摘要
Abstract
In the southern region of the Ordos Basin,the thin,single-layer distributary channel sands in the Lower Shihezi Formation cause coupling between the sidelobes of the underlying Shanxi-Taiyuan coal seam reflections and the reflections of thin sand bodies within a limited seismic resolution,making it difficult to accurately analyze the reservoir response characteristics.Additionally,challenges in petrophysical analysis arise owing to the poor quality of the logging curves and insufficient shear wave data in this area block,which impede quantitative reservoir prediction.To address these issues,based on the improvement of logging curve quality through multi-parameter fitting this study establishes a three-phase(sand-mud-coal)rock physics modeling workflow by conducting multiple modelings and stepwise integrations in accordance with the theory of the Xu-White rock physics model.This workflow effectively improves the quality of logging curves and enhances the accuracy of shear wave velocity prediction,thereby providing reasonable logging information for subsequent inversions.Furthermore,to address the reservoir prediction problems mentioned above,this study introduces a multidimensional facies-controlled pre-stack geostatistical inversion method suitable for the study area.First,based on the existing geological understanding and well log information,seismic attributes related to channel sands were analyzed,and a two-dimensional lithofacies probability density conforming to sedimentary variation patterns was extracted as a planar constraint for the Shihezi Formation reservoir.Then,using the coal seam inversion volume combined with Bayesian discrimination principles,a three-dimensional coal facies probability density was extracted as a spatial constraint for the underlying coal seam.Finally,both two-and three-dimensional constraints were comprehensively integrated to conduct a pre-stack geostatistical inversion.The prediction results obtained using this method comprehensively considered the coupling characteristics of the underlying coal seams and sandstone reservoirs,effectively reducing the uncertainty in predicting thin reservoirs.This method has shown a good practical application result,with a significant improvement in drilling accuracy.关键词
三相岩石物理建模/含煤地层/多维相控/叠前地质统计学反演/薄砂岩Key words
three-phase rock physics modeling/coal-bearing stratum/multidimensional phase control/pre-stack geostatistical inversion/thin sandstone分类
天文与地球科学
