	US 12,129,423 B2
	Well conditioning method for wireline logging using dedicated aqueous based drilling fluid composition
Angelo Marinho Vianna, Rio de Janeiro (BR); Walter Francisco Cardoso Junior, Niterói (BR); Fabio Fabri, Santos (BR); Sebastiao De Andrade Loureiro, Niterói (BR); Kaio Augusto Gonzaga, Santos (BR); and Leonardo Silva De Almeida, Rio de Janeiro (BR)
Assigned to Petróleo Brasileiro S.A.—Petrobras, Rio de Janeiro (BR)
Filed by Petróleo Brasileiro S.A.—Petrobras, Rio de Janeiro (BR)
Filed on Sep. 30, 2022, as Appl. No. 17/957,912.
Claims priority of application No. 10 2021 019806 0 (BR), filed on Oct. 1, 2021.
Prior Publication US 2023/0104709 A1, Apr. 6, 2023
Int. Cl. C09K 8/12 (2006.01); C09K 8/10 (2006.01); C09K 8/26 (2006.01)

CPC C09K 8/10 (2013.01) [C09K 8/12 (2013.01); C09K 8/265 (2013.01)]

15 Claims

1. A well conditioning method comprising:

preparing an aqueous based drilling fluid with polyols wherein preparing comprises:

pre-hydrating filtrate viscosifying and reducing polymers water;

adding NaCl brine to produce a mixture;

adding polyol to the mixture;

adding a precipitating additive of Ca⁺⁺ and Mg⁺⁺ ions, a buffer additive, an alkalizing additive, and a bactericidal additive, to the mixture;

adjusting a pH of the mixture to be alkaline;

densifying the mixture to a specific mass of 1,000 kg/m³to 2,000 kg/m³;

performing rheology, filtrate, and salinity tests; and

adjusting a concentration of the filtrate viscosifying polymers and reducing polymers;

conditioning a hole, previously formed by drilling, and pumping fluid, wherein conditioning the hole and pumping fluid comprises:

pumping cushion into the hole and displacing the cushion with the aqueous based drilling fluid with polyols up to 100 m above a casing shoe of a previous drilling phase with a flow rate the same as a drilling fluid flowrate used during the previous drilling phase, wherein densifying comprises adjusting a weight of the mixture to match a weight of a previously used drilling fluid;

withdrawing a drill string by performing backreaming by pumping the aqueous based drilling fluid with polyols to the hole;

withdrawing the drill string from the casing shoe, with circulation and without rotation, by pumping the aqueous based drilling fluid with polyols at a reduced flow rate and controlled speed up to 200 meters above the shoe or according to an availability of the aqueous based drilling fluid with polyols;

after pumping the aqueous based drilling fluid with polyols, pumping 15 to 32 m³of a cushion and withdrawing the drill string in a section of the hole by pumping a fluid;

after passing the cushion through a blowout preventer, turning on a booster; and

from a pre-defined depth, completing the withdrawal of the drill string; and

conducting, after conditioning the hole, wireline logging operations within the hole with a wireline logging tool.