safety valves

Copyright 2007, , All rights reserved

Safety Valves

Copyright 2007, , All rights reserved 2

Safety Valves in Well Completion

Surface Safety Valve - SSV Automatic fail-safe close valve installed at the Upper Master

Valve of the x-mas tree A positive shut-off flow in case of

– line leaks– process upsets in the surface facility– emergency shutdown.


Safety Valves in Well Completion

SubSurface Safety Valve - SSSV A valve installed in the tubing down the well. When activated it stops well flow. Valve usually activated in combination with Surface Safety

Valve

Used for Emergency Only


SubSurface Safety Valves - SSSVApplication (1)

Why Install?– Protect people, property and the environment in case of

blowout from sabotage or human error, collision, equipment failure, fire or leaks

Factors determining whether to install?– Location and types of wells– Government legislation– effect of blowout on people and the environment– damage to the producing reservoir


SubSurface Safety Valves - SSSVApplication (2)

Which type of wells require SSSV?– offshore flowing oil and gas production wells– offshore wells gas injection wells capable of flow– onshore gas producing and injection wells– onshore flowing sour (H2S) oil/gas wells– wells in earthquake-prone zones – Certain onshore oil wells

• near major roads and or near populated areas• near environmental sensitive areas• near security sensitive areas


Tubing Safety ValvesFunctional requirements

Flow barrier in the tubing when required. Fail-safe closing at a pre-determined condition or command To withstand the maximum reservoir pressure in closed

position Minimum pressure drop in during production In closed-position, pump through capability


Subsurface Safety Valves - SSSVApplication (3)

Tubing Safety Valves SC-SSSV - Surface Controlled SubSurface Safety Valve:

– controlled from the surface – installed and retrievable by wireline WR SC-SSSV– installed as an integral part of the tubing TR SC-SSSV

SSC-SSSV - SubSurface Controlled SubSurface Safety Valve (Storm Choke)– actuated by the flow characteristics of the well– installed by wireline


SC-SSSV Wireline Retrievable type

Control line

Landing nipple

WR SC-SSSVseals


SC-SSSV Tubing Retrievable type

Flapper closedFlapper open


Tubing Retrievable SC-SSSV

Features– integral part of tubing– no restriction in flow path ID– flapper shut off– robust design– equalizing while opening– lock open option– WR-SC-SSSV can be installed as backup

Note: valve sensitive for tubing loads


SSSV Setting Depth (3)

Recommended minimum setting depth offshore

– 50 meter below the deepest pile penetration onshore

– 100 meter below ground level

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