延长油田CO_2驱储层物性变化规律

Physical property variation law of CO_2 flooding reservoir,Yanchang Oilfield

CO_2驱油可有效动用低渗透、特低渗透油藏,目前延长油田已经开展了CO_2驱矿场先导试验,并取得了一定的成果。文中根据延长油田储层物性特征,针对CO_2注入储层引起孔隙度、渗透率及润湿性等物性特征的变化,进行了CO_2驱储层物性变化规律的实验研究。结果表明:延长油田靖边CO_2试验区储层矿物中,不同程度的含有斜长石、石英、钾长石、浊沸石、方解石及黏土矿物,其中以斜长石和黏土矿物为主,其次是石英和钾长石,还有少量的浊沸石和方解石;在一定的压力范围内,随着注入压力增大储层孔隙度变化率先升高后降低;随着CO_2与储层反应时间的增加,储层渗透率恢复值是增大的;随着注入压力的不断增大,储层渗透率降低;CO_2与储层接触后储层的亲水性增强,有利于提高原油采收率。

CO2 flooding can develop low permeability and ultra-low permeability reservoirs effectively; now Yanchang Oilfield has carried out CO2 flooding field test and has obtained certain achievement.In this paper,according to the characteristics of Yanchang Oilfield and the changes of physical characteristics such as porosity,permeability and wettability（caused by CO2 injection）,the experiment on the physical property changes were carried out.The experimental results show that CO2 test area contains plagioclase,quartz,potash feldspar,laumonite,calcite and clay minerals,and the main minerals are composed of plagioclase and clay mineral content,followed by quartz and potassium feldspar,a small amount of laumonite and calcite; within a certain range of pressure,the reservoir porosity rate increases first,then decreases; with the increase of CO2 and reservoir response time,the reservoir permeability recovery value increases; with the increase of injection pressure,the reservoir permeability decreases; the hydrophilic enhancement after water contact with the reservoir improves the oil recovery.