Characterization of organic contaminants and assessment of remediation performance in subsurface formations

• US 6,321,595 B1
• Filed: 05/17/1999
• Issued: 11/27/2001
• Est. Priority Date: 01/23/1995
• Status: Expired due to Fees

• Current Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Pope, Gary A., Jackson, Richard E.
• Primary Examiner(s): Geist, Gary
• Assistant Examiner(s): Maier, Leigh C.
• Application Number:
  US09/312,755
• Time in Patent Office: 925 Days
• Field of Search: 731/523.9, 731/524.1, 731/524.2, 436/27, 436/29, 166/252.2, 166/252.5, 166/310
• US Class Current: 73/152.39
• CPC Class Codes: B09C 1/00 Reclamation of contaminated soil
• CPC Class Codes: B09C 2101/00 In situ
• 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: G01N 33/24 Earth materials G01N33/42 takes precedence

Abstract

Characterization of organic contaminants in subsurface formation is performed by methods for detecting the presence of nonaqueous phase liquid in a subsurface formation, and for determining the composition and for determining the volume of nonaqueous phase liquids. Generally the methods comprise introducing one or more partitioning tracers and one or more non-partitioning tracers at one or more injection points located in the subsurface formation and measuring separation between the one or more partitioning tracers and the one or more non-partitioning tracers from one or more sampling points located in the subsurface formation to determine presence, composition and/or volume of nonaqueous phase liquid in the subsurface formation. In addition, the methods can be used to assess the performance of an attempted remediation.

Claims

1. A method for determining a composition of nonaqueous phase liquid located in a subsurface formation and consisting of a known number n, where n is two or more, of major organic species, comprising:

(A) introducing one or more non-partitioning tracers and at least n partitioning tracers into one or more injection points located in the subsurface formation;

(B) measuring separation between the one or more non-partitioning tracers and the at least n partitioning tracers from one or more sampling points; and

(C) comparing the measured separation with a reference separation of the one or more non-partitioning tracers and the at least n partitioning tracers when contacted with nonaqueous phase liquids of known composition to determine the mole fraction of at least one major organic species of the nonaqueous phase liquid in the subsurface formation.

2. The method of claim 1, wherein two or more injection points are employed at different depths.

3. The method of claim 1, wherein two or more sampling points are employed at different depths.

4. The method of claim 1, wherein the injection point and the sampling point are the same.

5. The method of claim 1, further comprising:

performing an attempted remediation to treat or remove nonaqueous phase liquid in the subsurface formation;

repeating steps (A)-(C) to assess performance of the attempted remediation.

6. The method of claim 1, further comprising determining the volume of nonaqueous phase liquid in the subsurface formation.

7. The method of claim 1, wherein the nonaqueous phase liquid is more dense than water.

8. The method of claim 7, wherein the nonaqueous phase liquid is a chlorinated hydrocarbon, creosote or coal tar.

9. The method of claim 1, wherein the distribution of the nonaqueous phase liquid is irregular.

10. The method of claim 1, wherein the nonaqueous phase liquid is located in a substantially unconfined formation.

11. The method of claim 1, wherein one or more of the partitioning tracers are reactive tracers.

12. The method of claim 11, wherein at least one of the reactive tracers is chemically reactive.

13. The method of claim 11, wherein at least one of the reactive tracers is biologically reactive.

14. The method of claim 11, wherein a thickening agent is introduced with the tracers.

15. The method of claim 1, further comprising determining the composition of the nonaqueous phase liquid by:

expressing each tracer partitioning coefficient as a function of activity coefficients for two or more of said components; and

calculating the respective mole fractions for each of said two or more components and volume of total nonaqueous phase liquid by simultaneously solving the following equation expressed in term of each of said components and said volume of total nonaqueous phase liquid;

16. The method of claim 6, wherein a volume of total nonaqueous phase liquid in said subsurface formation is determined using the following equation:

17. The method of claim 16, wherein samples are taken at two or more sampling points located in the subsurface formation, the two or more sampling points being at different depths.

18. The method of claim 1, wherein one or more of the partitioning tracers is a substance which hydrolyzes to form an alcohol and a carboxylic acid.

