Optimization of Heat-insulating Pipes for Thermal Recovery of Heavy Oil in Bohai Sea and Optimization of Nitrogen Injection Technology

The thermal recovery wells in Bohai Oilfield have been subjected to multiple rounds of thermal recovery, and optimizing wellbore insulation technology has become one of the most critical technologies in thermal recovery steam injection. At present, the A23 well in the L oilfield of Bohai Oilfield has carried out three rounds of steam stimulation on-site operation, and the third round of steam injection has been optimized and improved on the basis of the second round of steam injection, using 4-1/2″ aerogel insulated tubing steam injection. Comparing with high vacuum insulated tubing used in the second round of Well A23, the second steam injection effectively reduces the heat loss per kilometer of insulated tubing from 14.24% to 10.21%. Meanwhile, the intermittent nitrogen injection process in the empty wellbore reduces the heat loss in the wellbore annulus and effectively reduces the total nitrogen injection volume by 11.86% compared with the previous round. By using aerogel insulated tubing and annulus intermittent nitrogen injection technology, the heat loss of steam injection is reduced and the cost of steam injection for offshore thermal recovery wells is effectively saved.