Integrated Deepwater MPD Control System Increases Accuracy, Ease of Use
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This paper presents lessons learned regarding design, testing, and installation of a completely integrated managed-pressure-drilling (MPD) control system on a deepwater drilling rig. For the installation described, all MPD control functions were installed permanently on the main drilling-control network of the drilling unit, providing direct access to high-speed data from other drilling machines that influence wellbore pressure. Moreover, the MPD control system has the ability to actively control these drilling machines.
The authors have discussed in previous work that seamless integration with existing rig infrastructure will be instrumental in using MPD as standard operating procedure during drilling. Installing the MPD control system as an equal peer in the drilling-control network is key to this strategy. This allows for using existing high-speed, robust data networks, and optimization of the overall drilling process by including topdrive, mud pumps, drawworks, and MPD equipment in the management of pressure.
Other authors have discussed strategies for integration and economic deployment of MPD on a contractor’s fleet of vessels. This strategy includes integration of MPD hardware and control systems with existing rig systems in close collaboration with original equipment manufacturers (OEMs) and suppliers. In this strategy, the drilling contractor will be responsible ultimately for delivering MPD functionality as an integral part of its drilling service.
A key part of the drilling contractor’s strategy is to use the same user interfaces, topologies, and infrastructure on all their drilling vessels. To accomplish this, the MPD control system must be integrated into the overall OEM drilling control system. These integrated drilling control systems are built for seamless integration of machine control, process management, and information sharing. The system networks, forming the backbone of the system architecture, are secured and prepared for any machine integration with redundant setups for a high level of system and operational availability. The segregated networks offer increased security and reliability.
For the MPD-specific control tasks, the OEM maintains a code base of core MPD functionality that can be deployed quickly for standard deliveries. For integrated systems, the OEM and drilling contractor work together to review the existing drilling control system versions to ensure that the MPD installation is performed on the correct version of the drilling control system.
The MPD control system consists of a control and interface hardware. To ensure proper interface and management of the overall system, the MPD components are designed to be installed in the rig’s local equipment room. The MPD control system has a real-time communication interface toward the drilling contractor’s MPD network on the rig to ensure precise control of the MPD equipment and the rig’s drilling control network. MPD functionality is available for both the driller and any user on the rig with access to standard rig remote workstations. Only certain users are allowed to configure and modify the system. The complete paper contains a detailed description of the high-speed data-communication networks in detail.
Smart Drilling Functions. When managing pressure, including not only the MPD equipment but also the other drilling machines that influence wellbore pressure is critical in achieving the overall objective. Consequently, new functionality was implemented on the programmable logic controllers (PLCs) that manage the mud pumps, topdrive, and drawworks. These functions should be used to minimize pressure fluctuations and to drive consistency and repeatability in the drilling operation.
The drawworks PLC was updated to limit the maximum allowed block speed on the basis of configured sections or tight spots. These sections can be configured and updated during the operation as tight spots are identified. When the bit passes through one of these sections or tight spots, the speed and acceleration will be limited automatically to minimize the effect of surge and swab when hoisting or lowering the drillpipe. The configuration can be stored and retrieved for several wells. Speed and acceleration limitations will be disregarded when running with an empty block.
Another smart function of the system entails updating the mud-pump and topdrive PLCs to enable the driller to coordinate and automate speeds. This function allows the operator to configure up to 10 sequences to increase or lower the flow rate and drillstring rotation, ensuring repeatability when ramping up topdrive and mud pumps during connections, flow checks, and fingerprinting. Each step will, at a minimum, require a flow- and string-rotation and a ramp rate. Additional extra conditions for flow out, standpipe pressure, and volume also can be configured by the operator. When a ramp is activated, the system will wait until all condition setpoints are reached before moving to the next step. That step either will be activated automatically or manually on the basis of the activated trigger set by the operator for the corresponding step.
Driller’s View. In this integrated MPD system, the driller will not use a separate operator station to monitor and control the MPD process. Instead, the key parameters needed to understand and control the whole drilling process are integrated seamlessly in the main Drilling Process screen in the driller’s chair as part of the control system’s context-based content. This includes setpoints for surface and bottomhole pressure, alignment of MPD valves, and trending of MPD parameters.
Development and Testing
Before the project began, all components of the MPD control system had been tested in a range of real and simulated environments. The OEM maintains a full-scale test rig with full drilling capabilities, using a high-speed telemetry wired drillpipe as the main test string, and a backup of all PLC software and configurations installed on individual vessels. As part of the development process, all main drilling control system PLCs are loaded into a virtual hardware-in-the-loop simulator (Fig. 1). This includes duplicating the actual hardware and PLC software for mud pumps, drawworks, topdrive, drilling control system, and smart-drilling-instrumentation layer, together with the new MPD control system hardware. All controllers are set up in the same network configuration as on the rig in question.
The simulator is further configured with an advanced virtual wellbore, and the outputs from the machine controllers are applied to the virtual well. The simulated environment enables the developer to trigger errors in the system, such as choke clogging, lost circulation, and influxes. A simulation layer between the controllers and the virtual wellbore communicates sensor data to the controllers, with the controllers seeing no difference from a real rig, as illustrated in Fig. 2. The simulation layer includes the ability to simulate sensor noise and faults.
The second part of the rig-specific testing included a system interface test in which all relevant OEMs installed their control system hardware and all control system interfaces were tested.
Installation and Commissioning
For the first installation, a team of trained OEM field-service engineers was mobilized to the rig while preparing for a move. Detailed installation and commissioning procedures were available before the job had been started. The MPD control hardware was installed in the local equipment room.
For the software upgrade, a new PLC was installed to control the main MPD equipment. The controllers for the other drilling machines were subsequently updated with new advanced functionality for pressure management. Finally, the human/machine interface (HMI) and smart-drilling-instrumentation layers were updated to account for the new screen layouts and additional MPD equipment.
The drilling control system must be taken offline to complete certain steps of the upgrade. Sufficient time must be planned for this upgrade, so that new functionality can be confirmed in a noncritical phase of the operation.
Training and Operations
Both the drilling contractor and the control system OEMs have advanced training facilities for realistic simulation of drilling operations. For an integrated control system, the drilling-training simulator should include MPD functionality and the driller’s HMIs with the addition of MPD components and control functions. Consequently, the OEM’s drilling-training simulator will be updated to allow hands-on training of drillers and drilling crews before and between operations as part of regular competency development.
For the first operation with an integrated system, the MPD equipment and control system OEMs will provide engineers on site to support and train drilling-contractor personnel. The operator that contracted the rig also included the OEMs in pre-spud planning meetings and risk assessments.
The first two installations of an MPD control system integrated seamlessly with a drilling control system confirm the potential of this strategy. An integrated system results in a design of a pressure management system that considers all main drilling machines that affect annulus pressure during drilling operations. Industrial, high-speed communications protocols ensure accuracy and robustness in the system. Incorporating MPD control screens into the standard drilling process screens improves ease-of-use and increases the drilling crew’s ability to understand and control the MPD operation.
Integrated Deepwater MPD Control System Increases Accuracy, Ease of Use
01 October 2019
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04 October 2019
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