A method for identifying pore types in calcareous sandstone reservoirs

Abstract

The present invention provides a method for identifying the pore type of calcareous sandstone reservoirs. By identifying the lithology of calcareous sandstone and selecting the dry layer of calcareous sandstone, the acoustic porosity curve and density porosity curve are obtained, and the porosity is compared. The positive curve corrects the density porosity curve and the acoustic porosity curve, and uses the difference between the density porosity and the acoustic porosity to identify the pore types that meet the proportion conditions in the calcareous sandstone reservoir, and the calcareous shale lithology The corresponding relationship between the recognition standard and the degree of difference and the type of pores that meet the proportion conditions is summarized through experiments. This method does not need to collect samples after the lithology identification standard and corresponding relationship are established, and it has good adaptability to calcareous sandstone reservoirs with strong heterogeneity, and overcomes the lack of data on cores and thin sections of cuttings in previous wells. Due to the large number of wells and the large amount of cuttings selected, it is difficult to identify or classify the pore types of calcareous sandstone in the whole well section, which broadens the scope of identification and is easy to grasp.

Description

technical field [0001] The invention belongs to the field of oil and gas exploration and development, in particular to a method for identifying pore types of calcareous sandstone reservoirs. Background technique [0002] Reservoir pore type is one of the key contents of understanding and evaluating reservoir, and pore type can reflect the formation mechanism of reservoir to a certain extent; different pore types have different pore structures, which can eventually lead to development effects controlled by permeability There are huge differences. At present, it is common to use drilling core samples to grind cast thin sections and observe them under a microscope, or directly use core samples to observe under a scanning electron microscope to determine the pore type of a certain target reservoir and describe its distribution characteristics. The method is suitable for relatively homogeneous reservoirs, but it is not suitable for calcareous sandstone reservoirs with strong res...

AI Technical Summary

Problems solved by technology

[0006] In order to solve the problem of determining the pore type of calcareous sandstone reservoirs in the above-mentioned prior art, due to the limitation of drilling and coring costs, the number of corings is small, and due to the strong heterogeneity, there is an error between the actual coring and the designed coring. The representativeness of coring is poor, and the samples taken cannot truly and comprehensively reflect the reservoir pore types of the entire well section; the number of wells is large, and the workload of cuttings selection is too large, which makes the distribution characteristics of reservoir pore types in the vertical and horizontal directions difficult to be accurate Description; and the existing method of utilizing conventional logging curves to judge the pore type is difficult to apply to the technical problem of the calcareous sandstone reservoir. The present invention provides a method for identifying the pore type of the calcareous sandstone reservoir. The specific scheme is as follows:

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