Relying on wireless technology, ZADCO is able to monitor wellhead temperature and pressure, as well as activities at offshore oil rigs, from a remote, onshore location.

Remote operations capabilities are dependent on the existence of adequate communications links and power availability. Achieving wired communications by means of subsea cables costing hundreds or even thousands of dollars per foot is typically prohibitively expensive, especially for smaller satellite platforms and jackets. Likewise, power supplies are limited on offshore platforms, being typically supplied by generators or solar systems.

Any proposed practical approach to remote operation of equipment should consider use of wireless technology and alternative means of addressing power consumption considerations.

ZADCO (Zakum Development Co.), developer and operator of the United Arab Emirates’ Upper Zakum field, deployed low-power wireless sensor and camera surveillance technology to monitor well production and field operations. Use of this new generation of wireless digital oil field technology has had a positive impact on production operations.

In addition to remote monitoring and control, the company wanted video surveillance capabilities to verify when operations are being performed and by whom, and to ensure the safety and security of personnel and facilities.

ZADCO worked with vMonitor, a provider of wireless communication systems for the oil and gas industry. Project goals included:
• Wireless monitoring of wellhead pressure and temperature;
• Wireless platform video surveillance;
• Reduced cabling;
• Web-based data access for the enterprise; and
• Power requirements of less than three watts.

Getting it done

To achieve well-pressure and temperature monitoring, conventional SCADA systems incorporate pressure/temperature instruments, remote terminal units (RTUs) to acquire the data from sensors, radio communication systems, antennae, and power systems (usually solar panel with battery). Running instrument cables and conduit pipes to connect instruments to the RTU on offshore platforms is a time-consuming and costly proposition, especially given the limited real estate available and logistics involved.
Instead, the operator used wireless sensors for well pressure and temperature monitoring.

The explosion-proof wireless sensors include an embedded micro RTU; radio (2.4 GHz Zigbee — other radio frequencies can be installed for longer range); battery pack; and antenna. The sensors transmit data by exception only and messages only when there is a deviation more than 1% from the setpoint range. Data are transmitted to a nearby central data hub or gateway, which can be up to six miles (10 km) from the wireless sensors, depending upon radio power and frequency. In this application, the wireless gateway was installed on the platform.

Two wireless CCTV cameras were also installed and interfaced to the gateway. The high-resolution camera is designed for harsh outdoor and explosion-hazardous environments. It has a low power requirement and can be configured for on-board motion detection in both day and night-time scenarios.

The gateway manages the data received from the sensors and camera; then transmits data and images to the central processing facility located a few miles away from the remote platforms. The gateway also executes control commands received from the facility control room applications.

Conventional UHF radios transmitting over several miles use a great deal of power (5W) and have limited bandwidth (9,600 bits per seconds); so they cannot transmit images from a CCTV camera that requires a bandwidth of several megabits per second. Since the maximum available power on the platform is limited, there was inadequate power for UHF radios. Instead, the operator chose a long-range, lower-power 2.4 GHz spread-spectrum wireless communication system with throughput of up to 11 megabits per second.

Data transmitted from the gateways is captured and managed by a control-room software application called TotalAccess. The software interface incorporates well parameter visualization, historical reports, trends, and alarms. The software also provides access to video captured from CCTV cameras and image storage facility.

Benefits accrued

This wireless solution delivers significant benefits. Wellhead temperature and pressure are captured on a timely basis without trips to the wellsite. This data has the potential to help detect severe well problems before they occur and to avoid well shutdowns and costly well interventions. Further, well pressure and temperature data can be integrated to reservoir and analysis software back in headquarters, allowing better prediction of production trends and reservoir conditions.

CCTV cameras monitor activities and personnel access on the remote offshore facilities, supporting intrusion detection and preventing unauthorized access to the platform.

Maintenance and repair task completions also can be verified, and contractor visits can be logged for invoice verifications. As a result, less regular check-up trips are made by maintenance and facility personnel, reducing operations cost and enhancing personnel safety.

The digital oil field is a strategy enacted by oil and gas companies looking to increase production and enhance reservoir recovery by means of newly emergent technologies. Achieving these goals is supported by the ability to acquire data and control processes from remote or onshore facilities.

Comments