Well Testing Analysis in HeterogeneousReservoir Using Semi-Analytical Model

摘要

This paper presents a general methodology to deal with thewell testing analysis in heterogeneous reservoir using semi-analytical model. Traditionally, homogeneous reservoir isassumed to facilitate the analysis process and only averagedreservoir properties have been diagnosed for the formation. This has been basically a significant oversimplification withtwofold aftermaths, one has eased the data interpretation andanother has hindered the technology development. Thisoversimplification may be partially responsible for the inabilityto differentiate the effects of various factors behind similar wellresponses, and valuable information contained in pressure datamay also be ignored, for example, the connectivity amongreservoir bodies. The main objective of this research is to develop a full-scalesemi-analytical model to compute the pressure responses in such a way that it possesses the capacity to integrate formationheterogeneity, so that it can be used as a means of detailedreservoir characterization. Currently, the hexahedron andoctahedron grid blocks have been implemented to built thediscrete reservoir models, and flexible grid block cannot behandled easily using this method. The semi-analytical approach proposed consists ofdecomposing the reservoir into a number of grid blocks, similarto what we have done usually in reservoir simulation. Analytical solutions are written down for each grid block ateach facet in terms of the unknown pressures and fluxes at theirboundaries. Then, the reservoir system is integrated by transferof fluid from the surrounding grid blocks and equality ofpressure over the hydraulic contacted facets for each gridblock. The coupled systems are finally solved for the desiredwellbore responses. The model has been verified by comparing