Design of oilfield metering data acquisition and monitoring system

0 Introduction
    At present, with the widespread application of automation technology in the industrial field, the automation transformation of traditional production processes and working methods has become a hot trend. As an important national oil production base, the large-scale automation transformation of oil fields has become a necessary development trend. This paper analyzes the construction of data acquisition and monitoring systems to a certain extent from the data acquisition automation transformation plan of the oil field joint station, combined with the author's actual experience in construction. The interconnection and communication of the host computer, PLC, and various instruments are introduced, and the monitoring interface is configured using the force control 6.1 configuration software as a configuration tool.
    The oilfield metering data acquisition and monitoring system combines automation technology with the oilfield production process, and replaces the traditional old production methods such as meter reading and special inspection by personnel with the automation of data acquisition, thereby constructing an automation platform that can monitor the production process in real time, accurately, safely, and conveniently, which can streamline redundant personnel, reduce production costs, and significantly improve the production efficiency of oil and gas fields. It has guiding significance for the automation transformation of other joint stations and water injection stations.

1 System Structure
1.1 Overall Structure
    The data acquisition system of the joint station is to provide the PLC with the collected values ​​of the pressure, temperature and flow sensors on the oil, gas and water three-phase separators in the station. The PLC communicates with the industrial computer through the switch on the one hand, and displays the data on the interface configured by the configuration software for the station duty personnel to monitor and control; on the other hand, the data is transmitted to the oilfield server, and the server transmits it to the oil production plant computer in the form of a report, thereby completing the data collection, reception and monitoring process of the entire joint station. The overall structure of the oilfield metering data acquisition and monitoring system is shown in Figure 1.

    The detailed setup of the three-phase separator instrumentation is shown in Figure 2.

[page]

1.2 Hardware Structure
1.2.1 Industrial Computer
    Industrial Computer is an industrial control computer, referred to as IPC in English. This system uses Advantech industrial computer, which has the following characteristics:
    (1) The chassis adopts steel structure, which has strong dustproof, anti-magnetic and impact resistance;
    (2) There is a special bottom plate in the chassis, which has PCI and ISA slots;
    (3) There is a special power supply in the chassis, which has strong anti-interference ability.
1.2.2 PLC
    The PLC selected is the intelligent WAT05 controller of Guangyu Technology Company. The PLC adopts a modular structure. The CPU module, power module, analog input module and RS485 communication module are used in this system.
1.2.3 Instrument
    Selection The most basic requirements for sensors are: strong anti-interference ability, good linearity within the working range, and output of standard voltage or current signals to ensure good cooperation with the intelligent acquisition module. At the same time, it must have good protection measures to adapt to the construction site with many oil stains, dust, bumps and sand. The specific transmitter type and parameters used are shown in Table 1.

2 Network Structure
2.1 Ethernet
    Ethernet is the most commonly used LAN currently, and it has largely replaced other LAN standards such as token ring, FDDI and ARCNET. After the rapid development of 100M Ethernet at the end of the last century, Gb Ethernet and even 10G Ethernet are now expanding their application scope under the promotion of international organizations and leading enterprises.
    In this system, the PLC in the joint station is connected to the server through a switch using twisted pair as the transmission medium, and the server is connected to the oilfield computer, forming an Ethernet LAN together, forming a local star topology. The entire Shengli Oilfield uses optical cable as the transmission medium to form a large ring topology Ethernet LAN.
2.2 MODBUS Communication Protocol The
    MODBUS communication protocol is used for serial communication between the industrial computer and the PLC. The standard MODBUS port uses an RS232 compatible serial interface. The controller can be networked directly or via a modem, and the communication uses master-slave technology, that is, only one device (master device) can initiate transmission (query). Other devices (slave devices) respond accordingly based on the data provided by the master device query. Typical master devices are host computers and programmable instruments, and typical slave devices are PLCs.
    The master device can communicate with slave devices individually or with all slave devices in broadcast mode. If communicating individually, the slave device returns a message as a response. If it is queried in broadcast mode, no response is given. The MODBUS protocol establishes the format of the master device query: device (or broadcast) address, function code, all data to be sent, and an error detection field.

3. Configuration monitoring interface design
3.1. Configuration analysis
    There are 6 separators in the joint station, and the collected data on the pressure transmitter, flow transmitter, and temperature transmitter on each separator need to be monitored. In the holding register in the PLC, all pressure data and temperature data are placed in the HRU storage area; natural gas export flow data, low water content oil flow data, and gas cumulative data are placed in the HRF storage area; sewage export flow data, sewage cumulative data, and low water content oil cumulative data are placed in the HRD storage area.

[page]

3.2 Configuration process
    (1) Double-click the desktop force control shortcut to enter the work interface, and click New to open the new project navigation;
    (2) Click Development to enter the development environment;
    (3) Click IO device configuration in the navigation bar, select standard MODBUS (RTU), and start setting the connection with the PLC;
    (4) Click Database Configuration in the navigation bar, select Area 0, Simulate IO variables, and start defining all data variables, as shown in Figure 3, and establish a real-time curve as shown in Figure 4;

    (5) After the equipment is debugged, it can enter the running state and establish the configuration field monitoring interface as shown in Figure 5.

4 Conclusion
    The automated data acquisition system is developing towards the three major trends of computerization, standardization and networking. The PLC-based oilfield metering data acquisition and monitoring system solves the problem of unattended data acquisition and transmission at the joint station. The network structure is simple, the solution is feasible, and it makes full use of the existing line resources. It is cheap and effective and plays a certain role in practical applications. Based on this, the oilfield automation monitoring system can be further improved, the labor intensity can be reduced, personnel can be saved, production efficiency can be improved, and efforts can be made to establish a digital oilfield.