天然气水合物原位补热降压充填开采方法

    A NOVEL METHOD FOR NATURAL GAS HYDRATE PRODUCTION: DE-PRESSURIZATION AND BACKFILLING WITH IN-SITU SUPPLE-MENTAL HEAT

    • 摘要: 天然气水合物资源量丰富,被公认为最有潜力的新型高效清洁替代能源,是未来能源革命的战略突破口。由于天然气水合物分解是伴随相变的复杂物理化学过程,安全经济地开采天然气水合物仍有许多瓶颈难题亟待解决。当前降压法是相对经济有效的开采方法,但天然气平均日产量远远达不到产业化开发的需求。在分析降压法规模化开采面临的瓶颈问题的基础上,提出了一种全新的天然气水合物开采方法——原位补热降压充填开采法,重点剖析了该方法的3个基本原理,提出了该方法的开采技术方案、关键技术与工艺步骤。得出了如下结论:(1)天然气水合物降压法规模化开发需要突破“天然气水合物分解热补给”(补热)、“储层结构稳定性”(保稳)和“提高储层渗透率”(增渗)等3个方面的瓶颈难题;(2)基于“降压分解原理”、“原位补热原理”和“充填增渗原理”,提出了天然气水合物原位补热降压充填开采法,该方法将氧化钙(CaO)粉末注入天然气水合物储层,反应产生的大量热量补充天然气水合物的分解热,同时,反应生成的氢氧化钙(Ca(OH)2)既填充了天然气水合物分解后留下的空隙,多孔结构又提高了储层的渗透性;(3)提出了天然气水合物原位补热降压充填开采所涉及的具体技术方案、关键技术与工艺步骤。当前天然气水合物开采技术手段距离产业化开发的需求还有一定距离,未来需要加强国际科研合作,深度学科交叉,研发变革性技术,早日实现天然气水合物规模化开发。

       

      Abstract: Natural gas hydrate(NGH) is the most promising clean alternative energy resource for world, which will be the strategic breakthrough of energy revolution in the future. Because the decomposition of NGH is a complicated physical and chemical process accompanied by phase change, there are still many bottleneck problems to be resolved with respect to the safe and economic exploitation of NGH. At present, the depressurization method is relatively economic and effective, but the average daily production of natural gas is far from the demand of commercial development. Based on the analysis of the bottleneck problems in depressurization method, a novel method for natural gas hydrate production, depressurization and backfilling with in-situ supplemental heat, is proposed. Three basic principles of the method are emphatically analyzed. The technology scheme, key techniques and implementation steps of the method are introduced. The conclusions are as follows: (1)The achievement of large-scale production of NGH by depressurization depend on three key factors, namely heat supply, reservoir stability and reservoir permeability. (2)Based on the three principles of depressurization, in-situ supplemental heat and backfilling and increased permeability, the novel method was proposed. In this method, calcium oxide(CaO)powder is injected into the hydrate reservoir, which will provide a large amount of heat for the decomposition of NGH. At the same time, the Ca(OH)2 produced by the reaction will backfill the void volume left by hydrate decomposition and improve the permeability of the reservoir. (3)This study put forward the technology scheme, key techniques and implementation steps of the novel method. The method is mainly implemented in three stages, i.e., horizontal well drilling and completion, high-pressure air powder injection and depressurization and backfilling. In the future, it is necessary to strengthen international scientific research cooperation, deepen interdisciplinary R&D of innovative technologies, and realize the large-scale production of NGH as soon as possible.

       

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