UCRL-JC-108835 PREPRINT

Oil and Gas Evolution Kinetics for Oil Shale and Petroleum Source Rocks Determined from

Pyrolysis-TQMS Data at Multiple Heating Rates

Robert L. Braun Alan K. Burnham John G. Reynolds

This paper was prepared for submittal to Energy & Fuels

November 1991

This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author.

DISCLAIMER

This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the University of California, and shall not be used for advertising or product endorsement purposes.

Oil and Gas Evolution Kinetics for Oil Shale and Petroleum Source Rocks Determined from Pyrolysis-TQMS Data at

Multiple Heating Rates

Robert L. Braun, Alan K. Burnham, and John G. Reynolds

Lawrence Livermore National Laboratory, University of California

Livermore, California 94550

Abstract

Seven oil shales and petroleum source rocks were subjected to programmed-

temperature pyrolysis at heating rates of 1 and 10 °C/min using triple-quadrupole mass

spectrometry to monitor volatile compound evolution. Kinetic parameters were deter­

mined for evolution of hydrocarbons and various heteroatom species. Normalized cumu­

lative generation of oil, light hydrocarbon gas (C2-C4), methane, carbon dioxide, acetic

acid, hydrogen sulfide, and methylthiophene were calculated for generic geologic condi­

tions using kinetic parameters that were lumped and averaged into type I, Ha, and lib

source rock classes. The four heteroatom species are largely generated before oil and the

hydrocarbon gases. Using these kinetics to simulate hydrous pyrolysis gives favorable

comparison with hydrous pyrolysis measurement of acetic acid generation for several

different source rocks.

Introduction

A variety of techniques have been used to measure oil and gas generation kinetics

for kerogen pyrolysis, but most workers do not report detailed information for individ­

ual pyrolysis products. The latter information is important for many reasons: to help

establish the origin of activation energy distributions, to provide diagnostics of kerogen

structure and depositional conditions, to understand variations of gas/oil ratios during

kerogen maturation, to make complex chemical models needed for realistic calculation

of overpressuring, and to define the source terms for components that are involved in

important secondary reactions, such as mineral diagenesis.

Laboratory pyrolysis at a constant heating rate using triple-quadrupole mass spec­

trometry (TQMS) as the detection method is particularly well-suited for measuring the

generation rate of individual pyrolysis products. It provides on-line, time-resolved anal­

ysis to follow the evolution of various light hydrocarbons and N-, S-, and O-containing

1

compounds as a function of temperature. Pyrolysis at a single heating rate allows deter­

mination of evolution range and Tmax for that heating rate. Reynolds et al} applied this

method at 10 °C/min to study 15 oil shale and petroleum source rocks. Multiple heating

rates, however, are required to determine more useful kinetic parameters. This reports

adds 1 °C/min data for 7 of the 15 sampes previously presented, allowing the determi­

nation of generation kinetics for many individual pyrolysis products. These kinetics are

useful in developing generic chemistry models for type I and type II source rocks.

Experimental Section

The instrumentation, samples, and pyrolysis experiments are described by Reynolds

et al} Pyrolysis-TQMS data were collected at 1 and 10 °C/min for one lacustrine oil

shale (AP24), two high-carbonate marine source rocks (LLNA and WNZN), and four

low-carbonate marine source rocks (NAKY, KIMR, WDFD, and PHOS). We will later

refer to these three groupings as types I, Ha, and lib. Table 1 gives several important

properties of the materials. Pyromat data2 show that hydrocarbon generation for type I

is mosdy at one activation energy, while for type Ha and lib it spans a significant range

of energies.

Although calibrated thermocouples were used at both heating rates, preliminary

data analysis indicated that the temperatures for the 1 °C/min experiments were still

significantly in error for most of the samples. Therefore, a temperature correction was

applied to the 1 °C/min data to make the mean calculated activation energy for C3H8

and m/z 57 (primarily the C4Hp~ ion) agree with our Pyromat results.2 These two species

were chosen because they had strong TQMS signals and they should have generation

rates similar to the hydrocarbons measured by the Pyromat. The indicated temperature

corrections ranged from -0.79 °C for AP24 to -11.3 °C for PHOS. Therefore, the

kinetics presented in this report can be considered as calibrated to kinetics determined in

more accurate experiments.

Results and Discussion

Analysis of TQMS data. We selected 14 species (or combinations of species)

for kinetic analysis. Species designations are shown as the first column of Table 2. The

meanings of most are self-evident. The exceptions may be TLO (total light organics that

pass the 140 °C trap), C2-C4 (combination of 02*14, C2H<5, C3H8, and C 4 HK)) and Ci~

C4 (combination of CH4 and C2-C4). For CO2 and H2S, effort was made to use only the

lower-temperature portion of the rate profiles (~400 °C) from kerogen pyrolysis and to

2

exclude the portion from mineral decomposition. The same set of species was analyzed

for all seven source rocks, except satisfactory CO2 data were not available for KIMR.

For each species or combination, temperature-corrected data were smoothed by means

of a running 3-point average for time, temperature, and rate. The reader is referred to

Reynolds et al.1 to see the kinds of evolution profiles analyzed. The kinetic analysis

was done in several ways with our KINETICS program. Detailed results of the kinetic

analysis are given in the Supplementary Material.

