WELL CONSTRUCTION METHOD Russian patent published in 2012 - IPC E21B7/00 E21B33/10 

FIELD: gas and oil production.

SUBSTANCE: well construction involves drilling and fixation of direction, conductor and intermediate or operation column. Process water is used as drilling mud in drilling of intermediate or operation column. Rock caving zone is reamed, lower zone of non-caving rock is drilled. Drilling set is lifted from the well, drilling pipe string with open end is lowered into the well. Clay drilling mud is pumped through the well and displaced to the surface by process water, drilling pipe string is rotated, cement slurry is injected into drilling pipe string. When cement slurry enters annular space, rotation is stopped, and drilling pipe string is reciprocated to 10-14 m length. Cement slurry is pushed out to annular space by process water of the same density as in the well till drilling pipe strin and annular space have the same level. Drilling pipe string is lifted from the well, process maturing is performed till cement solidification, cement bridge is reamed by the same drilling set used earlier, and well construction is continued to the project level.

EFFECT: prevented cavern formation an drilling tool seizing during drilling.