Method for selective extraction of surfactants from crude oil

Patent metadata

Field	Value
Publication number	US-10883055-B2
Application number	US-201815935471-A
Country	US
Kind code	B2
Filing date	Mar 26, 2018
Priority date	Apr 5, 2017
Publication date	Jan 5, 2021
Grant date	Jan 5, 2021

Abstract

A method for selective extraction of naphthenic acids from an acidic crude oil, including: providing an acidic crude oil including naphthenic acids and having a total acid number (TAN) greater than 0.4; mixing the acidic crude oil with a first aqueous solution including water and a weak base to extract a portion of naphthenic acids from the acidic crude oil thereby creating a second aqueous solution containing a mixture of the portion of naphthenic acids, the water and the weak base in an emulsion; separating the second aqueous solution from the emulsion; wherein the second aqueous solution contains an additional portion of the acidic crude oil; adding a salt to the second aqueous solution, thereby causing the additional portion of the acidic crude oil to separate from the second aqueous solution; removing the additional portion of the acidic crude oil from the second aqueous solution; and extracting the portion of the naphthenic acids from the second aqueous solution.

First claim

The invention claimed is:

1. A method for selective extraction of naphthenic acids from an acidic crude oil, comprising the following steps in order:
providing an acidic crude oil comprising naphthenic acids and having a total acid number (TAN) greater than 0.4;
mixing the acidic crude oil with an aqueous solution comprising water and a weak base to create an emulsion;
separating an excess of the acidic crude oil from the emulsion and removing the excess acidic crude oil from the emulsion to form a separated emulsion, wherein the separated emulsion comprises the water, the naphthenic acids, and a remaining portion of the acidic crude oil;
adding a salt to the separated emulsion, thereby causing the remaining portion of the acidic crude oil to separate from the separated emulsion;
removing the separated remaining portion of the acidic crude oil from the separated emulsion; and
extracting a portion of the naphthenic acids from the separated emulsion;
wherein the pH of the aqueous solution is from 10.5 to 11.5 and wherein the portion of the naphthenic acids extracted have a molecular weight from 200 to 700.

2. The method of claim 1 , wherein the pH of the aqueous solution is from 10.9 to 11.2.

3. The method of claim 1 , wherein the weak base is sodium carbonate.

4. The method of claim 1 , wherein the t is sodium chloride.

5. The method of claim 1 , wherein the extracted portion of the naphthenic acids is soluble in solutions with a pH less than 11.1.

6. The method of claim 1 , wherein the step of mixing of the acidic crude oil with the aqueous solution is carried out in a co-current or countercurrent flow or a mixing vessel.

7. The method of claim 1 , wherein the extraction of the portion of the naphthenic acids from the separated emulsion is carried out through a multistage liquid-liquid extraction using an organic solvent.

8. The method of claim 7 , wherein the organic solvent is a dichloromethane solvent.

Assignees

• Exxonmobil Res & Eng Co

Inventors

• Mohan Aruna
• Yeganeh Mohsen S
• Cherney Daniel P
• Mennito Anthony S
• Deighton Shane P
• Vreeland Jessica L

Classifications

• C10G2300/203

  Naphthenic acids, TAN · CPC title

• E21B43/20

  Displacing by water · CPC title

• C09K8/584

  characterised by the use of specific surfactants · CPC title

• C10G53/12 Primary

  including at least one alkaline treatment step · CPC title