Methods of Reservoir Modeling on Braided River Sandstones
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摘要: 辫状河储层在我国陆相盆地中广泛分布,而对这类储层的认识却较差。辫状河砂体的非均质性严重,这是影响开发效果的重要原因。本文以张家口地区的露头砂体为例,在密集取样的基础上建立了砂体的地质模型,分析了砂体的非均质性特征,探讨了辫状河储层的建模方法。根据孔隙度和渗透率的变差函数分别建立了孔隙度和渗透率的克里金模型和条件模拟模型;利用频谱分析法和变尺度分析法对渗透率进行了赫斯特指数的求取,得到该砂体的赫斯特指数的平均值在0.8左右,同时利用分形几何的插值理论建立了渗透率的分形几何模型。对各种模型进行的比较显示克里金模型较好地表现了物性参数的整体趋势;条件模拟模型较好地再现了储层非均质性;而分形几何模型既反映了储层宏观物性分布,又反映了其内部非均质性变化。整体上看,分形几何模型是一种相对比较好的模型,可应用于油田开发早期。Abstract: Braided river sandstones are widely distributed in Chinese continental ba sins;however,development for these reservoirs is not very satisfactory.The most important reason is the heavy heterogeneity of braided sandstones.This paper tak es the outcrop in the Zhangjiakou region,Hebei province as an example,which was densely sampled.Geological models are established based on the heterogeneity ana lysis of the sandstone,and then methods of modeling are probed.Kriging models a nd conditional simulation models are built based on porosity and permeability va riogram.Hurst indexes are calculated based on spectral analysis and rescale rang e analysis,which vary at the level of 0.8.One fractional permeability model is b uilt based on fractional geometry interpolation principles.The results suggest t hat Kriging models could reflect the macroscopic change of reservoir physical pr operties,conditional simulation models could reveal the reservoir heterogeneity, and the fractional model could reveal both the macroscopic physical properties a nd microscopic heterogeneity.Comparison of these models show that the fractional model is relatively the most effective model,which could be used in reservoir i n early development of oil fields.
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Key words:
- braided /
- river /
- sandstones /
- heterogeneity /
- Kriging
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