Abstract: Subsea petroleum wellhead assembly, which main parts are wellhead flange, tubing-hanger block (TH-block), flow-block, Christmas tree (XT), tubing hanger (TH) and tubing-hanger extension. The system's advantage is that it allows retrieval and installation of either the XT or the TH independently of each other. That is achieved by breaking the direct connection between the XT and the TH, and instead leading the production flow through a bypassing flow-block that is integrated in the TH-block. The flow-block runs outside the TH and XT, and bridges between them by help of a flow-connector and flow-loops. By breaking the direct connection between the TH and the XT, it is possible to install and retrieve them independently of each other. Over the well's lifetime, the saving in operation expenses—compared with a vertical XT—is estimated to be at least 10 million US$ compared with a horizontal XT.

Abstract: Subsea petroleum wellhead assembly, which main parts are wellhead flange, tubing-hanger block (TH-block), flow-block, Christmas tree (XT), tubing hanger (TH) and tubing-hanger extension. The system's advantage is that it allows retrieval and installation of either the XT or the TH independently of each other. That is achieved by breaking the direct connection between the XT and the TH, and instead leading the production flow through a bypassing flow-block that is integrated in the TH-block. The flow-block runs outside the TH and XT, and bridges between them by help of a flow-connector and flow-loops. By breaking the direct connection between the TH and the XT, it is possible to install and retrieve them independently of each other. Over the well's lifetime, the saving in operation expenses—compared with a vertical XT—is estimated to be at least 10 million US$ compared with a horizontal XT.