天然气水合物储层微波加热能量补充装置设计

Design of Microwave Heating Device for Energy Replenishment in Natural Gas Hydrate Reservoir

针对天然气水合物降压开采后期储层温度下降、产气速率下降、开采效率逐渐降低的问题,设计了储层微波加热能量补充装置,该装置能够对储层进行能量补充,提供水合物分解所需的温度和热量。通过建立储层微波能量补充仿真模型,研究了不同微波天线的结构参数对储层内平均电场强度的影响,优化了微波天线的结构参数;并针对优化后的结构参数,分析了不同微波参数下微波加热10 h后储层的升温效果。模拟结果表明:微波天线的最优结构参数为槽口形状为椭圆形槽口,槽口周期长度为187 mm,长轴为50 mm,短轴为11 mm,槽口角度为19°;微波频率为1.5 GHz、微波输入功率为3 kW时,微波加热10 h后水合物储层半径1 m范围内的平均温度为10.43℃,升高约5℃。所设计的微波加热能量补充装置能为水合物的分解提供驱动力。研究结果可使微波加热技术应用在水合物开采中,为天然气水合物的高效开发提供了一种新的方案。

Decreases of reservoir temperature,production rate and recovery efficiency are witnessed in the later stage of depressurization-induced natural gas hydrate exploitation.To solve these problems,a microwave heating device for energy replenishment in reservoir has been designed.The device can replenish the energy in reservoir and provide the temperature and heat required for hydrate decomposition.In this paper,a simulation model of microwave heating for energy replenishment in reservoir was established to identify the influence of different structural parameters of microwave antennas on the average electric field strength in the reservoir.Then,the structural parameters of microwave antennas were optimized.The heating effect of the reservoir after microwave heating for 10 h under different microwave parameters was analyzed based on the optimized structural parameters.The simulation results show that the optimal structural parameters of microwave antennas are as follows:elliptical notch,187 mm notch cycle,50 mm major axis,11 mm minor axis and 19°notch angle.When the microwave frequency is 1.5 GHz and the microwave power is 3 kW,after microwave heating for 10 h,the average temperature within a radius of 1 m of the hydrate reservoir is 10.43℃,which increases by about 5℃.The designed microwave heating device for energy replenishment in reservoir can provide driving force for the decomposition of hydrates.The study results enable the microwave heating technology to be applied in hydrate exploitation,and provide a new solution for the efficient development of natural gas hydrate.