Abnormal phenomena

Possible causes

Judgment and handling methods

Riser pressure gauge index rises suddenly

Motor sluggish

Lift the drilling tool 0.5-1m away from the bottom of the well. If the circulating pressure is correct, the WOB can be increased slowly.

Motor drive shaft stuck

Lift the drilling tool 0.5-1m away from the bottom of the well. If the circulating pressure is very high, trip out and check and replace the drilling tool.

Riser gauge index increases, but not the normal pressure drop that increases with drilling depth

Drilling ice and snow to melt the water hole or the water hole inside the drilling tool is blocked

Lift the drilling tool away from the bottom of the well. If the circulating pressure is still higher than the normal circulating pressure, the circulating flow can be changed or the drilling tool can be moved up and down. If it is not effective, check and replace the bit.

Bit wear

Continue drilling. If there is no footage, trip out and replace the bit

Stratigraphic change

Lift the drilling tool away from the bottom of the well and continue drilling if the circulating pressure is normal

Pressure gauge index slowly decreases

Pressure loss

Lift the drilling tool away from the bottom of the well. If the circulating pressure is lower than the normal circulating pressure, trip out for inspection

Loss change

Check whether the drilling fluid flow changes

No footage

Stratigraphic change

Proper change of flow and WOB within allowable range

The bypass valve is in "open" position

Lift the drilling tool away from the bottom of the well, if the circulating pressure is lower than the normal circulating pressure, the mud pump can be started and stopped twice. If it is invalid, trip out and check the bypass valve

Motor sluggish

Lift the drilling tool 0.5-1m away from the bottom of the well. If the circulating pressure is correct, increase the WOB slowly

Cardan shaft damaged

With pressure fluctuation, if the screw drilling tool is lifted, the pressure fluctuation range will be reduced, trip out for inspection and replace the drilling tool

Bit wear

Circulation pressure is normal, Pooh check and replace drilling tools