BOREHOLE CONDITIONING METHOD Russian patent published in 2017 - IPC E21B33/138 C09K8/46 

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to oil and gas industry, in particular to methods of hydromechanical hardening of borehole during drilling of wells for various purposes. The method of borehole conditioning comprises the jetting by drilling fluid of borehole walls during drilling, adding of Portland cement 3-4 wt % for formation in near-borehole zone of instantly hardening cemented screen with the depth down to 50 mm, increasing the hydromechanical strength of the borehole by repression in the interval 0.3÷0.5⋅10^-1 MPa/m, and at depression - in the range 0.3÷0.5⋅10^-1 MPa/m. Hydromechanical mudding of the borehole is performed simultaneously with drilling at the discharge rate of the drilling fluid from the nozzle 30÷150 m/s with the bit speed 0.5÷2.5 s^-1 and the force of dynamic impact of the jet onto the well wall 0.12÷0.65 tf. The contact time of the jet spot and rock is 0.01÷0.001 s.

EFFECT: invention provides non-linear increase in quality and efficiency of well construction by hydromechanic strengthening of borehole up to rock pressure gradient.

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