鄂尔多斯盆地长7页岩储层长岩心注水实验

Long Core Water Injection Experiment of Chang 7 Shale Reservoir in Ordos Basin

为了探索页岩储层有效注水方式,采用鄂尔多斯盆地长7页岩露头分别制作长度近100 cm、直径近10 cm长岩心12个,通过室内实验研究了长岩心连续注水、脉冲注水、不稳定注水、周期注水、水平井注水吞吐及常规井注水吞吐的采出情况。结果表明,在相同的采出程度下,连续驱替含水率最高,间注间采的周期注水方式含水率最低;最终采出程度间注间采的周期注水方式最高,为35.24%,连续注水最低,为28.35%。在相同轮次下,注入压力越高,注水吞吐采出程度越高,最高值为5.08%;在一定吞吐压力下,第一轮次采出程度最高,随着轮次增加,单轮次采出程度大幅下降,第三轮次降幅可达82.61%;水平井注水吞吐效果优于常规井注水吞吐。较高的注水压力,有利于获得较高的采出程度;压力变化幅度大有利于启动微小孔隙中的原油,提高原油采收率。注水吞吐由于缺乏能量连续补充,采出程度比周期注水低约30%。

In order to explore effective water injection methods for shale reservoirs,12 long cores with a length of nearly 100 cm and a diameter of nearly 10 cm were made from the Chang 7 shale outcrop in the Ordos Basin.Through laboratory experiments,the production conditions of continuous water injection,pulse water injection,unstable water injection,periodic water injection,horizontal well water injection and conventional well water injection were studied.The results show that under the same recovery degree,the water content of continuous displacement is the highest,and the water content of cyclic water injection method with interval injection and interval recovery is the lowest.The cyclic water injection method of inter injection and inter extraction is the highest at 35.24%,and the continuous water injection method is the lowest at 28.35%.Under the same rotation,the higher the injection pressure,the higher the degree of recovery through water injection,with a maximum value of 5.08%.Under a certain throughput pressure,the first round of extraction has the highest degree.As the number of rounds increases,the single round of extraction significantly decreases,with a decrease of 82.61%in the third round.The effect of horizontal well water injection stimulation is better than that of conventional well water injection stimulation.A higher water injection pressure is beneficial for achieving a higher degree of recovery.The large amplitude of pressure change is beneficial for activating the crude oil in small pores and improving crude oil recovery efficiency.Due to the lack of continuous energy replenishment during water injection huff and puff,the recovery rate is about 30%lower than that of cyclic water injection.