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 degrees C and well pressure of 0.1P(0), 0.2P(0) (P-0 is the initial pressure of the reservoirs, simplifying 42 degrees C & 0.1P(0), 42 degrees C & 0.2P(0)). While the production behavior of 42 degrees C & 0.5P(0), 42 degrees C & 0.8P(0) 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 x 10(5) m(3) gas would be collected within 4500 days and 1.1 x 10(6) kg water could be produced within 1500 days in the well at 42 degrees C & 0.1P(0). 3.5 x 10(5) m(3) gas would be collected within 8500 days and 1.1 x 10(6) kg water could be produced within 1500 days in the well at 42 degrees C & 0.2P(0). The heat flow was 1620W at the beginning and then decreased rapidly in the two cases. For reservoirs of 1495.2 m in length, about 6.7 x 10(8) m(3) and 5.3 x 10(8) m(3) gas would be collected in the well corresponding to conditions of 42 degrees C & 0.1P(0), and 42 degrees C & 0.2P(0). (C) 2013 Elsevier Ltd. All rights reserved.