Adoption of communication protocols may help improve data sharing, automation
By Brad Rosenhagen, AWC
As the mechanization and automation of drilling rigs become more demanding and complex, it is vital that existing and prospective communication technologies meet the ever-changing and dynamic requirements of the oil and gas industry.
In addition, existing drilling rigs have a myriad of control and monitoring systems from multiple tool manufacturers that communicate over different networks/buses and use a variety of protocols. Concerns for tool and personnel safety, along with secure data exchanges, also create challenges in information sharing between operators and contractors.
It is important to understand the requirements for providing data among the control systems, status on drilling rig operations, diagnostics from tools and sensors, and overall data accessible to oil companies, drilling contractors, tool manufacturers and third parties, and how best to meet the requirements.
This article will cover some of the earlier communications technologies and protocols adopted for drilling operations, as well as potential future technologies to meet continuing demands for better solutions. Additional information from a 2008 survey conducted by IADC provides the current status on many of today’s rig control systems.
The ongoing need for improved communications between drilling rig tools and monitoring and controls systems to provide reliable, efficient and safe drilling operations also will be addressed.
Communication protocol survey
In 2008, the IADC Advanced Rig Technology Committee’s Drilling Control Systems Subcommittee conducted a survey of drilling equipment manufacturers on the prevalence of communication protocols on drilling control, subsea, dynamic positioning and power systems.
Figures 2 and 3, generated from survey data, illustrate that the drilling industry has few standards in communication protocols and has a significant assortment of proprietary protocols in serial and peer-to-peer formats.
In 26 years of automation experience, this author has worked with the drilling industry, as well as automotive, petrochemical, pharmaceutical, semiconductor and other technical industries. Each of these industries has faced similar challenges, and many have discovered that the ability to develop innovative automation solutions requires a balance between dependable communications standards and available communication interface devices. This combination enables interoperability among existing systems and can help address new challenges.
The basic idea behind a communications standard is to establish a specification in a rigid and formal way, ruling out the possibility of quick changes. This attaches a notion of reliability and stability to the specification, which results in securing the trust of the customers and, consequently, the market position.
This article will cover some of the early and current communication protocol technologies adopted for drilling operations, as well as identify potential future technologies for improved communications between drilling rig tools and monitoring and controls systems.
From the beginnings of oil and gas drilling, communications has played an important role in safety and efficiency. The first steps in communications were verbal and hand signals between the driller and roughnecks during the setup and drilling processes. Direct tubing and piping from the process lines to driller gauges gave current conditions of the process.
As holes got deeper, equipment became larger and more sophisticated, requiring more powerful motors and larger spaces to house the equipment. This created the need for additional process monitoring and control and more accurate data. To meet this demand, more sensor feedback needed to be employed.
The relay of information from a sensor through signal media became the first stage in industrial communications. This included using physical switches with open or close valves/contacts to relay the particular status of a device. Limit switches, pressure switches and level switches conveyed process status over pneumatic and electrical lines. For proportional information, transmitters were incorporated to provide real-time analog data through 3-15 psig pneumatic lines and 4-20 mA current loops.
These signals were fed into local controllers and displays for each major tool, creating islands of control. The islands helped provide the driller with the real-time data needed to achieve efficient drilling processes.
Great gains were made during this period. Drilling accuracy improved with the availability of reliable data from multiple sources. Algorithms were employed along with open-loop control to provide quicker response to processes changes.
The continued development in automation systems meant that programmable logic and process loop controllers could share information with data displays, graphic operator interfaces and data acquisition systems. Serial communications protocols were developed to convey digital data among controllers, operator interfaces and data storage devices.
Serial communication is used to send strings of binary data (0s and 1s) between two or more systems. RS232, RS422, RS485 and TTL are communication physical standards (media formats) that normally send data over low DC voltage wires. To achieve greater distances, media converters and modems were developed to transmit these signals through fiber optic cables and wireless units.
Communication protocols were developed to send the binary signal in a specific arrangement that includes details on what is being sent, along with the value and a way to confirm that the data was received. Protocols such as Modbus, HART, ASCII and TIWAY were created to share data between devices and simplify the process of connecting two dissimilar devices.
