Wellbore packer, method and tubing string

Abstract

A wellbore packer for setting one or more packing elements in a borehole having an open hole section. The wellbore packer comprises a port-less mandrel configured with one or more packing elements and one or more setting mechanisms. The setting mechanism is responsive to a driving force and configured to set the packing elements in the borehole, wherein the driving force is not tubing string pressure. Where packers are set by annular pressure, a method for setting a plurality of such packers may include sequentially operating the packers. A mechanism may be provided for the packers to allow sequential operation thereof.

What is claimed is: 
     
         1 . A method for setting a plurality of packers on a wellbore string, the method comprising:
 operating a first wellbore packer by exposing a mechanism of the first wellbore packer to annular pressure; and   delaying the setting of a second wellbore packer that is axially spaced along the wellbore string from the first wellbore packer until after operating the first wellbore packer.   
     
     
         2 . The method of  claim 1  wherein operating includes at least one of triggering and setting. 
     
     
         3 . The method of  claim 1  wherein delaying includes triggering the second wellbore packer only after operating the first wellbore packer. 
     
     
         4 . The method of  claim 1  wherein delaying includes awaiting the expiration of a timer to ensure that operating the first packer proceeds before setting the second packer. 
     
     
         5 . The method of  claim 1  wherein delaying includes operating a delay mechanism after triggering. 
     
     
         6 . An apparatus for fluid treatment in a wellbore, the apparatus comprising:
 a tubing string having a long axis and including a wall portion defining an inner bore therein;   a first packer operable to seal about the tubing string and mounted on the tubing string;   a second packer operable to seal about the tubing string and mounted on the tubing string in a position axially offset along the tubing string from the first packer; and   a packer setting mechanism for selectively operating sequentially the first packer and the second packer toward setting.   
     
     
         7 . The apparatus of  claim 6  wherein the packer setting mechanism comprises a hydraulically actuated mechanism. 
     
     
         8 . The apparatus of  claim 6  wherein the packer setting mechanism is operable in response to fluid pressure communicated to the setting mechanism from outside the tubing string. 
     
     
         9 . The apparatus of  claim 6  wherein the packer setting mechanism is operable in response to annular fluid pressure. 
     
     
         10 . The apparatus of  claim 6  wherein the packer setting mechanism is operable in response to hydrostatic pressure. 
     
     
         11 . The apparatus of  claim 6  wherein the packer setting mechanism is operable in response to a signal conveyed through the annular fluid. 
     
     
         12 . The apparatus of  claim 6  wherein the packer setting mechanism is for selectively triggering at least one of the first packer and the second packer to set. 
     
     
         13 . The apparatus of  claim 6  wherein the packer setting mechanism is for selectively setting at least one of the first packer and the second packer. 
     
     
         14 . A method for securing a tubing string in a wellbore, the method comprising:
 running a tubing string into the wellbore, wherein the tubing string includes a long axis, a wall portion defining an inner bore;   a first packer operable to seal about the tubing string and mounted on the tubing string;   a second packer operable to seal about the tubing string and mounted on the tubing string in a position axially offset along the tubing string from the first packer;   positioning the tubing string in the wellbore forming an annulus between the tubing string and a wall of the wellbore; and   selectively operating the first packer and the second packer sequentially by application of annular fluid pressure.   
     
     
         15 . The method of  claim 14  wherein selectively operating includes triggering a packer to set. 
     
     
         16 . The method of  claim 14  wherein selectively operating includes setting a packer. 
     
     
         17 . The method of  claim 14  wherein the first packer is downhole of the second packer and annular fluid pressure is hydrostatic pressure and selectively operating includes operating the first packer in response to hydrostatic pressure before setting the second packer. 
     
     
         18 . The method of  claim 14  wherein selectively operating includes conveying a pressure signal from surface to the first packer and the second packer. 
     
     
         19 . The method of  claim 18  wherein conveying a pressure signal includes increasing the annular fluid pressure and/or conveying a pressure pulse. 
     
     
         20 . The method of  claim 18  wherein the pressure signal is conveyed downwardly through the annulus. 
     
     
         21 . The method of  claim 20  wherein the first packer is downhole of the second packer and selectively operating includes operating the first packer in response to the pressure signal before setting the second packer. 
     
     
         22 . The method of  claim 18  wherein the pressure signal is conveyed through the inner bore and upwardly through the annulus. 
     
     
         23 . The method of  claim 22  wherein the first packer is downhole of the second packer and selectively operating includes operating the second packer in response to the pressure signal before setting the first packer. 
     
     
         24 . The method of  claim 14  wherein after operating, the first packer and the second packer create therebetween a first annular wellbore segment substantially isolated from other portions of the annulus.