鄂尔多斯盆地裂缝性低渗透油藏渗吸驱油研究

裂缝性低渗透油藏储层岩性致密,裂缝发育,非均质性强,注水开发效果差,利用水的自发渗吸作用驱油是一种经济有效的开发手段。文中利用鄂尔多斯盆地延长油田西区采油厂的天然露头岩心,通过自发渗吸实验,研究了边界条件、润湿性、温度、原油黏度、界面张力及渗透率等因素对渗吸驱油作用的影响。实验结果表明:润湿性、黏度、界面张力及渗透率是影响渗吸驱油的主要因素,岩石越亲水,原油黏度越低,渗吸驱油效果越好。对于亲水岩心,渗透率相近时,界面张力为0.04 m N/m时渗吸效果最佳;岩石渗透率差异明显时,渗透率为2.94×10~(-3)μm~2时渗吸效果最佳。实验结果为鄂尔多斯盆地裂缝性低渗透油藏渗吸驱油提供了重要的指导作用。

Study on imbibition flooding in fractured low-permeability reservoir of Ordos Basin

Because the lithology of fractured low-permeability reservoir is compact,crack-developed,strongly heterogeneous,the water flooding is poor.Thus oil displacing by spontaneous imbibition of water is an economic and effective means of development.In this paper,the natural outcrop cores from the west oil production plant of Yanchang Oilfield were used to study the effects of boundary condition,wettability,temperature,viscosity,interfacial tension,and permeability on the oil displacing function by spontaneous imbibition experiments.The result shows that the wettability,viscosity and interfacial tension are the main factors that affect the oil displacement.The more hydrophilic the rock is,the lower the viscosity of crude oil is,the higher the recovery ratio is;the spontaneous imbibition with hydrophilic core and similar permeability reaches the highest when interfacial tension is 0.04 mN/m;spontaneous imbibition is best when the permeability is greatly different and 2.94×10-3 μm2.The experimental results provide an important guidance for the spontaneous imbibition in the fractured low-permeability reservoir in the Ordos Basin.