OPC UA provides interface protocol for SPE drilling automation initiative

Paul Miller, ARC Advisory Group

Historically, the downstream and midstream sectors of the oil and gas industry have relied extensively on automation technology to help improve safety and optimize the operations of its refineries, gas plants, petrochemical plants, and pipelines. At the same time, the upstream sector, particularly in drilling operations, has been relatively slow to embrace automation. To date, there has been only limited deployment of drilling automation technology on land rigs and offshore platforms.

Cultural reasons include the diversity of organizations involved in a drilling operation (owner, operator, service companies, and equipment suppliers). Each has its own agenda and priorities. Technological reasons include the diversity of equipment installed on the surface (top drive, mud pumps, hoist, auto driller, sensors) and downhole (bits/hole openers, motors, measurement tools, telemetry). Typically, each piece of equipment has its own dedicated controls or control system, which all must be integrated into a common system before the rig can be automated successfully. While many other industrial sectors have addressed the integration issue with a reasonable degree of success – largely through adoption of standard interfaces – this is a relatively recent initiative for drilling operations.

However, much progress is being made in this area. Dr. Clinton Chapman, Schlumberger drilling automation project architect, addressed this issue in his presentation at the ARC World Industry Forum earlier this year in Orlando. Chapman also serves as deputy chairman and comms team leader for the Society of Petroleum Engineers (SPE) Drilling System Automation Technical Section (DSATS), which was formed "to accelerate the uptake of drilling systems automation by supporting initiatives that communicate the technology, standardize its nomenclature, promote lessons learned and best practices, and help define its value proposition." DSATS participants include Shell, Statoil, BP, ExxonMobil, Chevron, Schlumberger, Baker Hughes, Halliburton, National Oilwell Varco, Helmrich & Payne, the Energistics Communications Standards Group, and John DeWardt Consulting.

Recognizing and building upon the Well Information Transfer Standard, the DSATS comms team recommends guidelines to allow open and secure communications between rig control systems, applicable surface and downhole measurements, and authorized third parties. According to Chapman, progress to date includes defining the architectural components and associated roles, identifying and defining the key interface points between rig components, agreeing upon a list of tag names for the key interface points, and selecting and demonstrating OPC UA (Unified Architecture) as an open communications protocol between components.

According to recent studies, automation has been shown to increase the rate of penetration during drilling operations, a key optimization parameter. In one test, in which several wells were drilled in the same pad, automation dramatically reduced the time required to drill the holes compared to manual control. In this test case, it took approximately eight and a half, eight, and seven days, respectively, to drill holes manually, but approximately five and a half to six days to drill holes using an automated process. Furthermore, all the wells drilled with the automated process were completed within 14 hours of each other, demonstrating increased consistency and predictability.

After reviewing different protocol options, DSATS selected OPC UA to develop consistent tags that could be used to integrate the various topside and downhole rig control systems.

Chapman said that with strong encouragement from Shell and other organizations, DSATS selected OPC UA because of general agreement that OPC has broad industry support; OPC UA components are available "off the shelf" with drivers; and OPC UA offers an attractive security model. The latter is particularly important since drilling operations typically involve multiple third parties. Compatibility with multiple HMI/SCADA systems and the availability of OPC DA-to-OPC UA converters also strongly influenced the decision.

OPC UA provides connectivity to all address spaces for the rig, its equipment and associated attributes, and all real-time values and setpoints. It provides drilling service organizations and rig operators the ability to perform device discovery on existing rigs, access real-time tags for feedback from the top drives, and write to setpoints by automation agents and automation consoles. It also enables organizations to customize security models to allow for control selection.

The SPE DSATS architecture for drilling automation is organized into:

• Equipment
• Composite control system and HMI
• Communications device
• Automation console
• External systems.

The equipment includes hoist, top drive, mud pumps, and generic equipment. These are all concentrated within a composite control system and associated HMI that the driller uses to control the rig. From the composite control system, an interface is exposed to allow digital control and automation of the equipment. The rig contractor would generally provide this interface. A communications device (effectively an OPC UA server) attached to this interface provides a common technology/interface between the rig and external systems. An automation console attached to the comms device provides the driller with a user interface to manage the automation or; if necessary, disconnect the automation and resume manual control. External systems from the equipment suppliers, service companies, or operators could attach to the comms device via a private cloud to obtain real-time, remote access to data from the comms device or their own sensors. A communications device attached to the interface incorporates an interface enabling digital control of the equipment.

The DSATS team organized a successful demonstration to prove the architecture at the SPE Annual Technical Conference in October 2011. According to Chapman, the objective of the demonstration project was to show control of the top drive, which for the purpose of the demonstration, was simulated using a 3D simulator from NOV. Also acting as a "drilling/rig contractor," NOV provided a digital interface to allow external control of the top drive. With technical assistance from the OPC Foundation, the DSATS team configured the comms device/OPC UA server. An automation console, which the team created using Siemens' WinCC HMI product, was easily connected to the customized OPC UA server. Finally, the team created external software agents using OPC UA Foundation libraries. By choosing the appropriate agent, the "driller" could switch between slide drilling and rotary drilling.

Lessons learned included:

• OPC UA provides an important toolset, but not a complete solution. OPC Foundation technical support was critical for successfully configuring the comms device
• The ultimate goal should be to develop an off-the-shelf standard
• Need to develop an open standard for security mechanisms
• Need to identify an OPC supplier for tag-level security
• OPC UA worked well in terms of initiating the basic communications, but equipment suppliers need help to correctly implement security
• Need to develop schema to support communications with top drive and other surface equipment.

According to Chapman, while much progress has been made, it is clear that the DSATS team can still learn much about automation approaches implemented successfully in other industries to be able to leverage this existing expertise. It also will be important to track the ongoing evolution of OPC UA and other standards, and, if possible, leverage a faster communications protocol.