Expro is the only supplier of subsea safety systems for dual bore completions deployed in conjunction with vertical xmas trees. The ELSA-DB (dual bore) product line started more than ten years ago with the introduction of dual bore subsea test trees.  These systems enabled our clients to deploy dual bore completions, flow the well to the drilling vessel and suspend the well with wireline plugs in production and annulus bore.  These systems are adaptable to interface with any subsea production tree.

Upon successful deployment of the initial systems on dual bore risers, a bore selector was added to the landing string providing selective access to either the annulus or production bore when using a monobore landing string and surface tree.  The bore selector is a hydraulically actuated sleeve and hinged gate, which controls toolstring access to either bore.  This concept significantly reduced the rig time for deployment as well as the capital investment requirements.

In recent years most clients are utilising tubing hangers for dual bore completions without the requirement for wireline plugs in the annulus bore for well suspension.  This is provided through isolation sleeves in the tubing hanger.  This enabled Expro to simplify the safety systems and mono bore systems, in combination with a dual bore THRT interface and orientation helix are used for deployment.  Monitoring and controlling the annulus pressure during well flowback operations is provided via annulus communication through the BOP stack’s choke and kill lines back to surface.  These systems are compatible with EXPRESS subsea control systems.