摘要
碳酸盐岩油藏基质致密,且发育裂缝和溶洞,使得注水开发过程中含水率上升快、采收率低。低盐度注水是一项成本低廉、效果显著的注水提高采收率技术,始于20世纪90年代,近年来在国内外均受到广泛关注。梳理了碳酸盐岩油藏低盐度注水的增产机理、室内实验评价方法和矿场实施条件。综合分析指出,低盐度注水提高碳酸盐岩油藏采收率的主要机理是润湿性反转和孔喉连通性改善。润湿性反转由表面电荷改变或者矿物溶解引起,其实质是水相中的关键二价离子(SO_4^(2-),Ca^(2+),Mg^(2+))与岩石表面发生了化学反应;孔喉连通性改善主要由矿物溶解引起。低盐度注水主要的室内实验评价方法有水驱实验、自吸测试、表面张力测定、接触角测定、核磁共振、离子成分分析及Zeta电势测定等。开展低盐度注水能够有效降低注入压力,提高洗油效率,增加波及体积。我国碳酸盐岩油藏分布广泛,开展低盐度注水提高采收率技术的机理研究和应用研究,具有重大的现实意义。
For carbonate reservoirs, it is common that oil recovery is relatively low and water cut rises quickly due to the complex underground conditions, such as a wide range of fractures and caves. Low salinity waterflooding is an enhanced oil recovery （EOR） technique with low cost and high effects, and it has been extensively researched since 1990s. The stimulation mechanism, laboratory methods and field operation conditions for low salinity waterflooding of carbonate reservoir were analyzed. Experimental results reveal that wettability alteration and enhancement of connectivity among different pore systems are responsible for the improved recovery. The wettability alteration can be attributed to surface charges alteration or microscopic dissolution of minerals, which is in fact the reaction between main determining ions （SO42-, Ca2＋ and Mg2＋） and rock surfaces. However, the enhancement of connectivity among different pore systems is caused mainly by microscopic dissolution of minerals. Numerous laboratory methods are applied to obtain the main mechanisms for low salinity waterflooding on carbonate oil reservoirs, such as coreflooding study, imbibition test, interfacial tension measurement, contact-angle measurement, nuclear magnetic resonance technique, ion analysis and Zeta potential measurement. When performing low salinity waterflooding, higher oil recovery will be achieved if ions composition can be optimized. In addition, the combination of low salinity waterflooding and polymer flooding will also remarkably improve oil recovery. In China, there is large number of carbonate reservoirs, therefore, it is of significance to conduct theoretical and applied researches related to low salinity waterflooding
出处
《岩性油气藏》
CSCD
北大核心
2016年第2期119-126,共8页
Lithologic Reservoirs
基金
国家重大科技专项"渤海油田高含水水平井智能控水技术研究与应用"(编号:2016ZX05009003-001)
中海油重大专项"海上低渗油藏有效开发模式
方法与适用技术研究(注水部分)"(编号:CNOOC-SY-001)联合资助
关键词
低盐度注水
碳酸盐岩油藏
提高采收率
润湿性反转
孔喉连通性
low salinity waterttooding
carbonate reservoir
enhanced oil recovery
wettability alteration
pore connectivity