First, Tmax at each heating rate was determined by a parabolic, least-squares fit of

the top 10% of the reaction rate profile. Using a larger portion of the profile is usually

undesirable, because it is more likely to depart from a stricUy parabolic shape. For some

of the profiles, however, it was necessary to use the top 25% of the profile, since the top

10% was too noisy to give a reliable determination of Tmax- This was true for CH3COOH

with all samples and for a few other species with some of the samples. The T^x results

are shown in Table 2. These are useful in indicating the relative order of evolution of

the pyolysis products. They are also useful in the kinetic analysis described next.

Our KINETICS program performs a number of simple kinetic analyses as part

of the initial data reduction. Often the most useful one is the approximate Gaussian

analysis,2 when data are available at 2 or more heating rates: (1) initial values of A

and E0 are determined by linear regression from the shift of T^^ with heating rate;

(2) an approximate Gaussian distribution parameter (CTE) is estimated from a correlation

function of the width of the reaction profiles; (3) a correction term for Tm^ is estimated

from another correlation function of A, E0, and <?&; and (4) final values of A and E0 are

again calculated from the shift of the corrected Tma,x with heating rate.

Useful kinetic parameters can be derived by this method, if a wide range of heating

rates is used (preferably a factor of 50) and if the temperatures are measured to an

absolute accuracy of a few °C with no systematic dependence of the temperature error

on heating rate. For the factor of 10 in heating rates used here, a temperature error of

only —2 °C at one heating rate and +2 °C at the other heating rate would cause an

error of about 5 kcal/mol in the principal activation energy and a compensating error of

about a factor of 32 in the frequency factor. Effects of temperature measurement errors

on the quality of derived kinetic parameters are discussed by Burnham et al.4 and by

Braun and Burnham2. In this work, we tried to minimize the temperature error by the

calibration procedure described in the experimental section. The other principal error in

Tmax is due to the inability of exactly determining the point at which the maximum rate

is reached. Errors far greater than 2 °C can easily arise for species having a noisy TQMS

signal. Therefore, the quality of the approximate Gaussian parameters determined from

3

TQMS data is not particularly good for many species and direct use of the parameters for

geologic extrapolation is not recommended. For most samples, the approximate Gaussian

analysis could not be done for H2 or CO2, because the data were inadequate to define

the width of the evolution profiles.

The next step of our analysis consisted of using the approximate Gaussian pa­

rameters as a starting point for a more rigorous, nonlinear regression analysis to more

accurately determine A and a discrete E distribution. The results of this analysis suffer

from the same temperature uncertainties that affect the Tmax-shift results, with large,

inconsistent variations in A. For comparison purposes, we condense the entire E distribu­

tion into a single energy £ave> the average energy weighted by the distribution fractions.

This is a better method of estimating the principal activation energy than just picking

the energy having the maximum fraction in the distribution, particularly for distributions

having several large fractions of similar magnitude.

We find large variations in A and Eiwt among the species for a given sample. We

suspect that these are statistical variations caused by the broad minimum in regression

space due to noise in the TQMS signal. Ungerer5 illustrated that various measurements of

pyrolysis kinetics show a high correlation between A and the principal E, corresponding

to A-E couples yielding approximately the same rate constant at a given temperature

characteristic of laboratory pyrolysis measurements. A wider range of heating rates than

the factor of 10 used here would increase the time-temperature resolution in helping to

select the correct A-E couple. Even then, however, the weak TQMS signal for some of

the species may preclude satisfactory results.

Therefore, we explored the following alternative. A rigorous, discrete analysis using

an A fixed at the value measured for Pyromat data2 gives an E distribution for C3H8 and

m/z 57 with a principal energy which closely matches that deduced from Pyromat data.

Using the same fixed A for all TQMS species, moreover, eliminated most of the random

fluctuations in the average E among the species. In this analysis we used fixed A values

of 5 x 1013, 3 x 1013, and 2 x 1014 s"1 for types I, Ha, and lib, respectively. These are

actually a factor of 2 smaller than the Pyromat averages for type I, Ila, and lib samples.

The reason for the factor of 2 is that we believe a shift of about —1 kcal/mol in E from that

given by the discrete analysis of Pyromat data is best for geologic extrapolation.2 Using

a fixed A for all pyrolysis products of a given material requires that the progression of

the reaction be the same at laboratory and geologic conditions. Although this assumption

is not necessarily the case, it is justified by the large statistical variations in A obtained

with our data. Again, for comparison purposed, we condense the entire E distribution

into a weighted average E[y&.

4

Table 3 gives the three E parameters (E0, £ave» and £a've) averaged over all four

of the type lib samples. Both E0 (from the approximate Gaussian analysis) and EaVe

(from the rigorous discrete analysis) show large variations among the species and have

relatively high standard deviations for a given species. For E^ (from the discrete

analysis with fixed-/!), however, the differences among the species are much smaller and

are consistent with generation of the heteroatom species at a lower activation energy and

generation of H2 and CH4 at a higher activation energy than the bulk of the hydrocarbon

products. Furthermore, the standard deviations are very small for E£ve. This gives

us some confidence in the validity of the fixed-A analysis. Comparing the weighted-

average E's is not strictly valid in analyzing reaction rate profiles that arc truncated at

the higher temperatures, since it will underestimate the weighted average of the complete

E distribution. Only H2, CO2, and sometimes H2S had truncated reaction rate profiles.

