Moridis and Reagan [132] indicated that production at a constant bottom-hole pres­sure is the most promising strategy in Class 3 hydrate deposits because it is appli­cable to a wide range of formation k, allows continuous and automatic rate increases to match the increasing keff (the result of the dissociation-caused reduction in SH), and it eliminates the possibility of ice formation through the selection of a bottom­hole pressure above that at the quadruple point of hydrates (Fig. 14).

Figure 15 shows the gas production rates from a Class 3 deposit with the proper­ties of the 18 m-thick Tigershark accumulation (see [132]) when using constant bottomhole-P depressurization. QP followed a cyclical pattern that includes long rising segments, followed by short precipitous drops (a behavior caused by the self — controlled formation and destruction of secondary hydrates around the well). It reached a maximum QP=4.3 x 105 ST m44day of CH4 (=15 MMSCFD), with an average Qavg = 2.3 x 105 ST m3/day (=8.10 MMSCFD) over the 6,000-day production period, and with manageable water production. These results indicated that gas can

be produced from Class 3 deposits at high rates over long times using conventional well technology.