氮气驱室内实验研究

以中原油田文188块为研究对象，进行氮气驱室内实验研究。细管实验研究表明，氮气无法与地层原油形成混相，但可获得60％的采收率；在氮气突破时，细管流出物中有明显的甲烷峰出现，是非混相驱的重要的标志；两组长岩心驱替实验研究表明，先注O．04PV的水时采出程度为6．35％，转注氮气后，见气时的采出程度为43．77％；氮气驱的最大注入压差为0．89MPa，是最大注水压差的0．227倍，说明在注水困难地区实施注氮是可能的。在长岩心驱替实验中，氮气突破前，出现采出油体积高于注入气体积的现象；氮气突破后，被萃取的甲烷和中间组分依然发挥一定的作用，此期间仍可获得一定的采收率；氮气突破后采出油量会大幅度下降，如何有效控制氮气的突破是氮气驱成功的关键。图5表1参11

Laboratory research on nitrogen drive

A nitrogen drive laboratory test was carried out on the samples taken from the Wen 188 Block of Zhongyuan Oilfield. The slim tube test shows that although nitrogen can't be miscible with reservoir oil, the recovery efficiency is still up to 60%. An obvious methane peak in the capillary effluent after nitrogen breakthrough is a significant sign of immiscible displacement. Two long-core displacement tests show that the recovery percent of reserves is 6.35% when injected water volume is equivalent to 4% pore volume. After converting to nitrogen injection, recovery percent of reserves is 43.77% at the point of gas breakthrough. The maximum pressure differential in nitrogen drive is 0.89MPa, which is 22.7% of that in water flooding differential, suggesting that it is possible to adopt nitrogen drive in the area where water flooding is difficult to carry out. Before nitrogen breakthrough in the test, the volume of oil produced is larger than the volume of nitrogen injected. After gas breakthrough, oil is still produced because methane and intermediate components extracted still plays a role during the displacement, whereas the production drops greatly. So how to control the nitrogen breakthrough efficiently is key to the success of nitrogen drive.