AMOCO LIUHUA TRITON™ ROV(S) / AROWS-Pre-Planned Remote Intervention for Subsea Production Systems
Authors: Stroud Doug , Openshaw Graham 
Published: October 2008

This paper discusses the development and design of two (2) Advanced Remotely Operated Heavy Work (AROW) systems which have been designed specifically to support the AMOCO LIUHUA FPSO and Subsea Production system remote intervention tasks in the South China Sea. The two ROV systems (Portable and Permanent) incorporate features and tools which have been pre-planned and designed to perform all aspects of the remote intervention requirements of the LIUHUA project. The two systems include:

Permanent ROV System

Designed to be installed on the FPS semi-submersible. Incorporates a 4g Cursor Launch System designed to work in Typhoon conditions. ROV tools and Controls are interchangeable with Portable System. Designed to deploy tools including: Manipulators. Torque Tools. MIR Spool Piece Measurement Control System. Hot Stabs, Grease and Chemical Injection and other Maintenance Tools.

Portable ROV System

Supplements the FPS "Permanent" ROV system. Designed to operate from a field support vessel of opportunity as required. Includes a portable 4g rated ‘l1’-frame launch system designed to work in typhoon conditions. ROV tools and controls are interchangeable with permanent system.

This paper will address the design, coordination and planning performed to ensure that all phases of the subsea intervention were achievable in a cost effective, reliable and innovative manner. The emphasis is on the design solutions selected in relation to the project application requirements.

The importance of early coordination between the client(s), operator and manufacturer to optimize the required system is also addressed.

Subsea Remote Intervention Trends

Trends in ROV remote intervention technology are driven by the global trends in offshore oil & gas exploration and technology. These are driven largely by the economics of development, and also by the geographic and technological barriers which stand in the way of exploration and production. Key economic and technological drivers of subsea intervention technology including:Increased deep water exploration and development.Marginal field development - lower expenditure per well, including:subsea completion and inter-field subsea pipelines.use of subsea templates.Increased use of total diverless subseaintervention systems.Increased regulatory requirements and oversight in offshore production.Increased emphasis on personnel safety and equipment certification.Increasing emphasis on cost effective development.

These global trends in exploration and production have had an overriding impact on the development of subsea remote intervention technologies including the ROV systems used. They have led to the development of new and innovative approaches to achieve cost-effective development and production of offshore oil and gas reserves.

One significant worldwide trend in the past few years has been the phasing out of fixed production platforms in favor of subsea templates, tension leg platforms, and floating production systems, with the corresponding increase in use of inter-field pipeline systems. This trend has resulted in radical expansion of subsea intervention tasks, and has boosted the use of totally diverless intervention to new levels. Typical ROV intervention tasks (by no means all inclusive) for these types of installation include.