The rate profile for H2 was truncated because Hj evolution continues from pyrolysis

of residual organic matter to temperatures far higher than we used. E£ve is probably

least meaningful for H2, because the principal peak of the rate profile and only part of

the residual pyrolysis were included in the analysis. The rate profiles for organic CO2

and H2S were truncated to eliminate interference from inorganic CO2 and H2S. Despite

this, Ea've for these species are probably quite meaningful, because most of the energies

associated with release of the organic portions are included.

Detailed kinetics for hydrocarbon and heteroatom generation. The fixed A's

and complete E distributions determined in the preceding analysis could, in principle, be

used to model pyrolysis reactions in great detail. In practice, however, using such a large

number of individual sets of rate parameters is probably unnecessary and may require

excessive computer time. Therefore, we have simplified the kinetics for hydrocarbon

generation. For light hydrocarbon gas we normally use the separate results for CH4 and

C2-C4 from our discrete analysis with fixed A. Alternatively, it may be adequate in some

models to use the single combined species C1-C4 for the light hydrocarbon gas. The

average kinetic parameters for type I, Ha, and lib samples for these three species or

combinations are given in Table 4. The oil generation parameters were determined by

subtracting the TQMS hydrocarbon gas contribution from the total hydrocarbons mea­

sured by Pyromat. These kinetic parameters, or a subset of them, will be adequate for

modeling hydrocarbon generation in many basin analysis models (e.g., model 5 of Braun

and Burnham).6

In a very detailed chemical model, however, it may be desirable to account for

the significantly different kinetics for the generation of heteroatom species (such as CO2,

CH3COOH, H2S, and CH3C4H4S). The average kinetic parameters for type I, Ha, and

5

lib classes for these four species are given in Table 5 and the kinetic parameters for all

seven individual source rocks are given in the Supplementary Material. We emphasize

that only one type I sample (AP24) was included in our analysis. For most species, the

TQMS data for AP24 were representative of other type I samples not analyzed in detail.

This is not true for CH3COOH, which evolved at significantly lower temperatures for

AP24, as illustrated by published rate profiles.1 Other type I profiles for CH3COOH, in

fact, appear to be more similar to those of type Ha and lib samples.

Comparisons of calculated rate profiles for four species at 10 °C/min using the

type lib E-distribution and fixed-.A from Table 5 are shown in Figure 1 along with

the measured rate profiles for the type lib samples. The best agreement among the

measured profiles and with the calculated profile was obtained for m/z 57 and a few

other hydrocarbon species that had a strong TQMS signal. Most species had agreement

as good as that shown for C2-C4 and CH3C4H4S. The poorest agreement was obtained

for CH3COOH.

Comparisons of calculated and measured acetic acid generation are shown in Fig­

ure 2. The measurements are from 72-h, hydrous pyrolysis experiments of Lundegard

and Senftle7 using a non-marine shale and Barth et a/.8 using a marine shale. The two

sets of measurements are essentially identical. Although it is not certain that CH3COOH

generation in hydrous pyrolysis is governed by the same mechanism as in our open-

system experiments, the final half of the measured generation agrees very well with that

calculated with our type Ha and lib kinetics. The single E of 5.43 kcal/mol reported by

Barth etal., however, is markedly lower than our weighted average of 49 and 50 kcal/mol

for type Ha and lib, respectively. A likely explanation is that large errors in E can be

obtained by interpreting rate data in terms of a single E, when a distribution is actually

required. Burnham and Braun9 have previously discussed this problem in interpreting oil

generation data from hydrous pyrolysis.

Using the kinetic parameters in Tables 4 and 5, we calculated the generation of oil,

C2-C4, CH4, C02 , CH3COOH, H2S, and CH3C4H4S at a typical geologic heating rate

of 4 °C/My. Comparisons of normalized cumulative generation are shown in Figure 3

for AP24, Ha, and lib. Generation of the four heteroatom species largely precedes oil

generation, while generation of much of the hydrocarbon gas (especially CH4) follows

oil generation. There is some departure from these generalizations, because the kinetics

for oil were determined from Pyromat data. Pyromat data appear to give a smaller E

distribution compared with TQMS data, due to the inherently greater dispersion in the

TQMS measurements. For example, the Gaussian distribution parameter, CTE, determined

6

by Pyromat data for oil is approximately 2 % of E0 smaller than the value determined

by TQMS data for TLO.

Eglinton et a/.10 demonstrated that thiophenic sulfur is eliminated from kerogen at

an earlier stage of maturation than hydrocarbons. The kinetic parameters from this report

provide a means to compare the laboratory and the natural maturation trends. Figure 4

shows our calculated ratio of CH3C4H4S precursor to TLO precursor at a heating rate of

4 °C/My as a function of Rock-Eval r ^ x , starting with equal amounts of each precursor.

The calculated trends for type II kerogen follow those reported by Eglinton et al.

Our E distribution to describe H2S generation profiles from type I and II source

rocks agrees qualitatively with the H2S kinetics of Kelemen et al.11 for coals. However,

their more accurate data indicated a lower A and a compensatingly lower mean E for

H2S compared with hydrocarbons. We can not eliminate that possibility for type I and II

source rocks. Kelemen et al. were also able to use XANES spectroscopy to demonstrate

that the E distribution is due in part to faster generation of H2S from aliphatic sulfur in

the coal than from aromatic sulfur, and we suspect the same may be true for type I and

II source rocks.

