针对页岩储层的低孔隙度、特低渗透率且中性偏油润湿特征,本文设计了相应的微流控毛细管束微观模型.基于该模型,研究了分子膜剂(DM)与表面活性剂十八烷基三甲基氯化铵(STAC)复配体系改变微观模型润湿性情况.发现在DM(1000 mg/L)/STAC(浓度≤临界胶束浓度)条件下,在玻璃表面润湿改性接触角与STAC浓度呈正相关,接触角最大能达到100.51°,且为单层吸附,吸附平均厚度为2.064 nm;在DM(1000 mg/L)/STAC(浓度＞临界胶束浓度)条件下,在玻璃表面润湿改性接触角与STAC浓度呈负相关,吸附层为多层吸附.以吉木萨尔凹陷二叠系芦草沟组页岩油储层为研究对象,刻蚀出与孔喉直径等效的毛细管束模型,半径为 5 μm,流道深度为 5 μm.然后通过DM/STAC润湿改性,基于亲水润湿和润湿改性后毛细管束模型进行压差—流量法测试流体渗流规律.结果表明,流体在低速流动时,呈非达西渗流特征,具有启动压力梯度.并且,润湿性改变致使毛管力转向,从而影响流体渗流规律.

According to the low porosity,ultra-low permeability and neutral partial oil wetting of shale reservoir,the corre-sponding microscopic model of capillary bundle is designed.The wettability of microscopic model changed by the compound system of molecular film agent(DM)and surfactant octadecyl trimethyl ammonium chloride(STAC)was studied.It is found that DM(1000mg/L)/STAC(concentration≤critical micelle concentration),the wetting modified contact angle is positively correlated with the STAC concentration,the maximum contact angle can reach 100.51°,and it is a monolayer adsorption with an average adsorption thickness of 2.064nm;Dm(1000mg/L)/STAC(concentration＞critical micelle concentration),the wetting modified contact angle is negatively correlated with the STAC concentration,and the adsorption layer is multilayer adsorption.Taking shale oil reservoir of Permian Lucaogou Formation in Jimusar sag as a feature,a capillary bundle model equivalent to pore throat diameter was etched,with radius of 5μm and depth of flow channel of 5μm.Then,through DM/STAC wetting modification,based on hydrophilic wetting and wetting modified capillary tube bundle model,the differential pressure-flow method was used to test the fluid percolation law.As a result,when the fluid flows at low speed,it is characterized by non-Darcy percolation and has a threshold pressure gradient.Moreover,the change of wettability causes the capillary force to turn,affecting the law of fluid percolation.