沉积相约束下的碳酸盐岩滩体储层有利区波形差异模拟预测——以川中古隆起北斜坡沧浪铺组为例

Waveform Difference Simulation and Prediction of Favorable Reservoir Zones in Carbonate Shoal Bodies Constrained by Sedimentary Facies—A Case Study of Canglangpu Formation in the Northern Slope of Central Sichuan Paleo-Uplift

摘要: 川中古隆起北斜坡沧浪铺组一段是四川盆地重要天然气战略接替层系，但颗粒滩非均质性强，常规地震反演难以区分薄层滩体与非储层。本文基于研究区3182.32 km²三维地震及9口钻井资料，采用沉积–地球物理联合思路，开展沉积相分析与沉积相约束的地震波形差异模拟反演。结果表明：沧浪铺组受德阳–安岳古裂陷与古隆起双重控制，沧一段发育高能颗粒滩优质储层，与沧二段浅水陆棚细粒沉积构成“下滩上陆棚”有利储盖组合；优选AC、DTC、CNL为储层识别核心敏感曲线，反演方法可精准刻画沿古地貌高部位条带状展布的有效储层。本研究建立了碳酸盐岩滩体定量预测体系，为研究区天然气勘探部署提供了科学支撑。

Abstract: The first member of the Canglangpu Formation on the northern slope of the Central Sichuan Paleo-uplift is an important strategic replacement layer for natural gas exploration in the Sichuan Basin. However, grain shoals exhibit strong heterogeneity, and conventional seismic inversion struggles to distinguish thin-layer shoals from non-reservoirs. Based on 3182.32 km² of 3D seismic data and 9 drilling datasets in the study area, this paper adopts an integrated sedimentological-geophysical approach to conduct sedimentary facies analysis and sedimentary facies-constrained seismic waveform difference simulation inversion. The results show that the Canglangpu Formation is under the dual control of the Deyang-Anyue Paleo-rift and the paleo-uplift. High-quality reservoirs developed in high-energy grain shoals in the first member of the Canglangpu Formation, forming a favorable “lower shoal-upper shelf” reservoir-cap assemblage with the fine-grained deposits of the shallow shelf in the second member of the Canglangpu Formation. AC, DTC and CNL were selected as the core sensitive curves for reservoir identification, and the inversion method can accurately delineate the effective reservoirs distributed in bands along paleogeomorphic highs. This study establishes a quantitative prediction system for carbonate shoals and provides scientific support for natural gas exploration deployment in the study area.