ABSTRACT

This paper presents an innovative solution, invented by Cybernetix and called SWIMMER, to performing intervention, maintenance and repair (IMR) tasks on deepwater offshore installations. After the concept was proven in 2001, Cybernetix and Total are now collaborating to assess the actual financial benefits of using the SWIMMER solution instead of conventional means. The results of the study demonstrated that the system is highly competitive when compared with conventional ROV-based operations. The solution developed by Cybernetix over the years is now technically mature and ready to move into the industrialisation stage.

Concept

Although oil prices are currently high, operators are always keen on finding new approaches to reducing the costs associated with oil production. There are cases, such as deepwater offshore fields or remote locations, where the economics plays a great role in the decision to develop. Inspection, maintenance and repair tasks are an important part, and their costs are increasing over the years.

(Fig. 1 is available in full paper) The SWIMMER concept is aimed at reducing the operating expenditures (OPEX) associated with the inspection and maintenance of subsea facilities once they are installed and operational throughout the lifespan of an offshore field.

As illustrated in Figure 1, it is based on using an autonomous underwater vehicle (AUV): (1) to transport an ROV (remotely operated vehicle); (2) to a docking platform (3) attached to a subsea production system (SPS) (4); and to connect that ROV to the SPS production umbilical (5). The ROV then uses the power and real-time data transfer from that umbilical and is operated from the surface production facility or a vessel of opportunity (6).

Technical Feasibility

In October 2001, Cybernetix, in collaboration with IFREMER, the University of Liverpool and Total, have carried out the final full-scale sea trials (Marty 2002) of the SWIMMER prototype, and demonstrated its ability to navigate to its target area and land into its docking station and connect the ROV to the surface operator for IMR tasks in a fully autonomous mode. Figure 2 and Figure 3 show the recovery and docking phases of the feasibility campaign. To date, oil and gas operators have shown a keen interest in this hybrid ROV/AUV concept and its potential OPEX savings when considering routine IMR tasks for an offshore subsea field.

Economical Feasibility

In November 2005, Total positioned itself as prime promoter of the SWIMMER technology, and asked Cybernetix a study in order to establish the cost-effectiveness of the SWIMMER solution in the current and near-future context of offshore oil and gas extraction, in the perspective of the installation of the SWIMMER architecture on an actual deepwater oilfield in the short term.

(Fig. 2 is available in full paper) For a given, typical Total oil field, the costs, both capital expenditures (CAPEX) and OPEX, associated with either the conventional ROV and its support vessel or a SWIMMER system solution, were carefully estimated.

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