饶阳凹陷页岩油储层应力敏感规律

饶阳凹陷页岩油储量丰富，但页岩容易发生应力敏感，需测试该区块的应力敏感程度，寻找应力敏感规律，为生产制度提供基础数据。室内利用X-射线衍射全岩分析、荧光薄片及电镜扫描等方法，分析了储层矿物的组成、微观结构及连通度共11组，储层应力敏感性流动实验3组，利用数据拟合的方法获得该区块的应力敏感在渗透率损失20%时的规律，净应力与黏土及脆性矿物含量的公式为Pc=-0.09796mc+0.2385mb-7.8145；不可逆渗透率伤害率与黏土及脆性矿物含量公式为Ki=93.24+0.2797mc-0.6809mb的关系；其中，不可逆渗透率伤害率为52.09%，在渗透率损失20%时对应的净应力在3 MPa以内，进一步分析其原因是由于不同黏土含量造成不同的微裂缝的开合程度，但是脆性矿物含量决定不可逆渗透率伤害率及渗透率损失20%时对应的净应力值。结果表明，饶阳凹陷地区的页岩油储层应力敏感与与黏土矿物含量呈负相关，与脆性矿物含量呈正相关。同时通过研究页岩油储层应力敏感性规律的拟合方法，为再解决上述类似储层由于岩样样本数量少，利用有限的岩心柱塞表征整个地层的敏感规律，提供一种新的测试方法。

Patterns of Stress Sensitivity of the Shale Oil Reservoirs in Raoyang Depression

The Raoyang depression is enriched with abundant shale oil. It is well known that shale formations are generally developed with stress sensitivity, therefore the degree of stress sensitivity in this area should be measured and patterns of stress sensitivity be found to provide basic data for field production. Eleven sets of experiments on the mineral composition, microstructure and connectivity of the reservoir formations, and three sets of flow experiments on reservoir stress sensitivity were conducted using XRD whole mineral analyses, fluorescent thin layer analyses and SEM. At permeability loss of 20%, the stress sensitivity patterns of the Raoyang depression was obtained with data fitting. The relationship between net stress, clay content and brittle mineral content is this:-0.09796mc+0.2385mb-7.8145. The relationship between irreversible permeability loss, clay content and brittle mineral content is this:93.24+0.2797mc-0.6809mb. The percent irreversible permeability loss is 52.09% and the net stress corresponding to permeability loss of 20% is within 3 MPa. Further analyses showed that different opening sizes of the micro fractures resulted from different clay contents are responsible for the relationships, the content of brittle minerals decides the irreversible permeability impairment and the net stress corresponding to 20% of permeability loss. The experimental results showed that stress sensitivity in the shale oil reservoirs in Raoyang depression is negatively correlated to the content of clay content, and is positively corelated to the content of brittle minerals. When the amount of reservoir rock samples is not enough to characterize the patterns of the whole formation, the data fitting method described in this study provides a way of using limited core plugs to realize the goal of whole formation characterization.