This paper discusses the design capabilities of a computerized supervisory system installed in the Countess-Lathom Oilfields in Southeastern Alberta and describes the anticipated benefits and difficulties associated with this application. This system will monitor alarm conditions, gather and manipulate data, perform automatic well testing and output reports containing production and injection data. On-line input through a terminal keyboard will enable the operator to modify the system to reflect daily operational changes.
Oil production has become increasingly complex due to the need for more efficient production practices and more accurate data gathering_ Time, distance and manpower are problems which can adversely affect this efficiency and accuracy. PanCanadian Petroleum Limited, in an attempt to salve these problems, is in the advanced stages of installinga computerized supervisory system in the Countess and Lathom Oil fields in Southeastern Alberta. These fields contain various oil reservoirs under waterflood pressure maintenance which extend over a distance of twenty miles as illustrated in Figure 1. Four of these reservoirs are monitored by the supervisory system. The reservoirs in the system produce from several Upper Mannville Zones at a depth of 3500 – 3800 feet and contain 75 production wells and 25 injection wells. The average daily oil production is in the order of 10,000 barrels and the average daily water injection is approximately 20,000 barrels. Solution gas is gathered, treated and sold at a rate of 7 MMCFD. A dedicated FM radio communication link is used to connect remote terminal units (RTU) with the central computer site. The entire system is quiescent meaning that the remote terminals will not supply data to the master terminal until the master interrogates them. The system is designed to perform the following functions:
Point Scanning This involves retrieval of data from the remote terminal units and will be the primary function of the system. The scan must be performed on a continuous basis in order to maintain the most current data base information.
Determination of State Changes The state changes indicate abnormal conditions and as a result the operator is to be notified of the location and nature of these conditions so that corrective action can be initiated.
Manipulation and Storage of Data Analog data such as pressures, temperatures and flow rates will be analyzed to determine that the values lie within predefined operating limits.
Appropriate messages will be output to the operator when required to indicate that an item of data is unacceptable. Data within operating limits must be modified by correction and calibration factors, converted to appropriate engineering units and stored in a disc file
Automatic Level Control The level in the water intake reservoir must be maintained between high and low levels. This is to be achieved by starting and stopping supply pumps in a predefined sequence. A similar level control is required for two remote tanks which are used for water supply for injection pumps.