Adaptability Of Hydrate Reservoir Developing Method And Economic Evaluation

Natural gas hydrate,as a new kind of green energy resource,has high calorific value,big reserves and wide distribution.Due to its obvious advantage,gas hydrate has been widely researched by national governments and research institutions in recent years.The study of how to economically and effectively develop gas hydrate is a hotspot in energy consumption.On the basic of different gas hydrate types,to build gas hydrate models that developed by depressurization,only heat injection and the combination of depressurization and heat injection by CMG-STARS respectively.Then contrast these three developing methods from production evaluation and economic evaluation to confirm the adaptability of different types of hydrate reservoir.Class 1 hydrate deposits are based on Messoyakha hydrate gas field,which includes Class 1(G)and Class 1(W).The results suggest that three developing methods can all get high cumulative gas,decomposition recovery efficiency and economic benefit,but due to high gas-to-water ratio,lower capital cost,shorter payback period and higher FNPV for depressurization,so the adaptability for Class 1(G)hydrate deposits is depressurization.For Class 1(W)hydrate deposits,even heat injection can improve decomposition recovery efficiency and decomposition rate,get higher cumulative gas,but take the economic and technology into consideration,the adaptability for Class 1(W)hydrate deposits is depressurization.Class 2 hydrate deposits are base on Mallik hydrate gas field,the results shows that heat injection can improve decomposition rate for hydrate,but for higher cost,lower energy utilization and gas-to-water ratio,only depressurization can get economic benefits,so the adaptability for Class 2 hydrate deposits is depressurization.Class 3 hydrate deposits are base on Qilian Mountain permafrost zone,for these three developing methods,all have shown low decomposition rate,unconspicuous heat injection effects,no economic benefits,then to contrast depressurization,it can get high cumulative gas and keep high gas-to-water radio,to the combination of developing factors and economic factors,the adaptability for Class 3 hydrate deposits is depressurization.On this basis,the economical sensitivity analysis of geological parameters were performed,including permeability,initial temperature and hydrate saturation.Results shows Class 1 hydrate deposits can get economic benefits at different geological conditions;Class 2 hydrate deposits can get economic benefits at higher permeability which is greater than 500 md,higher initial temperature which is higher than 7?,medium and low hydrate saturation which is lower than 0.6.Class 3 hydrate deposits can get economic benefits at higher permeability which is greater than 500 md,low hydrate saturation which is lower than 0.4.