疏水纳米颗粒在油层微孔道中的吸附机制

Adsorption of hydrophobic nanoparticles in reservoir microchannels

基于对疏水纳米颗粒在储集层微孔道系统中的受力分析,建立了作用对象间的微观作用能数学模型,计算了疏水纳米颗粒和水分子所受的微观作用能量级,进而阐述了两者的竞争吸附机制。计算结果表明,疏水纳米颗粒受到的综合作用为指向孔壁的引力作用,总作用能量级约10-18～10-17J,是水分子与孔壁的作用能量级的103倍左右,在竞争吸附中占绝对优势,这使得疏水纳米颗粒可以突破孔壁表面的水化层并与孔壁产生牢固吸附。通过扫描电子显微镜和能谱仪检测了疏水纳米颗粒在岩心孔壁的吸附状况。结果显示,经纳米液处理过的岩样表面具有大量纳米颗粒组成的微结构,说明纳米颗粒确实突破了水化层并在岩心孔壁形成了吸附层。

Based on the analysis of the forces acting on a hydrophobic nanoparticle（HNP） in a reservoir microchannel,a model of the interacting energy was presented.The competition adsorption mechanism between HNPs and water molecules was investigated by the comparison of interacting energies on a HNP and on a water molecule from microchannel wall.The calculated results show that the combined force for the HNP is an attractive force toward the microchannel wall and the acting energy on the HNP from the wall is on the order of 10-18-10-17J,which is about 103 times that on the water molecule.Thus the HNP can penetrate hydrated layer and can be absorbed on the microchannel wall.To validate the model,an experiment was conducted using scanning electron microscope（SEM） and Energy Disperse Spectroscopy（EDS） to investigate the adsorption of HNPs on the surface of the core which was treated with HNPs fluid.The results show that micro-and nano-structures of HNPs layer can be observed clearly on the core surface,which confirms that HNPs have broken through the hydrated layer and have formed an adsorption layer on the core surface.