PSEUDOPLASTIC DRILLING FLUID FOR IMPROVING WELLBORE CLEANING AND DRILLING METHOD USING IT (VARIANTS) Russian patent published in 2023 - IPC C09K8/24 C09K8/12 E21B7/00 

FIELD: drilling technologies.

SUBSTANCE: group of inventions relates to water-based drilling fluids and can be used for drilling oil and gas wells with large bit diameters, mainly in clay deposits. The technical result is an increase in the carrying capacity of the hydrodynamic fluid flow, stabilization of the walls of the wellbore when drilling clay deposits. The polycationic drilling fluid contains clay powder, water, cationic and anionic polymers to control the rheological parameters of the hydrodynamic fluid flow in the annulus, and additionally, as a component for dissolving polyelectrolyte complexes, a low molecular weight electrolyte in an amount based on the mass of the polycationic drilling fluid, wt.%: sodium chloride 2.63, or sodium nitrate 2.89 or sodium bromide 3.50 or sodium formate 5.10 or sodium sulfate 6.39 or sodium acetate 8.20 or potassium chloride 3.12 or potassium sulfate 6.96 or ammonium chloride 2.25, or ammonium acetate 6.55, or magnesium chloride 1.43, or calcium chloride 1.67, or calcium bromide 3.00. In the well drilling method according to the first variant, drilling is carried out with a bit with a diameter of 508 mm, a pump flow rate of 55 l/s and an upward flow rate in the annulus of 0.24-0.28 m/s, the above-mentioned polycationic drilling fluid with rheological properties is used as the drilling fluid in the annulus during drilling: effective viscosity at 6 rpm≥1000 mPa*s, shear stress at 6 rpm≥10 Pa. In the well drilling method according to the second variant, drilling is carried out with a bit with a diameter of 393.7 mm, a pump feed of 55 l/s and an upward flow rate in the annulus of 0.45-0.48 m/s, the above polycationic drilling mud is used as the drilling fluid with rheological indicator of hydrodynamic fluid flow in the annulus during drilling: shear stress at 20 rpm≥12 Pa.

EFFECT: increase in the carrying capacity of the hydrodynamic fluid flow, stabilization of the walls of the wellbore when drilling clay deposit.

3 cl, 6 dwg, 5 tbl