Experimental study on the hydrate dissociation in porous media by five-spot thermal huff and puff method

A novel method for hydrate production named “Five-spot thermal huff and puff (HP-5S)” is designed and employed to investigate the behaviors of hydrate dissociation in the Cubic Hydrate Simulator (CHS). This method uses the thermal huff and puff method in a five-spot well system. In addition, the experiments with the methods of the five-spot thermal huff and puff in conjunction with depressurization (HP-5S-D), the heat stimulation with a five-spot well (HS-5S), the heat stimulation in conjunction with depressurization with a five-spot well (HS-5S-D), the thermal huff and puff (HP), and the huff and puff in conjunction with depressurization (HP-D), are also carried out in this work. The energy efficiencies, thermal efficiencies, gas recoveries, and average gas production rates are used to evaluate these production methods. The analysis of hydrate decomposition shows that the thermal huff and puff method in a five-spot well system is superior to that in a single vertical well on the aspects of the energy efficiency, thermal efficiency, gas recovery, and average gas production rate. The HP-5S-D method, which can obtain the highest gas recovery, thermal efficiency, and energy efficiency, is the optimal method for hydrate production in this work.