涠洲12-1油田注伴生气近混相驱替机理实验及模拟研究

近混相驱可以在降低注入压力的同时尽可能使驱替效果达到与混相驱相同的低界面张力驱替效果。以涠西南油田群外输气回注涠洲12-1油田地层原油的互溶性膨胀试验和多次接触过程PVT实验数据为基础,结合PVT物性参数及相态特征的模拟计算,分析了涠洲12-1油田注伴生气膨胀特征和多次接触非混相驱和近混相驱特征。研究表明,涠洲12-1油田地层原油在目前地层压力(20.47~20.77 MPa)下,当注入气摩尔比例达到0.68左右时,体系达到理论上的一次接触混相状态,对应的理论混相压力在39.45 MPa以上。注涠洲12-1油田外输气形成的驱油机理为多次接触动态非混相驱和较弱的近混相驱,要达到明显的近混相驱和混相驱,则需要把注入压力提高到40 MPa以上。

Experimental and simulation study on the mechanism of associated gas near-miscible flooding in

Near miscible flooding may make the same displacement effects of low interfacial tension as that of miscible displacement besides reduces injection pressure.Based on the PVT experimental data of multi-contact process and miscibility expansion test by injecting gas from Wei Southwest oilfield group into formation oil in Weizhou 12-1 oilfield,combining the analog computation of PVT properties and phase behavior,the displacement characteristics of muti-contact immiscible and near miscible analyzes and expansion characteristic of accompanying gas injection in Weizhou12-1 oilfield are analyzed.It shows that under present formation pressure(20.47~20.77 MPa),the theoretical miscible pressure of formation oil in Weizhou12-1 oilfield corresponding to is above 39.45 MPa when mole proportion of injecting gas reaches about 0.68 and system reaches a theoretical contacting mixed phase status.Displacement mechanism formed by injecting external transmitting gas into Weizhou12-1 oilfield is multi-contact dynamic non-miscible flooding and weak near miscible flooding.If achieving obvious near miscible flooding and miscible flooding,the injecting pressure should be increased to 40 MPa above.