The main objective in this study is to experimentally investigate how two types of shales different in swelling characteristic and organic carbon content behave in terms of the mechanical and infiltration properties when being subjected to changing osmosis with varying brine salinity under in-situ stress conditions. This research also aims to determine the swelling tendency of thePierre shale and replicate the effect of selection of brine salinity on oil recovery in liquid-rich shales. A series of coupled measurements from the triaxial experiments at reservoir conditions was conducted on Pierre shale core samples to determine rock properties and behavior under fluid pore pressure intrusion. The main use of the measured properties is to demonstrate the impact of fluid transport induced by low salinity water injection accompanied by osmosis, clay swelling, and rock elasticity change on oil recovery from rock matrix. The Young's modulus, bulk modulus, and Poisson's ratio of the Pierre shale were determined from measurements on the two types of Pierre shale samples obtained from an outcrop having high 65 wt% of smectite content and well core having lean clay content and 3.5 wt% TOC (total organic carbon). The first two experiments were performed on the outcrop samples comprising of similar characteristics of 65 wt% smectite with negligible TOC while the last experiment was performed on the well core sample containing negligible smectite content with 3.5 wt% TOC.

The membrane efficiencies of the shale samples were experimentally determined to range from 5% to 28% depending on clay content and stress. The outcrop shale showed 1% of swelling that is significantly higher than 0.07% of swelling developed in the well core shale lean in clay content. One of the most important findings of this research is that the membrane coefficient representing the stress sensitivity of membrane efficiency of organic-rich well core shale was found to be 11.5%/kpsi which is significantly higher than that of the swelling shale ranging from 2.2 to 3.5%/kpsi. This is interesting because the approximately 5.5 times stiffer matrix of organic-rich shale shows the significantly higher stress sensitivity in terms of the membrane efficiency. The Young's modulus of swelling shale declined with water saturation as well as the water transfer driven by osmotic pressure with low salinity brine. In contrast, the well core shale showed significant increase in the dynamic Young's modulus.

The experimental data were used to evaluate the mass exchange between the fractures and rock matrix using a coupled fluid flow and geomechanics model accounting for shale swelling and osmosis transport to evaluate how fluid and rock interaction affect the oil recovery from the rock matrix of the Pierre shale during low salinity water injection (LSWI). A 25% increase in oil recovery factor was determined after considering the effects of changing membrane efficiency due to clay swelling resulting from LSWI. The modeling results therefore suggest that the variation of membrane efficiency due to swelling can be an important factor affecting the oil recovery from matrix block during LSWI enhanced oil recovery.

本研究的主要目的是通过实验研究两种类型的膨胀特性和有机碳含量不同的页岩在原位应力条件下经受不同盐水盐度的渗透本研究还旨在确定皮埃尔页岩的膨胀趋势，并复制盐水盐度选择对富液页岩采收率的影响。对 Pierre 页岩岩心样品进行了储层条件下三轴实验的一系列耦合测量，以确定流体孔隙压力入侵。测量特性的主要用途是证明低盐度注水引起的流体输送伴随渗透、粘土膨胀和岩石弹性变化对岩石基质采油的影响。杨氏模量、体积模量和泊松比Pierre 页岩的含量是通过对两种类型的 Pierre 页岩样品的测量来确定的，这些样品来自具有高 65 wt% 蒙脱石含量的露头和具有贫粘土含量和 3.5 wt% TOC（总有机碳）的井芯。前两个实验是在露头样品上进行的，该露头样品含有 65 wt% 的绿土，TOC 可忽略不计，而最后一个实验是在含有可忽略不计的绿土含量且 TOC 为 3.5 wt% 的井芯样品上进行的。

根据粘土含量和应力，通过实验确定页岩样品的膜效率在 5% 到 28% 之间。露头页岩显示出 1% 的膨胀，这明显高于在粘土含量贫乏的井芯页岩中发育的 0.07% 的膨胀。本研究最重要的发现之一是，代表富有机质井芯页岩膜效率的应力敏感性的膜系数为 11.5%/kpsi，显着高于膨胀页岩的 2.2 至3.5%/千磅/平方英寸。这很有趣，因为大约 5.5 倍硬度的富含有机质页岩基质在膜效率方面显示出显着更高的应力敏感性。年轻人' 膨胀页岩的 s 模量随着含水饱和度以及低盐度盐水渗透压驱动的水转移而下降。相比之下，井芯页岩的动态杨氏模量显着增加。

实验数据用于评估裂缝和岩石基质之间的质量交换，使用耦合流体流动和地质力学模型，考虑页岩膨胀和渗透输送，以评估流体和岩石相互作用如何影响 Pierre 页岩岩石基质的石油采收率在低盐度注水（LSWI）期间。考虑到由于 LSWI 导致的粘土膨胀而改变膜效率的影响后，确定石油采收率增加了 25%。因此，建模结果表明，膨胀引起的膜效率变化可能是影响LSWI 提高采收率过程中基质块