CO_2置换联合热采技术开采天然气水合物可行性分析

Feasibility analysis on CO_2 replacement combined with heating technology for production of natural gas hydrate

对于海底浅层天然气水合物,常规的开采方法均不能进行相应的地层回填,进而会造成严重的地质灾害。从热采联合CO_2置换开采天然气水合物方法出发,针对该复合方法进行了理论论证,指明置换过程没有水合物笼形结构的液化,不会因为硬度的丢失造成地层失稳情况发生;另一方面,CO_2水合物强度远高于海底浅层疏松孔隙结构,在保证地质回填的同时能对海底浅层实现进一步加固处理。同时,通过热交换技术能够升高矿藏内部温度,从而加快置换反应速率,增大置换反应进行的程度,进而解决单一CO_2置换过程中置换程度小与置换效率低的问题。分析了CO_2注入压力、CO_2注入形态、反应温度、微波频率、微波功率等因素对开采天然气水合物过程的影响,为我国温室气体的存储、天然气水合物的开采和海底浅层地层维持稳定提供了理论支持。

For the seabed shallow natural gas hydrate,the conventional mining methods cannot be used for the corresponding strata backfill,and then will cause serious geological disasters. A new method of CO2 replacement combined with heating technology for natural gas hydrate combined mining is presented and the theory demonstration is studied. It is pointed out that there is no liquidation of hydrate cage structure in the replacement process,and therefore stratum instability resulted by hardness reduce will not occur. On the other hand,the intensity of generated CO2 hydrateis is much higher than that of seabed shallow loosen pore structure,and the seabed shallow can be further reinforced when subbottom geological backfill is carried out. At the same time,applying heating exchange technology can increase the temperature inside the mine,speed up the replacement reaction rate,increase the degree of substitution reaction,thus solving the problem of low efficiency in the process of CO2 replacement. The effects of CO2 injection pressure,reaction temperature,CO2 injection form,microwave frequency and microwave power on the process of exploitation of natural gas hydrate are analyzed,which provide theoretical support for greenhouse gas storage,gas hydrates exploration and stability of the seabed shallow strata study in our country.