致密储层微纳喉道微尺度效应流动模拟

Flow simulation of micro-scale effect in micro-nano throat of tight reservoir

利用耗散粒子动力学（dissipative particle dynamics,DPD）方法进行了微圆管的流动计算,通过模拟致密储层纳米喉道中流体与岩石的相互作用,实现了1~10nm纳米喉道中微尺度流动模拟,从介观尺度初步揭示了微纳米喉道中边界层产生的机理;在离散介质力学方法基础上,利用统计方法得到了1~10nm不同喉道半径的流动剖面,表征了微纳米喉道中流体的边界层特征,为利用连续介质力学表征非线性渗流奠定了基础。结果表明：由于壁面分子的吸引,近壁处水的密度较高;半径1nm喉道中,分子热运动对流动影响很大,速度剖面不明显,随着半径变大,速度剖面的抛物线特征逐渐加强。

A model of deioned water flowing in nano-throats was designed through dissipative particle dynamics（DPD）method,the interaction between rock surface and water considered and the flow in throats with radius from 1nm to 10 nm.The mechanism of boundary layer in nanotubes was revealed preliminarily.On the base of the discrete medium mechanics method,the velocity profiles in throats were obtained through statistical methods.The thickness of the boundary layer was characterized.The results of the model show that the density of water near the throat boundary was higher due to the attractive force of the throat boundary molecules;in throat with radius of 1nm,the velocity profile oscillated violently due to the effect of the thermal motion of molecules;with larger radius,the velocity profile matched the parabola better.