Gas properties change with pressure, and that is why gas well analysis differs from oil well analysis. Viscosity and compressibility factor both vary substantially across the pressure range between the reservoir and the wellbore, which means the flow equation cannot be integrated with constant properties. Pseudo-pressure handles this by absorbing the property variation into a transformed variable, and using it correctly is what makes gas well analysis quantitative. Pressure squared approximations work at low pressure and pressure approximations work at high pressure, but neither works across a wide range.

Stabilisation is the practical difficulty in deliverability testing. The backpressure equation describes stabilised flow, which requires the transient to have reached the drainage boundary. In a high permeability well this takes hours. In a tight gas well it can take months, which makes a conventional flow after flow test impossible. Isochronal testing solves this by using equal duration flow periods that need not be stabilised, combined with one extended flow to establish the stabilised curve position. Understanding why the method works is necessary to apply it correctly.

Non-Darcy flow is a gas well phenomenon with real consequences. At the high velocities near a gas wellbore, the relationship between pressure drop and rate becomes non-linear, producing an apparent skin that increases with rate. A single-rate test cannot distinguish this rate dependent skin from mechanical damage, which is why multi-rate testing is required to separate them. Treating a turbulence-dominated well for damage produces no benefit.

Finally, deliverability declines through field life as reservoir pressure falls, and the shape of that decline determines when compression must be installed and when the contracted rate can no longer be met. Forecasting deliverability rather than only production is what allows compression timing, well count and contract commitments to be planned rather than discovered.

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

• Apply real gas pseudo-pressure formulation and select appropriate approximations for the pressure range
• Derive and apply the empirical backpressure deliverability equation and determine its coefficients
• Apply the laminar-inertial-turbulent deliverability equation and interpret its coefficients physically
• Design flow after flow, isochronal and modified isochronal tests appropriate to reservoir permeability
• Analyse deliverability test data and construct stabilised deliverability curves
• Determine absolute open flow potential and interpret it correctly
• Separate mechanical skin from rate dependent non-Darcy skin using multi-rate data
• Assess the effect of condensate banking and water production on gas well deliverability
• Forecast deliverability decline through field life and determine compression timing
• Use deliverability results in well count, contract commitment and development planning

Organisations sending participants to this training will:

• Establish gas well deliverability reliably for contract commitment and field planning
• Design deliverability tests that produce interpretable results in low permeability reservoirs
• Avoid stimulation spend on wells whose skin is turbulence rather than damage
• Improve compression timing decisions and their capital planning
• Improve well count determination for gas developments
• Strengthen the technical basis of gas supply commitments

Participants will:

• Analyse gas deliverability tests independently and correctly
• Design tests appropriate to reservoir permeability and operational constraint
• Distinguish damage from turbulence in gas well performance
• Forecast deliverability decline and its consequences
• Apply pseudo-pressure correctly rather than defaulting to approximations
• Build a specialist skill applied across every gas producing asset

• Reservoir engineers working gas and gas condensate assets
• Production engineers responsible for gas well performance
• Well test engineers and analysts
• Development engineers planning gas field well counts and compression
• Reserves and evaluation engineers assessing gas properties
• Operations engineers managing gas delivery against contract
• Commercial staff requiring technical understanding of deliverability commitments

Upon successful completion of this training course, delegates will be awarded an official Certificate of Completion issued by the Petroleum Engineers Association (PEA), an ISO 9001:2015 certified training organization. The certificate carries 10 Credits and formally records the total learning hours completed.

Each certificate is signed by the Course Facilitator and the CEO of the Petroleum Engineers Association, and serves as verifiable proof of professional training that delegates can present to employers and professional bodies worldwide.