稠油油藏高温凝胶改善蒸汽驱开发效果可视化实验

针对稠油油藏蒸汽驱汽窜现象严重的问题,为了研究高温凝胶改善稠油注蒸汽开发的效果,利用二维可视化物理模拟设备,通过图像采集系统对比了注入高温凝胶前、后的图像,并全程跟踪了蒸汽驱开发稠油时汽窜产生的过程以及注高温凝胶后蒸汽驱油层的波及情况,据此研究了利用高温凝胶改善蒸汽驱开发效果的微观机理。实验结果表明:稠油蒸汽驱过程中,由于压力梯度的差异,注采井间容易形成窜流通道;蒸汽在油层中产生明显的指进现象,从而降低蒸汽的波及范围,窜流通道两侧存有大量的剩余油;凝胶溶液首先进入窜流通道,并占据颗粒间的大孔隙,成胶之后对高渗通道有良好的封堵作用;后续注入的蒸汽绕过主流通道,能够进一步驱出剩余油。驱油结果表明:注入凝胶之后的最终波及效率能够达到70.44%,最终驱油效率达到60.45%,分别比单纯蒸汽驱提高了22.35%和15.17%。

A visible experiment on adoption of high-temperature gel for improving the development effect of steam flooding in heavy oil reservoirs

Aiming at severe steam channeling in the steam flooding of heavy oil reservoirs, 2D visible physical simulation equipment was used for studying the effect of high-temperature gel on improvement of steam flooding. An image acquisition system was adopted to compare the images prior and posterior to high-temperature gel injection. Meanwhile, the whole process of steam channeling in steam flooding for heavy oil development was tracked, as well as the sweep situation of steam flooding layer posterior to high-temperature gel injection. Accordingly, the micro-mechanism of high-temperature gel for improving steam flooding was also studied. Experimental results indicate that in the process of steam flooding for heavy oil, steam channels tend to form between the injection and production wells due to different pressure gradients. Steam results in obvious fingering phenomenon in oil layers, thus reducing the sweep range of steam, leading to a large amount of residual oil on both sides of steam channels. The gel solution firstly flows into the channeling path, and occupies large intra-particle pores. Gel has a good plugging performance on channels with high permeability. The following steam bypasses the mainstream channels for further residual oil flooding. Oil flooding results show that posterior to gel injection, the final sweep efficiency can reach 70.44%, and the ultimate oil flooding efficiency is 60.45%, higher than that of pure steam flooding by 22.35% and 15.17% respectively.