WELL CONSTRUCTION METHOD Russian patent published in 2020 - IPC E21B7/00 E21B21/00 

FIELD: construction.

SUBSTANCE: invention relates to construction of wells and can be used during well drilling through flushing fluid loss zone. Method of well construction involves rotation and axial feed of layout with bit and supply of flushing fluid through inner cavity of layout to face, drilling, not reaching productive formation. When drilling during planting of 3–10 t during lowering of assembly with bit, well is flushed with reciprocating in places of planting by length of drive pipe at a rate of up to 30 m/h and consumption of up to 40 l/s for at least 1 cycle of natural water suspension to possibility of continuing descent. Drilling is stopped, not reaching 1–50 m to roof of productive formation at absolute elevations, based on strength of roof and properties of formation. Well is analysed through a drill string with well head insulation immediately after drilling is stopped at pressure lower than the allowable one for the given well. Well is analysed by injection of service water in at least two modes. Pressure boost is increased in each subsequent mode, constant pressure is maintained constant, delivery pressure and injection volume are fixed for each mode, well permeability coefficient is calculated as a quotient of dividing difference of volumes of injected fluid at next and previous modes to difference of fluid injection pressures at next and previous modes. Intake factor is taken to be the arithmetic average of the pickup ratio at three or more pumping modes after determining the pick-off ratio between the next and previous modes. At intake ratio equal to or higher than 0.6, waterproofing operations are performed, associated with descending of pipe string with packer, which successively from bottom to top is installed above each interval of the absorption zone with pumping through the pipe string to the zone of absorption of clay solution containing inert filler, forcing it with drilling fluid at pressure below the allowable value for the well and to obtain an injectivity of not more than 0.6. Each time after packer removal and before each subsequent installation, the well is flushed with a natural water suspension in volume, which ensures complete cleaning of the well in the packer setting interval. Before lowering drilling assembly and drilling for opening productive formation well is filled with drilling fluid with required for given formation density, conditional viscosity and filtration, containing lubricating additives, followed by washing. After the productive formation is opened into the well, the casing string is lowered and cemented with filling of its annular space along the whole length.

EFFECT: elimination of emergency situations, reduction of time costs, high-quality installation of the casing string and cementing of its cotyledon space.

1 cl