Well Barrier

Abstract

A well barrier is for sealing off a first portion of a wellbore from a second portion of the wellbore, the first portion having a higher fluid pressure than the second portion. The well barrier is held in place in the wellbore by a holding means. The well barrier is preshaped to disintegrate in at least three barrier elements upon activation of a disintegration means, at least one of the barrier elements having a surface area facing the first portion of the wellbore that is larger than the surface area facing the second portion of the wellbore. A method is for controlling a disintegration of the well barrier.

1 . A well barrier for sealing off a first portion of a wellbore from a second portion of the wellbore, the first portion having a higher fluid pressure than the second portion, wherein the well barrier is held in place in the wellbore by a holding means preventing movement of the well barrier in a direction from the first portion to the second portion, the well barrier comprising:
 multiple barrier elements initially held together by a connection means to form the barrier, the barrier having a surface area facing the first portion of the wellbore that is larger than the surface area facing the second portion of the wellbore;   a sealing means for preventing fluid flow from the first portion to the second portion; and   a destabilizing mechanism arranged for disengaging the connection means from at least one of the barrier elements upon activation of the mechanism, so that support between adjoining barrier elements is removed thereby disintegrating the well barrier.   
     
     
         2 . The well barrier of  claim 1 , wherein the multiple barrier elements are formed in one piece provided with notches in at least a portion of the surface of the well barrier, and the connection means comprises the non-notched portion of the well barrier. 
     
     
         3 . The well barrier of  claim 1 , wherein the barrier elements are provided by means of separate, preshaped barrier elements being connected to each other by the connection means, the connection means being selected from one of or a combination of: an adhesive; a wire; the sealing means, to form the well barrier. 
     
     
         4 . The well barrier of  claim 1 , wherein the well barrier is further provided with a support element for supporting the barrier elements, the support element facing the second portion of the wellbore. 
     
     
         5 . The well barrier of  claim 1 , wherein the sealing means is a sealing element facing the first portion of the wellbore. 
     
     
         6 . The well barrier of  claim 5 , wherein the sealing element is selected from the group consisting of an elastomeric membrane, a coating, and an adhesive. 
     
     
         7 . The well barrier of  claim 1 , wherein the sealing means is the non-notched portion of the well barrier. 
     
     
         8 . The well barrier of  claim 1 , wherein the well barrier is provided with a pressure arch towards the first portion of the wellbore. 
     
     
         9 . The well barrier of  claim 1 , wherein the well barrier is provided with a further well barrier, the further well barrier being mirrored with respect to the well barrier about a plane being perpendicular to a longitudinal axis of the wellbore. 
     
     
         10 . The well barrier of  claim 9 , wherein the second portion of the wellbore is defined between the well barrier and the further well barrier. 
     
     
         11 . The well barrier of  claim 1 , wherein the destabilizing mechanism comprises a releasable holding means arranged such that upon releasing the holding means the well barrier is moved by the fluid in the first portion, the movement causing the well barrier to disintegrate. 
     
     
         12 . The well barrier of  claim 1 , wherein the destabilizing mechanism is an arrangement for raising the pressure of the fluid in the second portion to a level higher than the fluid pressure in the first portion of the wellbore facing the further well barrier. 
     
     
         13 . The well barrier of  claim 1 , wherein at least one of the multiple barrier elements has a form as a keystone supporting adjoining barrier elements, the keystone element having a surface area facing the first portion of the wellbore that is larger than the surface area facing the second portion of the wellbore. 
     
     
         14 . The well barrier of  claim 13 , wherein the at least one keystone element is provided by means of multiple elements. 
     
     
         15 . The well barrier of  claim 1 , wherein the barrier facing the first portion of the wellbore has a concave lens shape, and wherein a majority of the barrier elements are wedge shaped with a surface area facing the first portion of the wellbore that is larger than the surface area facing the second portion of the wellbore. 
     
     
         16 . A method for controlling a disintegration of a well barrier for sealing off a first portion of a wellbore from a second portion of the wellbore, the first portion having a higher fluid pressure than the second portion, wherein the well barrier is held in place in the wellbore by a holding means prevention movement of the well barrier in a direction from the first portion to the second portion, the well barrier comprising:
 multiple barrier elements initially held together by a connection means to form the barrier, the barrier having a surface area facing the first portion of the wellbore that is larger than the surface area facing the second portion of the wellbore;   a sealing means for preventing fluid flow from the first portion to the second portion; and   a destabilizing mechanism arranged for disengaging the connection means from at least one of the barrier elements upon activation of the mechanism, so that support between adjoining barrier elements is removed, thereby disintegrating the well barrier, the method comprising:   pre-shaping the barrier to disintegrate in multiple barrier elements of desired size and shape; and   activating a destabilizing mechanism that will provide a force sufficient to break a connection means initially holding the multiple barrier elements together, thereby causing the barrier to disintegrate into said multiple barrier elements of desired size and shape.