QUALIFICATION TRIALS OF A DEEPWATER DEVICE FOR THE CONNECTION OF FLEXIBLE LINES [PHASE 1] : FEASABILITY

Ziel

The aim of the project is to qualify a specific diverless method for connecting flexible lines to a subsea structure or another rigid or flexible line : A heavy duty manipulator arm, fitted on either a crawler vehicle or a running tool lowered on the subsea structure takes the extremity of the flexible line on the seabed and brings it to the locking position on the structure. The arm is fitted with a strength sensor and a gripping tool. On this one, a specific acoustic detection system permits to gain the geometric configuration of the two parts to be connected. Thanks to this system, the connection is performed in automatic mode, thus granting the necessary accuracy which could not be gained with a manual mode.
FEASIBILITY STUDIES OF THE RUNNING TOOL
The MDI can be as well fitted on a running tool which can be lowered and clamped on guide posts on the subsea structure. Its design is finalized : particular attention has been paid in order that most structures can accomodate it without requiring major modifications. Meanwhile, a lowering procedure has been studied, to avoid the use of guidelines and thus permit the operation with a light dynamically positioned surface vessel.
ACOUSTIC DETECTION SYSTEM
It comprises three nets of acoustic sensors : the first is used for grabbing the end of the pipe, the second for localization of the hub on the structure and approach of the pipe towards it, the last one for the insertion.
CONTROL-COMMAND OF THE ARM
An analysis of the different tasks of a connection involving the manipulator arm has been performed (taking the end of the flexible, removing the blind flange, installing the gasket, pulling toward the structure, penetration then unlocking of thearm and retrieval).
For each of above tasks, the elementary steps have been defined, and the various parameters to be taken into account have been identified. From these, the specifications have been written up, which includes :
- The study of the system safeties and contingencies
- The global architecture of the system
- The realization of the command, hardware and software
- The controls (internal and surface controls).
The command of the arm must includes both a feedback on the control of position and one on the control of strength: the strengths on the arm must be accurately known on a real time basis, and the power of the arm minimized to diminish the impact should a collision occurs. A sensor, located between the arm and the grabbing device, permits to continually know the strengths and to modify the arm trajectory, and to control the sliding friction during the stroking phase. This sensor has been manufactured and tested by Ste Logabex and fitted at the end of the arm.
The manipulator arm has been manufactured, outside the scope of this project. Phases 1 and 2 consist in developing the other equipments necessary for the performance of a connection (mainly the control -command of the arm) and to qualify the method by running extensive shallow water trials. Later on, deepwater trials will be run.
PHASE 1 : Engineering and trial preparation :
The works on the acoustic operational detection system are now over, together with the development of the command of the manipulator arm. This command takes into account the various phases of a connection, with their specific characteristics :
- first preliminary approach toward the structure in manual mode, and then,
- final approach and simulation of an entry of the connector in robot mode,
- manual approach of the arm toward the end of the flexible line,
- gripping the end of the line in robot mode,
- installation of a gasket in the connector,
- approach toward the structure at the previous position, finalapproach and entry of the connector in robot mode,
- closure of the connector and hydrostatic test,
- unlocking of the arm,
- contingencies and other phases for disconnection.
The acoustic detection system as been redesigned for operational use. It includes three different acoustic nets, one for the gripping task, another for the final approach and the last one for the entry. This system, fitted at the end of the arm, includes also video cameras and other ancillaries.
Other works, including the design of a crawler vehicule, and the predesign of a running tool and the preparation of all other equipments and procedures necessary for the performance of the trials have been performed.
PHASE 2 : The procedures and telemetry system qualification trials which remains the first priority have been run in a pool near Toulouse.
A large number of connections and disconnections have been performed. These trials have first demonstrated the feasibility and interest of this method, as well as confirmed the parameters which have been taken into accountfor the preparation and realization of a connection job.

Programm/Programme

ENG-HYDROCARB 2C - Programme (EEC) of support for technological development in the hydrocarbons sector, 1986-1989

Thema/Themen

1.10 - TRANSPORT

Aufforderung zur Vorschlagseinreichung

Data not available

Finanzierungsplan

DEM - Demonstration contracts

Koordinator

GERTH

EU-Beitrag

Keine Daten

Adresse

232 AV. NAPOLEON BONAPARTE
92500 Rueil Malmaison
Frankreich

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