Abstract
Before the early eighties, identification of flow regime has been a difficult task for reservoir engineer and welltest analyst until the emergence of the derivative approach. This approach has helped to reduce the uncertainties of the interpretation of welltest result because key regions of radial flow and boundary features required for reservoir characterization, description and evaluation have been adequately diagnose. However the approach is complex for non-mathematician and an alternative method for improving its interpretation and reducing the difficulty of its practical application haven't been discovered most especially where there is inconsistency in data sampling.
The statistical approach(VEMST) utilized simple statistical tools such as StatDiff, StatDev and StatExp derived from time series analysis to identify possible unseen features, diagnose key flow regime for reservoir description and act as checkmate/alternative to the derivative approach to interpret complex features.
Result from channel sand, low and high permeability reservoir, infinite conductivity fractures, dual porosity and/or permeability reservoir show same trend as the derivative approach and also diagnose unseen features such as dual permeability, geologically interpreted as layered reservoir system and also double porosity model with high degree of accuracy.
