Numerical simulation of Class 3 hydrate reservoirs exploiting using horizontal well by depressurization and thermal co-stimulation

Class 3 hydrate reservoirs exploiting using horizontal well by depressurization and thermal co-stimulation was simulated using the HydarteResSim code. Results showed that more than 20% of hydrates in the reservoirs had been dissociated within 450 days at the well temperature of 42 °C and well pressure of 0.1P0, 0.2P0 (P0 is the initial pressure of the reservoirs, simplifying 42 °C & 0.1P0, 42 °C & 0.2P0). While the production behavior of 42 °C & 0.5P0, 42 °C & 0.8P0 were not so exciting. In order to understand the production character of the well in long term, the cross section of 1 m length reservoirs was simulated. Simulation results showed that 4.5 × 105 m3 gas would be collected within 4500 days and 1.1 × 106 kg water could be produced within 1500 days in the well at 42 °C & 0.1P0. 3.5 × 105 m3 gas would be collected within 8500 days and 1.1 × 106 kg water could be produced within 1500 days in the well at 42 °C & 0.2P0. The heat flow was 1620 W at the beginning and then decreased rapidly in the two cases. For reservoirs of 1495.2 m in length, about 6.7 × 108 m3 and 5.3 × 108 m3 gas would be collected in the well corresponding to conditions of 42 °C & 0.1P0, and 42 °C & 0.2P0.