Compositions of oil-based biodegradable drilling fluids and process for drilling oil and gas wells
AssigneePetroleo Brasileiro S.A. - Petrobras
InventorsJose Thomaz Goncalves, Marcelo Fontes De Oliveira, Atila Fernando Lima Aragao
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Abstract
Compositions of oil-based biodegradable drilling fluids are described, the compositions comprising an oil phase composed by methyl esters of soybean oil fatty acids, an aqueous phase finely dispersed in the oil phase by specific emulsifiers and several other additives having specific functions for providing suitable performance to the finished drilling fluid composition. The process to manufacture the inverted emulsion and the drilling process that employs the compositions of the invention are described too.
Claims33
Compositions of biodegradable oil-based drilling fluids, the compositions being inverted emulsions specifically formulated to be compatible with the oil phase, wherein such compositions comprise, on a weight basis:
- a) of from 48 to 75% of a continuous oil phase essentially made up of fatty acid methyl esters of natural source oils;
- b) of from 22 to 42% of an aqueous phase compounded with a finely dispersed alkali metal halide;
- c) of from 2 to 8% of at least, one emulsifying agent consisting essentially of fatty acids soaps suitable to yield an oil-in-water emulsion;
- d) of from 0.5 to 1.0% of a viscosifying agent of the organophilic clays type;
- e) of from 0.1 to 0.5% of, at least, one fluid loss polymeric additive, from the class of polyacrylates and related compounds;
- f) of from 0.1 to 0.5% of, at least, one antioxidant additive as 2, 6, di-tert-butyl-p-cresol (DBPC);
- g) of from I to 3% of a metallic oxide of alkaline reaction in order to produce in situ the fatty acids soaps and provide an alkaline reserve to the compositions.
The compositions of claim I, wherein the compositions additionally comprise a pour point depressant additive.
Dependencies are inferred from the claim text.