METHOD OF WELL DRILLING Russian patent published in 2017 - IPC E21B21/00 E21B7/00 

FIELD: construction; mining.

SUBSTANCE: invention relates to construction of wells and can be used during well drilling through flushing fluid loss zone. To implement the method a pipe string with a packer is lowered, the packer is placed above the lower interval of the loss zone. When the pipe string with the packer is lowered in case of slacking-off up to 3 ton the lowering is stopped, the well is washed with no reciprocation of the pipe string with the flow rate of up to 15 l/sec during 1.5 cycle, the lowering is continued. Before each injection via the pipe string to the loss zone before each packer setting the well is washed for 1.0–1.5 cycle with a natural water suspension. Setting of the packer is performed in the natural water suspension, after the setting the well is examined by pumping with process water on at least two modes, increased is the injection pressure at each subsequent mode, kept constant is the injection pressure, registered is the injection pressure and the volume for each mode, the well injection capacity coefficient is calculated as a quotient of division of the difference of volumes of the pumped liquid on the next and on the previous modes to the pressure difference of pumping the liquid on the next and the previous modes. When the intake capacity coefficient is up to 0.4 insulation works are not performed. When the intake capacity coefficient is from 0.4 to 1.0 the drilling fluid is pumped with sawdust or rubber crumb, when the intake capacity coefficient is from 1.0 to 1.5 the drilling fluid is pumped with sawdust and/or cord fibre, when the intake capacity coefficient is from 1.5 to 2.0 the drilling fluid is pumped with cord fibre and motes, when the intake capacity coefficient is from 2.0 to 2.5 the drilling fluid is pumped with motes with further pumping of the drilling fluid with cord fibre, the pumping is performed to the loss termination pressure, and prior to lowering the drilling assembly and the well drilling-in the well is filled with the drilling fluid with the density of 1.35 g/cm³, the relative viscosity of 25–60 c, the filtration of 1–2 cm³/30 min, pH=8–9, containing oil up to 10 %, washing during 1.5 cycle and lifting the drilling tool with the well make-up every 250–300 m of the lifting.

EFFECT: expanded range of the loss isolation in the well.

1 cl