Rubber-metal seal for ring preventer

Abstract

This utility model relates to rubber-metal seals with a spherical outer surface (type PU2 or PK2) used in annular blowout preventers (BOPs) for sealing the wellheads of oil and gas wells during their construction, development, and repair to ensure safety, prevent and eliminate oil, gas, and water leaks, and protect the subsoil and the environment. The rubber-metal seal has a spherical outer surface at the top, the geometry of which allows the seal to move along the mating inner surface of the BOP cover when the plunger is raised under control pressure.The through-hole in the seal is designed to enclose and seal pipes passing through it or to close them to zero if there are none. The rubber surface of the seal on the underside is designed without a protruding rubber portion facing the plunger, with a "flat" bottom. The through-hole on the underside of the seal is made with a lead-in chamfer, with a depth of 21 mm or more, and an entry angle of less than 85° (Fig. 1). These features ensure the effective operation of the seal at elevated control pressures for closure of the preventer. The changes made to the seal design, which led to the elimination of the "excess" rubber mass on its underside, have yielded a positive effect, increasing the service life and resource. 1 fig.

Description

[0001] The utility model relates to seals, rubber-metal, with a spherical outer surface (type PU2 or PK2) used in annular preventers used to seal the mouth of oil and gas wells during their construction, development and repair in order to ensure safety, prevent and eliminate oil, gas and water shows, protect the subsoil and the environment.

[0002] A rubber-metal seal is known (RU 2398954 C1, published 10.09.2010, Fig. 1, pos. 15) with a spherical outer surface in the upper part, a through hole for covering and sealing pipes passing through it or closing to “zero” if there are none, in its lower part, having a protruding rubber part directed towards the plunger and partially filling the depression made on the surface of the plunger on which it rests, the through hole on the lower side of the seal has a small lead-in chamfer up to 20 mm deep and an angle of no more than 60° (classic seal design).

[0003] This seal design, with a properly designed preventer, is typically designed for a control pressure of 10.5 MPa at a well pressure of up to 35 MPa.

[0004] Currently, deeper drilling requires the BOP to withstand significantly higher wellbore pressures of up to 70 MPa or more, necessitating an increase in control pressure to 14 MPa or more. This increase negatively impacts the seal's performance and service life. As control pressure increases to 14 MPa or more, the force exerted by the plunger on the seal increases, increasing internal stress within the seal's rubber component. Compressive forces aimed at gripping the pipe, sealing, and maintaining wellbore pressure push out excess rubber from the bottom of the seal, near its protruding portion facing the plunger along the pipe toward the wellbore. Cyclic loading of the seal accelerates its deterioration (the excess rubber component is torn away from the seal), leading to a significant reduction in seal service life and ultimately its failure.

[0005] The technical solution to the problem is to improve the performance of the seal by changing its design and eliminating the extrusion of “excess” rubber from its lower part along the pipe towards the well at higher control pressures of the preventer.

[0006] This problem is solved due to the fact that the annular preventer seal is rubber-metal, in its upper part with a spherical outer surface, the geometry of which allows, when the plunger is raised when the control pressure is applied, the seal to move along the mating inner surface of the preventer cover and a through hole for covering and sealing the pipes passing through it or closing to "zero" in the absence of such, on the lower side the rubber surface of the seal is made without a protruding rubber part facing the plunger, a "flat" lower part, the through hole on the lower side of the seal is made with an entry chamfer, in depth from 21 mm or more, and an entry angle of less than 85 °, the listed design changes should ensure the effective operation of the seal at increased control pressures for closing the preventer.

[0007] The technical result was the solution to remove the “excess” rubber mass from the bottom side of the rubber-metal seal and to manufacture a seal with a “flat” bottom part, without a protruding rubber mass from the bottom side and an entry chamfer with a depth of 21 mm and an entry angle of 40° Fig. 1 (H≥21 mm, α<85°).

[0008] This seal was manufactured and submitted for field testing as part of a preventer operating at a control pressure of 14 MPa and a well pressure of up to 70 MPa.

[0009] The modified design of the seal has had a positive effect, the operating time and service life have increased.

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