Method for determining the extent of recovery of materials injected into oil wells during oil and gas exploration and production

• US 20030006036A1
• Filed: 05/23/2002
• Published: 01/09/2003
• Est. Priority Date: 05/23/2001
• Status: Active Grant

• Current Assignee: Core Laboratories LP (Core Laboratories NV)
• Original Assignee: Core Laboratories NV
• Inventors: Broacha, Earuch, Malone, Scott, Hampton, Tom, Shaw, Don
• Granted Patent: US 6,659,175 B2
• Time in Patent Office: Days
• US Class Current: 166/250.12
• CPC Class Codes: C09K 8/035 Organic additives
• CPC Class Codes: E21B 47/11 using tracers; using radioactivity
• CPC Class Codes: E21B 49/08 Obtaining fluid samples or testing fluids, in boreholes or wells
• CPC Class Codes: Y10S 507/907 Indicating means, e.g. dye, fluorescing agent
• CPC Class Codes: Y10S 507/924 with specified propping feature

Abstract

Disclosed is a method of determining the extent of recovery of materials injected into a oil well comprising the steps of: a) preparing a material to be injected into an oil well; b) admixing therewith a chemical tracer compound at a predetermined concentration; c) injecting the admixture into an oil well; d) recovering from the oil well a production fluid; e) analyzing the production fluid for the concentration of the chemical tracer present in the production fluid; and f) calculating the amount of admixture recovered from the oil well using the concentration of the chemical tracer present in the production fluid as a basis for the calculation. Fluorinated benzoic acids are disclosed as a preferred tracer.

Claims

1. A method for determining the extent of recovery of materials injected into a oil well comprising the steps of:

a) preparing a material to be injected into an oil well;

b) admixing therewith a chemical tracer compound at a predetermined concentration;

c) injecting the admixture into an oil well;

d) recovering from the oil well a production fluid;

e) analyzing the production fluid for the concentration of the chemical tracer present in the production fluid; and

f) calculating the amount of admixture recovered from the oil well using the concentration of the chemical tracer present in the production fluid as a basis for the calculation.

2. The method of claim 1 wherein the tracer is selected from the group consisting of fluorinated benzoic acids, perfluoromethylcyclopentane (PMCP), perfluoromethylcyclohexane (PMCH), perfluorodimethylcyclobutane (PDMCB), m-perfluorodimethylcyclohexane (m-PDMCH), o-perfluorodimethylcyclohexane (o-PDMCH), p-Perfluorodimethylcyclohexane (p-PDMCH), perfluorotrimethylcyclohexane (PTMCH), perfluoroethylcyclohexane (PECH), and perfluoroisopropylcyclohexane (IPPCH).

3. The method of claim 2 wherein the tracer is a fluorinated benzoic acid.

4. The method of claim 3 wherein the fluorinated benzoic acid is selected from the group consisting of including 2-fluorobenzoic acid;

3-fluorobenzoic acid;

4-fluorobenzoic acid;

3,5-difluorobenzoic acid;

3,4-difluorobenzoic acid;

2,6-difluorobenzoic acid;

2,5-difluorobenzoic acid;

2,3-difluorobenzoic acid;

2,4-difluorobenzoic acid;

pentafluorobenzoic acid;

2,3,4,5-tetrafluorobenzoic acid;

4-(trifluoro-methyl)benzoic acid;

2-(trifluoromethyl)benzoic acid;

3-(trifluoro-methyl)benzoic acid;

3,4,5-trifluorobenzoic acid;

2,4,5-trifluorobenzoic acid;

2,3,4-trifluorobenzoic acid;

2,3,5-trifluorobenzoic acid;

2,3,6-trifluorobenzoic acid; and

2,4,6-trifluorobenzoic acid.

5. The method of claim 1 wherein the tracer is present in the mixture injected into an oil well at a concentration of at least about 1 part per trillion.

6. The method of claim 5 wherein the tracer is present in the mixture injected into an oil well at a concentration of less than or equal to 10,000 parts per million.

7. The method of claim 6 wherein the tracer is present in the mixture injected into an oil well at a concentration of from about 100 parts per trillion to about 100 parts per million.

8. The method of claim 1 wherein the material injected into the oil well is a material useful for hydraulically fracturing the oil well.

9. The method of claim 1 wherein the amount of injected admixture recovered is determined using the formula:

AMT_r=((T_r/T_i)×

AMT_i)

Wherein;

(i) AMT_r is the amount of injected admixture recovered,

(ii) T_i is the amount of tracer injected;

(iii) T_r is the amount of tracer recovered;

(iv) AMT_i is the amount of admixture injected; and

(v) T_r is determined by multiplying the concentrations of the tracer in the production fluid by the total quantity of production fluid recovered.

10. The method of claim 1 wherein the tracer is in the form of a coating on a solid support.

11. A method for determining the extent of recovery of materials injected into a oil well comprising the steps of:

a) preparing a material to be injected into an oil well;

b) admixing therewith a chemical tracer compound at a predetermined concentration;

c) injecting the admixture into an oil well;

d) recovering from the oil well a production fluid;

e) analyzing the production fluid for the concentration of the chemical tracer present in the production fluid; and

f) calculating the amount of admixture recovered from the oil well using the concentration of the chemical tracer present in the production fluid as a basis for the calculation,

wherein the tracer is a fluorinated benzoic acid.