SCSSV Leak Rate Calculation Utility

Viking Case Study
Written By GATE Energy

A Gulf of Mexico operator requested GATE Energy to develop a tool to allow them to calculate the SCSSV leak rate based on the wellhead pressure response during the SCSSV test following the Burau of Safety and Environmental Enforcement (BSEE) requirement to periodically test the SCSSV. The tool identifies the phase between SCSSV and wellhead (gas / liquid / gas-liquid two phase) and calculates the SCSSV leak rate to be compared with the regulation.

CHALLENGES

  • No direct means of measuring the SCSSV leak rate.

  • The API RP14B (2015) does not provide the SCSSV leak rate calculation formula should both gas and liquid (two phase) exist in the wellbore.

  • The API RP14B (2015) suggests the wellbore cooldown to be considered during the calculation process and the USV leak during the SCSSV test to be taken into account in the SCSSV leak rate calculation.

SOLUTION

GATE Energy developed an alternate SCSSV leak rate calculation methodology utilizing GATE’s proprietary simulator GATE Prho™ building blocks that, with one simulation run, allows the operator to:

  • Calculate the SCSSV leak rate.

  • Determine the phase between SCSSV and wellhead (gas / liquid / two phase).

  • Determine the gas-liquid interface, if any.

  • Calculate the mass of hydrocarbon liquid, hydrocarbon gas and water in the wellbore.

  • Estimate the average wellbore cooldown.

  • Calculate the USV leak rate.

  • Calculate the average overall fluid bulk modulus.

  • Provide the leak rate calculated using the single phase formula provided by API RP 14B (2015)

It is important to note, prior to delivering the SCSSV leak rate calculator, GATE Energy conducted an extensive benchmarking study between the tool, available field data to ensure it is representative of the actual field conditions.

TECHNICAL BENEFITS

  • A robust, physics-based SCSSV leak rate calculator which takes into account the entire SCSSV test sequence namely: (1) Steady-state production, (2) Ramped-down production, (3) Shut in , (4) Wellbore venting, (5) SCSSV monitoring time

  • Simple to operate and takes less than approximately one man-hour to input minimal requirements and a current leak rate of the SCSSV.

  • In future, easy to share with GATE engineers to further support with more thorough analysis and troubleshooting.

GATE Energy
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