The Horizontal Tie-In System for Gas Lift Applications has been designed in conjunction with an oil major for fields in West Africa and the Gulf of Mexico to provide a quick and effective solution for small bore gas lift applications.
Typically for small bore horizontal connections a hot stab setup is used, however this is less than ideal as hot stabs by design rely upon elastomeric seals to provide the pressure integrity. Our design incorporates our Optima connector system along with the Duoseal metal sealring, which has been subsequently tested to 15,000psi.
For this system we completed dual barrier PR2 qualification on the Duoseal size required for this application. This is where we initially qualify our inner seal as a primary bore seal and the outer seal as a primary environmental seal. We then repeated the PR2 test to qualify our inner seal as a secondary environmental seal and then qualify our outer seal as a secondary bore seal. This qualified our Duoseal sealring for up to 10,000psi (690 Bar).
The Horizontal Tie-In System was designed to enable a quick and simple installation process. The inboard hub along with guide post, which can be seen to the right of the picture, is installed subsea on the manifold and can be provided with a choice of long term or short term pressure caps. Our client opted for a short term pressure cap for their system and this can be seen in the middle, towards the bottom of the picture. This cap was designed so that it can be installed and removed subsea via ROV intervention. During installation of the outboard system a flexible is connected to the outboard hub and the outboard system is lowered in to place, aligning the guide funnel within the capture angle of the guide post. The outboard hub is designed to swivel on its axis. This allows the flexible to relieve any tension it may have as it is unwound from the spool on the installation vessel. As the outboard system is lowered down onto the guide post, any radial misalignment of the system is taken up by the guidance system which is design to centralise the outboard hub with the inboard system.
To provide a controlled final decent a control system has been implemented where, on the outboard system, an arm is extended prior to deployment. The outboard system initially contacts on this arm, which is then retracted via a 90° gearbox by the ROV. This system is designed so that it can also be used to split the outboard hub from the inboard to allow for seal replacement and seat cleaning activities.
Once the arm has been fully retracted the Optima connector can be closed and the system is ready to be used. A control panel on the inboard system can be included for which will enable subsea activities such as backseal testing to ensure a successful installation has been achieved, not shown in the picture.