Research on Logging Classification and Evaluation Method for Tight Gas Reservoirs in Yichuan Block, Ordos Basin

The tight gas reservoirs in the Yichuan block of the Ordos Basin have practical problems such as multiple gas bearing layers, poor reservoir properties, complex micro pore structures, strong heterogeneity, and complex gas-water relationships. It is urgent to study reservoir classification and evaluation methods to provide reliable technical support for the production and development of tight gas reservoirs. Firstly, guided by the weighted normalization method, an evaluation method was constructed based on reservoir property response parameters and reservoir quality response parameters. Then, weight coefficients were assigned to the two evaluation parameters to establish a logging classification and evaluation method for tight gas reservoirs in Yichuan Block based on logging data. At the same time, based on the evaluation method, dynamic gas testing data and core analysis data in Yichuan Block, a logging classification and evaluation standard for tight gas reservoirs in Yichuan Block was proposed. The example well analysis and reservoir type classification plan results show that Class I and Class II are relatively high-quality tight gas reservoirs, accounting for over 40%, indicating a high development potential. The reservoir types in the western and southern parts of the block are significantly better than those in the central and eastern parts, and there is a good correlation between reservoir types and reservoir thickness and gas content. The core of this evaluation method lies in constructing and calculating physical and quality response parameters that can fully reflect the characteristics of reservoir types, which has profound guiding significance for accurately evaluating the tight gas reservoir types in the Yichuan block of the Ordos Basin.