19. The method of claim 1, wherein one or more of the partitioning tracers is capable of being used as a fuel or nutrient for microorganisms.

39. The method of claim 7, wherein the tracers are introduced at two or more injection points located in the subsurface formation, the two or more injection points being at different depths.

40. The method of claim 7, wherein samples are taken at two or more sampling points located in the subsurface formation, the two or more sampling points being at different depths.

41. The method of claim 7, wherein the injection point and the sampling point are the same.

42. The method of claim 7, further comprising:

performing an attempted remediation to treat or remove nonaqueous phase liquid in the subsurface formation;

repeating steps (A)-(C) to assess performance of the attempted remediation.

43. The method of claim 7, further comprising determining the volume of dense nonaqueous phase liquid in the subsurface formation.

44. The method of claim 7, wherein the distribution of the nonaqueous phase liquid is irregular.

45. The method of claim 7, wherein the nonaqueous phase liquid is located in a substantially unconfined formation.

46. The method of claim 7, wherein one or more of the one or more partitioning tracers are reactive tracers.

47. The method of claim 46, wherein at least one of the reactive tracers is chemically reactive.

48. The method of claim 46, wherein at least one of the reactive tracers is biologically reactive.

49. The method of claim 7, wherein a thickening agent is introduced with the tracers.

50. The method of claim 7, wherein said dense nonaqueous phase liquid comprises two or more components, and further comprising determining the composition of the nonaqueous phase liquid by:

expressing each tracer partitioning coefficient as a function of activity coefficients for two or more of said components; and

calculating the respective mole fractions for each of said two or more components and volume of total nonaqueous phase liquid by simultaneously solving the following equation expressed in terms of each of said components and said volume of total nonaqueous phase liquid;

51. The method of claim 43, wherein a volume of total dense nonaqueous phase liquid in said subsurface formation is determined using the following equation:

52. The method of claim 51, wherein samples are taken at two or more sampling points located in the subsurface formation, the two or more sampling points being at different depths.

53. The method of claim 7, wherein one or more of the partitioning tracers is a substance which hydrolyzes to form an alcohol and a carboxylic acid.

54. The method of claim 7, wherein one or more of the partitioning tracers is capable of being used as a fuel or nutrient for microorganisms.

20. The method of claimed 1, wherein the presence or absence of nonaqueous phase liquid in said subsurface formation is unknown.

21. The method of claim 20, wherein the tracers are introduced at two or more injection points located in the subsurface formation, the two or more injection points being at different depths.

22. The method of claim 20, wherein samples are taken at two or more sampling points located in the subsurface formation, the two or more sampling points being at different depths.

23. The method of claim 20, wherein the injection point and the sampling point are the same.

24. The method of claim 20, further comprising:

performing an attempted remediation to treat or remove nonaqueous phase liquid in the subsurface formation;

repeating steps (A)-(C) to assess performance of the attempted remediation.

25. The method of claim 20, further comprising determining the volume of nonaqueous phase liquid in the subsurface formation.

26. The method of claim 20, wherein the nonaqueous phase liquid comprises dense nonaqueous phase liquid.

27. The method of claim 20, wherein the nonaqueous phase liquid is a chlorinated hydrocarbon, creosote or coal tar.

28. The method of claim 20, wherein the distribution of the nonaqueous phase liquid is irregular.

29. The method of claim 20, wherein the nonaqueous phase liquid is located in a substantially unconfined formation.

30. The method of claim 20, wherein one or more of the one or more partitioning tracers are reactive tracers.

31. The method of claim 30, wherein at least one of the reactive tracers is chemically reactive.

32. The method of claim 30, wherein at least one of the reactive tracers is biologically reactive.

33. The method of claim 20, wherein a thickening agent is introduced with the tracers.

34. The method of claim 20, wherein said nonaqueous phase liquid comprises two or more components, and further comprising determining the composition of the nonaqueous phase liquid by:

expressing each tracer partitioning coefficient as a function of activity coefficients for two or more of said components; and

calculating the respective mole fractions for each of said two or more components and volume of total nonaqueous phase liquid by simultaneously solving the following equation expressed in terms of each of said components and said volume of total nonaqueous phase liquid;

35. The method of claim 25, wherein a volume of total nonaqueous phase liquid in said subsurface formation is determined using the following equation:

36. The method of claim 35, wherein samples are taken at two or more sampling points located in the subsurface formation, the two or more sampling points being at different depths.

