二连盆地阿南凹陷白垩系腾一下段致密油有效储层物性下限研究

二连盆地阿南凹陷白垩系腾格尔组一段下亚段是该凹陷致密油勘探的主要目的层系，发育沉凝灰岩和砂岩2类有利的致密储层。腾一下段致密储层孔隙度、渗透率变化范围较大，含油非均质性强，受物性条件控制明显。在物性、试油、压汞等分析资料基础上，运用含油产状法、经验统计法、分布函数曲线法、试油法和最小有效孔喉法等多种方法，综合厘定了腾一下段致密油储层物性下限:其中沉凝灰岩类有效储层孔隙度下限为4.0%，渗透率下限为0.008×10-3 μm2；砂岩有效储层孔隙度下限为5.0%，渗透率下限为0.05×10-3 μm2。有效储层下限的确定可为致密油"甜点"储层预测、资源潜力评价和勘探目标优选提供依据。 

Petrophysical property limits of effective tight oil reservoirs in the lower part of the first member of Cretaceous Tengger Formation,A'nan Sag,Erlian Basin,North China

The lower part of the first member of Cretaceous Tengger Formation (K₁t1x) is a main target for tight oil exploration in the A'nan Sag. Two favorable tight reservoir types including tuffites and sandstones have been found. The porosity and permeability of tight reservoirs change greatly. The heterogeneity of oil-bearing strata is strong, which is controlled obviously by porosity and permeability. Based on physical property measurements, well testing, mercury injection data and so on, we determined the petrophysical property cutoffs of effective tight oil re-servoirs in K₁t1x using an oil-bearing occurrence method, experimental statistics, distribution function, well testing and minimum effective pore throat. The cutoff of effective reservoir porosity of tuffites is 4.0%, and that of permeability is 0.008×10-3 μm2. The cutoff of effective reservoir porosity of sandstones is 5.0%, and that of permeability is 0.05×10-3 μm2. The determination of cutoffs of an effective reservoir provides a scientific basis for "sweet spot" reservoir prediction, resource potential evaluation and exploration target selection of tight oil.