CLAY-FREE DRILLING FLUID FOR COMPLETION OF FORMATIONS OF CONTROLLED DIRECTIONAL AND HORIZONTAL WELLS IN CONDITIONS OF ABNORMALLY HIGH FORMATION PRESSURES Russian patent published in 2012 - IPC C09K8/08 

FIELD: oil and gas industry.

SUBSTANCE: clay-free drilling fluid for completion of formations of controlled directional and horizontal wells in conditions of abnormally high formation pressures involves the following, wt %: potash or sodium formiate 10.0-50.0; Robus KK biopolymer 0.40-0.45; modified KREM amylase 1.0-1.1; water-repellent fluid "Osnova-GS" 0.25-0.30, complex lubricant KSD 1.0-1.5; water 46.65-87.35; marble powder 30-65 plus 100; barite weighting material - up to 65 plus 100.

EFFECT: providing high density of drilling fluid, required carrying-over and retaining capacity, reducing hydraulic resistances at movement, high lubricating and water-repellent properties of drilling fluid for improvement of the operating conditions of rock-destructing tool on working face; simplifying the passage of drilling string and preventing seizures in horizontal well shaft, high inhibiting and colmatation properties, low filtration rate for maintaining the stability of clay rocks forming the walls of the well at maintaining collecting properties of productive formation.

1 tbl, 7 dwg