## 1 Introduction  
Natural gas hydrates (NGHs) are compact crystalline substances from the combination of water and gas [1]. Deep sea and permafrost geological environments are suitable places for the formation and occurrence of hydrates [1; 2; 3]. NGH resources are considered a significant alternative energy source for future global sustainable development [3; 4]. The recent offshore NGH trial production completed in the South China Sea (SCS) and Japan's Nankai Trough verified the efficiency of the depressurization method, but their production capacity is still far below the standard for industrial development [5; 6; 7; 8; 9]. To achieve industrial development of NGHs, various studies likewise contribute relevant information and background on environmentally friendly, safe, and efficient exploitation of NGHs (e.g., [PERSON] et al., 2019; [PERSON] et al., 2019; [PERSON] et al., 2021) [10; 11; 12]. Currently, the most promising method for achieving industrial development is the complex structured well or well-pattern production mode combined with the composite production method (such as assisted-thermal extraction) and/or reservoir stimulation technologies (such as hydraulic fracturing) [13]. The depressurization-assisted thermal extraction method can be divided into two categories as follows: one is fluid-assisted thermal mining methods (suchas hot water injection, geothermal assistance, etc. ), and the other is non-fluid assisted thermal mining methods (such as electric heating, microwave heating, in situ backfill heating, etc.) [13]. The fluid-assisted thermal mining method is prone to forming high-pressure injection zones, which inhibits hydrate dissociation and makes injection in low-permeability reservoirs problematic; the method also has the problem of significant heat loss [13]. The non-fluid-assisted thermal mining method is less likely to cause reservoir instability and other issues and is thus especially suitable for low-permeability reservoirs [13]. In recent years, the non-fluid-assisted thermal mining method has attracted a lot of attention and research effort. For example, [PERSON] et al. (2018) conducted a sensitivity analysis on the dissociation front of hydrates under the conditions of depressurization combined with wellbore heating [14]. [PERSON] et al. (2021) used depressurization assisted with the heating method to extract Class 2-type hydrate reservoirs, and their numerical results confirmed the efficiency of the method [15]. [PERSON] et al. (2021) numerically validated the effectiveness of extracting NGHs by depressurization combined with in situ backfilling CaO powder [16]. [PERSON] et al. (2021) found that when using the five-point method to extract hydrate reservoirs, the recovery rate of hot water injection was almost the same as that of electric heating combined with water injection, with only wellbore heating suitable for low-permeability hydrate reservoir extraction [17]. [PERSON] et al. (2021) analyzed the production performance of the NGHs in the SCS using a mathematical model of low-frequency electric heating and depressurization (LF-EHAD). Their results showed that after more than 5 years of continuous production, the gas production of LF-EHAD is 2.37 times that of depressurization [18]. [PERSON] et al. (2022) found that intermittent heating has higher energy utilization efficiency than continuous heating in depressurization-assisted thermal for extracting hydrates [19]. [PERSON] et al. (2022) numerically validated the effectiveness of using LF-EHAD to develop Class 1-type hydrate deposits with five-point wells [20]. [PERSON] et al. (2022) found that microwaves can quickly respond to the energy demand for hydrate dissociation [21]. [PERSON] et al. (2022) discovered that combining brine flooding and electric heating can result in low heat loss and enhanced thermal convection [22]. [PERSON] et al. (2023) numerically compared the recovery efficiency of different assisted heating methods under dual horizontal well depressurization mining.