tubular member in response to movement of a fracture ball plug through said annular fracture plug seat assembly from the ball exit end thereof to the ball entrance end thereof.

### Claim 14 (depends on 1)

The wellbore fracturing apparatus of claim 1 wherein:
said expandable ring includes a split ring diametrically restricted by an encircling spring.

### Claim 15 (depends on 1)

The wellbore fracturing apparatus of claim 1 wherein:
said expandable ring is a collet with one end thereof being diametrically expandable.

### Claim 16 (depends on 1)

The wellbore fracturing apparatus of claim 1 wherein:
said expandable ring is coupled to said tubular member by a shearable member.

### Claim 17 (depends on 1)

The wellbore fracturing apparatus of claim 1 wherein:
said tubular member is a sliding sleeve.

### Claim 18

Wellbore fracturing apparatus comprising:
a tubular member; and
a fracture plug seat assembly carried within said tubular member and comprising a ring having a axial opening that may be varied to permit or preclude passage therethrough of a fracture plug, said ring being axially movable within said tubular member, by a fracture plug passing through said fracture plug seat assembly in a first axial direction, from a first position in which said ring is diametrically constricted and capable of being diametrically expanded, and a second position in which said ring is restricted against diametrical expansion.

### Claim 19 (depends on 18)

The wellbore fracturing apparatus of claim 18 wherein:
said ring in said second position is capable of being axially shifted back to said first position thereof by a fracture plug passing through said fracture plug seat assembly in a second axial direction opposite to said first axial direction.

### Claim 20 (depends on 1)

The wellbore fracturing apparatus of claim 1 wherein:
said expansion control structure further includes a setting ring and a second ring structure between which said ring is coaxially sandwiched.

### Claim 21 (depends on 20)

The wellbore fracturing apparatus of claim 20 wherein:
said second ring structure is integrated with said tubular member.

### Claim 22 (depends on 20)

The wellbore fracturing apparatus of claim 20 wherein:
said ring is a first expandable ring, and
said second ring structure is a second expandable ring.

### Claim 23 (depends on 22)

The wellbore fracturing apparatus of claim 22 further comprising:
a biasing structure operative to exert an axially compressive force on said first and second expandable rings and said setting ring.

### Claim 24

A wellbore fracturing method comprising the steps of:
providing a fracture plug seat comprising a tubular member having an expandable ring coaxially disposed and axially translatable therein;
operatively positioning said fracture plug seat in a wellbore; and
using said expandable ring to selectively permit and block passage of fracture plugs through said fracture plug seat.

### Claim 25 (depends on 24)

The wellbore fracturing method of claim 24 wherein:
said using step includes positioning said expandable ring in a first axial position within said tubular member and passing a fracture plug in a downhole direction through said expandable ring without axially shifting said expandable ring away from said first position.

### Claim 26 (depends on 25)

The wellbore fracturing method of claim 25 further comprising the step of:
causing the fracture plug to diametrically expand said expandable ring while it remains in said first position.

### Claim 27 (depends on 24)

The wellbore fracturing method of claim 24 wherein:
said using step includes axially shifting said expandable ring from a first position within said tubular member in a downhole direction to a second position within said tubular member and subsequently utilizing the shifted expandable ring to block passage of a fracture plug through said fracture plug seat.

### Claim 28 (depends on 27)

The wellbore fracturing method of claim 27 further comprising the step, performed subsequent to the performance of said using step, of:
returning said expandable ring to said first position from said second position by moving a fracture plug in an uphole direction through said fracture plug seat.

### Claim 29

Wellbore fracturing apparatus comprising:
a tubular member; and
an annular fracture plug seat assembly carried within said tubular member, said fracture plug seat assembly being operative to permit axial passage therethrough and exit therefrom of fracture ball plugs only of diameters less than a predetermined magnitude, said annular fracture plug seat assembly including a ring stack in which an expandable ring is coaxially sandwiched between a second ring structure and a setting ring.

### Claim 30 (depends on 29)

The wellbore fracturing apparatus of claim 29 wherein:
said expandable ring is a first expandable ring, and
said second ring structure is a second expandable ring.

### Claim 31 (depends on 29)

The wellbore fracturing apparatus of claim 29 wherein:
said second ring structure is integrated with said tubular member.

### Claim 32 (depends on 29)

The wellbore fracturing apparatus of claim 29 wherein:
said setting ring is a fixed diameter ring.

### Claim 33 (depends on 30)

The wellbore fracturing apparatus of claim 30 wherein:
said first expandable ring is diametrically retractable and telescopeable into said second expandable ring in response to an axially compressive force imposed on said ring stack.

### Claim 34 (depends on 31)

The wellbore fracturing apparatus of claim 31 wherein:
said expandable ring is diametrically retractable and telescopeable into said second ring structure in response to an axially compressive force imposed on said ring stack.