Centralizers for oil well casings
AssigneeWeatherford U.K. Limited
InventorsPaul D. Gullet, Manfred Jansch
Life of this patent
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Abstract
A centralizer for well casings is disclosed which, in one aspect has spring strips which are normally bowed to centralize the casing, but which are held in a collapsed disposition against the casing while the casing is positioned in a borehole. The holding force may be provided by a band and/or an arrangement of struts which are released when the casing is positioned. An additional energizing device may be provided to increase the bowing of the spring strips for more certain engagement with the surrounding borehole.
Claims29
A centralizer for well casings, said centralizer comprising,
- a mounting means by which the centralizer may be mounted on an outer surface of a casing,
- a plurality of members carried by the mounting means at spaced positions therearound, the members held by a control device in a collapsed position in which the members extend along said casing closely adjacent said outer surface thereof,
- said control device actuatable so that the members move from said collapsed position to a deployed position in which the members extend away from said mounting means for engagement with an associated borehole, and said control device is actuable when said casing is disposed in said borehole, said control device disposable wholly radially outwardly or wholly radially inwardly of said casing,
- each member resiliently biased towards said deployed position, the control device holding the members in said collapsed position, each member comprising a spring strip whose inherent resilience provides resilient bias to bias each member toward said deployed position,
- the mounting means including two spaced annular sleeves, the ends of each spring strip connected to respective sleeves so that, in said deployed position, the spring strips bow outwardly between said sleeves, and
- the control device comprising a band extending around said spring strips and holding said spring strips in said collapsed position against said resilient bias, said band releasable to allow movement of said spring strips to said deployed position.
A centralizer according to 1 wherein the control device comprises at least one pair of struts which are hinged together at a hinged connection and which, at ends opposite said hinged connection are pivotally connected to respective sleeves, the struts releasably held in a position in which spacing between said sleeves is a maximum to maintain said spring strips in said collapsed position, release of said struts causing said struts to pivot as the spring strips move to said deployed position and to cause the spacing of the sleeves to decrease from said maximum.
A centralizer for well casings disposable in a borehole said centralizer comprising
- mounting means by which the centralizer is mounted on an outer surface of a casing disposable in a borehole,
- a plurality of members carried by the mounting means at spaced positions therearound,
- a control device holding the members in a collapsed position in which the members extend along said casing closely adjacent said outer surface thereof,
- said control device actutable when the casing is disposed in a borehole without contacting an interior of the borehole so that the members move from said collapsed position to a deployed position in which the members extend away from said mounting means for engagement with the borehole.
Dependencies are inferred from the claim text.