METHOD FOR FLUSHING OF INCLINED AND HORIZONTAL WELL Russian patent published in 1995 - IPC

FIELD: drilling of oil and gas wells. SUBSTANCE: method for flushing of inclined and horizontal wells provides for pumping into well through drill string the main drilling mud with density to ensure sinking of well at balance of hydrostatic and formation pressures. Direct flushing is employed. Beginning from interval of curvature and further in drilling horizontal part of well, in each final drilling of the last 1-2 m of length of kelly, flushing is effected with mud having high cutting-carrying capacity at viscosity of 60- 80 s. Such viscosity us attained by adding to main mud of aqueous solution of hydrolyzed polyacrylamide or aqueous solution of hydrolyzed polyacrylnitrile. Used as main mud is polymer-clay mud with viscosity of 20-25 s. Aqueous solution of hydrolyzed polyacrylamide is prepared with viscosity of 100-150 s. EFFECT: trouble-free drilling of well down to design depth due to efficient flushing of bottom hole in course of rilling, increased footage per bit, improved operation of downhole motor and higher grade of cleaning of bottom hole. 4 cl, 1 dwg