37. The method of claim 20, wherein one or more of the partitioning tracers is a substance which hydrolyzes to form an alcohol and a carhoxylic acid.

38. The method of claim 20, wherein one or more of the partitioning tracers is capable of being used as a fuel or nutrient for microorganisms.

55. A method for determining mole fractions of components of a nonaqueous phase liquid located in a subsurface formation, the liquid having two or more components, comprising:

(A) selecting an assumed mole fraction for each of the N, where N is two or more, selected components to represent an assumed composition of the nonaqueous phase liquid;

(B) selecting at least N partitioning tracers for the assumed composition of the nonaqueous liquid and determining a partition coefficient for each partitioning tracer;

(C) introducing one or more non-partitioning tracers and at least N partitioning tracers into one or more injection points located in the subsurface formation;

(D) recovering one or more non-partitioning tracers and at least one of the at least N partitioning tracers from the subsurface formation at one or more recovery points located in the subsurface formation and measuring to develop a plurality of measured concentrations of the non-partitioning and the partitioning tracers;

(E) using the plurality of measured concentrations for the one or more non-partitioning tracers, developing a plurality of calculated concentrations for at least one of the at least N partitioning tracers using the partition coefficient determined in step (B); and

(F) adjusting the assumed mole fraction for the N components until the plurality of calculated concentrations match the plurality of measured concentrations of the tracers, thereby determining mole fractions of the N components.

56. The method of claim 55 wherein step (F) is performed using an inverse method for parameter estimation.

57. The method of claim 56 wherein the inverse method uses a least squares regression algorithm.

58. The method of claim 55 wherein the step of determining partition coefficients of the N partitioning tracers includes experimental measurements.

59. The method of claim 55 wherein the step of determining partition coefficients of the N partitioning tracers includes use of activity coefficient models.

60. The method of claim 55 wherein at least one of the partitioning tracers is selected to have a partition coefficient sensitive to one component of the nonaqueous phase liquid.

61. The method of claim 55 wherein at least one of the components of step (A) is a mixture.

62. A method for determining mole fractions of components of a nonaqueous phase liquid located in a subsurface formation, the liquid having two or more components and a total volume, comprising:

(A) selecting an assumed mole fraction for each of the N, where N is two or more, selected components to represent an assumed composition of the nonaqueous phase liquid;

(B) selecting at least N partitioning tracers for the assumed composition of the nonaqueous phase liquid and determining a partition coefficient for each of the at least N partitioning tracers;

(C) introducing one or more non-partitioning tracers and at least N partitioning tracers into one or more injection points located in the subsurface formation;

(D) recovering one or more non-partitioning tracers and at least two of the N partitioning tracers from the subsurface formation at one or more recovery points located in the subsurface formation and measuring to form a plurality of measured concentrations of the non-partitioning and the partitioning tracers;

(E) using the plurality of measured concentrations of the tracers for the one or more non-partitioning tracers, developing a calculated total volume of the nonaqueous phase liquid using method of moments equations and the plurality of measured concentrations of at least two of the N partitioning tracers and the partition coefficient determined in step (B) for each of the N partitioning tracers; and

(F) adjusting the assumed mole fraction for the N components until the total volume of the nonaqueous phase liquid calculated from the first moment of at least two of the N partitioning tracers agrees, thereby determining the mole fractions of at least two of the N components.

63. The method of claim 62 wherein step (F) is performed using an inverse method for parameter estimation.

64. The method of claim 63 wherein the inverse method uses a least squares regression algorithm.

65. The method of claim 62 wherein the step of determining partition coefficients of the N partitioning tracers includes experimental measurements.

66. The method of claim 62 wherein the step of determining partition coefficients of the N partitioning tracers includes use of activity coefficient models.

67. The method of claim 62 wherein at least one of the partitioning tracers is selected to have a partition coefficient sensitive to one component of the nonaqueous phase liquid.

68. The method of claim 62 wherein at least one of the components of step (A) is a mixture.