The carbonate rocks in the southeast margin of the Pre-Caspian Basin have huge hydrocarbon resources, but the diversity of reservoir space types and the complexity of oil-water relationship restrict the hydrocarbon exploration. Therefore, a novel method based on the electric imaging logging with high resolution and coverage is developed to characterize the reservoir space structure and identify fluid types in the near wellbore regions. On the one hand, the maximum connected path algorithm is utilized to realize the automatic identification of fractures, pores and vugs, then respectively mark the connected domains from the sub-images of the extracted fractures, pores and vugs, and calculate the attributes of these connected domain including plane porosity, fracture occurrence, reservoir space structural spectrum, etc. On the other hand, the apparent formation water resistivity spectrum is constructed to indicate fluid types such as oil, water, and oil-water, especially for the low-contrast reservoirs. The reliability of the reservoir space structure characterization and fluid identification method has been verified by comparing with digital cores, thin sections and two-dimensional NMR from two wells. This novel method accurately describes the distribution of reservoir spaces and identifies the fluid types of the carbonate reservoirs in the southeastern margin of the Pre-Caspian Basin.

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