Sliding sleeve having contracting, segmented ball seat
A sliding sleeve opens with a deployed ball. The sleeve has a seat disposed in the housing, and the seat has segments biased outward from one another with a C-ring or other biasing element. Initially, the seat has an expanded state in the sliding sleeve so that the seats segments expand outward against the housing's bore. When an appropriately sized ball is deployed downhole, the ball engages the expanded seat. Fluid pressure applied against the seated ball moves the seat into the inner sleeve's bore. As this occurs, the seat contracts, which increases the engagement area of the seat with the ball. Eventually, the seat reaches the shoulder in the inner sleeve so that pressure applied against the seated ball now moves the inner sleeve in the housing to open the sliding sleeve's flow port.
1. A sliding sleeve opening with a deployed plug, the sleeve comprising:
a housing defining a first bore and defining a flow port communicating the first bore outside the housing;
an inner sleeve defining a second bore with an engagement point and being movable axially inside the first bore from a closed position to an opened position relative to the flow port; and
a seat disposed in the sliding sleeve and having a plurality of segments biased outward from one another,
the segments in a first axial position expanded outward in the first bore of the housing and defining a first internal dimension initially engaging the deployed plug,
the seat being movable axially from the first axial position in the first bore of the housing to a second axial position in the second bore of the inner sleeve in response to fluid pressure applied against the same deployed plug engaged in the seat,
the segments in the second axial position contracted inward against the same deployed plug in the second bore of the inner sleeve and defining a second internal dimension subsequently engaging the same deployed plug, the second internal dimension being less than the first internal dimension,
the seat in the second axial position engaging the engagement point of the inner sleeve and moving the inner sleeve axially open in response to the applied fluid pressure.
2. The sleeve of claim 1 , wherein the seat comprises at least one biasing element biasing the segments outward from one another.
3. The sleeve of claim 1 , wherein the housing defines a spacer disposed inside the first bore of the housing and separating the seat in the first axial position in the first bore from the second bore of the inner sleeve in the closed position.
4. The sleeve of claim 3 , wherein the spacer comprises an attachment holding the inner sleeve in the closed position and being disengageable to permit axial movement of the inner sleeve from the closed position.
5. The sleeve of claim 3 , wherein the segments transition over the spacer from the first axial position to the axial second position and compress against the deployed plug.
6. The sleeve of claim 1 , wherein the first internal dimension is narrower than an outer dimension of the deployed plug; wherein the second internal dimension is narrower than the first internal dimension; and wherein the second bore of the inner sleeve defines a change in a third internal dimension at the engagement point.
7. The sleeve of claim 1 , wherein the segments in the second axial position engage the plug with more surface area than in the first axial position.
8. A sliding sleeve opening with a deployed plug, comprising:
a housing defining a first bore and defining a flow port communicating the first bore outside the housing;
an inner sleeve defining a second bore and being movable axially inside the first bore from a closed position to an opened position relative to the flow port; and
a seat disposed in the sliding sleeve, the seat comprising:
means for expanding the seat to an expanded state in a first axial position inside the first bore of the housing,
means for passing one or more first plugs deployed through the seat in the first axial position,
means for engaging a second plug deployed in the seat in the expanded state of the first axial position,
means for contracting the seat, against the same engaged second plug, to a contracted state in a second axial position inside the second bore of the inner sleeve, and
means for moving the inner sleeve from the closed position to the opened position with the seat engaged with the same second plug in the second axial position.
9. The sleeve of claim 8 , wherein the means for expanding the seat to the expanded state comprises means for biasing segments of the seat outward from one another.
10. The sleeve of claim 8 , wherein the means for contracting the seat comprises means for separating the seat in the first axial position from an end of the inner sleeve in the closed position.
11. The sleeve of claim 10 , wherein the means for separating comprises means for disengageably holding the inner sleeve in the closed position.
12. The sleeve of claim 8 , wherein the means for contracting comprises means for wedging the second plug in the seat.
13. The sleeve of claim 8 , wherein the means for moving the inner sleeve from the closed position to the opened position with the seat engaged with the second plug comprises means for engaging the seat in the inner sleeve.
14. A fluid treatment method for a wellbore, the method comprising:
deploying a first plug downhole to a sliding sleeve in the wellbore;
expanding a seat in an expanded state in a first axial position inside a housing of the sliding sleeve;
engaging the first plug against the seat in the first axial position;
moving the seat from the first axial position inside the housing to a second axial position inside an inner sleeve in the housing by applying fluid pressure against the same first plug engaged in the seat;
contracting the seat, against the same first plug, from the expanded state in the first axial position inside the housing to a contracted state in the second axial position inside the inner sleeve; and
moving the inner sleeve axially open relative to a flow port in the housing in response to the applied fluid pressure.
15. The method of claim 14 , wherein expanding the seat in the expanded state comprises biasing segments of the seat outward from one another.
16. The method of claim 14 , wherein moving the seat from the first axial position inside the housing to the second axial position inside the inner sleeve comprises separating the seat in the first axial position with a spacer from an end of the inner sleeve in a closed position.
17. The method of claim 16 , further comprising disengageably holding the inner sleeve in the closed position with the spacer.
18. The method of claim 14 , comprising initially passing one or more second plugs deployed through the seat in the expanded state in the first axial position.
19. The method of claim 14 , wherein contracting the seat from the expanded state in the first axial position inside the housing to the contracted state in the second axial position inside the inner sleeve comprises engaging the first plug with more surface area in the contracted state than in the expanded state.
20. The method of claim 14 , wherein contracting the seat from the expanded state in the first axial position inside the housing to the contracted state in the second axial position inside the inner sleeve comprises wedging the first plug with the contracted seat.