Summary and Conclusions

Activation energy distributions are required to describe the evolution of individual

gas species from kerogen. Although our data are not sufficiently accurate to determine

absolute kinetic parameters, the data are consistent with a mean E in the 50 kcal/mole

range for all species investigated. This implies that relative evolution rates of the gas

species will be similar in natural and laboratory maturation as long as the mechanism

is sufficiently similar. For example, the kinetic measurements are consistent with early

elimination of oxygen and sulfur from the kerogen.

Because the amount of kinetic information obtained from these experiments can

be overwhelming, the results from individual samples have been averaged to obtain

approximate values for type I, Ha, and lib source rocks. These kinetic parameters have

been useful for making generic kinetic models of kerogen maturation for basin modeling

purposes.6

Acknowledgements

This work was performed under the auspices of the U.S. Department of Energy by

the Lawrence Livermore National Laboratory under Contract W-7405-ENG-48. It was

supported by the US DOE Offices of Basic Energy Sciences and Fossil Energy and a

group of industrial sponsors.

7

References

1. Reynolds, J. G.; Crawford, R. W.; Bumham, A. K. Energy Fuels 1991, 5, 507-523.

2. Braun, R. L.; Bumham, A. K.; Reynolds, J. G.; Clarkson, J. E. Energy Fuels 1991,

5, 192-204.

3. Braun, R. L.; Bumham, A. K. Lawrence Livermore Nat. Lab. Report UCID-21588,

Rev. 1, 1990, Livermore, CA, Avail. NTIS, Springfield, VA.

4. Bumham, A. K.; Braun, R. L.; Gregg, H. R.; Samoun, A. M. Energy Fuels 1987, 1,

452-458.

5. Ungerer, P. Org. Geochem. 1990,16, 1-25.

6. Braun, R. L.; Bumham, A. K. Lawrence Livermore Nat. Lab. Report UCRL-JC-

105371, 1991, presented at 15th Int. Meeting on Org. Geochem., Manchester, Sept.

16-20, 1991.

7. Lundegard, P. D.; Senftle, J. T. Appl. Geochem. 1987, 2, 605-612.

8. Barth, T.; Borgund, A. E.; Hopland, A. L. Org. Geochem. 1989, 14, 69-76.

9. Bumham, A. K.; Braun, R. L. Org. Geochem. 1990, 16, 27-39.

10. Eglinton, T. I.; Damste, J. S. S.; Kohnen, M. E. L.; de Leeuw, J. W.; Larter, S. R.;

Patience, R. L. In Geochemistry of Sulfur in Fossil Fuels; Orr, W. L.; White, C. M.,

Eds.; ACS Symposium Series 429; American Chemical Society: Washington, DC,

1990; pp 529-565.

11. Kelemen, S. R.; Gorbaty, M. L.; Vaughn, S. N.; George, G. Prepr. Pap.—Am. Chem.

Soc, Div. Fuel Chem. 1991, 36(3), 1225-1232.

8

Table 1. Selected properties of source rocks. Other properties are given by Reynolds et al.

AP24 LLNA WNZN NAKY KIMR WDFD PHOS

Type

I Ha Ha lib lib lib lib

/ / /* (mg/g TOC)

850 650 700 560 430 420 450

T b •"max

CO

All 463 462 460 459 461 459

Ec

(kcal/mol)

54 52 52 54 54 55 56

pd

(%)

85 46 46 49 28 32 24

* Hydrogen Index from Rock-Eval data.1

b Tmax at 25 °C/min from Pyromat data.2

c Principal discrete activation energy from Pyromat data.2

d Portion of hydrocarbons generated at the principal activation energy.

Table 2. Experimental 7max (CC) at heating rates of 1 and 10 °C/min determined by parabolic, least-squares fit of top 10% of generation profile, unless otherwise indicated.

C3H8

m/z 57 TLOb

H2

CH4

C2-C4

C1-C4

C4H10

C5H12 Q H 6

AP24 427 426 426

438 426

422 423 418 422 421

CH3C4H4S 407* CH3COOH230* H2S

co2

392 403

467 468 467

478 465 467 467 465 467 470 449* 262* 430 445

LLNA 413 408 406 414

463 408 411 397 404 402

395 375* 385 418

454 449 448 464

512 454

456 443 445 445

435 411* 423 455

WNZN 409 408 413

416 456 405 411 396 402 396 382

369* 371 377

453 451 450

461 496 453 456 444 449 441

425 417* 408 423

NAKY 405* 402

400

413 467 404

407 395 399 396* 390* 363* 390 363

442* 441 442

466 498

443 447 432 436 432* 428* 383* 429 392

KIMR 410 408 416

420 448

409 419 378 398* 383 367 368* 384 —

450 448 445 462 484

450 458 434 441* 428 419 421* 428 —

WDFD 410 405 406

413 466 409 426 385 396 397* 385 348* 380* 357

449 445 446 454

507

456 461 433 440 438* 431 386* 417* 372

PHOS 412 405 415

418 474

407 417 389 397* 405 387 370* 375* 319

445 444

446

445 520 447 452 433 438* 449 430 412*

416* 346

* These used top 25% of generation profile for determining T, bTLO — total light organics which pass the 140°C trap.

