Method and device for determining gamma ray intensity critical value for dividing lithology types

The invention discloses a method and a device for determining a gamma ray intensity critical value for dividing lithology types, and belongs to the technical field of petroleum geological exploration.The method comprises the following steps: obtaining a natural gamma logging curve of each oil and gas well in a target area and a relation curve of the shale content value and the depth, determininga relationship between the gamma ray intensity value and the shale content value of each oil and gas well; and obtaining a detection shale content value of the target area, determining a target gammaray intensity value of a target oil and gas well in the target area under the detection shale content value, and taking the target gamma ray intensity value as a gamma ray intensity critical value ofthe divided lithology type of the target area. According to the method, the gamma ray intensity critical value for dividing the lithology types is determined, the detection argillaceous content valuefactor of the target area is