Objective
The project aims to design, manufacture and field test an innovative subsea deep water horizontal X-mas Tree. The expected cost of the related industrialized product will be substantially lower than the conventional equipments. The envisaged product will have an improved reliability level with respect to the existing horizontal X-mass trees, and with respect to the conventional and more expensive (vertical) trees. Main characteristics are :
1) Horizontal configuration
2) Capacity to work with aggressive production fluids
3) Suitability for deep waters (up to 1000 m)
4) Rating for 10.000 p.s.i. working pressure
5) Provision of artificial lift arrangements.
6) Accomplishment to the "double barrier" rule required by API standards.
The project is concerned only with the mechanical part of the assembly, while, for the control system, existing solutions will be adopted; consequently, no cost has been charged to the project for the control system.
TASK 1
1.1 Project initiation
Acquisition of Agip SAF data
Stipulation of H.O. Mohr contract
Visit to Agip Ortona for examination and catalogue of SAF equipment.
1.2 Design basis
Conceptual design review and release of design specification.
1.3 Conceptual design layout
Several modifications have been introduced due to the necessity to accomplish different configurations i.e. SAF taylored design and conventional API guidelineless design.
1.4 Design review
A second design review has been carried out in H.O. Mohr to verify that basic design criteria and subsequent design modifications to increase optional flexibility of the Horizontal tree were accomplished.
1.5 Detail design
All major x-mass tree components have been laied out.
On some components the detailed design has been partially performed.
For buy out equipment basic specs have been draft.
Exploration and production of hydrocarbons in low-depth water has been extended all over the world. However, as a results of the increased oil demand, the deep water oil production becomes more and more required. On the other side, the production operation in deep-water conditions results, at the present state-of-the-art, extremely expensive, due to the following reasons:
1) requirement of dynamic positioned drilling vessels;
2) need of very sophisticated equipments for the production, required by the diverless and guidelineless technology, like sub-marine Remote Operated Vehicles (ROV), sub-sea manipulators, control systems, re-entry and orienting equipments, etc;
3) necessity of long and complex "completion and work-over risers".
For these reasons the deep water hydrocarbon exploitation becomes economically justified only when rich reservoirs are involved. This is the case of the offshore Brazil discoveries, where Petrobas was in a position to develop, more than anybody else, alarge experience.
The horizontal or spool subsea X-mas tree is the next generation of "large bore" subsea wellhead completion arrangement developed for wells requiring an high level of maintenance during their life or wells where enhance recovery is expected, e.g. by artificial lifting equipment.
The large bore configuration allows the operator to install and retrieve downhole equipment through the tree, without having to disturb the tree or its external connections to flowlines, service lines, or control umbilicals. The configuration also provides well control and vertical access to downhole equipment directly through a conventional drilling riser/blow-out preventer (BOP). The horizontal tree has the most compact profile. This characteristic optimizes the load transfer into the wellhead and reduces the cost of the tree assembly. The horizontal X-mas tree to be developed is composed by the following sub-assemblies :
1) SIDE VALVE SPOOL TREE
It is composed by a main body spool, lodging the tubing hanger and internal tree cap. It is provided with several side port outlets, where the in-line valve blocks are connected. A lower connector provides the means to latch the spool tree to the wellhead body. An upper profile allows the connections of the BOP drilling riser.
2) TUBING HANGER
It consists of a tubing suspension device, fitted with vertical access to tubing and annulus. It presents side outlet bores with "double barrier" sealing features between adjacent outlets. The hanger body lands, latches and seals into the spool tree.
3) INTERNAL AND EXTERNAL TREE CAPS
The internal tree cap provides a secondary vertical barrier to the tubing hanger. The external one provides a protection for the tubing spool external and internal profile.
4) FLOW-LINE CONNECTOR
It provides the interfacing connection between the flow-line termination and the tree. The horizontal stab flow-line connector allows to retrieve the tree or the flow-line independently, without using a jumper.
Programme(s)
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
20126 Milano
Italy