中国致密油藏水平井注水吞吐技术进展与发展趋势

中国致密油藏多采用水平井体积压裂衰竭式开发，水平井产量递减快，一次采收率不足10%。因此，有效补充地层能量是致密油藏体积压裂水平井稳产的关键。注水吞吐是致密油藏水平井的一种有效注水补充能量方法，近年来针对该方法进行了大量的研究和实践。在介绍注水吞吐工艺的基础上，从渗吸采油微观机理以及压力对渗吸排油影响两个方面对注水吞吐机理的研究进展进行了概述，并系统总结了储层性质和工艺参数对注水吞吐采油效果的影响。为了提高注水吞吐的开发效果，目前主要形成了化学处理剂辅助注水吞吐技术、大排量注水强化注水吞吐技术和水平井同井缝间异步注采技术3种改善注水吞吐开发效果的技术。进一步通过总结注水吞吐油藏数值模拟和工艺参数优化的研究成果，分析矿场实践经验，提出了中国致密油藏注水吞吐技术未来发展趋势。

Progress and development trend of water huff-n-puff technology for horizontal wells in tight oil reservoirs in China

Tight reservoirs are mostly developed by volumetric fracturing horizontal wells with the elastic drive of natural energy in China. As the production of horizontal well decreases rapidly, the primary oil recovery is less than 10%. To effectively supplement the formation energy is the key for stable production of the volumetric fracturing horizontal wells in tight reservoirs. Water huff-n-puff is an effective method for the supplementation of formation energy in tight reservoir for horizontal wells. In recent years, a lot of researches and practice have been performed on this method. This paper introduces the process of water huff-n-puff technology, outlines the research progress on the mechanism of water huff-n-puff from two aspects:micro-mechanism of imbibition oil recovery and influence law of pressure on imbibition oil recovery, and further systematically summarizes the influence law of reservoir properties and process parameters on the oil recovery of water huff-n-puff technology. To improve the oil recovery of water huff-n- puff, there are mainly three technologies, including the water huff-n-puff technology assisted by chemical treatment agent and enhanced by large displacement water injection, and inter-fracture asynchronous injection-production technology in the same horizontal wells. Through summarizing the research results from reservoir numerical simulation and process parameter optimization for water huff-n-puff, and analyzing field practise experience, this paper further proposes the future development trends of water huff-n-puff technology in tight reservoirs.