MECON: A High Voltage Subsea Connector

Abstract

Abstract The objective of this paper is to report on the highly successful Qualification of a novel, wet matable, high voltage subsea connector called the Marine Electra Connector - MECON (NO and US Patents granted, see [1]) developed by ABB Offshore Systems AS in Norway. The status per end January 1999 is that the various components, having passed separate Fabrication Acceptance Tests, are being prepared for Integration Testing to be run in shallow water. The first MECON Connector System, Fig. 1, is under order, to be delivered to the Norsk Hydro TROLL PILOT PROJECT; the world first subsea installation featuring water separation and re-injection by electrical powered injection pumps. The MECON Connector System for the TROLL PILOT separation station is rated at 11 kV/240 Amp, due to be installed in the North Sea late summer of 1999. This subsea power connector aims to make it an economically viable scheme to have high voltage electrical power supply to processing and electrical power distribution systems placed on the seabed. The MECON Connector enables wet "make-and-break" of high voltage electrical interfaces, essential for a variety of subsea systems based on a modular equipment architecture. The MECON Connector introduces a novel concept of full metal encapsulation of the electrical connecting parts, using metal sealing technology to maintain a high integrity seawater barrier. A technique has been developed of flushing and replacing trapped seawater with a di-electric fluid, prior to electrical make-up of the connector. This feature makes it possible to maintain high quality electric insulation inside the connector, essential for high voltage equipment. Hence, the MECON Connector is designed to offer safe and reliable long-term in-service operation. This concept features independent retrieval of the FM connector part, making the MECON Connector specifically attractive for deep-water applications. ABB is currently offering the MECON Connector for 11kV/240Apm systems, with current conceptual design extendable up to 36 kV. Introduction In a future regime of smaller economical margins, it is believed that making effective use of existing processing capacity and infrastructure will become essential. The production schemes must facilitate flow of produce from remote or deep subsea wellheads, ensuring flow by removing water contents at the seabed. Indeed, such cost effective field development schemes may involve considerable parts of the process equipment to be moved from topside platforms to the seabed. Recognizing the market potential, ABB launched a High Impact Project (HIP) called SUBSIS (Subsea Separation and Injection System) in 1996. The SUBSIS subsea installation features the wellstream to be separated into water, oil and gas. See [2]. The produced water may either be dumped to sea, or re-injected into the reservoir to maintain pressure and enhance recovery. The energy required to drive the subsea processing units at a scale outlined above will, for most practical application, involve the use of high voltage electrical power to drive variable speed motor drives, power ranging from 500 kW to 3000 kW. Compared to umbilical costs for electrical consumers such as subsea control system pods, the cost of the power cables to feed such drives, may influence significantly on the field economics. More so for remote installations, hence creating an incentive to transmit electrical power at higher voltages. The MECON Connector System was initiated based on the realization that the SUBSIS concept would require the transmission and distribution of high voltage electric power, at voltage levels from 11 kV to 36 kV (HV). The SUBSIS installation is a modular system, i