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US-12625127-B2 - Field test for determining concentration of emulsifiers in drilling fluids using dyes

US12625127B2US 12625127 B2US12625127 B2US 12625127B2US-12625127-B2

Abstract

Oil-based drilling fluids can include an emulsifier to help stabilize the phases of the fluid. During repeated use, the amount of free emulsifier can become depleted. A field test can be used to determine the amount of free emulsifier in the fluid. Top oil from an aliquot from the fluid can be placed into a testing vial and mixed with an aqueous solution including a dye and optionally a pH adjuster or an acid or acidic buffer to facilitate dye transfer from the aqueous phase to the oil phase. The amount of dye transferred to the oil phase can be used to determine the amount of free emulsifier. Reference samples can be prepared with a known concentration of the emulsifier to visually compare the amount of dye transfer in the testing vial to the reference sample. Spectroscopy can also be used to compare the dye transfer in the test vial to the reference sample.

Inventors

  • Jeffrey J MILLER
  • Jay Deville

Assignees

  • HALLIBURTON ENERGY SERVICES, INC.

Dates

Publication Date
20260512
Application Date
20230331

Claims (18)

  1. 1 . A method for determining an amount of free emulsifier in a drilling fluid comprising: obtaining an aliquot of the drilling fluid, wherein the drilling fluid comprises a base oil, an aqueous phase, and an emulsifier; obtaining top oil from the aliquot; preparing an aqueous solution comprising water and a dye at a concentration by weight percent of the water; placing an amount of the top oil and an amount of the aqueous solution into a testing vial; evaluating an amount of the dye transferred from the aqueous solution phase to the top oil phase in the testing vial; correlating the amount of the dye transferred from the aqueous solution phase to the top oil phase to the concentration of free emulsifier in the drilling fluid; and determining the amount of free emulsifier in the drilling fluid based on the amount of the dye transferred from the aqueous solution phase to the top oil phase.
  2. 2 . The method according to claim 1 , further comprising: mixing the top oil and the aqueous solution in the testing vial after the top oil and the aqueous solution have been placed in the testing vial; and allowing the testing vial to remain stationary to allow any of the free emulsifier in the top oil to transport the dye from the aqueous solution to the top oil.
  3. 3 . The method according to claim 1 , wherein the emulsifier is a polyamide emulsifier.
  4. 4 . The method according to claim 1 , wherein the emulsifier has a hydrophilic/lipophilic balance greater than 3.
  5. 5 . The method according to claim 1 , wherein the water is selected from deionized water, fresh water, or water containing a water-soluble salt.
  6. 6 . The method according to claim 1 , wherein the dye is a water-soluble dye selected from fluorescein, Brilliant-Yellow, Bromocresol-Green, sodium 1,2-naphthoquinone-4-sulfonate, Thymol-Blue, Bromophenol Blue, or Clayton-Yellow.
  7. 7 . The method according to claim 1 , wherein the dye is in a concentration in a range of 0.1 to 5 wt % of the water.
  8. 8 . The method according to claim 1 , wherein the amount of top oil from the aliquot placed in the testing vial is in a range from 0.5 to 10 grams.
  9. 9 . The method according to claim 1 , wherein the amount of the aqueous solution is greater than the amount of the top oil.
  10. 10 . The method according to claim 1 , wherein the top oil is obtained from the aliquot by allowing the aliquot to settle within a collections container and withdrawing the top oil that has floated to the top of the container; centrifuging the aliquot to separate the top oil from the aqueous phase; or filtering the aliquot through a filter paper into a container and then collecting the top oil from the container.
  11. 11 . The method according to claim 10 , wherein the top oil is obtained by filtering the aliquot through the filter paper, and wherein the filter paper has a pore size in a range of 2 micrometers to 20 millimeters.
  12. 12 . The method according to claim 1 , wherein the aqueous solution further comprises a pH adjuster, an acid, or an acidic buffer.
  13. 13 . The method according to claim 12 , wherein the aqueous solution has a pH in a range of 5 to 11.
  14. 14 . The method according to claim 1 , further comprising preparing a reference sample by placing an amount of the base oil of the drilling fluid with a known concentration of the emulsifier and an amount of an aqueous solution comprising water and the dye at a concentration by weight percent of the water into a reference sample vial.
  15. 15 . The method according to claim 14 , wherein determining the amount of free emulsifier in the drilling fluid comprises visually comparing the amount of the dye transferred from the aqueous solution phase to the top oil phase in the testing vial against an amount of dye transferred from the aqueous solution phase to the base oil phase in the reference sample vial.
  16. 16 . The method according to claim 15 , wherein determining the amount of free emulsifier in the drilling fluid further comprises adding incremental amounts of the emulsifier in the drilling fluid to the testing vial until a desired amount of the dye is transferred to the top oil phase while visually comparing against the amount of dye transferred in the reference sample vial.
  17. 17 . The method according to claim 14 , wherein determining the amount of free emulsifier in the drilling fluid comprises: measuring an absorbance of the dye transferred to the top oil in the testing vial; measuring an absorbance of the dye transferred to the base oil in the reference sample vial; and comparing the absorbance from the testing vial against the absorbance from the reference sample vial.
  18. 18 . The method according to claim 17 , wherein determining the amount of free emulsifier in the drilling fluid further comprises: preparing more than one reference sample, wherein each of the reference samples are identical except for a different concentration of the emulsifier; generating a calibration curve from an absorbance from each of the reference samples; and comparing the absorbance from the testing vial to the calibration curve.

