Well conditioning method for wireline logging using dedicated aqueous based drilling fluid composition
AssigneePetroleo Brasileiro S.A. - Petrobras
InventorsAngelo Marinho Vianna, Walter Francisco Cardoso Junior, Fabio Fabri, Sebastiao De Andrade Loureiro, Kaio Augusto Gonzaga, Leonardo Silva De Almeida
Life of this patent
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Abstract
The present invention addresses to a wireline logging method using an aqueous based drilling fluid with xanthan gum and polyols in order to improve the quality of the acquisition of geological data from wireline logging (final logging) in open hole and reducing the risk of the tool getting stuck. It can also be applied in well control situations and used in the integral drilling of the reservoir, but with different application bias of the multifunctional fluid.
Claims13
A WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION, characterized in that there is the combination of technology and fluid conditioning comprising the following steps:
- a) Preparation of the aqueous fluid with polyols according to the following steps:
- a.1) Pre-hydrate the filtrate viscosifying and reducing polymers with reduced concentrations in industrial water;
- a.2) Add the NaCl brine;
- a.3) Add the polyol to the mixture with prehydrated polymers in a.1);
- a.4) Add precipitating additive of Ca++ and Mg++ ions, buffer additive, alkalizing additive, and
- bactericidal additive, in the composition, and consider the use of defoamer, if foam formation is evidenced;
- a.5) Adjust the pH in the alkaline range;
- a.6) Densify to a specific mass of not less than 1,000 kg/m3;
- a.7) Carry out rheology, filtrate and salinity tests;
- and
- a.8) Adjust the concentration of filtrate viscosifier and inhibitor polymers;
- b) Open holes conditioning and fluid pumping:
- b.1) At the end of the drilling, pump a viscous cushion, a fluid with a rheology superior to that of the active system indicated by the viscometer reading at 3 RPM equal to or greater than 20 degrees, at the bottom and displace with aqueous fluid with polyols with the same weight as the drilling up to 100 m above the casing shoe of the previous phase with drilling flow rate;
- b.2) Withdraw the drill string by performing backreaming by pumping aqueous fluid with polyols to the cased hole;
- b.3) From the casing shoe, withdraw the drill string with circulation and without rotation by pumping the aqueous fluid with polyols at a reduced flow rate and controlled speed up to at least 200 m above the shoe or according to the availability of aqueous fluid with polyols;
- b.4) At the end of pumping the aqueous fluid with polyols, pump 15 to 32 m3 of viscous cushion, a fluid with a rheology superior to that of the active system indicated by the viscometer reading at 3 RPM equal to or greater than 20 degrees, and proceed with the withdrawal of the string in a cased hole by pumping the fluid from the system;
- b.5) After passing the viscous cushion through the BOP, turn on the booster;
- b.6) From the pre-defined depth, complete the withdrawal of the string.
Dependencies are inferred from the claim text.