摘要:
利用自制的一维天然气水合物开采模拟实验系统,模拟海洋地质条件,在填砂模型中生成天然气水合物,再注入热盐水进行注热开采的物理模拟实验,分析注热参数对水合物分解动态及注热开采能量效率的影响。分别设定注热水温度为60、80、100℃,注热水速度为12、15、18 mL/min,最长注热水时间220 min。结果表明:在相同的注热水速度下,注热水温度越高,水合物分解产气速率越大,能量效率越低;在相同的注热水温度下,注热水速度越高,水合物分解产气速率越大,能量效率也越低;随着注热水时间的延长,水合物注热分解的能量效率逐渐降低。因此,建议采用"热水段塞+常温水驱替",或者注热与降压相结合的开采方式,提高水合物藏开采的经济效益。
Abstract:
A new one-dimensional experimental system for modeling natural gas hydrate (NGH) development has been designed to study the formation and dissociation process of NGH. In order to simulate the marine geological environment, NGH was made in a sand-packed tube, and then hot-brine was injected into the tube to study the thermal dissociation characteristics, and the injection parameters which will influence the thermal dissociation behavior and energy efficiency of NHG. The temperatures of the injected hot-brine were 60℃, 80℃ and 100℃, and the injection rates 12 mL/min, 15 mL/min and 18 mL/min respectively, and the time span for injection was 220 min to the maximum. The experimental results show that if the injection rate is fixed, the higher the temperature is, the larger releasing rate of gas from hydrate dissociation is and the lower energy efficiency becomes. Moreover; if the temperature of injected hot-brine is fixed, the higher the injection rate is, the larger releasing rate of gas from hydrate dissociation is and the lower energy efficiency becomes. As the injection time becomes longer,the energy efficiency of thermal stimulation decreases gradually. In this regard,the option of "hot brine slug + water flooding at normal temperature", or the combination of the thermal method and depressurization were proposed in this paper to improve the economic efficiency to develop NGH reservoirs.
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