Effects of Hydrate Saturation and Sand-Filling Content on Hydrate Exploitation Using In-Situ Heat Supply with Chemical Reagents

The methods of gas recovery from hydrate-bearing sediments (HBS) for the earth are on further validating and field trial, which is quite far from a technical and commercial demonstration. Based on the efficient heating way to accelerate the hydrate dissociation, a new gas recovery from HBS termed the “in-situ heat generation method with chemical reagents” is proposed by our previous work, and the chemical reagent huff and puff method (CHP) can achieve better gas production and higher energy efficiency (η) and thermal efficiency (ξ) than chemical reagent thermal flooding method (CTF). In this work, the influences of the hydrate saturation and sand-filling content in a three-dimensional cylindrical hydrate simulator (CHS) on the response characteristics (including gas production, temperature change, and ξ) during hydrate exploitation via CHP with separated injection mode are obtained by laboratory experiment. The results indicate that by this method, we could obtain advantageous gas production and realize high η with ideal heat utilization by reducing the heat lost for the HBS framework. In addition, the higher hydrate saturation and more extensive sand-filling scale benefit hydrate exploitation. However, high η cannot be considered a qualitative improvement, and how to efficiently mix the chemical reagents in HBS to generate sufficient heat for hydrate dissociation has not been broken through.