致密油微观充注动态过程及控制因素

致密储层微观结构影响着原油在储层中的充注行为，制约着致密油的富集和分布规律。基于致密油充注模拟、恒速压汞、扫描电镜与核磁共振等实验，文章定量表征致密储层的原油充注行为和孔喉结构特征，剖析成岩作用、自生矿物生长形态以及孔喉结构特征对原油在致密储层中充注行为的影响。研究表明，原油充注过程可分为3个阶段：充注启始阶段、快速充注阶段和缓慢充注阶段，这是充注过程中驱替压力与毛管力的动平衡以及主要储集空间分布的结果。其中，快速充注阶段又存在两种增长模式，即持续增长模式和跳跃增长模式，这两种模式揭示了主流喉道半径分布特征的差异。通过分析发现，压实、胶结、溶蚀、自生矿物生长等成岩作用极大程度上影响着储集空间和喉道半径的尺寸和分布，决定了致密储层品质的优劣。故此，在油源充足的条件下，具备足够的驱动力和品质优良的储层，是致密油富集的关键，而开启的断层/微裂隙附近的砂体正是满足这些条件的有利区带。

Microscope dynamic process and controlling factors of oil charging in tight reservoir

The microstructure of tight reservoir affects the charging efficiency of crude oil,and restricts the abundance and distribution of tight oil.Based on experiments including the physical simulation of tight oil charging,stable rate mercury injection,Scanning Electron Microscopy (SEM) and nuclear magnetic resonance (NMR),the charging process of crude oil and structural characteristics of pore throats of the tight reservoir were quantitatively characterized,and the effects of diagenesis,authigenic mineral growth patterns and pore throat structural features on oil charging in tight reservoirs were discussed.The results show that the oil charging process can be divided into three stages:initial stage,rapid-increase stage and slow-increase stage.This is a result of the dynamic balance between displacement pressure and capillary pressure during the charging process and the distribution of main reservoir space.In detail,there are two increasing modes in the rapid-increase stage,namely,the sustained rapid-increase and rapid-increase by pulses.The two modes reveal the differences in the distribution characteristics of mainstream throat radii in these samples.It is found that diagenesis,including compaction,cementation,dissolution,and authigenic mineral growth,has greatly affected the size and distribution of reservoir space and throat radius,and determined the quality of tight reservoir.Therefore,under the condition of abundant oil source,the key to tight oil enrichment lies in the sufficient driving force and high-quality reservoir,and thus the sand bodies near the open faults/micro-fractures are concluded to be the favorable zones for hydrocarbon exploration.