Apache Corporation, one of the world’s top independent oil and
gas exploration and development companies, needs to continually monitor
and control oil export pumps located in the Forties oil field in the
North Sea. Originally discovered by BP, the Forties oil field has been
owned by Apache Corporation since 2003 and the company has modernised
the facilities extensively. Apache intends to exploit the field - the
eighth largest in the North Sea - to its full potential.
The Forties oil field has five production platforms
called Alpha, Bravo, Charlie, Delta and Echo. Oil from four of them
is pumped to Charlie, together with oil from other locations. Charlie
platform has three powerful electric pumps controlled by Variable
Speed Drives (VSDs) for oil export. Each pump is monitored by staff,
to control oil production and flow, in the platform’s main
control room.
Performance information about the pumps is sent across
the serial interface to Perle’s IOLAN Terminal Servers (IOLAN
SDS4) and via the Ethernet network to the main control room.
By presenting the VSD’s serial data across the
network to the SCADA system, personnel on and offshore are able to
monitor the output of the three pumps and control this according
to demand.
The communications interface available at each VSDs
was a Modicon Modbus communications adapter, with an RS485 serial
data connection.
The design brief from Wood Group Engineering (North
Sea) which provides engineering, design, procurement, construction
and commissioning services to Apache’s Forties platforms, was
to provide a Modbus communications gateway between the RS485 serial
network of the VSDs and the SCADA Ethernet based network, and present
data from the VSDs on their Ethernet based SCADA system.
To this end, Wood Group made use of the Perle IOLAN
SDS4 which ship with the Modbus gateway feature. This allowed a server
on the Ethernet network to obtain data from the serial network, using
the Modbus Ethernet protocol, with the Perle IOLAN SDS Terminal Server
acting as a Modbus RTU / Modbus Ethernet gateway.
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