Analysis of hydrate exploitation by a new in-situ heat generation method with chemical reagents based on heat utilization

Hydrate exploitation effect by a new in-situ heat generation method is investigated by experiment. The chemical reagent thermal flooding method (CTF) (produces gas with injection of chemical reagents) and huff and puff method (HP) (comprises injection, soaking, and production cycle) are firstly combined in this study, namely, chemical reagent huff and puff method (CHP). The gas production, temperature and energy efficiency (eta) and thermal efficiency (xi) are obtained during exploitation. For gas production, CTF is beneficial for hydrate exploitation. But CHP with the mixed injection mode is likely to further promote gas production. So, according to heat transfer, the optimization of CHP is proposed by the separated chemical reagents injection mode. The temperature of the hydrate sediment with this mode is far less than that by traditional in-situ heating method. From the aspect of energy, eta and xi of CTF is also lower than that of CHP. Furthermore, the final eta (9.5) and xi (about 0.58) of CHP with separated injection mode are more than ten and 1.2 times larger the two of the traditional in-situ heating method, respectively. The results verify that by this new method, not only advantageous gas production can be obtained with a better heat transfer effect; most importantly, it has the ability to realize high eta with ideal heat utilization by reducing the heat lost for increasing the temperature of the hydrate sediment. So, it is promising for commercial exploitation, and then the sustainable development and clean production are potential to be achieved. (C) 2019 Elsevier Ltd. All rights reserved.