WELLBORE TOOL AND METHOD
A wellbore tool includes a seat within the tool's inner diameter. At least the seating surface of the seat, which is that surface exposed within the tool, is formed of a dissolvable material. The tool also includes a support area on the tool body, on which the seat is mounted. The support area is formed of a material stronger than the dissolvable material.
1 . A wellbore tool comprising: a tool body including a tubular wall and an inner bore; a seat formed of dissolvable material and positioned within the inner diameter, the seat including an upper end, a lower end, a bore with an inner diameter that tapers through a seating surface and a backside surface opposite the bore, the backside surface having an outer diameter that tapers from a position adjacent the upper end to a position adjacent the lower end; and a support area on the tool body, the support area formed of a material stronger than the dissolvable material and having a tapering bore sized and shaped similarly to the outer diameter of the backside surface, the seat mounted in the support area with the backside surface supported against the support area and the bore exposed in the inner bore.
2 . The wellbore tool of claim 1 wherein the backside surface and the support area are frustoconically formed.
3 . The wellbore tool of claim 1 further comprising a lock-nut arrangement for the support area to clamp the seat in the support area.
4 . The wellbore tool of claim 1 wherein the seat is secured to the support area to prevent axial shifting.
5 . The wellbore tool of claim 1 wherein the seat is formed entirely of dissolvable material.
6 . The wellbore tool of claim 1 further comprising a projection on the seat extending radially outwardly from the backside surface, the projection engaged in a groove on the support area.
7 . The wellbore tool of claim 1 further comprising a seal between the seat and the support area to seal against fluid leaking between the seat and the support area from the upper end to the lower end of the seat.
8 . The wellbore tool of claim 1 , wherein the seat further comprise a protective coating applied to at least a portion of an outer surface thereof.
9 . The wellbore tool of claim 8 , wherein the protective coating is at least partially removable from the outer surface of the seat by exposure to elements in a stimulation fluid.
10 . A wellbore frac valve tool comprising: a tubular body including a wall, an upper end, a lower end and an inner bore extending from the upper end to the lower end, the inner bore having an inner diameter; a port through the wall; a sleeve valve in the inner bore and having a inner facing surface exposed in the inner bore, the sleeve valve moveable from a port-closed position over the port and a port-open position retracted from the port; a support area on the inner facing surface of the sleeve; and a ball seat in the support area and connected for movement with the sleeve, the ball seat including a portion exposed in the bore having a diameter less than the inner diameter and the portion is formed of dissolvable material.
11 . The wellbore frac valve tool of claim 10 wherein the seat includes a backside surface set against the support area and the backside surface and the support area are each frustoconically formed with a taper towards the lower end of the backside surface.
12 . The wellbore frac valve tool of claim 10 wherein the sleeve valve includes a lower portion and an upper portion connected by a threaded connection and the ball seat is clamped between the upper portion and the lower portion.
13 . The wellbore frac valve tool of claim 10 wherein the ball seat includes a projection extending radially outwardly and the projection is clamped in a groove at the threaded connection between the upper portion and the lower portion.
14 . The wellbore frac valve tool of claim 10 wherein the ball seat is formed entirely of dissolvable material.
15 . The wellbore frac valve tool of claim 10 wherein the ball seat includes a seating surface exposed in the bore and the seating surface is formed entirely of dissolvable material.
16 . The wellbore frac valve tool of claim 10 wherein the sleeve has a diameter no less than the inner diameter.
17 . The wellbore frac valve tool of claim 10 further comprising a seal between the ball seat and the support area to seal against fluid leaking between the ball seat and the support area.
18 . The wellbore frac valve tool of claim 10 further comprising a ball for sealing in the ball seat, the ball being formed of a material dissolvable in a wellbore fluid.
19 . The wellbore frac valve tool of claim 10 , wherein the portion of the ball seat formed of dissolvable material further comprise a protective coating applied to an outer surface thereof.
20 . The wellbore tool of claim 8 , wherein the protective coating is at least partially removable from the outer surface of the portion of the ball seat by exposure to elements in a stimulation fluid.
21 . A method for completing a wellbore, the method comprising: landing a ball on a ball seat to actuate a frac valve tool to open ports to the formation; treating the formation;
and opening up the frac valve tool to a full bore diameter by providing time for the ball seat to dissolve.
22 . The method of claim 21 wherein opening up the frac valve tool to a full bore removes the ball seat from a sleeve valve of the frac valve tool.
23 . The method of claim 21 further comprising reclosing the port by moving the sleeve valve to cover the port.
24 . The method of claim 21 further comprising dissolving the ball.
25 . The method of claim 21 , further comprising at least partially removing a protective coating from an outer surface of the seat prior to opening up the frac valve tool to a full bore diameter.