New Advances in Well Test Interpretation

Well Test Interpretation Methodology

• Well testing as a signal analysis problem
• Concept of interpretation model
• Straight-Line and pressure log-log analyses        

Participants will be introduced to the main concepts of well test analysis and to two historic approaches for interpreting well test data.  Specific topics will include the concept of the interpretation model, as well as straight-line and pressure log-log analyses.

Evolution of Well Test Analysis Techniques

• Derivative analysis
• Start of radial flow
• Radius of investigation     

Day two will review of some common beliefs in well test analysis that have been proven to be incorrect yet keep being used and promoted. This day will go back to the original papers helping participants to understand the assumptions under which these methods were developed and why they may no longer be applicable.     

Practical Use of Deconvolution

• Methodology
• Determination of initial pressure
• Rate correction     

The use of deconvolution will be illustrated using examples of short and long duration tests. Examples will include DST’s with erroneous rates, which deconvolution can be used to correct.  Another example will be data from permanent downhole pressure gauges in vertical and horizontal wells, where deconvolution shows compartmentalization and recharge from other layers, which could not be seen in the original data.

Well Test Analysis of Complex Reservoir Systems

• Semi-infinite channel with non-parallel sides
• T-shaped and meandering channels
• Bounded commingled reservoirs     

On day three, complex geometries will be covered in regards to the well test pressure derivative by a non-standard transition between the main radial flow derivative stabilization and the late time boundary behavior. This transition will give access to quantitative information related to the complex geometry that is usually ignored in routine well test interpretation.                 

Well Test Analysis of Complex Fluid Systems

• Gas condensate and volatile oil
• 2-phase pseudo-pressure analysis
• Skin effect – rate relationship     

The last day will cover well test analysis of complex fluid systems.  Well testing in gas-condensate and volatile oil reservoirs with flowing bottomhole pressure below the saturation pressure can be difficult to interpret due to multiphase flow in the reservoir. They can be analyzed using single-phase and two-phase pseudo-pressures, as well as two- or three-region radial-composite interpretation models. Analysis with 2-phase pseudo-pressures is required to correctly estimate the zero-rate wellbore skin effect and the non-Darcy coefficient.