Sealing device for well components

A sealing device is for sealing fluid transmittable openings in well components. The sealing device includes an elastic element which is arranged between two shoulders. The elastic element, before being placed in the fluid transmittable opening, has a larger external dimension than the fluid transmittable opening to be sealed. A gap is arranged between at least one of the shoulders and the elastic element, allowing liquid to enter between the shoulder and the elastic element. The ridge is arranged on an intermediate piece which is located between the shoulder and the elastic element. The intermediate piece is constituted by as ring in which the ridge is surrounding and divided, and projects from an end surface opposite an abutment surface facing the elastic element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national stage application of International Application PCT/NO2012/050151, filed Aug. 22, 2012, which international application was published on Feb. 28, 2013, as International Publication WO2013/028079 in the English language. The International Application claims priority of Norwegian Patent Application 20111158, filed Aug. 25, 2011. The international application and Norwegian patent application are fully incorporated herein by reference.

FIELD

This invention relates to a seal for well components. More particularly, it relates to a seal for sealing fluid transmittable openings in well components, the seal including an elastic element which is arranged between two shoulders, and the elastic element, before being placed in the fluid transmittable opening, having a larger external dimension than the fluid transmittable opening to be sealed.

BACKGROUND

When sealing fluid transmittable openings in a well, such as in a petroleum well, it is usual to move a seal having an elastic element of a larger external diameter than the diameter of the fluid transmittable opening to be sealed, into the fluid transmittable opening. By the elastic element being arranged between two shoulders, the volume that the elastic element may occupy is restricted, whereby a greater surface pressure is achieved between the elastic element and the inner jacket of the fluid transmittable opening, as compared to if the elastic element could lengthen freely.

During operation, damage may occur in the sealing surface of well components. For example, during wireline operations in the well, it is not unusual for one or more axial grooves to be worn into the sealing surface of a downhole safety valve. Other causes may cause other types of damage in the sealing surfaces.

Known seals often cannot be brought to seal damaged fluid transmittable openings. The reason is that the damage is not filled by the elastic element and thereby sufficient sealing of the damage for a differential pressure to be established across the elastic element is not achieved.

As known seals notoriously provide an unreliable seal, it is usual to place a seal outside the damaged sealing surface. Seals of this kind may be functionally unreliable, which has turned out to possibly result in operational interruptions and need for repairs.

SUMMARY

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art.

The object is achieved according to the invention through the features which are specified in the description below and in the claims that follow.

A seal is provided for sealing fluid transmittable openings in well components, the seal including an elastic element which is arranged between two shoulders, and the elastic element, before being placed in the fluid transmittable opening, having a larger external dimension than the fluid transmittable opening to be sealed, and where the seal has a gap being formed between at least one of the shoulders and the elastic element, allowing liquid to enter between the shoulder and the elastic element, wherein the gap is arranged in an intermediate piece located between the shoulder and the elastic element, and where the intermediate piece is constituted by a ring, in which a surrounding divided ridge is arranged to rest against the shoulder.

By liquid being able to enter the gap, a hydraulic axial force is imparted to the elastic element, contributing to further increasing the surface pressure from the elastic element against the sealing surface of the fluid transmittable opening. The elastic material thereby penetrates deeper into a groove in the sealing surface, for example. Thereby the leakage through the groove is reduced, whereby the differential pressure across the elastic element increases further and the elastic element fills the groove and enables the establishment of full differential pressure across the seal.

The ridge prevents the ring from closing a gap between the ring and the shoulder, while, at the same time, liquid may penetrate past the ridge to the part of the gap that is located behind the ridge.

The abutment surface of the ring towards the elastic element may be conical. A conical shape has proved appropriate in order to achieve a good seal.

It may be advantageous for there to be an adapted clearance between the ring and the shoulder before insertion a the seal in an fluid transmittable opening, to facilitate the insertion of the seal.

The device according to the invention solves a long-felt problem in a mechanically simple way, and the seal may be set and activated without complicated procedures having to be followed.

DETAILED DESCRIPTION OF THE DRAWINGS

In the drawings, the reference numeral1indicates a well component which is formed with a fluid transmittable through opening2with a sealing surface4, damage in the form of a groove6having been inflicted on the sealing surface4. The groove6is shown inFIG. 2as well. The fluid transmittable opening2has an internal diameter d.

A seal10includes a cylindrical seal mount12which is formed with a turned-down portion14, in which shoulders16are formed. The seal mount12is movable into the fluid transmittable opening2of the well component1.

An elastic element18is placed in and tightly surrounds the portion14. Externally, the elastic element18has been given a convex surface20which is arranged to seal against the sealing surface4. The convex surface20has a largest diameter D which is larger than the internal diameter d of the fluid transmittable opening2.

At either end portion of the elastic element18, an intermediate piece22in the form of a ring is arranged, which is formed with a conical surface24towards the elastic element18. On the opposite side, the ring22is provided with a surrounding, divided ridge26, seeFIGS. 5-7. The ridge26provides for there always to be a gap28between a substantial portion of the ring22and the corresponding shoulder16.

The total length of the elastic element18and the rings22is normally equal to or smaller than the length of the portion14when the seal10is in the non-activated state. Thus, there may be a distance30between at least one of the rings22and the corresponding shoulder16, seeFIG. 5. The purpose of this distance30, when present, is to facilitate the insertion of the seal10in the fluid transmittable opening2.

As the seal10is moved into the fluid transmittable opening2, the elastic element18is resting against the sealing surface4. Since the sealing surface4has a smaller diameter d than the free external diameter D of the elastic element, the external diameter of the elastic element is reduced, which has the effect of the length of the elastic element18being increased until both rings22abut against their respective shoulders16, seeFIG. 6. In a manner known per se, a larger surface pressure is thereby built up between the elastic element18and the sealing surface4.

However, this surface pressure is not sufficient to force the material of the elastic element18to the bottom in the groove6. Because of the relatively modest cross section of the groove6, a minor differential pressure is still built up across the elastic element18. The pressure from the surroundings enters the gaps28, working there as a hydraulic force against the rings22which are thereby moved in the direction of the elastic element18. The elastic element18is compressed further, and the groove6is sealed by the elastic element18so that full differential pressure may be built up across the seal10. Practical tests show that if the distance30is too large, the elastic element18will not be forced to the bottom inside the groove6.