These early serial communication protocols communicated at lower baud (symbols per second) rates and were often single master-slave networks. One master would request (read) data from slave devices and feed (write) data back to the slave devices.
Serial protocols used in the drilling industry can be proprietary or open. Proprietary protocols require purchase of specific hardware and/or software interfaces but often provide faster and more secure communications needed for operations. Open protocols can reduce costs and provide multiple vendor solutions, yet their openness may limit the security of the data.
As drilling became increasingly more complex, these separate islands of control limited the ability to collaborate process data from each major rig tool. The drawworks needed to communicate to the top drive, which needed to communicate to the pipe-racking systems, mud pumps and more.
The islands needed communication highways and bridges to share data among them.
In the mid-’90s, communication media and protocols speeds greatly increased. These advances meant that a tool could receive data from another tool and execute it in real time. The challenge was not to put all data on one communication media and slow down the whole network. At this time, Ethernet was not deterministic (correct data received and time-specific) and hardened enough to ensure that data would be shared in real time, and the overhead cost of an Ethernet driver on small devices was cost-prohibitive.
Specific communications technologies were developed and executed to handle unique levels of control and to feed data to higher levels for supervisory control and data acquisition.
Sensors and valves can operate with small packets of data in bytes (8 bits) or words (16 bits). This level of communication is called device or bit level networks and is the base of the communications pyramid. Since these devices do not require large arrays of data, the driver interfaces are simpler, smaller, less expensive and easier to configure.
Device-level protocols include AS-Interface, DeviceNet, Profibus PA, Foundation Fieldbus and J1939, which are all open (nonproprietary), have been implemented on drilling rigs and are extensively used in the automotive, petrochemical, pharmaceutical and semiconductor industries. Since these device-level networks were designed for simpler devices, they typically communicate at speeds in the kilobyte range (for example, AS-Interface = 167 kbaud).
The majority of current drilling rig tools incorporate fieldbus networks in place of device-level to handle larger volumes of data among more complex devices. Fieldbuses provide speeds of up to 12 Mbaud and can communicate and control blocks of data between devices in real time. Main fieldbuses in drilling applications are Profibus DP, DeviceNet and Canbus. Fieldbus masters read and write data to the fieldbus slaves, which may also serve as gateways to the device-level network. This hierarchy of simple to more complex devices extends itself to the local-area network level in the communication pyramid.
LAN & enterprise networks
Ethernet has made significant advances since its inception in 1973 by Bob Metcalfe at the Xerox PARC facility. Initially Ethernet communicated over coaxial cable media at 10 Mbps (bits/sec) with the Carrier Sense Multiple Access/Collision Detection (CSMA/CD) protocol. The Ethernet interfaces and media (cable, connectors) were difficult to use and expensive. Other computer networks – Token Ring, developed by IBM; H1, developed by Siemens; ARCNET; and others – offered some determinism, which means a signal is sent and received without loss of data, and ruggedness that Ethernet couldn’t meet. Those were the main industrial networks used in the 1980s.
In 1983, the IEEE 802.3 subcommittee formed to develop standards for Ethernet, but the real advances came with the introduction of the Internet in the early 1990s. IEEE approved the 10-Base T standard in 1991, which allowed Ethernet to communicate at 10 Mbps over twisted pair, which lowered the cost of Ethernet interfaces and media devices. Additional advances in 1995 (100BaseT), 1999 (Gigabit Ethernet) and 2002 (10 Gigabit Ethernet) made Ethernet the standard communication media for the future.
Current Ethernet communication protocol layers like Transmission Control Protocol/Internet Protocol (TCP/IP) and User Datagram Protocol (UDP) are easier and less expensive to use but still do not provide real-time deterministic communications. Hence the Ethernet LAN is still essentially used to communicate stored data between computers and not for control on drilling rigs.
Newer Ethernet-based protocols such as Modbus TCP, ProfiNet, Ethernet/IP, WITSML and others are now providing more reliable high-speed (up to Gigabit) communications between devices. Many of these layer-seven networks are deterministic and provide synchronicity between devices and/or redundancy to ensure reliable data.
Wellsite Information Transfer Specification (WITS) was developed in the 1980s by POSC (now Energistics) to communicate wellsite information from one computer system to another. WITSML is web-based and built on XML technology, which is both platform- and language-independent.
