Water Control Gel for High Temperature Geothermal Reservoir Using Hydrothermal Process of Hectorite.

Abstract

Hectorite is a smectite clay having an ideal composition of Na0.33 (Mg2.67Li0.33) Si4O10 (OH) 2·nH2O, which has been used as an effective colloidal dispersion system due to its favorable rheological properties.When amorphous slurry comprising approximately 2-5 weight % of hectorite composition, which is prepared from sulfuric-acid solved water glass mixed with aqueous solutions of MgC12, LiOH and NaOH, is hydrothermally treated at 150-350°C conditions for 1-2 hour, viscous hectorite gel is formed above 200°C: the process may be applicable to water control of flowing and/or plugging in the geothermal reservoir fractures. Laboratory test for a water control system has been carried out using a simulator, a newly designed thermal gradient-type reactor. The results are satisfied: the flow path between the granite fragments filled in the reactor is plugged with hectorite gel formed by hydrothermal process of amorphous slurry comprising 2 weight % of hectorite compositon at 200°C and 250°C conditions.Such gel material for the underground high temperature conditions may be useful to make design of extracting huge geothermal energy through artificial fractures developed in the hot dry rock.