CO_2吞吐增油机理及矿场应用效果

对国内几个油田的原油样品进行了CO2 —原油体系的高压物性测定及室内CO2 吞吐实验 ,评价并分析了原油溶解CO2 后体积膨胀、黏度降低、油 /水界面张力降低 ,以及CO2 对原油萃取的作用、岩石润湿性的改变、酸化解堵作用、形成内部溶解气驱等增产机理 .根据矿场试验结果 ,分析了CO2 吞吐的增产潜力 ,将现场作业增油机理划分为解堵型和增能型两类 .第一类油层含油饱和度高 ,能量充足且渗透率较高 ,处理后日产量急增 ,有效期长 ;CO2 的主要作用是清除井底的各类污染 .第二类油层含油饱和度低 ,地层能量不充足或渗透率低 ,处理后日产量有所增加 ,但有效期相对较短 ;CO2 处理的主要作用是增加地层能量

Oil production enhancing mechanism and field applying result of carbon dioxide huff-puff

The measurement of the high-pressure properties and the carbon dioxide huff—puff experiment of the crude oil samples from 4 oilfields are carried out. On the basis of the measured and experimental results, the oil production enhancing mechanisms of carbon dioxide huff—puff are analyzed: after carbon dioxide dissolves in crude oil, all the expansion of crude oil, the reduction of its viscosity, the reduction of oil/water interfacial tension, the extraction effect of carbon dioxide on crude oil, the change of rock wettability, the plug removal effect of acidization, the oil displacement effect of dissolved gas have the results of oil production enhancing. According to the results of field carbon dioxide huff—puff tests, the potential of oil production enhancing by carbon dioxide huff—puff is analyzed, and the mechanisms of it are classified into two types: plug removal type and energy increasing type. The main effect of the first type is cleaning various bottom-hole pollutions. This kind of reservoirs has high oil saturation, sufficient energy and high permeability, and the increase of the oil production is obvious and keeps up a longer time. The main effect of the second type is to increase reservoir energy. This kind of reservoirs has lower oil saturation, lower energy or lower permeability. The increase of oil production is finite and continues a shorter time.