METHOD OF ISOLATING UNSTABLE AND SLOUGHABLE ROCKS IN CONSTRUCTION OF INCLINED AND HORIZONTAL WELLS Russian patent published in 2012 - IPC E21B33/13 

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to oil industry and may be used in construction of inclined and horizontal wells. Proposed method comprises bottomhole flushing, injecting cementing solution, squeezing said solution and square rod reciprocation. In compliance with this invention, flushing with flushing solution is stopped, mud solution is injected, process is held to equalise pressure in the well and settle mud particles. Thereafter, flushing is resumed. In injecting cementing solution unless its outflow from drill pipes, drill string is revolved. To ensure laminar flow of cementing solution in hole annuity cementing solution is squeezed down at low rate while reciprocation of square rod is performed with amplitude of 1-3 metres.

EFFECT: stable lining.