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Tidal effects
The relative motion of the Earth, Moon and Sun results in some changes in gravitational forces that act on the sea and lithosphere. This creates some tidal changes in water depth and can lead to some changes in hydrostatic head and reservoir pressure for some offshore wells. These tidal effects can be observed with some...
Coning
Coning occurs: when gas moves downwards towards the perforations of an oil well or/and when water moves upwards towards the perforations. Not only this phenomenon can impact the well performance and recovery factor, but it is also one of the "enemies" of pressure transient analysis and it should be avoided at all cost ! Viscous...
Get the most of production shut-ins and pressure build-up tests
How many of the PBUs/PFOs do your team analyse on your production/injection wells? When we ask this question, different answers come up: “how is this useful? Pressure build-up tests are for reservoir characterization with Exploration and Appraisal wells, not for production.” (moving on…) "We don’t analyse operations shut-ins. Sometimes when our reservoir engineer is not...
Constant Pressure Boundary
The constant pressure boundary is sometimes used to match a late-time drop in the derivative data, as shown below. Note that the changes in the derivative are due to the short initial production times and the derivative calculation algorithm (more information is available in the training video called Deconvolution). The three marked PBU tests can be seen in...How much rate history to use in pressure transient analysis
This is a common question and a source of error. The rate data will affect the derivative plot, the selection of the interpretation model and the calculated well and reservoir parameters. Accuracy in the rate measurement The derivative is rate-normalized. As a result, the derivative of the PBU tests should share the same stabilization level,...The Skin Factor
When the reservoir production is established, the flowlines converge towards the well with a radial geometry. This defines the most fundamental flow regime in well testing: radial flow regime. As we have seen in the post Radius of Investigation and the training course Well Test Theory and Practice, the radial flow regime is defined at...

