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孟买海湾油田的生产层都是薄层、致密、非均质碳酸盐岩储集层,具有典型的岩性模式。短期内,所有井的产量急剧下降。采取有效措施使油井增产一直是公认的难题。常规的增产方法都不成功,而独特的多级酸压技术被证实在这样的地层非常有效。技术人员经过研究确定了地层岩性,找到了一种适合的酸液体系,并考察了不同酸液对地层岩石的酸蚀形态。研究表明,通过黏性压裂液进行多级压裂,并用改良酸液体系交替酸化裂缝表面能提供更好的侵蚀形态。最后,闭合裂缝并以低排量注入大量硝酸进一步提高渗透率。在实施过程中,只要控制好各级的酸反应速度,就能均匀地酸化和侵蚀裂缝的最远部分、中间部分和近井部分。地层岩心的室内和现场试验结果验证了该技术的效果。在后期工作评估中会在增产措施前后进行温度测量和不稳定试井。本文描述了改良酸液体系的技术基础,包括室内测试结果。也讨论了措施设计、实施和裂缝几何结构评估。生产对比显示,裂缝酸化后油井产能有了质的飞跃。本文的意义在于:通过控制酸反应速度,更好地酸化致密的非均质碳酸盐岩储集层,从而生成更长的裂缝和获得更高的导流能力。
The production zones in the Mumbai Gulf Oilfield are all thin, tight, heterogeneous carbonate reservoirs with typical lithological patterns. In the short term, the production of all wells dropped sharply. It has been a recognized challenge to take effective measures to increase the production of oil wells. None of the conventional stimulation methods succeeded, and the unique multi-stage acid pressure technique proved to be very effective in such formations. The technicians determined the lithology of the strata through research, found a suitable acid system, and investigated the acid etching morphology of the formation rock by different acid solutions. Research shows that multi-stage fracturing with viscous fracturing fluid and alternating acidizing fracture surface with a modified acid system provide better erosion morphology. Finally, closing the fracture and injecting a large amount of nitric acid at a lower rate further increases the permeability. In the process of implementation, as long as the acid reaction speed at various levels is controlled, the farthest part, the middle part and the near well part of the fracture can be acidified and eroded uniformly. The results of laboratory and field tests of formation cores verify the effectiveness of this technique. In the post-work evaluation, temperature measurement and unstable well test will be conducted before and after stimulation measures. This article describes the technical basis for improving acid systems, including indoor test results. Measure design, implementation, and fracture geometry assessment are also discussed. The comparison of production shows that there is a qualitative leap in oil well productivity after fracture acidification. The significance of this article is that by controlling the acid reaction rate, the acidification of dense, heterogeneous carbonate reservoirs can lead to longer fractures and higher conductivity.