# US 11,993,999 B2 · Retrievable anti-extrusion foldback-ring backup for sealing element > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,993,999 B2 - Document ID: US11993999B2 - Status: Granted - Kind: B2 - Application number: 17/551,422 - Filed: 2021-12-15 - Published: 2022-04-07 - Granted: 2024-05-28 - Earliest claimed: 2019-02-05 - Assignees: Weatherford Technology Holdings, LLC - Applicants: Weatherford Technology Holdings, LLC - Inventors: Michael W. Mitchell; Gary D. Ingram - Web page: https://patentgrep.com/patent/US11993999B2 ## CPC - E21B 33/1216: {Anti-extrusion means, e.g. means to prevent cold flow of rubber packing} - E21B 23/06: for setting packers - E21B 33/128: with a member expanded radially by axial pressure (E21B33/122, E21B33/124 take precedence) - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract A well barrier can include an annular seal element, an anti-extrusion backup having radially inward and radially outward portions, and a biasing device that exerts a biasing force against the radially outward portion of the anti-extrusion backup. A method of operating a well barrier can include setting the well barrier by decreasing a longitudinal distance between abutments of the well barrier, thereby compressing a seal element between the abutments, and unsetting the well barrier by increasing the longitudinal distance between the abutments and radially inwardly retracting an anti-extrusion backup positioned longitudinally between the seal element and one of the abutments. Another well barrier can include an annular seal element, an anti-extrusion backup, an abutment displaceable relative to the seal element to compress the seal element, a sleeve reciprocable relative to the abutment, and a biasing device that biases the sleeve toward the anti-extrusion backup. ## Claims ### Claim 1 A well barrier, comprising: an annular seal element; an anti-extrusion backup having radially inward and radially outward portions; and a biasing device configured to exert a biasing force against the radially outward portion of the anti-extrusion backup during setting of the well barrier, in which the biasing force urges the anti-extrusion backup towards a radially retracted position, and in which the radially outward portion of the anti-extrusion backup rotates inward to the radially retracted position when the well barrier is unset in response to the biasing force applied to the radially outward portion of the anti-extrusion backup. ### Claim 2 (depends on 1) The well barrier of claim 1, further comprising an abutment, in which the radially inward portion of the anti-extrusion backup is secured against longitudinal displacement relative to the abutment. ### Claim 3 (depends on 2) The well barrier of claim 2, in which the radially outward portion of the anti-extrusion backup is longitudinally displaceable relative to the abutment. ### Claim 4 (depends on 1) The well barrier of claim 1, in which the biasing device comprises at least one Belleville spring washer. ### Claim 5 (depends on 1) The well barrier of claim 1, in which the biasing device exerts the biasing force against a sleeve reciprocably disposed relative to the anti-extrusion backup. ### Claim 6 (depends on 5) The well barrier of claim 5, in which the sleeve is reciprocably disposed relative to an abutment, the seal element extends radially outward in response to a compressive force applied between the abutment and the seal element, and the sleeve surrounds the abutment. ### Claim 7 (depends on 6) The well barrier of claim 6, in which the anti-extrusion backup includes a fold-back ring, and the fold-back ring retracts radially inward in response to application of the biasing force to the radially outward portion of the anti-extrusion backup. ### Claim 8 A method of operating a well barrier, the method comprising: setting the well barrier by decreasing a longitudinal distance between first and second abutments of the well barrier, thereby compressing a seal element between the first and second abutments, and thereby compressing a biasing device; and unsetting the well barrier by increasing the longitudinal distance between the first and second abutments, the unsetting further comprising radially inwardly retracting an anti-extrusion backup positioned longitudinally between the seal element and the first abutment, in which expansion of the biasing device causes a sleeve of the well barrier to displace and force the anti-extrusion backup to retract radially inward. ### Claim 9 (depends on 8) The method of claim 8, in which the anti-extrusion backup expands radially outward in response to the compressing of the seal element. ### Claim 10 (depends on 8) The method of claim 8, in which the retracting comprises applying a biasing force to a radially outward portion of the anti-extrusion backup. ### Claim 11 (depends on 10) The method of claim 10, in which the biasing force applying comprises the biasing device biasing the sleeve to displace relative to the first abutment and toward the seal element. ### Claim 12 (depends on 11) The method of claim 11, in which the sleeve surrounds the first abutment. ### Claim 13 (depends on 11) The method of claim 11, in which the setting comprises displacing the sleeve relative to the first abutment in a first direction, and the unsetting comprises displacing the sleeve relative to the first abutment in a second direction opposite to the first direction. ### Claim 14 (depends on 10) The method of claim 10, in which the setting comprises increasing the biasing force. ### Claim 15 (depends on 8) The method of claim 8, in which the setting comprises rotating a portion of the anti-extrusion backup in a first direction, and the unsetting comprises rotating the portion of the anti-extrusion backup in a second direction opposite to the first direction.