Lewis Makes DP Riser Operations as Easy as EDP

Well-control engineering specialist, Lewis, has launched a groundbreaking high-angle Emergency Disconnect Package (EDP) that enables dynamically positioned (DP) monohull vessels and small semis to perform safe rigid riser subsea well intervention operations in shallow water for the first time. The Lewis EDP is Patent Pending.

This revolutionary equipment comprises a lightweight, high-speed, high angle EDP, which is essential for enabling rigid riser operations to be performed from DP vessels in shallow water without the potential hazards usually associated with existing EDP solutions.

EDPs are crucial for safe deployment of a riser to surface from a DP vessel, but existing ones are limited in their maximum disconnect angle and require such large stored hydraulic volumes that they do not integrate well into lightweight intervention systems, which are becoming increasingly popular in the subsea industry.

Lewis' EDP, which is fully compliant with the stringent ISO 13628-7 standard, among others, has been specially designed to handle the high bending and tension loads inherent in small bore high-pressure risers. The design removes the usual potential of the male half binding up inside the female half, transferring the maximum disconnect angle to the maximum tensile capacity of the dogs instead. This dramatically increases the maximum angle at which the connector will release and eliminates the potentially catastrophic consequences of being unable to release a riser from the subsea well control package in an emergency.

Another key, and unique, feature of the Lewis EDP is the very small hydraulic volume required to release the connector. Because the Lewis EDP uses minimal hydraulic fluid in the emergency disconnect process, it consequently offers a high-speed disconnect cycle, requires less hydraulic capacity for controls, and therefore reduces the overall weight of not only the connector itself, but also the associated hydraulic control system.

Lewis Managing Director, Drummond Lawson, said: "Our EDP clearly fills a gap in the market. Its creation is due in part to the increasing demand from oil companies for lower cost intervention systems which can be deployed from monohull vessels."

He added: "Its design has many other potential applications where either water depth requires the ability to achieve high angle release, or where the high angle release capability can increase operating windows, and our EDP has already received interest from the UK, Norway, USA and Asia."

Compatible with both direct hydraulic and electro hydraulic control systems, the EDP is well suited to operate in partnership with Lewis' Stackable Lightweight Intervention Connector (SLIC), which the company launched at OTC last year. Used together, the two state-of-the-art systems combine to create the Lewis Hybrid Intervention Solution, which allow combined riser and riserless intervention to be achieved, enabling low-cost riser intervention applications from smaller, lower cost vessels.

Mr Lawson commented that the successful development of the EDP and other Lewis products has been due to the involvement of design engineers, operations engineers and maintenance engineers throughout the design process.

He said: "By including staff members from all aspects of the engineering discipline, we deliver products that fulfill the demands of safety, ease of use, reliability and productivity."

Lewis has already secured an order for the first of its revolutionary EDPs and expects to deliver it in February 2009.