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The dolomite reservoir of the Middle Permian Qixia Formation in the Shuangyushi structure in northwestern Sichuan Basin is deeply buried, thin, and highly heterogeneous. With low-resolution seismic data, it is not easy to identify the reservoir signal and it is difficult to accurately describe the plane distribution of thin reservoirs. Based on high-resolution processing of seismic data, well-seismic combination technology, forward simulation technology, and cross-well profiles, in this study, we defined the waveform characteristics that correspond to different modes of reservoir development, summarized the seismic response modes of reservoirs in the area, optimized sensitive attributes, and finely depicted their plane distribution. The ability of seismic data to identify thin reservoirs was significantly improved after high-resolution processing. According to a comprehensive analysis, the reservoirs of the Qixia Formation in the study area had two response modes: "weak peak" and "complex wave." The waveform clustering attribute was optimized to describe the plane distribution characteristics of the Qixia Formation reservoirs in the study area. Type-I and type-II waveforms were favorable waveforms for reservoir development, and they mainly were distributed in the west of the Devonian denudation line, in a strip along the north–south direction, and mostly along faults. The predictions made with this method agreed well with the actual reservoir development, which provided a reference for the prediction of deep and thin reservoirs in this area. [ABSTRACT FROM AUTHOR]

In view of the unclear understanding of the development and distribution characteristics of the intra-platform shoal of the Changxing formation in the southern Sichuan Basin, analysis and summary of the petrological characteristics and sedimentary cycle characteristics of the intra-platform shoal in the Changxing formation in the Gaoshiti area were conducted. In this study, the idea of seismic sedimentology is adopted, the top geomorphology and the root mean square (RMS) amplitude attributes of the Changxing formation were used as constraints, combined with the granular rock thickness/stratum thickness (G/S) of wells to depict the planar distribution characteristics of the intra-platform shoal in the study area. Through the research and analysis, it is concluded that the Changxing formation in the Gaoshiti area has a geomorphological pattern of ‘three uplifts and two depressions’ at the end of the deposition. The geomorphological differentiation characteristics are highly consistent with the variation law of the RMS amplitude in the plane, and there is a good correlation between the two and the G/S of the strata. Thus, three belts of intra-platform shoals with NW–SE distribution are identified in the study area. [ABSTRACT FROM AUTHOR]