底水稠油油藏双水平井泡沫压脊技术及参数优化

Study on nitrogen foam anti-water-cresting by double horizontal wells for bottom water heavy oil reservoir

在水平井开采底水稠油油藏过程中,底水一旦脊进突破,导致含水率迅速上升,产油量很快下降,堵水作业困难。在生产水平井下方布置1口泡沫压脊水平井,可以减缓底水脊进,控制含水率上升速度,改善开发效果。利用数值模拟方法,研究了压脊水平井注泡沫( 氮气和发泡剂溶液) 、生产水平井采油的底水稠油油藏开采技术。结果表明,优化后双水平井泡沫压脊开发效果明显好于双水平井氮气压脊、单一水平井泡沫压脊和单一水平井无措施 3种开发方式。结合室内实验分析、数值模拟结果以及现场施工条件对压脊水平井参数进行模拟优化,设计发泡剂溶液质量分数为0.5%,气液比为1∶1,压脊水平井水平段长度为300m,避水高度为2.5m,注氮气速度为1.76×104m3/d,排液量为200m3/d 时,实施双水平井泡沫压脊生产,4个周期累积增产油量达1.9×104m3,增油幅度达48.7% 。

By means of numerical simulation, below the producing horizontal well, another horizontal well is placed to put off water cresting. When water cresting reached up to the height of producing horizontal well, we shut in the producing horizontal well and inject nitrogen foam into the horizontal well below. After two days'soaking, the upper horizontal well is opened to produce again. This process can be repeated for many times. The results of numerical simulation show that the development efficiency by double horizontal wells is much better, and the effect of water cresting can be alleviated greatly comparing to injecting nitrogen foam and producing oil only by a single well. The development style, distance away from the bottom water, length, liquid producing rate and the moment of injecting nitrogen foam are optimized by simulation. After optimization, the quantity and amplitude of incremental oil can reach up to 19,000 cubic meters and 48.7% respectively.