致密砂岩储层流体差异性赋存特征——以鄂尔多斯盆地三叠系延长组为例

为探讨致密砂岩油藏储层流体差异性赋存特征，以鄂尔多斯盆地HQ地区三叠系延长组长6、长8油层组及HS地区长6、长8油层组为研究对象，利用核磁共振技术、高速离心实验，按渗透率区间、地区、目的层层位定量分析储层岩石可动流体含量、不同级别喉道控制的可流动孔隙空间等储层流体差异性赋存特征。不同渗透性级别的储层中，不仅总可动流体饱和度差异较大，而且可动流体赋存的喉道区间也存在较大差异。渗透性好，可动流体由较大喉道控制；渗透性差，可动流体主要由较小喉道控制。在较小喉道半径区间（小于临界喉道半径），随喉道半径增大，可动流体饱和度增加；在较大喉道半径区间（大于临界喉道半径），随喉道半径增加，可动流体饱和度降低。渗透性越好的样品，其临界喉道半径越大。不同地区、不同层位，总可动流体饱和度值由高到低的顺序依次为HQ长8、HS长8、HQ长6、HS长6。

Differential characteristics of fluid occurrence in tight sandstone reservoirs: a case study of Triassic Yanchang Formation in Ordos Basin

In order to explore the differential characteristics of fluid occurrence in tight sandstone reservoirs, the Chang 6 and Chang 8 reservoirs in the Triassic Yanchang Formation in HQ and HS areas of the Ordos Basin were employed as research objects, the movable and non-movable fluid saturation of reservoir rocks were quantitatively analyzed with features including permeability interval, area and target strata by using nuclear magnetic resonance (NMR) test and high-speed centrifugal experiments. Results showed that the total movable fluid saturation, as well as the main throat intervals of movable fluid were different in reservoirs with different permeability levels. For the high permeability, movable fluid was mainly controlled by larger throat, while for the low permeability, movable fluid was mainly controlled by smaller throat. Movable fluid saturation positively correlated to the throat radius in the smaller throat radius range (critical throat radius). The higher the permeability, the larger the critical throat radius.