Wellbore actuators, treatment strings and methods

Abstract

A wellbore tubing string assembly with at least one port for communicating fluid between its inner bore and its exterior, can be actuated to move from a port-closed position to a port-exposed position using a series of deformable plugs of the same outer diameter that are placed in the inner bore, and that can deform so as to be squeezed through the inner bore, responsive to an application of force against each of the plugs. The plugs have an interference fit as they engage with the assembly at the inner bore. As a plug is squeezed through the inner bore and out of the assembly, its passage through the assembly is registered. When the number of plugs that have been so registered exceeds a predetermined threshold, the next plug that squeezes through the inner bore will cause the assembly to be actuated to the port-exposed position. The use of plugs having such an interference fit reduces the number of moving parts required to construct the assembly, which makes it more reliable and durable.

1 . A wellbore tool comprising:
 a tubular body with one or more fluid ports;   a sleeve with a central bore of an inner diameter, disposed in the tubular body and adapted to incrementally slide downhole from an initial inactive port-closed position, through a predetermined number of other inactive port-closed positions, and then to a port-exposed position, when engaged by one or more elastically deformable plugs each being acted upon by a variable fluid pressure applied in the downhole direction, and each having a same outer diameter that is greater than the inner diameter,   wherein the incremental sliding from one of the positions to another of the positions occurs when the fluid pressure is set higher than a threshold that is great enough to force an engaged elastically deformable plug to squeeze through the central bore and away from the tool in the downhole direction.   
     
     
         2 . The wellbore tool of  claim 1 , wherein the outer diameter OD of one of the plugs is temporarily reduced as the plug squeezes through the inner bore of the sleeve. 
     
     
         3 . The wellbore tool of  claim 1 , further comprising a sensor adapted to detect the number of inactive port-closed positions through which the sleeve has passed. 
     
     
         4 . The wellbore tool of  claim 1 , wherein the sleeve slides in a groove provided in the tubular body, the length of sleeve and groove being selected to keep the fluid port closed when the sleeve is any of the port-closed positions, and to keep the fluid port open when the sleeve is in the port-exposed position. 
     
     
         5 . The wellbore tool of  claim 1 , wherein the sleeve is kept in one of the port-closed positions by a holding pin, that when broken releases the sleeve for progression to a next position when the fluid pressure is greater than the threshold. 
     
     
         6 . The wellbore tool of  claim 1 , wherein the sleeve is driven to slide downhole from each of the respective inactive port-closed positions to a next position, by a force applied to the sleeve as one of the engaged elastically deformable plugs squeezes through the inner bore of the sleeve. 
     
     
         7 . The wellbore tool of  claim 1 , wherein the threshold is set by selection of the material of the one or more elastically deformable plugs, the fluid pressure, and the relative sizes of the inner diameter and outer diameter. 
     
     
         8 . The wellbore tool of  claim 1 , wherein the respective elastically deformable plug is adapted to actuate a second wellbore tool placed downhole from the wellbore tool. 
     
     
         9 . The wellbore tool of  claim 1 , wherein the sleeve is enabled to slide downhole by use of an indexing mechanism, associated with the sleeve. 
     
     
         10 . The wellbore tool of  claim 8 , wherein the indexing mechanism comprises a plurality of protrusions provided on the inner surface of the tubular body with inwardly extending bumps having smooth or sharp angles. 
     
     
         11 . The wellbore tool of  claim 8 , wherein the indexing mechanism includes a pin in a walking J-slot biased by spring. 
     
     
         12 . A wellbore treatment assembly comprising:
 a plurality of packers expanded about a tubing string to segment the wellbore into a plurality of successive treatment zones;   an elastically deformable ball of an outer diameter OD1; and   a first group of single cycle tools, each single cycle tool of the first group being associated with a respective zone, each single cycle tool comprising:
 a tubular body with one or more fluid ports; 
 a sleeve with a central bore of an inner diameter ID1 smaller than the outer diameter OD1, the sleeve disposed in the tubular body and adapted to slide downhole from an initial port-closed position to a port-exposed position, when engaged by the elastically deformable plug, when the fluid pressure applied to the elastically deformable plug engaging the sleeve is varied to exceed a threshold great enough to force the engaged elastically deformable plug to squeeze through the central bore and away from the tool in the downhole direction. 
   
     
     
         13 . The wellbore treatment assembly of  claim 12 , further comprising a delay opening mechanism for each zone that delays when the sleeve slides to the port-exposed position, wherein the delay for each mechanism is decreased the further downhole the delay mechanis is located. 
     
     
         14 . The wellbore treatment assembly of  claim 12 , further comprising a second group of single cycle tools disposed in the wellbore downhole from the first group and a second elastically deformable plug of a second outer diameter OD2 smaller than OD1. 
     
     
         15 . The wellbore treatment assembly of  claim 14 , wherein each single cycle tool of the second group comprising:
 a tubular body with one or more fluid ports;   a sleeve with a central bore of a second inner diameter ID2 smaller than inner diameter ID1 and smaller than the second outer diameter OD2, the sleeve disposed in the tubular body and adapted to slide downhole from an initial port-closed position to a port-exposed position, when engaged by the second elastically deformable plug, when fluid pressure applied to the second elastically deformable plug engaging the sleeve is varied to exceed a threshold that is great enough to force the engaged second elastically deformable plug to squeeze through the central bore and away from the tool in the downhole direction.   
     
     
         16 . The wellbore treatment assembly of  claim 12 , wherein the elastically deformable plug is a ball formed of one or more deformable materials such as metals, ceramics, plastics or rubber. 
     
     
         17 . The wellbore assembly of  claim 12 , wherein the elastically deformable plug has a multi-part construction, including a core and a coat laid over the core, the core and the coat being selected to serve a specified requirement for a particular wellbore treatment. 
     
     
         18 . The wellbore assembly of  claim 12 , wherein the elastically deformable plug regains its original outer diameter after squeezing through the inner diameter of the sleeve. 
     
     
         19 . The wellbore assembly of  claim 12 , wherein the sleeve is a valve controlling operation of the port-closed position and the port-exposed position. 
     
     
         20 . The wellbore assembly of  claim 12 , further comprising:
 a burst plug insert provided into at least a fluid port to initially restrict fluid flow through the port after the port is exposed; and   a ball stopper which stops the downhole movement of the elastically deformable plug temporally, for enabling the elastically deformable plug to regain its original outer diameter, while the pressure differential across the elastically deformable plug equalizes.