Pressure gradients are what make formation testing valuable beyond individual measurements. A series of pressures over an interval defines a line whose slope is fluid density, which identifies gas, oil or water directly, and whose intersections locate fluid contacts more precisely than logs can in many cases. Where two zones plot on different gradients that do not intersect at a physically sensible contact, they are not in pressure communication, and that observation is the strongest evidence of compartmentalisation available from a single well.

Data quality determines whether any of this holds. Supercharging, where mud filtrate invasion has raised the near-wellbore pressure above true formation pressure, biases measurements in low permeability intervals and produces gradients that suggest compartments that do not exist. Seal failures, tight tests and unstabilised pretests produce points that must be excluded rather than fitted. Recognising each of these from the pretest pressure trace is a specific skill, and gradients built without that screening have led to incorrect development decisions.

Sampling is where contamination governs everything. A sample drawn too early contains mud filtrate, and a sample contaminated beyond a few percent gives PVT properties that describe a mixture rather than the reservoir fluid. Downhole fluid analysis has made cleanup monitoring possible in real time, and understanding the contamination trend and when it has flattened is what determines whether a sample is worth capturing. Samples taken on time rather than on cleanup have produced PVT reports used for years to characterise fluids that were never in the reservoir.

Finally, the tools have advanced considerably and the interpretation opportunities with them. Interval pressure transient testing using dual packers gives permeability over a larger volume than a probe pretest. Vertical interference testing between an active and an observation probe measures vertical permeability directly, which is otherwise among the hardest parameters to obtain. Downhole fluid analysis provides composition and gas-oil ratio without capturing a sample. Knowing what a modern tool can deliver is necessary to specify a programme that acquires it.

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

• Select formation tester configurations and probe types appropriate to formation quality and objectives
• Quality control pretest pressure data and identify supercharging, seal failure and tight tests
• Construct and interpret pressure gradients to determine fluid density and fluid type
• Locate fluid contacts from gradient intersections and assess their uncertainty
• Identify compartmentalisation and pressure communication from multi-zone pressure data
• Estimate mobility from drawdown and buildup pretest data and state its accuracy limits
• Design fluid sampling programmes and monitor contamination using downhole fluid analysis
• Assess sample quality and determine whether a sample is representative
• Design and interpret interval pressure transient and vertical interference tests
• Integrate formation test results into reservoir description, appraisal decisions and development planning

The training works through formation test data as it is delivered in practice, with participants quality controlling raw pretest traces, screening points, constructing gradients and drawing conclusions about fluid type, contacts and communication. Data sets containing supercharged points, failed seals and ambiguous gradients are used deliberately. Sampling content is developed through contamination monitoring data from real jobs, with participants judging when a sample became representative. Interval pressure transient and vertical interference test interpretations are worked through numerically, and formation test results are compared against subsequent well test and production evidence.

Organisations sending participants to this training will:

• Improve appraisal decisions through better use of pressure and fluid data acquired at the well
• Identify compartmentalisation earlier, before development concepts are fixed
• Improve PVT data quality by obtaining representative fluid samples
• Reduce wasted rig time on testing programmes that do not deliver interpretable data
• Strengthen contact definition and its effect on in-place volume estimates
• Improve technical review of service company acquisition and interpretation

Participants will:

• Quality control formation test data and reject points that should not be used
• Build and defend pressure gradient interpretations
• Recognise compartmentalisation evidence and communicate it
• Specify sampling programmes that deliver representative fluid
• Design formation testing programmes against defined objectives
• Build a specialist skill that spans reservoir engineering and petrophysics

• Reservoir engineers working on appraisal and development
• Petrophysicists and formation evaluation specialists
• Geoscientists working on contacts, connectivity and compartmentalisation
• Operations and well engineers planning logging and testing programmes
• Production engineers using formation pressure data
• Service company technical staff supporting formation testing
• Graduate engineers and geoscientists entering subsurface roles

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.