Effects of vertical center well and side well on hydrate exploitation by depressurization and combination method with wellbore heating

The effects of depressurization and the combination method with wellbore heating on vertical center well and vertical side well on hydrate exploitation were investigated and compared in this study. Six combinations of experimental groups were conducted using different exploitation methods (i.e., depressurization and the combination method) and different types of wells (i.e., vertical center well and vertical double-side wells). The results show that the lower the production pressure is, the better it can generate hydrate productions. Meanwhile, it is further confirmed that the heating process can greatly increase the gas production rate of hydrates. In addition, when using depressurization within a certain exploitation range, the location of the production well has lithe impact on the effects of hydrate exploitation. However, with double-side wells using the combination method, the effect of driving force in hydrate decomposition is weakened due to the larger heat loss. Therefore, when the heating well is located close to the boundary of the hydrate deposit, the use of double-side wells is less productive than that of a center well. As a result, when using the depressurization method, the location of the production well within the exploitation zone should be as close to the coastal line as possible with a stable hydrate deposit layer. On the other hand, when wellbore heating is applied, it is suggested that the heating well should be arranged near the center of the hydrate deposit. Furthermore, it is found that there is a right-skewed bell curve shape relationship between the exploitation time and the energy generation level using the combination method.