Gas lift reverse circulation drilling technology for D19 well in broken thermal reservoir in Xiong’an New Area

Abstract:

Well D19 is an exploration hole in the geothermal clean energy survey and evaluation project in Xiong’an New Area. Drilling was completed at 4021.78m， penetrating two thermal reservoirs each in Wumishan Formation and Gaoyuzhuang Formation. Gas lift reverse circulation drilling was used to deal with serious leakage of the thermal reservoirs and protect the thermal reservoirs. The drilling equipment was selected， and the setting depth of the dual wall drilling string and the air volume were tested and optimized. In view of the drilling difficulty due to blockage in the return （cuttings） channel encountered in complex broken strata in the process of gas lift reverse circulation drilling， an anti-blocking inlet sub suitable for the reverse circulation drilling broken strata with protection of the inlet （cuttings） port have been developed. It effectively solved the blockage difficulty with gas lifting reverse circulation drilling in broken formation， and the drilling job was successfully completed. The gas lift reverse circulation drilling process for extremely broken thermal reservoir has been improved， which lays a foundation for the application and promotion of the gas lifting reverse cycle drilling process in broken thermal reservoirs.

Key words:clean energy survey;broken thermal reservoir;gas lift reverse circulation drilling;anti-blockage inlet sub;Xiong’an New Area