How wireless sensing can benefit offshore

Pressure, temperature, and flow are standard product offerings from the wireless sensor industry, and this covers most oil and gas measurement requirements. Wireless sensors are comprised of a sensing component, radio frequency (RF) transceiver, antenna, analog-to-digital conversion circuitry, and a power supply. Once a wireless sensor collects the specified data, it transmits the measurements to a gateway device, also known as a “base station.” Both sensor and base station have a variety of RF transceivers embedded into their design. The transceivers communicate via specific protocols such as ZigBee, WirelessHART, ISA100, and Bluetooth. Unlike wired, wireless sensors convert the analog signal collected from the sensing element into a digital signal with the on-board circuitry, and then transmit that to the gateway. Advanced wireless sensors have programmable memories through which users can configure the frequency of the data transmission to meet operational needs. Once the data is received by the gateway, it can be processed further and integrated into the user’s control system. While the gateway device decodes the encrypted data packets, it also can convert the measurements into different formats as required and specified by the end user. Gateways also can run applications directly to allow connection to a user’s PLC or SCADA system via Modbus or OPC. This interface makes the data accessible for integration into pre-existing control hardware/software.

Electrochem specializes in end-to-end wireless sensing systems by offering both customized and platform solutions. This includes pressure, temperature and/or flow wireless sensors, a gateway device, and an interface application. Additionally, the company also offers a product known as a signal conditioner. This mates with an existing wired sensor or alternative sensing hardware such as an accelerometer. The sensors are housed in a 316L stainless steel case powered by a lithium battery and designed for hazardous environments, and support an IP67 rating and are certified for Class I Division I and/or Class I Zone 0 environments. The standard units provide a reach of 100 m (328 ft), while the extended units provide a reach of up to 1,000 m (3,280 ft). The data reporting frequency is configurable from multiple transmissions per second, to once per hour or even once per day. The receiving portion, or base station, of the wireless sensing solution is a single compact unit that offers hardware interfaces such as serial RS-232 or USB and digital I/Os or relays, as well as software interfaces such as Modbus-RTU or TCP/IP, OLE for Process Control (OPC), or FTP and Telnet. With a multitasking RTOS onboard, the base station can monitor concurrent measurements from a plethora of wireless sensors.

Electrochem partnered with Rooney Petroleum Services (RPS), an oil services company specializing in well completion activities such as testing and flowback, to improve the accuracy and frequency of wellhead pressure data measurements. In the past, RPS monitored wellhead pressure using traditional means. Teams of field operators manually took pressure gauge readings from various wellheads in an area that frequently experiences extreme weather conditions. The operators would record the readings on clipboards and later enter the data into a local computer. After all of the data was collected and entered into the system, it was periodically uploaded to the customer. RPS originally considered using wired transducers to run signals to a remote command center. After evaluation RPS realized the wired approach would require 150 ft (46 m) of buried copper cable, along with a costly implementation process of $7,000 per transducer for a job that would last an average of four weeks.

Electrochem’s wireless sensing tools – PressureSensorOne, TemperatureSensorOne, FlowSensorOne, and BaseStationOne-NG.

After research into choosing an advanced system that was affordable and proven to eliminate their pain points, RPS soon adopted Electrochem’s PressureSensorOne (PS1) and BaseStationOne-U (BS1-U), wireless pressure sensing technology, to remotely report tubing and casing head pressure in real-time around the clock.

RPS mounted a PS1 sensor to all gas wellheads. The sensors were programmed to wirelessly transmit data to the BS1-U base station in a mobile command center. This command center then publishes all of the information in real-time via software through a satellite Internet connection for instant customer access. RPS’s wireless sensing system was customized to have each PS1 provide five readings:

1. Operating pressure of the fluid being measured

2. Internal pressure of the sensor’s body cavity

3. Temperature of the fluid being measured

4. Temperature of the electronics inside the sensor

5. Expected remaining battery life.

This customized solution collects readings from over 200 sensors in the filed simultaneously and allows RPS to receive each of these five readings at speeds of up to 10 readings per second. This wireless sensing solution reduced RPS’ annual operating costs by $80,000 to $250,000 owing to less manual labor and human error. At the same time, RPS offer customers more frequent and accurate measurements in real-time.

The wireless sensing advantages include the ability to:

• Work remotely over the Internet from anywhere
• Work smarter with efficient and timely condition-based maintenance and early detection
• Work reliably without user error, as happens on manual measurements and recordings
• Ensure immediate action by making real-time decisions
• Save space and money without cable runs to each sensor
• Reduce installation and maintenance costs
• Work with confidence in dirty, hazardous, and harsh conditions.