• Zeta Safety System

    The Zeta safety system consists of a real-time monitoring gauge and an advanced job design model for well intervention operations.The system was designed to avoid catastrophic buckling and bending failures of well intervention stacks. These failures are costly and could involve human injury and unplanned release of wellbore pressure to the atmosphere.

     

    Description

    The Zeta system was developed due to potential safety concerns associated with the use of longer and more complex intervention stacks. These tall stacks are more susceptible to bending excitation forces from crane, production riser, and platform movements. At present, a judgment call (based on little or no hard data) is made regarding how much lubricator sway or wellhead movement is acceptable, when to add supports, or even when to halt operations due to safety concerns. Motion associated with TLP's and Spars only compound this problem. The Zeta safety system eliminates guesswork and provides a tool for optimal rig-up configuration.

    The Zeta system utilizes a proprietary 3D finite element analysis (FEA) model in combination with highly accurate measurements from fiber optic gauges. This approach enables accurate modeling of changing stress levels across the entire riser/wellhead lubricator intervention stack.

    The system can be used for pre-job modeling to optimize and verify the safety margin of your job design.

    Pre-Job Modeling

    • Probability of exceeding pre-set safety limits during the operation 
    • Need for additional intervention stack supports and their location
    • Stress changes as a result of stack loading changes
    • Maximum stress location
    • Weight required to buckle the stack
    • Stack vibration frequency
    • Optimized rig-up configuration

    It can also be used in a real-time mode in the field to monitor and issue a warning when stresses are approaching unsafe limits.

    Field Monitoring

    • Monitor intervention stack stress levels
    • Impact of changing surface, downhole and/or offshore field conditions
    • Suspend operations if maximum stresses approach unsafe limits
    • Resume safe operations following remediation of problem

    Features/Benefits

    ZETA GAUGE

    • 2' lubricator spool built to API requirements 
    • Uses fiber-optic strain gauges to measure
      • Axial force
      • Internal pressure
      • Bending moment (left and right)
      • Bending moment (forward and backward)
       
    • Calculates Von Mises stress in the gauge
    • Displays force, pressure, moment and stress values
    • Communications with the Model software in real-time
    • No electricity to the gauge - no certification issues
    • Fiber optic gauges are very stable - remains calibrated

    ZETA MODEL

    • Used during job design to ensure safe stack design
    • Models entire wellhead/lubricator stack with its supports and applied loads
    • Calculates:
      • Displacement (motion) of the stack
      • Von Mises stresses in the stack components
      • Vibration frequency of the stack
      • String weight required to buckle or yield the stack
      • Static or dynamic loading in the guy wires or support structure
       
    • Real-time input from the Gauge can be used to determine maximum stresses in the stack 
    • Warning when pre-set stress levels are exceeded

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