Potential for enhanced energy production by periodic pressure stimulation of the production well in an HDR reservoir.

摘要

The results obtained by briefly shutting off flow to induce a periodic pressure rise in the production well of an HDR (Hot Dry Rock) system indicates the thermal power production of a reservoir can be enhanced by this cyclic mode of operation. An experiment designed to test this hypothesis of enhanced energy production was executed at Fenton Hill, in New Mexico. The experiment was conducted by closing the production wellhead valve for a 25 minute interval at a standard time on each of three consecutive days during a flow test that had previously been operating at nearly steady state with continuous injection and production. The pressure rise resulting from temporarily halting the production flow caused an increase in the subsequent flow rate after reopening the wellhead valve each day. The enhanced flow more than compensated for the production lost during the daily wellhead shut-in and the rate of flow remained at an elevated level 24 hours later. Consequently, the rate of thermal energy production increased as compared to the thermal power production during continuous circulation, and the integrated quantity of energy removed from the reservoir on a daily basis also increased. In addition, the rate of production flow demonstrated a hysteretic effect resulting in more total production from the reservoir on each consecutive day of periodic pressure stimulation. Thus, the total energy production from the reservoir increased on consecutive days dining the experiment. These results show the potential value for further cyclic-mode evaluation of HDR reservoirs.