Gas sales contracts, facility sizing and field development plans all rest on estimates of well deliverability. Deliverability testing provides the data behind those estimates. A well that has been tested and analysed correctly can be forecast with confidence; one that has not can lead to under-delivery against contracts or oversized facilities.

Gas wells behave differently from oil wells. Gas properties change strongly with pressure, so pressure-squared or pseudo-pressure methods are needed. At high rates, non-Darcy flow near the wellbore adds a rate-dependent pressure loss that can be larger than the Darcy term. And in tight reservoirs, stabilisation can take so long that conventional flow-after-flow tests are impractical, which is why isochronal methods were developed.

Common mistakes include analysing unstabilised data as if it were stabilised, ignoring the non-Darcy term when extrapolating to high rates, using the back-pressure exponent outside the range tested, and treating the absolute open flow as an achievable rate. This course explains the theory well enough for engineers to design better tests and analyse them correctly.

By the end of this training, participants will be able to:

• Calculate gas properties for deliverability work, including z-factor, gas formation volume factor, viscosity and pseudo-pressure.
• Explain Darcy and non-Darcy gas flow and estimate the non-Darcy coefficient.
• Apply the back-pressure equation to gas well deliverability data.
• Apply the laminar-inertial-turbulent deliverability approach.
• Design, run and analyse flow-after-flow, isochronal and modified isochronal tests.
• Determine absolute open flow potential and explain its limits.
• Plan deliverability test operations, including stabilisation time, measurement and safety.
• Combine deliverability with tubing performance and assess liquid loading risk.
• Forecast future deliverability as reservoir pressure declines.

The course is instructor-led. The theory of gas flow and deliverability is developed step by step and applied through worked examples of test analysis for each test type. Field cases show how tests are designed and run and where data quality problems arise. Participants are encouraged to bring questions and data from their own gas wells for discussion.

Organisations sending participants to this training will:

• Get more reliable gas well deliverability estimates for contracts and facility planning.
• Improve the design and cost-effectiveness of gas well tests.
• Reduce the risk of under-delivery against gas sales commitments.
• Improve gas well performance forecasting as fields deplete.
• Identify liquid loading risk in gas wells earlier.

Participants will:

• Understand the theory behind gas well deliverability testing.
• Be able to design and analyse the main deliverability test types.
• Be able to handle non-Darcy flow correctly.
• Be able to link reservoir deliverability to wellbore performance.
• Be able to forecast gas well performance with confidence.

• Production engineers working on gas wells
• Reservoir engineers
• Well test engineers
• Gas field operations engineers
• Well performance and surveillance engineers
• Regulatory and reporting engineers dealing with gas well tests
• Graduate engineers in gas field roles