Modified carbon black for oilfield fluids

• US 10,450,493 B2
• Filed: 03/26/2015
• Issued: 10/22/2019
• Est. Priority Date: 03/28/2014
• Status: Active Grant

• Current Assignee: Cabot Corporation
• Original Assignee: Cabot Corporation
• Inventors: Step, Eugene N., Natan, Michael J.
• Primary Examiner(s): Washville, Jeffrey D
• Application Number:
  US15/127,958
• Publication Number:
  US 20170096593A1
• Time in Patent Office: 1,671 Days
• Field of Search: None
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/19 Oil-absorption capacity, e.g. DBP values
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C09C 1/56 Treatment of carbon black ; Purification
• CPC Class Codes: C09C 3/08 Treatment with low-molecular-weight non-polymer organic compounds C09C3/006, C09C3/048 take precedence
• CPC Class Codes: C09K 8/36 Water-in-oil emulsions

Abstract

Surface treated modified carbon black particles and oil-based drilling fluids are described. The carbon blacks are incorporated into the oil-based drilling fluids to reduce the electrical resistivity of the oil-based drilling fluids. The surface treated carbon blacks can include a hydrophobic organic group and are readily dispersible in oil-based drilling fluids.

Claims

1. An organic drilling fluid comprising:

an invert emulsion including a continuous organic phase and an emulsified aqueous phase;

a surface treated carbon black having a OAN structure of greater than 150 mL/100 g by ASTM D2414 and a BET surface area of less than 500 m²/g dispersed in the invert emulsion at a concentration of at least 0.5% by weight; and

wherein the carbon black includes an attached organic group comprising either a) an aryl group, an alkyl group and a C═

O group and/or C—

O—

C group, or b) a fluorinated aryl group, the organic group being attached to the carbon black at a surface loading of 0.1 to 1.5 μ

mol/m², and

wherein the conductive organic drilling fluid has a volume resistivity of either a) less than 10⁵ ohm-m or b) at least a factor of 100 less than the resistivity of the organic phase in the absence of the surface treated carbon black.

2. The organic drilling fluid of claim 1 wherein a carbon black particle is in surface contact with both the aqueous phase and the organic phase.

3. The organic drilling fluid of claim 1 including an electrically conductive network of carbon black particles and aqueous phase droplets.

4. The organic drilling fluid of claim 1 wherein the modified carbon black shows no measurable increase in particle size after 24 hours of dispersion in the drilling fluid.

5. A method of producing an electrically conductive organic drilling fluid, the method comprising:

emulsifying a brine in a non-conductive organic liquid to produce a two-phase system, the brine making up less than 40% by weight of the two-phase system;

dispersing a plurality of surface treated carbon black particles having a OAN structure of greater than 150 mL/100 g by ASTM D2414 and a BET surface area of less than 500 m²/g in the two phase system to produce the conductive organic drilling fluid; and

wherein the carbon black includes an attached organic group comprising either a) an aryl group, an alkyl group and a C═

O group and/or C—

O—

C group, or b) a fluorinated aryl group, the organic group being attached to the carbon black at a surface loading of 0.1 to 1.5 μ

mol/m², and

wherein the drilling fluid has an electrical resistivity of less than 10⁵ ohm-m, a volume resistivity at least 100 times greater than that of the organic liquid in the absence of the carbon black particles, or both.

6. The method of claim 5 comprising adding the particles to the organic liquid prior to producing the two phase system.

7. The method of claim 5 comprising adding the particles to the brine prior to producing the two phase system.

8. The method of claim 5, further comprising maintaining the dispersion of carbon black in the two phase system for at least 24 hours.