孙致学, 朱旭晨, 刘垒, 何楚翘, 都巾文. 联合深层地热甲烷水合物开采方法及可行性评价[J]. 海洋地质与第四纪地质, 2019, 39(2): 146-156. DOI: 10.16562/j.cnki.0256-1492.2018120402
引用本文: 孙致学, 朱旭晨, 刘垒, 何楚翘, 都巾文. 联合深层地热甲烷水合物开采方法及可行性评价[J]. 海洋地质与第四纪地质, 2019, 39(2): 146-156. DOI: 10.16562/j.cnki.0256-1492.2018120402
SUN Zhixue, ZHU Xuchen, LIU Lei, HE Chuqiao, DU Jinwen. Feasibility study on joint exploitation of methane hydrate with deep geothermal energy[J]. Marine Geology & Quaternary Geology, 2019, 39(2): 146-156. DOI: 10.16562/j.cnki.0256-1492.2018120402
Citation: SUN Zhixue, ZHU Xuchen, LIU Lei, HE Chuqiao, DU Jinwen. Feasibility study on joint exploitation of methane hydrate with deep geothermal energy[J]. Marine Geology & Quaternary Geology, 2019, 39(2): 146-156. DOI: 10.16562/j.cnki.0256-1492.2018120402

联合深层地热甲烷水合物开采方法及可行性评价

Feasibility study on joint exploitation of methane hydrate with deep geothermal energy

  • 摘要: 随着全球能源消耗不断增加,天然气水合物和地热资源具有储量丰富、清洁高效等优势成为世界研究的热点,中国南海海域同时具有丰富的水合物资源和地热资源。由此,提出了联合深层地热资源开采浅部水合物的方法,通过向深层地热储层注入海水,海水在深层地热中吸收热量后循环至浅部水合物储层,结合降压法和注热法促使水合物分解。利用数值模拟对联合法的可行性进行评估,并对地层热物性、开采参数等储层敏感性进行分析。模拟结果表明:联合法能够有效地利用深层地热将海水加热,海水进入水合物层时的温度保持约为50℃,与注热法和降压法相比具有更高的产气量,具有良好的可行性;注入速度、井底压力、地层导热系数和地温梯度对联合法开采效果具有显著影响;注入速度和井底压力对前期的产气效果影响较大,而较大的地层导热系数有利于海水与地层的换热;地温梯度小于0.025 m/℃时,联合方法的换热性能极大减弱,甲烷累计产气量大幅度降低,联合方法的商业价值降低,可行性减弱。

     

    Abstract: With the drastic increase in energy consumption, both the natural gas hydrates and geothermal resources have become research focuses in the world due to their enormous reserves. Then the method to exploit shallow gas hydrates together with deep geothermal resources becomes attractive. In this method, seawater will be injected into the deep geothermal reservoirs and then bring into the shallow hydrate reservoirs after circulation and absorbing enough heat from the deep geothermal reservoir. Depressurization and thermal recovery technique are used to encourage the decomposition of gas hydrates. In this paper, the feasibility of the joint exploitation method is evaluated through numerical simulation, and the thermal properties of hydrate bearing sediment, exploiting parameters and reservoir sensitivities studied. Results show that effective utilization of geothermal resources to heat seawater may enable the temperature of seawater entering the hydrate layer to maintain on a level of about 50℃, and higher gas production will achieved comparing to the method of heat injection and depressurization techniques. It is indeed a method with good feasibility. Some factors, such as injecting rate, bottom hole pressure, thermal conductive factor of formation and geothermal gradient, have a significant impact on the exploiting results. In addition, the injection rate and bottom hole pressure may bring greatly influence to gas production in the early stage, while the thermal conductivity of larger formation has a favorable contribution to the heat exchange between the seawater and formation. Results also suggest that the performance of heat transferring of the method be largely attenuated and the cumulative gas production of methane be substantially reduced within the area with a geothermal gradient lower than 0.025m/℃. In such a circumstance, the commercial value of the deposits and their feasibility of exploitation will decrease.

     

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