Abstract

During 1994 – 1995, Wascana Energy Inc. implemented a supervisory control and data acquisition system.(SCADA) covering its entire southeast Saskatchewan operating area.

This SCADA system was implemented to improve operating efficiencies by reducing operating costs and increasing production volumes. The system provided for remote monitoring and control of certain production facilities and wells. Wascana contracted an automation system integrator to assist in customizing. the graphical user interface and configuring the PC based computer system to communicate with various end devices in several fields.

The master polling station and backup PC are located in Wascana's Estevan office. Data communications between the Estevan office, the field and district offices is accomplished with a UHF radio system and existing phone lines. Selected real time data is stored on an SQL database server, located on Wascana's local and wide area networks (LAN, WAN) to support corporate wide data sharing.

Field automation includes wellhead managers (WHM) on all horizontal producers for pump off control and real time dynamometer analysis, remote tank level monitoring, electronic flow measurement, water injection facility control and flowline leak detection.

Introduction

In 1994, Wascana Energy (WEI) increased the focus on production automation as one means to improve operating performance, through reduced operating costs and increased production volumes. Published literature, personal project visits and discussions with other companies, active in automation, confirmed that opportunities existed for improving cost and production performance.

Although Wascana already had several operations with field level automation (programmable logic controllers (PLCs) controlling a number of facilities, SCADA in a small number of gas fields and initial experience with pump off control for beampumped oil wells), a consistent area or corporate wide approach did not exist. Electronic flow measurement and remote monitoring andlor control were limited.

Initial experience with wellhead managers (WHM) for pump off control (POC) began in 1993 on a horizontal well drilled by WEI in the Weyburn area of southeast Saskatchewan. Since that initial installation, WEI has installed WHMs on over 40 horizontal wells in the southeast area. These horizontal wells account for more than 50% of WEI production from southeast Saskatchewan. WHMs are now routinely installed on new wells and monitored by the SCADA system from the company's area office at Estevan.

The initial SCADA system utilized during 1993/1994 consisted of VHF radio communications between several WHMs (horizontal wells) and Estevan using a basic, DOS-based, Graphical User Interface (GUI), provided by the WHM vendor. The radio communications was subsequently upgraded to UHF frequencies and a sophisticated, Windows-based, GUI was installed that includes a comprehensive voice callout and alarm system.

Wellhead managers are polled directly from the Estevan control centre and other remote monitoring is accomplished via field level remote terminal units (RTUs) and PLCs. Other field level sensors, end devices and electronic flow measurement devices are tied into these field RTUs and PLCs. Although primary control is at the field level, the SCADA system can pass certain control commands from the control centre to the field RTUs.

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