Case Study 

Scope:  

The project involved upgradation and modernizing of control and data acquisition systems of a pressure maintenance plant for an upstream Oil & Gas customer, aged between 25-30 years.  

The primary objective of this project included: 

1. Complete replacement and upgradation of control system utilizing Allen Bradley PLC5/40 and SLC 5/04. 
2. Integration and automation of existing equipment that was manually operated from field. 
3. Controller upgradation of existing control systems to ensure connectivity between the control rooms of the plant. 
4. Upgradation of existing SCADA (Supervisory Control and Data Acquisition) systems in engineering and operating stations. 
5. Hot Cutover to ensure an uninterrupted and seamless control system migration from the old system to the new all while guaranteeing zero downtime. 

Throughout the project, utmost priority was given to ensuring the uninterrupted operation of the plant, thereby minimizing any disruptions to production. 

 Background: 

Within the crude oil water filtration and injection process, pressure maintenance plants serve as key facilities. Operating relentlessly for over three decades, these plants had reached a critical juncture requiring a comprehensive overhaul. The control systems had aged and reached a point of obsolescence.  

Given the continuous operation of the plant 24/7, any upgrades or retrofits had to be executed without disrupting ongoing operations. 

System Description: 

The entire plant consisted of two control rooms, of which the first utilized Allen Bradley PLC5/40 and SLC 5/04 and dealt with processes such as filtration, and water injection back to the underground. The second control room, also using Allen Bradley system was responsible for oil recovery, water disposal and flare systems. 

On studying the system in detail, our team architected a solution to replace the existing controllers with the Rockwell ControlLogix 1756 system for several key reasons. Firstly, its integration capabilities with the existing control system ensured compatibility and smooth transition and compatibility with the current infrastructure. Additionally, the system’s redundancy features reliability and continuity, crucial for maintaining operational efficiency. 

Our Approach: 

Our team implemented a comprehensive 4-fold approach for executing a zero-downtime Hot-cutover procedure, encompassing the following steps: 

1. Study of the Existing System 
   • Understanding complete plant processes, critical loops, and interlocks. 
   • Collecting available documents from the end user. 
   • Identification of modifications made over the 30-year period, particularly undocumented changes. 
   • Trace out all undocumented changes in system through manual methods. 
   • Discussions and reviews with plant personnel for possible migration options.
2. Detailed Planning 
   • Developing a control and automation system architecture housing all the requirements as per scope. 
   • Filtering loops and I/Os based on criticality and complexity. 
   • Listing of preparations and procedures to be carried out during a shutdown window, whenever available.  
   • Analyze possible challenges that may occur and find solutions for the same. 
   • Develop an error-free hot cutover plan for smooth transfer of system. 
3. Design and In-house Testing 
   • Preparation of detailed engineering documents for smooth transition from old to new system. 
   • Design & manufacturing of electrical control panel meeting all the safety standards and requirements. 
   • Development of SCADA system incorporating all existing and additional control loops that are to be integrated with the system. 
   • Preparation of operation manuals for end-users to work on new system. 
4. Executing Hot-cutover Migration 
   • Pre-migration procedures: 
     • Installation of new control system and pre-pulling of terminations to the marshalling unit. 
     • Choosing a proficient team and providing detailed training and guidance on the entire work plan. 
   • Migration procedures: 
     • Bypassing all critical loops and I/Os in the system. 
     • Removal and proper insulation of existing loop connections, and interconnection of cables at the terminal strips without affecting existing control signal wires. 
     • System logic is validated, loop tuning is carried out, and SCADA screens are verified, thereby Site Acceptance Test (SAT) is carried out as well. 
   • Post-migration activities 
     • Monitoring of the entire system for 24 hours to ensure after each phase, to ensure system functions well with the new system. 
     • Removal of old cables from the cabinet without disturbing the running system. 
     • Provide detailed training for operators and maintenance team on the entire new system. 

Result 

• • Control System Upgrade: The complete replacement and modernization of the control system in the Oil and Gas Industry, transitioning from the outdated Allen Bradley PLC5/40 and SLC 5/04 systems to the advanced Rockwell ControlLogix 1756 platform, ensured enhanced functionality and future-proofing of the plant’s operations. 
  • Integration and Automation: By integrating and automating previously manually operated equipment from the field, operational efficiency and accuracy were significantly improved, reducing te likelihood of errors and streamlining processes. 
  • Connectivity Enhancement: The controller upgrade facilitated connectivity between the control rooms of the plant, enhancing communication and coordination between different operational sectors. 
  • SCADA System Upgrade: Upgrading the existing SCADA systems in engineering and operating stations provided operators with a more comprehensive and intuitive interface for monitoring and controlling plant processes. 
  • Zero-Downtime Transition: Through meticulous planning and execution of a hot cutover procedure, the transition from the old control system to the new one was achieved seamlessly, with no disruption to ongoing operations.