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As an important tool for oil drilling, liner hanger has been highly valued in the drilling industry. The following describes the common accident prevention and treatment of liner hanger:
Analysis of causes:
(1) The annular space between the liner hanger and the technical casing is small (in particular, the annular space of the embedded slips is smaller than that of the normal slips), which causes the circulating pressure to be too high and the liner hanger to open in advance;
(2) In the drilling process, the slip movement caused by casing deformation or mud accumulation at the slip or the hydraulic cylinder will lead to hanging.
Treatment:
If the casing has been run to the allowable depth, the cementing can be disengaged in situ; if not, pull out the casing immediately.
Preventive measures:
(1) Strictly control the circulating pump pressure and circulate with small displacement before hanging;
(2) Adjust the mud property, and carry out casing scraping to prevent falling objects.
Analysis of causes:
(1) The abnormal shear pressure of the hydraulic cylinder pin causes that the hydraulic cylinder cannot go up and the hanger is not opened;
(2) Slip failure, hanging failure, or the casing slips during cementing for its temporarily hanging;
(3) The hanger slip cannot be opened in that the ball seat is eroded, and the pressure can not be held up after the ball is cast.
Treatment:
(1) In case of hanging failures, the hanging position can be changed or the pressure-hold value can be increased for hanging again. If the hanging is invalid, the casing shall be put to the bottom of the well and be disengaged before cementing;
(2) If it is not allowed to put the casing into the shaft bottom, then pull out the casing immediately.
Preventive measures:
(1) The double cone and double hydraulic cylinder hanger can be used to increase the hanging reliability;
(2) Professional processing of slips and other key components can improve reliability.
Analysis of causes:
(1) The liner hanger cannot disengage due to the sticking of the reverse thread;
(2) The sheer value of the hydraulic release pin is abnormal.
Treatment:
(1) If it is difficult to back off, it is necessary to readjust the down pressure and then try again. If it is impossible to back off again, the casing shall be pulled out immediately;
(2) After repeatedly building the pressure, if it is still unable to be disengaged, the emergency release shall be adopted; if it still cannot be disengaged, trip out immediately.
Preventive measures:
(1) Carry out surface treatment for the reverse thread, apply lubricating oil during the installation, control the make-up torque, and disassemble for several times during the installation;
(2) Check the shear pin pressure carefully.
