METHOD FOR CONTROLLING THE LOWER STRING FOR DESCENT Russian patent published in 2022 - IPC E21B33/35 E21B34/16 

FIELD: petroleum and gas industry.

SUBSTANCE: method for controlling the lower string for descent includes: closing the lower ball valve of the testing subsea Christmas tree assembly and the shutoff valving of the bypass valve, ensuring cutting of the rope/cable/flexible tubing; activating the emergency disconnection mechanism, ensuring the planned disconnection of the lower string for descent; closing the shutoff valving of the testing subsea Christmas tree assembly, ensuring emergency plugging of the borehole; closing the shutoff valving of the testing subsea Christmas tree assembly, shutoff valving of the bypass valve, followed by activating the emergency disconnection mechanism, ensuring emergency disconnection of the lower string for descent; activating the backup control of the lower string for descent using the internal hydraulic service line in case of loss of control signals supplied to the lower string for descent, ensuring activation of the emergency disconnection mechanism with disconnection thereof and disconnection of the tool for descent and ascent of the tubing suspension.

EFFECT: ensured increase in the safety in case of emergency disconnection of equipment as a result of emergency situations.

1 cl, 1 tbl, 3 dwg