Clay Minerals, Fluid Inclusions and Stabilized Temperature Estimation in Two Wells from Los Azufres Geothermal Field, Mexico

Abstract

The of this work is to test the application of different geothermometers on the same samples from two wells from the same reservoir and to compare the obtained results. Wells A23 and A9 were chosen because they intersect a thick layer of rhyolites and andesites respectively, The clay minerals consist of: kaolinite, smectite and illite in the rhyolites and smectite, illite and chlorite in the andesites. Fluid inclusions in quartz contain low salinity waters and have homogenization temperatures of up to 345?C in the deepest samples. T,, increases as a function of depth, except in well A23 between 500m and where the temperature remains almost constant, prohahly due to convection. The stabilized temperatures were estimated by mathematical simulation using temperature logs. For comparison, results were summarized in graphs. Based on the relative proportion of clay minerals it is possible to define ranges of temperature and to draw a thermal profile which is plotted and compared with those given by fluid inclusions, present-day measurements and by stabilized temperatures. Results indicate that microthermometry may overestimate actual temperatures although ad underestimation of actual temperatures is also possible.