特低渗透砂岩储层可动流体赋存特征及影响因素

Characteristics and influencing factors of movable fluid in ultra-low permeability sandstone reservoir

利用核磁共振技术,对鄂尔多斯盆地延长组特低渗透砂岩储层样品进行了测试;对可动流体孔隙度参数进行了定义,分析了可动流体的赋存特征及影响因素。研究结果表明,特低渗透砂岩储层核磁共振T2谱截止值低,可动流体含量低。可动流体参数分布范围宽且具有较强的非均质性,渗透率越高,可动流体参数与渗透率的相关性越强;渗透率越低,可动流体参数衰减速度越快。特低渗透砂岩储层微裂缝发育程度、黏土矿物充填孔隙程度、次生孔隙发育程度及重结晶等微观孔隙结构特征是可动流体的主要影响因素。

The sandstone samples of the ultra-low permeability reservoir in Yanchang Formation of Ordos Basin were tested with the nuclear magnetic resonance technique. The porosity parameter was defined to analyze the characteristics and the influencing factors of movable fluid. The existing characteristics of movable fluid include the following aspects： The amplitude of T2 spectrum is relatively low, and the content of movable fluid is also low. The parameters of movable fluid is expanse and the heterogeneity is intense. The relation between the movable fluid parameter and the permeability gets better with the increase of permeability. The movable fluid parameter gets higher attenuation velocity with decrease of permeability and has more sensitivity to the changes of permeability. The micro-pore structure determines the existing state of fluid. The main influencing factors of the movable fluid include micro-fracture, filling degree of clay mineral in pores, secondary porosity and recrystallization.