Identifying oil layers with high gas-oil ratios in the Weizhou Oilfield is difficult because of the similar neutron excavation effect characteristics in oil layers with different gas-oil ratios. To address this problem, the logging response characteristics, formation mechanism, and influencing factors of the resistivity response in the invasion zone of oil layers with different gas-oil ratios were studied by synthetically using log interpretation, oil layer test analysis, rock electricity experiments, and numerical simulations. The results indicate the following: \mathrm{①} high gas-oil ratio oil layers have neutron excavation logging response characteristics that are close to those of medium gas-oil ratio layers. The neutron excavation effect method, which is a “narrow-spectrum” identification method, can only effectively distinguish gas-oil ratios when they are low and have close formation pressure. \mathrm{②} The oil-gas fluid compressibility is sensitive to the change in the gas-oil ratio; the higher the gas-oil ratio, the greater is the oil-gas fluid compressibility. A nearly linear relationship exists between the gas-oil ratio and the oil-gas fluid compressibility, which could serve as a new “broad-spectrum” identification method to identify the gas-oil ratio by compressibility of the oil-gas fluid. \mathrm{③} By calculating the mutual information matrix between the reconstructed array induction resistivity logging curves, information about the gas-oil ratio implicitly contained in the logging data of array induction resistivity can be highlighted. The value of mutual information in the matrix approximately reflects the information regarding the gas-oil ratio. The gas-oil ratio identification method based on a mutual information matrix can overcome the limitations of the neutron excavation effect method, and the “broad-spectrum” identification of different oil-gas ratios of the oil layer can be realized by using oil-gas fluid compressibility. This method has achieved good results in the application in the Weizhou Oilfield in the Beibu Gulf Basin of the South China Sea and provides a new idea for the quantitative identification of the gas-oil ratio of oil reservoirs in similar oilfields.