Study On The Gas Bearing Prediction Of Deep Carbonate Reservoirs In Central Sichuan Basin

Carbonate oil and gas exploration and development is an important component of oil and gas exploration and development in the world.The carbonate reservoirs in China have some features,such as deep burial and old geological age,and the gas-bearing reservoirs of the Sinian Dengying Formation in the central Sichuan region belong to such reservoirs,which have deep burial characteristics and strong heterogeneity,it has become a complex exploration problem,and it has more difficulties and challenges for the exploration and development and qualitative evaluation of such gas-bearing reservoirs.Based on this,this article mainly uses seismic post-stack inversion technology,PCA-RGB multi-attribute fusion technology and multi-scale PCA-RGB fusion technology for reservoir prediction of Dengying Formation reservoir.The main research contents and achievements of the paper are as follows:1.Three different post-stack inversion techniques for band inversion,model-based inversion,and sparse pulse inversion were used to invert the target interval in the region.By comparing the practical effects of the three different methods,the model-based inversion method is more effective and consistent with the logging results,providing a certain basis for exploration and development in the region.2.Through GST-based coherent attribute calculation method,a structural tensor matrix is constructed for the Dengying Formation reservoir seismic data and smoothed to obtain the eigenvalues,and then the coherent attributes are calculated according to the eigenvalues.The obtained coherent attributes can effectively identify faults and fracture-cavities structure;the results show that there are faults and caves in the Dengying Formation reservoir.3.The target layer structure is identified by using PCA-RGB multi-attribute fusion technology,and a certain basis is provided for the gas detection of the reservoir.This method extracts the main components of various seismic attributes and compares them to optimize the favorable attributes for RGB fusion,compared to a single seismic attribute,this method can use a variety of seismic attributes to improve the accuracy of the interpretation;The results show that the fault and discontinuity of Dengying Formation reservoir can be displayed by this method,and the gas-bearing nature of the reservoir can be consistent with the logging results.4.The reservior prediction of the target strata is performed by multi-scale PCARGB fusion technology,this method firstly uses the generalized S-transform to perform time-frequency analysis of seismic signals.Then,principal component analysis is used to extract the main components of each frequency,forming three bands of high,medium and low frequencies.Finally,the three bands are RGB-fused;the results show that the method can effectively identify the oil and gas layer of Dengying Formation reservoir and also realize the rapid interpretation of spectral decomposition data.