SCADA - Typical diagram representing the flow of data

SCADA (Supervisory Control and Data Acquisition) is normally associated with telemetry and wide area communications, for data gathering and control over large production sites, pipelines, or corporate data from multiple facilities. With telemetry, the bandwidth is often quite low and based on telephone or local radio systems the SCADA system is often optimized for efficient use of the available bandwidth. Wide area communication operates with wideband services, such as optical fibers and broadband internet.

Remote Terminal Units (RTU) or local controls systems on wells, wellhead platforms, compressor and pump stations are connected to the SCADA system by mean dot the available communication media. SCADA systems have many of the same functions as the control system, and the difference mainly comes down to data architecture and use of communications.

Ref: Oil & Gas Handbook