低渗裂缝砂岩油藏注富气试验评价研究

Experimental Evaluation of Rich Gas Injection in Low Permeability Sandstone Reservoirs

试验采用低渗基岩岩心造缝后制作成长岩心,研究带裂缝低渗砂岩油藏注富气的可行性,并评价其效果及最优注气方式。研究采用高、低渗两组岩心,分别进行水驱、伴生气/水交替驱、气驱6组试验,并对试验结果进行分析和评价。结果表明,高、低渗两组岩心驱油效果最佳分别为注伴生气/水交替驱和脉冲注伴生气驱,最终驱油效率约64%;在相同的驱替方式下,高渗组岩心试验压差明显低于低渗组岩心,采出程度则明显高于低渗岩心;对带裂缝的低渗油藏,采用提高体积波及效率的注气方式仍然可以达到很高的采收率;低渗轻油的富气驱在气突破后还有一个较长的采油过程。研究结果为低渗裂缝砂岩油藏的注气方式筛选提供了重要参考。

Low permeability matrix cores were used to make fractures in the experiment,to investigate the feasibility of rich gas injection into fractured low-permeability sandstone reservoirs.Two groups of cores——a high-permeability core and a low-permeability core were used for 6 water-flooding experiments,associated gas alternating water flooding and gas flooding,and then the experimental results were analyzed and evaluated.Results show that for the high-permeability core,the best oil displacement effect is associated gas alternating water flooding,and for the low-permeability core,it is pulsed associated gas injection that has the best effectiveness,the ultimate sweep efficiency is about 64%.For the same displacement pattern,the experiment pressure difference of high-permeability core is apparently lower than that of low-permeability core,their gas-oil ratio is close to each other,but the recovery factor of high-permeability core is higher than that of low-permeability core obviously.The results of the study indicate that for the fractured low-permeability reservoir,gas injection pattern can improve the sweep efficiency,it can still obtain higher recovery.Unlike other oil,rich gas flooding of low-permeability light oil has a relatively long production process after gas breakthrough.It provides important reference for the selection of gas injection pattern for low-permeability fractured sandstone reservoir.