浅层河流相天然气藏预测技术

本文针对浅层亮点及非亮点天然气藏,从形成机理出发,进行了岩石物理分析、频谱衰减、叠前AVO技术及叠前敏感参数反演等预测技术研究。结果表明:1对于浅层储层与围岩波阻抗差异较大的亮点气藏,单纯应用亮点技术识别具有多解性,需要结合分频技术、吸收衰减及叠前AVO等技术剔除水层、火成岩等造成的假亮点,可提高亮点气藏的识别精度。2非亮点气藏储层孔隙度较低,与围岩为互层结构时,受常规地震资料分辨率的限制及调谐干涉的影响,在叠后地震资料上难以分辨;通过岩石物理分析优选出流体体积压缩系数等敏感参数,应用叠前弹性参数反演技术进行识别具有较好的效果。

Gas reservoir prediction in shallow-fluvial facies

On the basis of rock physics analysis, we use spectral attenuation, prestack AVO attributes, and prestack sensitive parameter inversion to detect natural gas reservoirs of bright spot and non-bright spot. The following observations are obtained:A. The combination of frequency separation, AVO attributes, and spectral attenuation can identify false bright spots caused by water and igneous rock, and effectively predict natural gas reservoirs of bright spot, which have obvious difference in wave impedance with surrounding rocks; B. It is very difficult to identify gas reservoirs of non-bright spot with low porosity and inter-bedded surrounding rock on post-stack seismic data with low resolution and tuning interferences. Fluid compressibility and other sensitive parameters are optimized with rock physics analysis, and then this kind of gas reservoirs can be predicted by prestack elastic parameter inversion.