RESEARCH ON ANTI HIGH-TEMPERATURE PERFORMANCE OF FOAM FOR DRILLING ULTRA-HIGH TEMPERATURE GEOTHERMAL WELLS

Geothermal well's formation temperature is high up to 350℃ in OLKARI area,the main drilling mode is foam drilling in the area,however,its characteristics of low pressure and high temperature may cause change of the bubble fluid phase state.At present,the anti-high temperature capability of foam fluid wasn't studied at the phase change conditions.According to the particularity of foam drilling in ultra-high temperature geothermal wells,refoaming experiments and measuring experiment of high-temperature failure time were carried out.The experiment results showed that the vesicant had good refoaming performance in a single cycle period of drilling.If phase change of foam existed in the cycle period,the vesicant could also maintain a good refoaming performance,which provided an experimental basis for phase state analysis of foam drilling fluid in ultra-high temperature geothermal wells.