Imitating possible consequences of drilling through marine hydrate reservoir

Abstract

During the exploitation of marine hydrate, initial pressure-temperature condition of the reservoir will change. If the temperature of hydrate reservoir is increased beyond hydrate stability limit hydrate will dissociate. This in the worst case may lead to uncontrolled safety risks. Aiming at this problem, we investigate the effect of temperature increase on methane hydrate stability by forming hydrate in a Bentheim sandstone core. The amount and rate of hydrate decomposition are obtained experimentally under 24 different temperature and pressure conditions. When the temperature is increased higher, decomposition rate increases, then destruction rate of reservoir increases and its stability decreases faster. Increasing the same temperature has less effect on hydrate reservoir under higher pressure. Finally, results from the experiments are utilized in the case analysis of actual hydrate reservoir drilling. The consequences and risks caused by temperature increase of hydrate reservoir during drilling are assessed and analyzed. When the actual temperature is higher than the hydrate phase equilibrium temperature, hydrate decomposition rate will increase exponentially with the continuous increase of temperature. This study innovatively examine possible consequences of increased temperature on hydrate destabilization, which will have great significance to prevent uncontrolled decomposition in marine hydrate reservoir drilling and ensure construction safety.