Description

TECHNICAL FIELD A field test can be used to determine the amount of emulsifier available in an oil-based drilling mud. The test can include adding a dye to a sample of the drilling fluid and visually observing whether the dye has been transported from a water phase to an oil phase, which would indicate the presence of available emulsifier present in the drilling fluid. BRIEF DESCRIPTION OF THE FIGURES The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. The features and advantages of certain embodiments will be more readily appreciated when considered in conjunction with the accompanying figures. The figures are not to be construed as limiting any of the preferred embodiments. FIGS. 1A-1F are photographs of an invert emulsion with varying concentrations of an emulsifier showing dye transfer. FIG. 2 are micrographs of the invert emulsions of FIGS. 1B-1F. FIGS. 3A-3D are photographs of invert emulsions with different base oils, different emulsifiers, and varying concentrations of the emulsifier. FIGS. 4A-4D are photographs of an invert emulsion with and without an emulsifier showing different dyes. FIG. 5A is a plot of count rate and particle size versus concentration of an emulsifier using dynamic light scattering measurements. FIG. 5B is a logarithmic plot of the data from FIG. 5A. FIGS. 6A-6C are photographs of an invert emulsion with different emulsifiers—namely TOFA, nonylphenol polyethoxylate, and (PEG)9-Diolate, respectively—showing that the dye did not transfer from the water phase to the oil phase. FIGS. 7A-7E are photographs of an invert emulsion showing the effect of pH on fluorescein dye transfer. FIGS. 8A-8D are photographs of an invert emulsion showing the effect of pH on bromophenol blue dye transfer. FIGS. 9A-9E are photographs of an invert emulsion showing the effect of pH on Clayton-Yellow dye transfer. FIGS. 10A and 10B are photographs of an invert emulsion showing potential interference in dye transfer by two different surfactants. FIGS. 11A-11G are photographs of invert emulsions using top oil from a model drilling mud system with varying ingredients and fluorescein dye or bromophenol-blue dye. FIGS. 12A and 12B are photographs of an invert emulsion with and without calcium chloride to determine the effect of salt on dye transfer. FIGS. 13A-13J are photographs of invert emulsions to evaluate the effect of acids or acidic buffers on fluorescein dye transfer. FIGS. 14A-14D are photographs of invert emulsions to evaluate the effect of acids or acidic buffers on bromophenol-blue dye transfer. FIG. 15 are photographs of invert emulsions using top oil from a field mud with and without an emulsifier. FIGS. 16A-16C are photographs of invert emulsions using top oil from a field mud with and without an acid to determine the effect of lime on dye transfer. FIGS. 17A-17D are photographs of invert emulsions using top oil from a field mud with an acid and varying concentrations of an emulsifier. DETAILED DESCRIPTION Oil and gas hydrocarbons are naturally occurring in some subterranean formations. In the oil and gas industry, a subterranean formation containing oil and/or gas is referred to as a reservoir. A reservoir can be located under land or offshore. Reservoirs are typically located in the range of a few hundred feet (shallow reservoirs) to a few tens of thousands of feet (ultra-deep reservoirs). In order to produce oil or gas, a wellbore is drilled into a reservoir or adjacent to a reservoir. The oil, gas, or water produced from a reservoir is called a reservoir fluid. As used herein, a “fluid” is a substance having a continuous phase that can flow and conform to the outline of its container when the substance is tested at a temperature of 71° F. (22° C.) and a pressure of one atmosphere “atm” (0.1 megapascals “MPa”). A fluid can be a liquid or gas. A homogenous fluid has only one phase; whereas a heterogeneous fluid has more than one distinct phase. A colloid is an example of a heterogeneous fluid. A heterogeneous fluid can be a slurry, which includes a continuous liquid phase and undissolved solid particles as the dispersed or discontinuous phase; an emulsion, which includes a continuous liquid phase and at least one dispersed phase of immiscible liquid droplets; a foam, which includes a continuous liquid phase and a gas as the dispersed phase; or a mist, which includes a continuous gas phase and liquid droplets as the dispersed phase. As used herein, the term “base fluid” means the solvent of a solution or the continuous phase of a heterogeneous fluid and is the liquid that is in the greatest percentage by volume of a treatment fluid. An emulsion has a continuous phase of water and immiscible liquid oil droplets as the dispersed or discontinuous phase or has a continuous phase of an oil and immiscible liquid water