As the speed of Ethernet has increased, the costs of the interfaces and components have greatly decreased. It can now be economical to employ single devices with Ethernet interfaces. With commercial Ethernet products communicating at 40 GB and with 100 GB coming, industrial applications can share real-time data over the same network structure as the data storage levels.
Data can now be stored and retrieved offsite in virtual servers or clouds, allowing supervisory control to be implemented at a company’s corporate center, where drilling specialists can monitor and enable multiple operations. Cloud computing can enhance a company’s ability to share technical resources on several rigs and to develop standards in drilling operations.
These clouds can be made up of multiple servers and devices, each performing a specific function for a drilling rig to optimize their process. For example, during the casing and cementing process, it is possible to allow third parties to be involved with the operation and to run specific rig tools at their optimum. Operating a drilling rig with multiple remote controllers from third parties, however, creates issues in regards to security, safety and reliability.
Fred Florence, National Oilwell Varco, is chairman of the SPE Drilling Systems Automation Technical Section (DSATS). The group is working with the IADC ART Drilling Control Systems Subcommittee, under the leadership of Terry Loftis, Transocean, to develop standards to improve the implementation of communication between control systems during the drilling process. Some of the newer technologies will most likely be a part of this solution.
“A significant challenge involves using communication protocols in a way to ensure that a specific step in the process has the higher priority at the right time and is controlled by the right party. Understanding what these process steps are and how the hierarchy changes during drilling operations is critical in developing a secure and reliable process,” Mr Florence said.
Advances in OPC Unified Architecture (UA) could allow multiple protocols to share the same tool/device tags. Fiber-optic, wireless and DSL modems change Ethernet’s physical layer to meet demands for harsh and hazardous area communications on a drilling rig and to provide options for sharing information between tools.
OPC UA is the latest generation of the OPC standard and provides a common platform to access real-time data between devices. OPC UA exchanges data in an object-oriented manner rather than as isolated values. Data from drilling rig tools can be made more accessible to multiple parties by storing the values in a common object, which increases interoperability between rig tools and improves security.
Industrial wireless technologies were developed in the 1970s and established for remote telemetry systems in the 1980s and 1990s in most industries. The drilling industry has been cautious about adapting wireless technologies on rigs because of concerns with reliability, security and a lack of a standard. At one time, there was an industry fear that a wireless signal could set off perforating guns. This is technically no longer an issue but still a concern in the industry.
Only recently has there been significant adoption of wireless devices on drilling rigs. This includes Wi-Fi (802.11) for control and data sharing along with proprietary wireless protocols for remote IO and data.
Industrial Ethernet implementations that are based on the IEEE 802.3 standard can work equally well over wired and IEEE 802.11 wireless Ethernet networks. The environment around a rig means that Ethernet can be used for applications where wired connections are difficult. New wireless technologies, including WiMax2, LTE (Long Term Evolution), Wireless USB and Wi-Fi direct are being implemented in commercial applications and will eventually be developed for industrial applications.
Wireless access points act like switches between devices and can operate in a mesh-style network, routing data through the specific units or configured to take the “best” path. Sensors, valves and other end devices are also available with direct wireless connections and can be incorporated into these mesh networks.
A majority of these wireless technologies are simple to configure and install (no wires for power or signal), provide options for mobile equipment and short-term use, and are evolving to provide greater reliability and security at reduced costs.
Challenges still exist for establishing new communication technologies on a rig. Most rigs use a multitude of communication media and protocols. To improve drilling efficiency, safety and security, time and effort must be invested to develop the communications infrastructure.
The best communication tool is one that provides a high level of security, is fast and reliable, can work in hazardous areas with international approvals, is expandable for infrastructure changes and is cost-effective. This perfect storm of communication technologies does not exist today, requiring OEMs and end users to select the technology that works best for them.
Certainly, there also will always be advances in communication technologies. Infiniband, Fiber Channel, QsNet, Myrinet and others being used in commercial sectors may develop into an industry standard. It’s important to stay informed on changes in the marketplace and how they will affect the communication infrastructure on a rig.
Results of the survey cited are available at the ART Committee page.
This article is based on a presentation at the IADC Advanced Rig Technology Conference & Exhibition, 20 September, Houston, Texas.