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对于具有孔隙结构和微尺度效应的低渗透储层,其渗流现象的介观机理逐渐受到人们的重视。本文采用微流控技术在硅片上加工出微通道作为微观模型,模拟岩心内部的孔隙结构,对微通道中单相和油水两相的渗流规律进行了实验研究。研究结果表明,微观模型中带有喉道段的微通道存在启动压力梯度,这揭示了孔隙中的喉道是低渗透储层中产生启动压力梯度的主要介观因素。启动压力与孔隙结构和驱替介质的性质有关,在此基础上建立了适用于单相和油水两相渗流的启动压力预测模型。
For the low permeability reservoirs with pore structure and microscale effects, the mesoscopic mechanism of seepage phenomena gradually attracts people’s attention. In this paper, microfluidics is used to fabricate microchannels as the microscopic model on the silicon wafer to simulate the pore structure inside the core. Experimental studies on the seepage law of single phase and oil-water two-phase in microchannels are carried out. The results show that there is a starting pressure gradient in microchannels with throat sections in the microscopic model, which reveals that the throats in the pores are the main mesoscopic factors for the initiation pressure gradient in low permeability reservoirs. The starting pressure is related to the properties of pore structure and displacing media. Based on this, the starting pressure prediction model suitable for single-phase and oil-water two-phase seepage flow is established.