Braided fluvial sedimentary processes result in heterogeneous reservoirs with double matrix porosity.The heterogeneity and the double matrix porosity nature of these reservoirs are evident from the Lorenz Plot.Such sandstones can produce a variety of well test responses as the two matrices interact at various length scales. The two field examples come from testing in a braided fluvial oil reservoir.Other interpretational possibilities (e.g., sub-seismic faulting, fluid changes), which might also be considered given the non-uniqueness of pressure data, are eliminated by careful consideration of the geophysical interpretation, the depositional environment and the fluid properies.Sub-seismic faults are often interpreted in well tests from braided fluvial reservoirs.However, we consider that the response in these cases, and possibly in a wider range of cases, is due to geological effects of sedimentary heterogeneity due to secondary channels within the braided system. Abstract A new well test response has been identified.A distinctive restriction - shown as a hump on the derivative curve - is seen in double matrix porosity (dual permeability) reservoirs.High permeability lenses intersecting the well bore give rise to a negative geoskin response at early time.After the middle time period of flow restriction caused by the limits of the lenses connecting to the wellbore and the presence of additional limited extent, discontinuous, high permeability lenses within the reservoir.This phenomenon has been shown in a series of numerical models and is also observed in two field well tests.
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