# US 10,767,474 B2 · Surfactant selection methods for wetting alteration in subterranean formations

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- Number: US 10,767,474 B2
- Document ID: US10767474B2
- Status: Granted
- Kind: B2
- Application number: 15/512,724
- Filed: 2014-11-13
- Published: 2017-10-12
- Granted: 2020-09-08
- Earliest claimed: 2014-11-13
- Assignees: Multi-Chem Group, LLC
- Applicants: Multi-Chem Group, LLC
- Inventors: Lijie Feng; Liang Xu
- Web page: https://patentgrep.com/patent/US10767474B2

## CPC

- E21B 49/08: Obtaining fluid samples or testing fluids, in boreholes or wells
- C09K 8/584: characterised by the use of specific surfactants
- C09K 8/602: {containing surfactants}
- E21B 21/062: {by mixing components}
- E21B 43/16: Enhanced recovery methods for obtaining hydrocarbons
- E21B 43/25: Methods for stimulating production {(by vibrating earth formations E21B43/003)}
- G01N 33/2823: {Raw oil, drilling fluid or polyphasic mixtures}
- E21B 43/168: {Injecting a gaseous medium}
- E21B 43/20: Displacing by water
- E21B 43/24: using heat, e.g. steam injection
- E21B 43/26: by forming crevices or fractures
- E21B 43/267: reinforcing fractures by propping
- E21B 49/081: {with down-hole means for trapping a fluid sample (E21B49/10 takes precedence)}
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Systems and methods for selecting surfactants for use in subterranean formations are provided. In one embodiment, the methods comprise: providing a sample of oil from at least a portion of a subterranean formation; measuring at least one of the total acid number (TAN) and the total base number (TBN) of the oil sample; and selecting a set of surfactants to evaluate for a treatment in at least a portion of the subterranean formation based on at least one of the TAN and the TBN of the oil sample, the set of surfactants selected from the group consisting of: a set of cationic surfactants, a set of anionic surfactants, and a set of zwitterionic surfactants.

## Claims

### Claim 1

A method comprising:
providing a sample of oil from at least a portion of a subterranean formation;
determining the total acid number (TAN) and the total base number (TBN) of the oil sample by measuring the TAN and the TBN at a site where a well bore penetrating at least a portion of the subterranean formation is located, wherein the TAN of the oil sample is greater than the TBN of the oil sample;
based on the TAN of the oil sample being greater than the TBN of the oil sample by a difference of about 3.02 or greater, evaluating two or more cationic surfactants for a treatment in at least a portion of the subterranean formation without evaluating any anionic surfactants for the treatment in the portion of the subterranean formation; and
introducing a treatment fluid into the subterranean formation at or above a pressure sufficient to create or enhance at least one fracture in the subterranean formation, the treatment fluid comprising at least one of the two or more cationic surfactants.

### Claim 2 (depends on 1)

The method of claim 1 further comprising allowing molecules of the cationic surfactant introduced into the subterranean formation to form ion pairs with one or more anionic compounds in oil adsorbed onto a rock surface in a portion of the subterranean formation.

### Claim 3 (depends on 1)

The method of claim 1 wherein at least one of the TAN and the TBN are measured at a laboratory at a site where a well bore penetrating at least a portion of the subterranean formation is located.

### Claim 4 (depends on 1)

The method of claim 1 wherein the treatment fluid is introduced into the subterranean formation using one or more pumps.

### Claim 5 (depends on 1)

The method of claim 1 wherein the subterranean formation comprises rock selected from the group consisting of: sandstone, limestone, shale, clay, and any combination thereof.

### Claim 6

A method comprising:
providing a sample of oil from at least a portion of a subterranean formation;
determining the total acid number (TAN) and the total base number (TBN) of the oil sample by measuring the TAN and the TBN at a site where a well bore penetrating at least a portion of the subterranean formation is located, wherein the TBN of the oil sample is greater than the TAN of the oil sample;
based on the TBN of the oil sample being greater than the TAN of the oil sample by a difference of about 0.45 or greater, evaluating two or more anionic surfactants for a treatment in at least a portion of the subterranean formation without evaluating any cationic surfactants for the treatment in the portion of the subterranean formation; and
introducing a treatment fluid into the subterranean formation at or above a pressure sufficient to create or enhance at least one fracture in the subterranean formation, the treatment fluid comprising at least one of the two or more anionic surfactants.

### Claim 7 (depends on 6)

The method of claim 6 further comprising allowing molecules of the anionic surfactant introduced into the subterranean formation to form ion pairs with one or more cationic compounds in oil adsorbed onto a rock surface in a portion of the subterranean formation.

### Claim 8 (depends on 6)

The method of claim 6 wherein at least one of the TAN and the TBN are determined by measuring at least one of the TAN and the TBN at a laboratory at a site where a well bore penetrating at least a portion of the subterranean formation is located.