Multi-piece stacked sealing system and method of using same

Abstract

Subsea wells have a variety of proprietary well head configurations that require sophisticated locking and sealing profiles that allow the well bore to be sealed off and the production of hydrocarbons to be safely controlled. A universal tubing hanger and lockdown assembly uses a sealing apparatus to annularly seal the well bore. When compressed, a multi-piece stacked sealing system employs rigid and elastic members to seal the well bore annulus in both the top-down and bottom-up directions. Top-down pressure containment is needed for appropriate well system testing and bottom-up pressure containment is necessary to control the internal pressure of the well.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is based upon U.S. provisional patent application No. 61 / 176,441, filed on May 7, 2009, the priority of which is claimed.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates to a system and method of using same to seal a well bore such that the production of hydrocarbons may be safely controlled. More specifically, the invention relates to a multi-piece stacked sealing system and method for using same to seal the annulus between a production casing and a tubing hanger.[0004]2. Description of the Related Art[0005]A typical subsea wellhead assembly includes a wellhead housing installed at the sea floor. With a drilling blowout preventer (BOP) stack installed on the wellhead housing, the well bore is drilled while successively installing concentric casing strings in the well bore. Typically, each successive casing string is cemented at its lower end and includes a casing hanger sealed with a...

AI Technical Summary

Benefits of technology

The patent describes a multi-piece stacked sealing system designed to seal the annulus between tubular members, specifically between production casing and a tubing hanger. The system consists of rigid and elastic tapered rings that are positioned around the tubing hanger assembly. When an axial downward force is applied to the upper support ring, the rigid and elastic tapered rings compress, causing them to deform and seal with the inner wall of the production casing. The system can be activated using hydraulic, mechanical, electronic, or electrical methods and can be deactivated by removing or reducing the downward force. The technical effect of this system is to provide a reliable and effective sealing mechanism for oil and gas wells.

Problems solved by technology

The locking mechanism ensures that any subsequent pressure from within the well acting on the tubing hanger will not cause the tubing hanger to lift from the wellhead housing thereby resulting in an unsafe condition.

There are a limited number of subsea wellhead equipment manufacturers worldwide.

Quite frequently, a well is completed on Manufacturer A's wellhead housing and casing hangers using a tubing hanger and / or Christmas tree from Manufacturer B. However, since Manufacturer A's housing and casing hanger design are proprietary, Manufacturer B may not be able to connect its Christmas tree to Manufacturer A's housing without a license from Manufacturer A at a fee in order to design Manufacturer B's equipment to properly interconnect and mate with Manufacturer A's wellhead housing and casing hanger.

This results in a substantial amount of additional engineering and costs or additional equipment (such as a tubing spool) when electing to purchase Manufacturer B's equipment for use with Manufacturer A's wellhead housing.

Since each wellhead housing / system manufacturer has multiple models of housings and casing hangers with different proprietary details, it is not practical or economical for other manufacturers to build up an inventory of equipment for installation on other manufacturers' wellhead equipment.

In addition to the added costs, it also increases, the delivery time which is often vitally important to the well owner.

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