TECHNOLOGY OF STUCK PIPE FREEING USING GAS-LIFT METHOD IN QX-7 WELL

Exploratory QX-7 well was a sidetrack two-targets directional well with designed bottom depth of 3389 m, maximum deviation of 53°and horizontal displacement of 952 m. A differential pressure sticking was encountered at 2598 m under a circumstances of severe sloughing, and with enlarged hole gauge and dog-leg intervals during a pipe connection. After two spotting operations with water based spotting fluid and bore hole washing with a drilling fluid with lowered specific gravity were failed to eliminate the problem. A technology of gas-lift was applied successfully to free the stuck. The mechanism and engineering steps of freeing technology by gas-lifting and pressure lowering were described in the paper. The advantages of this technology are effective, low cost, simple and fast without influence to change the drilling fluid properties.