METHOD FOR DRILLING-IN AT CONTROLLED DRAWDOWN Russian patent published in 2018 - IPC E21B21/08 E21B44/00 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, and in particular to drilling of oil wells. Method comprises lowering a drill pipe string with a drilling bit into the well, a wellhead banding, flushing a borehole, and feeding washing liquid to the drilling bit when drilling, carrying out of researches on establishment of drilling modes, establishment of an optimum charge of a washing liquid according to the schedule. For the plotting of the data from neighboring wells, the average productivity coefficient is determined, and dependence of the wellhead pressure on the bottom-hole pressure on several modes of the same wells is established. Optimum drilling mode is selected according to the graphs of these dependencies at the point of intersection of the flow characteristic of the reservoir with the flow characteristic of the well, and drilling is performed by controlling the wellhead pressure such that the well rate is 30÷50 % of the maximum well rate of neighboring wells.

EFFECT: quality of drilling-in is increased, the bottom hole colmatation is prevented, its initial permeability is maintained.

1 cl, 2 dwg