DEALING WITH COMPLEX CONDITIONS ON WELL SHUANGMIAO-1 WITH BOTH LOST CIRCULATION AND UNDERGROUND BLOWOUT

The Well Shuangmiao-1 is a complex high pressure gas well with multi-pressure systems, multi-thief-zones, with lost circulation at upper formation and underground blowout at deeper formation. Cement plugs and bridge plugs had been attempted many times with cement added to stop the circulation loss without avail. And due to the lost circulation, the low hydraulic pressure resulted inside the wellbore, the bridge plug used to isolate the upper thief zone was forced out and the bit got blocked. Because the ram BOP had been working under high pressure for long time, and also had ever been pierced by solids carried in high pressure gas stream, the wellhead safety was seriously threatened. Therefore a new polymer LCM and special gelling additives were tried before the cement slurry for plugging, in one operation the thief zones and the annulus below the major thief zone and above the bit were finally blocked. The well logging showed cement sheath formed from 2250m to 3200m, slurry returns to 2355m, and a special gel column of 100m high formed in the annulus from return cement top to the thief zone. The complicated conditions with lost circulation and underground blowout on this well can thus be changed in a better way.