9

Table 3. Activation energies averaged over the four type lib source rocks.

C3H8

m/z 57 TLO

H2

CH4

C2-C4

Q-C4 C 4 H 1 0 C 5 H 1 2 C 6 H 6 CH3C4H4S CH3COOH H2Se

COf

E0* (std.dev.) (kcal/mol)

59.1 54.0 63.5

d

66.7 51.7 58.8

44.9 50.6 49.8 49.9 55.2 49.9

d

(4.9) (0.8)

(13.5)

(10.6)

(3.1) (5.7) (7.9) (3.6) (4.6) (6.4)

(25.0)

(3-D

Eaveb (std.dev.) (kcal/mol)

55.7 52.6 61.3 47.8 74.4 49.9 60.8 46.2 49.2 50.7 46.3 45.4 50.2 51.9

(4.1)

(1.7) (12.5) (2.0) (6.3) (4.2) (5.9) (5.3) (4.3) (4.0) (3.7) (8.2) (3.0) (3.5)

E^ec (std.dev.)

(kcal/mol)

54.3 54.0 54.7 56.3 60.8 54.6 56.9 52.6 53.5 54.1

52.7 50.5 52.3 46.1

(0.1) (0.4) (0.4) (0.5) (1.2) (0.4) (0.7) (0.5) (0.2) (0.3) (0.5)

(1.9) (1.7) (0.9)

a £ 0 = central E of approximate Gaussian analysis without fixed A. b£ave = weighted-average E of discrete distribution analysis without fixed A. c£ a 'v e = weighted-average E of discrete distribution analysis with fixed A = 2xl0 1 4 s"1. d Insufficient data. e Data truncated to eliminate interferences from inorganic sources.

10

Table 4. Pyrolysis model for type I, Ila, and lib source rocks, with hydrocarbon potentials [HI (mg/g TOC)] and kinetics [A (s_1), E (kcal/mol), and ^-distribution (%)].

I Ha l ib

OU CH4 C2-C4 C r C 4 OU CH4 C2-C4 C r C 4 Oil CH4 C2-C4 CrC4

HI 760 65 25 90 590 50 35 85 415 50 35 85 A 5xl0 1 3 3xl0 1 3 2x l0 1 4

E 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76

F'

1

2

6

2

89

53

Distribution 1

2

4

6

21

12

9

9

8

7

8

7

2

4

58

1

1

2

7

45

30

9

2

2

1

54

1

1

3

7

37

24

9

4

4

3

3

1

3

55

1

2 11 5

48 21

7 5

51

Distribution 1

2

3

11

10

19

16

9

9

7

7

2

2

2

57

3

3

13

28

28

19

3

2

1

52

2

3

9

22

22

19

7

5

3

3

2

1

2

54

1

1

2 3 6

27 37 13 8 2

54

Distribution

1

1

5

9

11

19

14

10

8

6

5

3

3

3

2

61

2

3

6

18

26

24

14

5

1

1

55

2

2

4

13

19

19

16

8

5

3

3

2

1

1

1

1

57

11

Table 5. E distributions (kcal/mol and %) from discrete E-distribution analysis for the principal heteroatom species generated from kerogen pyrolysis with A = 5xl0 1 3 , 3x l0 1 3 , and 2xl0 1 4 s_ 1 , for AP24 and type Ila and lib source rocks, respectively.

C0 2 CH3COOHa H2S CH3C4H4S

AP24 Ila lib AP24 Ila lib AP24 Ila lib AP24 Ila lib

E 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60

E'

Distribution 1 1 2 2 3 4 4 5 7

10 15 16 18 12

49

1 1 2 3 5 6 7 8 8

13 16 20 10

47

1 2 3 4 6 7 8 9

10 11 13 10 11 3 2

46

Distribution

7 13 13 12 11 9 6 6 5 7 5 2 4

43

1 2 2 3 3 7

29 31 10 11

1

49

1 1 1 4 7

13 24 31 9 7 2

50

Distribution

44 52

3 0 1

51

1 0 5

30 38 24

1 1

50

1 2 2 3 6 8

34 21 23

52

Distribution

1 2 7

14 39 28

3 4 2

52

2 6 2

18 5 36 16 24 33

8 28 3 11 2 4 1 1

50 53

CH3COOH for AP24 is not representative of other type I samples.

12

1.0

0.8

0.6

0.4

0.2

0

1.0

0.8

0.6

0.4

0.2

- m/z57

I T "i r

- NAKY • KIMR • WDFD • PHOS

0

1.0

0.8

0.6

0.4

0.2

-

-

-

-

I I

c2-c4

_.-K,wi'j )£&

I I

r * Jm 7 t

V • 1 •

.7* • ft*

1 1 1

A*-\ *

* 1 « A #

•V "A •

1 1 ^ s

-

-

-

-

-

"

1 1

CH3COOH

«.•>

^ ^ 1

1 1 1 1

* •* / ' • * \ • 1 / » \ •

• 1 1 1 • - r ?

1

t&u

-

0 200 250 300 350 400 450 500 550 600

Temperature, C

Figure 1. Measured generation rates at 10 °C/min (symbols) compared with calculated rates (lines) using kinetic parameters in Table 5 for type lib source rocks.

