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Content archived on 2022-12-27

CLUSTOIL (PHASE 1)

Objective

The project is aimed at studying subsea stations for oil production. The study is based on the following fundamental assumptions : modular design, diverless installation and maintenance, handling operations from light surface supports.
In addition, the concepts will use the results of previous studies and should lead to a significant cost reduction, both in investments and in development and maintenance costs.
SAPHIR
The station is a six-well cluster. X-trees are installed around an octagonal guide base supported by a central conductor pipe. Each X -tree is divided into two parts : the safety block tree and the production block tree. The sensitive equipments such as pressure transducers, remote-controlled choke and the most prompted valves are housed in the production block tree. In case of failure, this block can be entirely removed and replaced by a new one using a dedicated vessel. During this operation, the safety block tree insures well safety.
A common inert manifold gathers the fluids from the six wells and allows automatic connections between the X-trees and flowlines.
The subsea station is remotely controlled from the surface control room. Coded messages are sent to the central control module through an underwater cable. These messages activate the relevant pod installed on X-tree and activate the hydraulic pressure system driven from the surface through a hydraulic bundle.
Three lines are tied to the cluster, the 10" production line, the 6" test line and the 4" service line.
The installation of the whole station is carried out from the drilling rig through its moon pool.
Feasibility of the design, such as defined in 1986 has been confirmed by two detailed studies: Manifold study and Flowline connection study.
The functional analysis of the production block has been completed.
Feasibility of the design as defined in 1986 has already been controlled by two detailed studies : Manifold Study and Flowline connection Study.
The functional analysis of the production tree followed by a study on the reliability-availability-safety, has made it possible to confirm the choice made in the general architecture of SAPHIR in 1986, that is:
The production tree is divided in two blocks : the safety block and the production block. The production block comprises all the sensitive components and the telecontrol Pod. The safety block assures the safety of the well during the replacement of a production block.
CLUSTOIL:
The station is a twelve-well cluster. The solutions used for the SAPHIR design are fitted and re-used for the CLUSTOIL design.
The critical point of the design is the connection of the important diameter production manifold.
The connection of the 18" production flowline on the station is achieved thanks to a module comprising 2 mechanical connectors and a flexible loop.
SPECIFIC STUDIES
- During exploitation mode, the Pod receives from a platform electro-hydraulic energy and electric signals through a subsea umbilical.
During intervention, energy and signals are generated on a floating support placed above the station and conveyed to the Pod through a special umbilical. At each operation the subsea umbilical is automatically isolated and the Pod can no longer be controlled from the platform.
The whole study includes three phases :
- A feasibility phase
- A test phase for components and subassemblies
- An overall test phase on the offshore pilot.
The present project only applies to the first phase and concerns two diffrent subsea stations.
- The first one, called CLUSTOIL, will be designed for a North Sea application with the following fundamental assumptions : cluster of twelve wells, total production : 30000 m3/d, water depth : 350 meters, distance from treatment site : about 10 km, production life time : 15-20 years.
- The second one, called SAPHIR, will be designed for a Gulf-of -Guinea application with the main following requirements : cluster of six boosted wells, total production : 2000 m3/d, water depth : 160 meters, distance to onshore treatment site : 8 km, soft foundation, production life time : 12 years.
For both stations, the feasibility phase will include two stages : 1. Definition of subsea station design
The design will be specified according to exploitation conditions, production techniques, reliability of components and maintenance means.
2. Detailed study of subsea station
Once the layout is specified, the different modules and their links and connections will be the subject of detailed studies.
Modules and related connections studies will be carried out while keeping in mind the following objectives :
- acquisition of maximum reliability for the overall system
- optimization of dimensions and weight of different modules to facilitate handling operations.
The main subassemblies are : template, production wellhead, manifold, telecontrol system, production and electro-hydraulic connections.

Call for proposal

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Coordinator

GERTH
EU contribution
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Address
232 AV. NAPOLEON BONAPARTE
92500 Rueil Malmaison
France

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