Gas and oil fields mostly span numerous square miles across remote areas that often lack cellular coverage. Extreme outdoor conditions are typical - intense cold, snow and ice, searing heat, heavy dust, strong wind, torrential rain, high humidity and salt fog. Data communications for oil and gas fields need resilient and reliable, high capacity wireless networks that function over large areas under these extreme conditions.
Data from instrumentation and controls plays vital roles in today’s upstream oil and gas operations. Remote terminal units (RTUs), measurement devices, and controllers regulate and optimize well pad operations via widespread fields, developing efficiencies that save millions of dollars. Remote and local access to data and controls decreases costs for vehicle upkeep, gas, maintenance and insurance. Operators are capable of handling more wells while driving less.
Well pads and fields have become production facilities demanding centralized data transmission to and from remote locations in real time. These systems provide management the opportunity to control and supervise production from distant places, while improving compliance with environmental regulations and enhancing operator safety and productivity.
Measurement and Automation
Horizontal drilling and fracture techniques have resulted in smaller environmental footprints for natural oil and gas production. It is possible to consolidate multiple wellheads in a small area. Instruments and sensors provide data for temperatures, flowrates, pressures and level for wellheads, tank storage and separation equipment. One RTU can frequently automate and control the whole well pad with multiple wellheads while communicating with a remote central control room connected to multiple well pads in the field.
Production slows as wellheads age. Backpressure resulting from the buildup of water and oil halts flow from the well. Companies make use of enhancement techniques to enhance production. Techniques such as plunger lift, gas injection, intermittent lift, submersible pumps and surfactant injection can restore well production to optimum levels.
Besides optimizing production from individual wellheads, an RTU can be configured for measuring and controlling almost all the well pad functions. An RTU can turn wells on and shut them off based on complex and simple algorithms in order to optimize production. Connected to appropriate sensors, it is also capable of measuring the water, gas and oil produced. It is also capable of measuring and controlling separator temperatures and monitoring oil and water tank levels. It can shut down separate wells or the entire well pad during emergency situations.
Control routines within RTUs for pumps that provide artificial lift are capable of handling basic and on-off operations, and perhaps a drive to regulate working speed for better energy management and enhanced production. Measurements from these devices include position, torque and load. Modern RTUs monitor measurements from each wellhead in order to automate these operations, removing some burden from operators.
Flowmeters in piping from chemical tanks measure and then totalize the amount of fluid pumped into a well versus planned amounts. Flowmeters also totalize volumes of wastewater pumped into disposal wells. Pump drives control fluid flows while sensors prevent spills and overfilling.
Other equipment on the pad performs primary separation of oil, gas and water coming from the multiple or individual well heads. Instrumentation for measuring temperature and pressure control the separation process. Flowmeters measure the outputs from the separator - perhaps a magnetic flowmeter for water, a Coriolis flowmeter for the oil and an orifice element coupled with a DP transmitter on the gas. The RTU observes all these flow measurements and calculates the production amounts attributed to the wells and the water collected for disposal.
Custody transfer measurements come into play, whether for production piped offsite, or for tank truck unloading and loading. Systems record data such as driver name, volume of product and truck number. Producers use the data to account, invoice and reconcile. The records go to a central oil battery where the product goes into the piping system for transmission.
Communications for control and measurement operations on a well pad are generally direct wired and powered by solar charging and batteries. This indeed permits well pad operations to continue autonomously for a number of days. Solar powered wireless communications provide vital data that can be accessed centrally through a supervisory control a data acquisition (SCADA) system. Additionally, data, optimization and control routines may be available for the operator to execute remotely or locally, as necessary.
Wireless Transmission Systems
Networking infrastructures for collecting and transmitting data from the field to centralized remote locations are growing. Conventional unlicensed radio systems limit bandwidth. Wireless signals in fields with high-density drilling tend to compete, producing interference and signal drop offs. Companies are transitioning from traditional radio networks toward meshing systems in order to support growing data demands. Meshing networks boost the capabilities of remote routers and bandwidth communications.
Meshing networks contain multiple nodes and have the potential to self-correct. If a node fails, the network will search for alternate nodes and paths in order to transfer data. These networks connect to SCADA systems that supply widespread data in specialized formats to central locations.
The volume of data produced in the upstream oil and gas fields is growing exponentially. At one time there may have been just a valve, a wireless connection and one primary measurement device. Presently, there are multiple sensors for temperatures, flow rates, pressures, tank levels, alarms, valve positions and several other variables associated with optimization and safety.
The wealth of information available allows operators to decrease site visits and work safely during any required visits. The data becomes meaningful information for analysis and production oversight by management and a wide range of users at remote locations.
Additional functions provided by high bandwidth wireless network systems include:
Real-Time Video Feeds and Surveillance
Providing operations with remote situational awareness and information that can improve safety, facilitate decisions and deliver early visibility into critical unfolding situations.
Security and Surveillance Systems
Improving facility security with electronic access control at secure locations or entry points in the facility; video security at gates or around the site perimeter
Tracking and updating the location of mobile and fixed assets in the field enhances operations and contributes to security and safety.
Mobile Field Workforce Connectivity
Keeping workers in the field connected with access to SCADA data, email, instant messaging and voice at remote sites even if they lack cell service is vital for worker safety and operations.
This information has been sourced, reviewed and adapted from materials provided by ABB Measurement & Analytics.
For more information on this source, please visit ABB Measurement & Analytics.