Natural gas hydrate is widely recognized as one of the most promising clean energy alternatives with the potential to replace coal

petroleum and conventional natural gas in the 21st century. However

it still remains a major challenge to accurately analyze multi-physical field evolutions in the entire exploitation process. In this study

based on the time-updating approach

a semi-analytical model is developed within a multi-physical coupling framework. This model comprehensively considers the entire exploitation process

including both the drilling and support phases. Specifically

the proposed model is capable of analyzing the interactions between hydraulic flow

heat transfer

mechanical properties and hydrate saturations. Meanwhile

more actual mechanical properties of hydrate are incorporated in this model

such as shear expansion and strain-softening post-failure behaviours. As a verification step

a good agreement is observed between the results obtained by numerical predictions and those derived from the developed semi-analytical model. In parametric analyses

it is found that appropriately reducing the depressurization rate is beneficial for increasing gas production

while appropriately increasing the depressurization rate can enhance extraction safety. Interestingly

compared to the classical elastic-perfectly-plastic or elasto-brittle-plastic models

the developed strain-softening model can significantly improve the predicting ability to assess the safety performance during the extraction process.