天然气水合物非成岩出砂储层砂流数值模拟

天然气水合物(可燃冰)作为新兴洁净能源,受到全世界的重视,由中国地质调查局组织实施的中国海域天然气水合物第二轮试采取得成功,并超额完成目标任务.当前,中外天然气水合物模拟器开发和相关研究虽然有通过力学耦合描述"砂"的行为,但大部分都没有涉及"砂"的流动过程.针对天然气水合物分解后,储层多孔介质中"砂"流动过程的数值模拟,通过通用储层渗流模拟器GPSFLOW,实现水、气(甲烷)、砂三相三组分模拟,把砂当做一种非牛顿流体,即为一组分也是一个相态,按宾汉流体进行模拟,初步探讨砂流过程模拟的理论方法和模型实现方案,并通过理想模型进行验证.结果表明:相较于其他出砂数值模拟研究方法,提出的砂流模拟方法简单高效,能够有效地模拟砂流过程,后续通过耦合水合物开采渗流模型,有望实现对水合物开采过程中砂流的准确模拟.

Numerical simulation study of sand flow in gas hydrate non-diagenetic sand production reservoir

As a new clean energy, natural gas hydrate (combustible ice) has attracted worldwide attention. The second round of trial production of natural gas hydrate in China Sea area organized and implemented by China Geological Survey has achieved success and exceeded the target task. At present, although the development of natural gas hydrate simulators at home and abroad and related researches describe the behavior of "sand" through mechanical coupling, But most of them do not involve the flow process of "sand". Aiming at the numerical simulation of the "sand" flow process in the porous media of the reservoir after the decomposition of natural gas hydrate, the general-purpose subsurface flow simulator GPSFLOW was used to realize the three-phase three-component simulation of water, gas (methane), and sand. The sand was regarded as a non-Newtonian fluid: one component and one phase, and the simulation was performed according to Bingham fluid. The theoretical method and model realization scheme of sand flow process simulation are discussed preliminarily, and verified by ideal model. The results show that compared with other sand production numerical simulation research methods, the sand flow simulation method proposed is simple and efficient, and can effectively simulate the sand flow process. It is expected to realize the accurate simulation of sand flow in the process of hydrate production by coupling the seepage model of hydrate production.