Transient flow lasts a very long time in tight gas, and that governs almost everything else. At permeabilities in the microdarcy range, the pressure transient may not reach the drainage boundary for years, which means the well produces in linear or transitional flow throughout the period during which reserves are booked and development decisions are made. Conventional decline analysis assumes boundary dominated flow and produces the wrong answer during transient flow, generally too optimistic, and the resulting reserves revisions have been substantial across the industry.

Well spacing cannot be determined by drainage area in the conventional sense. In a reservoir with adequate permeability, wells drain a definable region and spacing follows from it. In tight gas, the volume contacted depends on the fracture created and on the very slow pressure propagation into the matrix, so wells placed closer together may each recover nearly as much as they would in isolation for many years before interference appears. Determining optimal spacing requires either pilot testing at multiple densities or careful transient analysis, and getting it wrong is expensive in either direction.

Stress-dependent permeability adds a further complication. Permeability in tight rock is more sensitive to effective stress than in conventional rock, so as reservoir pressure declines and effective stress rises, permeability falls. This accelerates production decline beyond what a constant permeability model would predict, and it affects both forecasting and the estimation of permeability from early production data.

Finally, tight gas economics are driven by well cost and by the tail. Each well requires drilling and stimulation at a cost comparable to a conventional well while recovering less, so the number of wells required per unit of reserves is high. Wells produce at low rates for long periods, which means a substantial fraction of recovery comes in the discounted tail and the economic limit is reached while significant gas remains. Small changes in well cost, stimulation cost or gas price move a large number of locations across the economic threshold.

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

• Characterise low permeability rock properties and account for measurement difficulty at microdarcy permeability
• Evaluate tight gas formations petrophysically and quantify the uncertainty in gas in place
• Assess stress-dependent permeability and its effect on well performance through depletion
• Specify hydraulic fracture geometry requirements from a reservoir engineering basis
• Identify and analyse long duration transient flow in tight gas wells
• Apply rate transient analysis appropriate to transient-dominated production
• Recognise where conventional decline analysis produces erroneous results and apply appropriate alternatives
• Estimate reserves for tight gas wells with appropriate evidence and constraints
• Determine well spacing using pilot testing and transient analysis rather than drainage area assumptions
• Evaluate tight gas development economics and their sensitivity to cost and price

Organisations sending participants to this training will:

• Improve reserves reliability for tight gas assets and reduce revision frequency
• Improve well spacing decisions and the capital efficiency of development programmes
• Improve stimulation specification through better reservoir engineering input
• Improve production forecasting for transient-dominated wells
• Assess tight gas acquisition and development opportunities more accurately
• Reduce development spend on locations that economics do not support

Participants will:

• Recognise where conventional reservoir engineering methods fail in tight rock
• Analyse transient-dominated production data correctly
• Estimate tight gas reserves with defensible evidence
• Contribute to spacing and development design decisions
• Understand the economics that govern tight gas viability
• Build a capability applicable to tight gas and to unconventional resources generally

• Reservoir engineers working tight gas assets
• Production engineers analysing tight gas well performance
• Development engineers planning tight gas programmes
• Reserves and evaluation engineers
• Completion engineers working on tight gas stimulation
• Petrophysicists evaluating low permeability formations
• Technical and commercial staff evaluating tight gas opportunities

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.