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Use of pressure and tracer test data for reservoir description

Thesis/Dissertation ·
OSTI ID:6728249
The first part of this research deals with non-communicating layered systems. Analytical models are used to compute pressure and tracer flow behavior for several hypothetical systems. Drawdown and buildup pressure responses are found to be insensitive to the degree of layering and permeability contrast. Because of balanced flooding conditions, differential depletion and the associated humping on a Horner buildup graph does not occur. Well-to-well tracer test responses are seen to be sensitive to both the degree of layering and permeability contrast. These results suggest that individual layer properties can be calculated by deconvolving tracer test data, while only averaged properties can be obtained from the analysis of conventional pressure test data. The second part deals with single-layer areally heterogeneous systems. Simulation of transient pressure tests shows that the geometric mean of effective permeabilities around the injection and production wells is a good approximation for the steady-state interwell permeability. A dimensionless permeability difference defined in terms of these quantities can be correlated with a heterogeneity index, defined as the product of permeability variance and a dimensionless correlation length scale. Simulation of well-to-well tracer flow indicates that tracer test data can be matched with solutions of the convection-diffusion equation to calculate effective dispersivities only when the heterogeneity index is small. When the heterogeneity index is large, preferential flow paths are generated in the system, which requires a pseudo-layered model to match tracer test data. A reservoir description procedure, based on the heterogeneity index and a combined analysis of pressure and tracer test data, is proposed.
Research Organization:
Stanford Univ., CA (USA)
OSTI ID:
6728249
Country of Publication:
United States
Language:
English