13

200 220 240 260 280 300 320 340

Temperature, C

Figure 2. Measured cumulative generation of acetic acid from 72-h hydrous pyrolysis experiments (symbols) compared with the calculated generation (lines) using kinetic parameters in Table 5 for AP24 and type Ha and lib source rocks. Acetic acid generation for AP24 is not representative of other type I samples.

14

E

u

o

o Z

1.0

0.8

0.6

0.4

0.2

0

1.0

0.8

0.6

0 . 4 -

0 . 2 -

0

1.0

0.8

0.6

0 . 4 -

0 . 2 -

1 1

- AP24

CH3C00H ^

>^

1 i__

1 1 1

0 I L \ f ^ s ^ I \.

^ CH3C4H4S ^ 1/ p

/ 1 1 ' / / 1 I 1

J ' V si s*S

1

" L ^ Z ^ ^ ^

/^c2 -c«

/ y^

^ C H 4

1

1 • 1

- Ha

CH3C4H4S -

H 2 S ^

— - — 1 • 1 * ^ -

1

O I L ^

' ^r* **^^~**

1

(J 1

7 / / ' ' / // 1/

1

fyij

1

'

c2-c,

1

-

- lib

_

-y^

1 1 1 1 1

0 , L \ ^-CH3C4H4S^ / f / /

CH3COOH^. / /if/1

• \ / / ' / c ° 2 \ y ^ v / ' / ^^ / 1 1 ' /

^/ / / ' / >/ / 1 y

1

/ C2-C4

^ C H 4

1

25 50 75 100 125 150 175 200

Temperature, C

Figure 3. Calculated cumulative generation of seven species at 4 °C/My using kinetic parameters in Tables 4 and 5 for AP24 and type Ha and lib source rocks.

15

1.2

1.0

0.8

% 0.6 oc

0 . 4 -

0 . 2 -

0 -400

—

—

m> i

Ua 1 1 \

1

1 1 1

AP24 i i \ \ \

V ^

1 1 1

—

^ - > . —

420 440 460

Rock-Eval Tmax, C

480 500

ure 4. Calculated normalized ratio of methylthiophene precursor to total light hydrocar­bon precursor as a function of maturation at 4 °C/My using kinetic parameters in Table 5 for AP24 and type Ila and lib source rocks.

16

Supplementary Material

Table Al. Measured Tmax and calculated kinetics parameters using several models.

Measured Tmax Approximate Gaussian Discrete l°C/min 10°C/min A E0 as A £ave ^ave

(°C) (°C) (s-1) (kcal/mol) (% of E„) (s-1) (kcal/mol) (kcal/mol)

AP24 ^3H8 m/z 57 TLO H2 CH4

C2-C4

q-c4 QHjo ^5^10 C6H6

«CH3C4H4S *CH3COOH H2S C02

LLNA C3Hg

m/z 57 TLO H2

CH4 C2-C4

C1-C4 C4H]o Q H J Q

C6H6 CH3C4H4S

•CH3COOH H2S C02

WNZN C3Hg

m/z 57 TLO H2 CH4

C2-C4 C 1" C 4 ^4H10 C5H10 C6H6 CH3C4H4S

«CH3COOH H2S C02

NAKY «C3H„ m/z 57 TLO H2 CH4

427 426 426 438 426 422 423 418 422 421 407 230 392 403

413 408 406 414 463 408 411 397 404 402 395 375 385 418

409 408 413 416 456 405 411 396 402 396 382 369 371 377

405 402 400 413 467

467 468 467 478 465 467 467 465 467 470 449 262 430 445

454 449 448 464 512 454 456 443 445 445 435 411 423 455

453 451 450 461 496 453 456 444 449 441 425 417 408 423

442 441 442 466 498

1.5E+14 4.6E+13 5.7E+13 5.0E+14 6.9E+14 4.6E+12 8.1E+12 4.0E+11 4.6E+12 3.3E+11 5.5E+12 1.1E+12 5.7E+14 —

4.4E+13 3.5E+13 1.8E+13 9.4E+10 7.0E+11 1.3E+12 3.2E+12 3.6E+11 4.5E+13 8.7E+12 3.9E+13 4.7E+15 4.6E+14 —

4.3E+12 1.5E+13 7.1E+15 2.7E+12 4.7E+15 2.0E+11 3.5E+12 1.8E+11 3.5E+11 8.7E+11 5.8E+12 2.2E+10 5.9E+14 —

1.4E+15 1.0E+14 9.4E+12 — 6.5E+20

55.3 53.7 54.0 57.6 57.7 50.3 51.2 46.7 50.4 46.9 49.4 35.9 54.1 —

52.7 52.0 51.0 44.3 50.9 47.8 49.2 45.3 52.2 49.8 51.2 55.8 53.5 —

49.4 51.0 59.6 49.4 62.9 45.1 49.4 44.4 45.7 46.5 47.9 39.8 52.9 —

56.9 53.0 49.9 — 81.0

1.8 2.2 2.5 — 6.9 2.6 2.9 2.6 2.8 3.7 3.6

18.8 0.9 —

3.4 3.2 3.9 — 8.1 4.4 5.4 5.1 4.1 3.7 3.7 3.8 2.9 —

3.7 3.2 4.6 5.6 5.7 4.6 5.4 5.0 4.4 5.5 4.3 3.5 4.0 —

4.0 3.2 4.3 — 6.2

3.4E+14 1.1E+13 4.8E+13 1.3E+15 9.7E+16 5.5E+12 5.3E+12 3.8E+11 1.4E+12 3.1E+11 7.7E+11 2.0E+11 1.4E+16 1.7E+11

4.8E+13 4.1E+13 2.1E+13 2.3E+10 3.6E+12 1.7E+12 8.2E+10 8.6E+12 1.0E+13 5.5E+12 8.2E+12 3.4E+14 3.0E+15 2.7E+15

2.3E+13 3.5E+13 3.7E+15 2.3E+12 2.7E+14 1.7E+12 1.8E+12 1.1E+12 8.1E+12 9.9E+10 1.8E+12 3.8E+10 7.8E+15 1.5E+13

5.4E+15 2.2E+13 1.3E+12 1.1E+11 1.5E+21

56.3 52.0 53.9

•60.0 69.1 51.1 52.1 47.1 50.0 47.5 46.6 37.2 58.7

•41.7

52.9 52.4 51.5

f44.6 54.3 48.4 45.9 49.7 50.2 49.9 49.1 51.3 55.7 '52.2

51.4 52.3 58.8

•51.0 60.3 48.2 49.7 47.0 50.1 44.2 46.5 41.1 •56.7 •48.0

58.8 51.1 47.6 •46.0 83.9

A=5.E+13a

53.6 54.1 53.9

•55.1 57.9 54.1 55.2 53.9 55.2 54.4 52.2 43.1 51.1

•48.9

A=3.E+13a

52.2 51.9 52.1

•55.0 57.6 52.4 54.2 51.4 51.5 52.2 50.8 48.1 49.7

•47.1

A=3.E+13a

51.9 52.1 52.1

•54.6 57.1 52.2 53.8 51.5 51.7 52.0 50.2 49.7

•49.7 •46.6

A=2.E+14a

54.3 53.9 54.5

•56.8 60.3

17

C2-C4 c2-c4 C4HJO ^5^10

•CeHg «CH3C4H4S *CH3COOH H2S C02

KIMR ^3^8 m/z 57 TLO H2 CH4

C2-C4 0 ^ 4 C4H10

'C 5H 1 0

C6H6 CH3C4H4S

*CH3COOH H2S C02

WDFD C3H8

m/z 57 TLO H2 CH4

C2-C4 C j - C 4

Q ^ i o C 5H 1 0

'CeHs CH3C4H4S

«CH3COOH *H2S C02

PHOS

Q}H8 m/z 57 TLO H2 CH4

C2-C4 C^-C^ C4H10

*C5H10

C6H6 CH3C4H4S

«CH3COOH *H2S C02

404 407 395 399 396 390 363 390 363

410 408 416 420 448 409 419 378 398 383 367 368 384

443 447 432 436 432 428 383 429 392

450 448 445 462 484 450 458 434 441 428 419 421 428

1.1E+14 3.0E+13 4.2E+14 7.2E+14 8.4E+14 3.3E+14 4.4E+28 4.9E+13 —

4.1E+14 1.4E+14 2.6E+21 — 1.2E+17 2.7E+13 3.6E+14 4.2E+08 4.6E+12 3.2E+11 2.7E+09 1.6E+09 1.9E+12

53.5 51.9 54.4 55.4 55.4 53.6 92.0 51.1 —

55.6 54.0 77.2 — 66.7 51.9 56.2 35.5 48.7 44.3 37.1 36.2 46.5

Satisfactory data not available

410 405 406 413 466 409 426 385 396 397 385 348 380 357

412 405 415 418 474 407 417 389 397 405 387 370 375 319

449 445 446 454 507 456 461 433 440 438 431 386 417 372

445 444 446 445 520 447 452 433 438 449 430 412 416 346

1.5E+15 1.7E+14 1.9E+14 — 4.0E+15 8.3E+11 6.0E+16 1.0E+11 1.7E+12 2.7E+13 3.5E+11 2.3E+13 5.4E+14 —

1.1E+18 3.7E+14 9.6E+19 — 1.0E+13 1.7E+14 6.8E+16 1.8E+12 2.5E+13 3.1E+12 3.3E+12 2.0E+12 1.3E+13 5.9E+18

57.4 54.0 54.2 — 63.6 47.3 63.7 42.9 47.2 50.9 44.4 47.1 53.5 —

66.4 55.0 72.7 — 55.6 54.2 63.2 46.9 50.9 48.7 47.5 45.7 48.5 59.8

4.6 5.9 4.1 3.8 4.6 3.5 6.0 2.7 —

3.9 3.7 5.2 — 5.2 4.9 5.4 4.2 4.3 5.4 3.1 0.0 3.6

4.2 3.9 4.7 — 7.0 4.9 6.3 4.5 4.1 4.7 3.9 7.7 6.6 —

4.6 3.7 5.2 — 8.8 5.4 7.5 5.0 5.0 4.6 4.4 5.6 8.4

18.9

9.1E+13 1.2E+15 3.6E+14 1.3E+14 2.6E+14 1.5E+13 7.6E+16 8.2e+12 6.9E+16

1.5E+13 9.6E+13 1.2E+18 2.4E+12 3.2E+17 4.1E+12 1.6E+13 1.4E+10 8.3E+10 6.6E+13 5.0E+10 3.0E+10 7.8e+12

1.4E+14 3.2E+14 2.8E+14 1.7E+11 9.3E+16 7.2E+10 4.0E+16 2.5E+12 6.4E+13 1.5E+13 8.9E+12 1.1E+12 1.9E+15 6.2E+14

1.1E+16 2.7E+13 5.6E+20 5.6E+11 1.7E+17 7.2E+13 4.1E+16 3.1E+11 6.9E+12 1.9E+11 7.2E+11 1.0E+11 1.1E+13 1.6E+18

53.3 59.7 52.9 52.7 54.5 49.6 57.8

t49.5 •52.8

50.7 53.7 66.7 •50.4 70.4 49.1 52.8 40.4 43.1 52.6 41.3 40.7 t49.7

54.0 54.4 55.0

•46.6 71.3 44.2 65.0 47.2 51.9 50.3 48.6 41.7 •54.3 •48.1

59.4 51.1 75.8

•48.2 72.2 52.9 65.6 44.2 49.2 45.2 45.6 41.6 •47.2 •54.9

54.5 56.5 51.9 53.2 54.1 53.1 50.2

•53.7 •45.7

A=2.E+14a

54.3 54.5 54.8

•56.5 59.3 54.4 56.1 52.9 53.7 54.1 52.0 52.6

•53.7

A=2.E+14a

54.4 53.8 54.4

•55.7 61.7 55.1 57.1 53.0 53.5 53.8 52.7 48.0

•51.7 •47.1

A=2.E+14a

54.2 53.7 55.3

•56.1 61.9 54.3 57.8 52.7 53.7 54.5 53.0 51.2

•50.1 •45.5

aFixed A value from Pyromat measurements. •These used top 25% of generation profile for determining Tmax'. others used top 10%. •Data truncated to eliminate interferences from inorganic sources.

18

Table A2. Kinetics for generation of four heteratomic species from kerogen: [A (s-1), E (kcal/mol), and E-distribution (%)].

A =

E 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 F'

E 34 36 38 40 42 44 46 48 50 52 54 56 58 60 F' ^ave " E 40 42 44 46 48 50 52 54 56 58 F' *-ave E 40 42 44 46 48 50 52 54 56 58 60 62 F' cave -

AP24 5.E+13

0.8 1.1 1.9 2.6 2.9 3.6 4.1 5.2 7.0

10.2 14.6 16.5 17.7 11.8

= 48.9

7.1 13.2 13.1 12.1 10.6 8.8 6.3 5.8 4.6 7.4 5.3 1.7 4.0

= 43.1

43.7 52.5 2.8 0.2 0.8

= 51.1

0.9 2.1 6.8

14.4 39.3 27.9

3.2 3.7 1.7

: 52.2

LLNA 3.E+13

WNZN 3.E+13

NAKY 2.E+14

KIMR 2.E+14

WDFD 2.E+14

E-distribution for generation of C 0 2

0.5 1.1 2.2 3.5 5.2 6.7 7.4 8.3 8.8 9.7 9.3

17.2 20.1

47.1

0.9 1.4 2.6 3.1 3.9 5.4 6.0 6.8 7.2

16.9 23.3 22.5

46.6

1.2 2.6 3.8 4.8 5.8 6.9 7.7 8.4 8.9

10.1 13.8 12.2 13.8

45.7

1.1 1.7 3.3 3.9 4.8 5.8 6.6 8.4 9.3

11.2 11.2 9.6 9.0 8.1 6.0

47.1

PHOS 2.E+14

0.4 0.8 1.8 3.6 6.6 9.3

10.8 11.3 12.0 12.1 13.1 9.3 8.9

45.5

E-distribution for generation of CH3COOH

2.2 3.3 2.3 2.6 6.6 8.8

26.8 30.8 7.5 7.6 1.5

48.1

1.8 3.9 0.0 5.9

31.6 31.1 12.0 13.7

49.7

1.7 3.5 8.1

20.2 27.4 24.5

7.7 4.5 1.2 1.2

50.2

21.2 51.5 6.4

18.4 2.5

52.0

2.6 4.8 3.7 9.9

14.4 17.2 23.7 18.6 5.1

48.0

E-<listribution for generation of H2S 0.4 1.1 0.0 5.4

21.8 52.7 13.9 2.7 0.9 1.1

49.7

4.7 37.9 24.0 33.4

49.7

42.6 30.3 27.1

53.7

42.9 27.6 29.5

53.7

0.5 1.4 1.9 3.8

11.3 18.8 25.7 19.7 16.9

51.7

E-distribution for generation of CH3C4H4S

0.1 0.9 4.2

15.3 36.9 28.4 9.0 2.6 1.8 0.8

50.8

0.8 0.5 2.0 8.5

20.8 34.4 19.2 8.1 2.9 1.4 0.5 0.9

50.2

0.1 0.2 2.8 8.8

38.3 36.3 9.2 4.1 0.2

53.1

6.2 27.8 35.6 21.1 7.2 2.1

52.0

0.1 0.8 2.5 5.6

15.9 30.0 27.2 12.0 3.7 2.2

52.7

0.1 3.7 6.8

12.4 21.0 28.4 16.8 6.0 4.8

51.2

2.5 7.4 7.9 7.7

11.1 13.6 22.7 7.6

19.5

50.1

0.1 0.8 2.7 5.3

12.7 28.3 27.9 13.0 6.3 1.5 1.4

53.0

19