Novel Geochemical Technologies Set the Stage for Correct Models of Complex Basins

Transcription

1 Novel Geochemical Technologies Set the Stage for Correct Models of Complex Basins J. M. (Mike) Moldowan Biomarker Technologies, Inc. Professor Emeritus, Department of Geological and Environmental Sciences, Stanford University

2 Connections between BPSM and Biomarker Technologies, Inc. Petroleum geochemistry courses offered to BPSM students Opportunity to include geochemistry into basin modeling thesis projects Thesis committee memberships and advising on geochemistry offered by Emeritus Professor Moldowan

3 What are the problems encountered when attempting to correlate oil by classical (biomarker fingerprinting) methods? ~ Major problems occur when biomarker fingerprints do not provide the whole story

4 Problems with using classical biomarker analysis often occur due to thermally cracked oil and/or biodegradation in which cases biomarkers are either altered, in low concentrations or absent. Similarities in source rock depositional environments of the different sources can challenge the ability to differentiate them and determine when mixtures are present.

5 The following conditions pertain to cracked oil and biodegraded oil: 1. Losses and alteration of compounds used for correlation: Alkanes, Isoprenoids, Biomarkers 2. Overprinting of fresh oil onto biodegraded or cracked oil hides the co-sources

6 Effective technologies for solving these problems 1. Diamondoid correlations - Diamondoids are not altered by biodegradation or oil cracking. 2. Generate fresh oil from asphaltenes Hydrous pyrolysis releases fresh alkanes, biomarkers and diamondoids in biodegraded oil. 3. Use partially biodegraded or remnant biomarkers Remaining biomarkers correlated by CSIA.

7 Diamondoids are nano-diamonds

8 What happens to diamondoids during oil cracking or biodegradation? F r e e E n e r g y D G O i l A c t i v a t i o n E n e r g y (Temp) M e t h a n e + G r a p h i t e + They undergo no chemical or physical change! They become more concentrated in the remaining cracked or heavy oil

9 Biomarkers Diamondoid-biomarker cracking method provides a means to recognize thermally cracked oil Low Maturity No Cracking Diamondoid baseline range ~1 to < 10 ppm (Up to peak oil-window maturity) High Maturity No Cracking Slightly Cracked Intensely Cracked Diamondoids Dahl et al., 1999

10 Use partially biodegraded or remnant biomarkers Remaining biomarkers correlated by CSIA.

11 Reconstruction of Carbon Flow using 13 C of individual biomarkers Algal Steranes Cyanobacterial Hopanes Methanotrophic Hopanes Reworked and preserved OM. CO 2 released Methanogenic Bacteria

12 Correlation of biodegraded seeps, produced oil and source rocks from Northern South America by CSIA-B Tertiary seep Cretaceous Mixed oil Mixed oil Tertiary seep Cretaceous seeps and source rock

13 Distinguishing four sources of biodegraded seeps and produced oil from Angola by CSIA-B Algal blooms Marine Marine Terrestrial Lacustrine

14 Correlations by two diamondoid methods 1 CSIA-D 2 QEDA [Review paper on diamondoid applications: in press, JPSE. Requests for preprints accepted]

15 Diamondoid correlation by CSIA-D Mixture of Cretaceous and Tertiary oil from Northern South America Diamondoid measured (adamantane and methylated adamantanes)

16 Structures of extended diamondoids measured in QEDA studies T1 T2 T3 Triamantane Used for normalization Tetramantanes P1 P2 P3 P4 H1 Pentamantanes Cyclohexamantane

17 Diamondoid correlation by QEDA Mixture of Cretaceous and Tertiary oil from Northern South America

18 We selected two heavy oils from Eastern Venezuela to demonstrate the application of QEDA Guarico Sub-basin Area Q 17 Ol K After Schlumberger (1997) and Mandini (1993) Z 8 GUYANA SHIELD

19 Diamondoid concentration relative to triamantane Log scale QEDA shows FAJA-Heavy-Oil-Z correlates to Cretaceous Oil. Heavy-Oil-Q might be also be Cretaceous if a different facies. Extended diamondoid measured ~1 ppb

20 Diamondoid concentration relative to triamantane Log scale QEDA shows asphaltenes of FAJA-Heavy-Oil-Z correlates to asphaltenes in Cretaceous Oil. Asphaltenes of Heavy-Oil-Q are different. Extended diamondoid measured

21 Diamondoid concentration relative to triamantane Log scale QEDA shows asphaltenes and maltenes of Heavy-Oil-Q are the same source/facies Extended diamondoid measured Cretaceous Facies 1a

22 Diamondoid concentration relative to triamantane Log scale QEDA shows asphaltenes and maltenes of Heavy-Oil-Z are different source/facies Heavy-Oil-Z and Cretaceous oil are THE SAME OIL same co-source combination Extended diamondoid measured Cretaceous Facies 1b Cretaceous Facies 2

23 These relationships suggest about oil migration in the Eastern Venezuela Basin Q Local Tertiary Source Ol K X Anaco Kitchen Area Z Oficina Kitchen Area GUYANA SHIELD After Schlumberger (1997) and Mandini (1993)

24 CONCLUSIONS For correlation of Venezuela heavy oil by QEDA QEDA of the whole oil and the asphaltenes reveals the Cretaceous end-member oil is co-sourced FAJA-Heavy-Oil-Z is exactly the same oil as the Cretaceous end-member oil Same original cosources in the same relative amounts. Same petroleum system from the same kitchen is likely Heavy-Oil-Q is related to a different Cretaceous facies different petroleum system from a different kitchen is likely

25 Now let s look at how diamondoids can be used to make correlations of the sources of cracked-oil with those of non-cracked oil, and determine possible oil-source mixtures in the Santos Basin of Brazil

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27 In this set of Santos Basin Oils most of the Post-salt oils are cracked. The Pre salt oils are evidently not cracked.

28 L L L L L Three different QEDA fingerprints Lacustrine oil QEDA fingerprints Two marine oil QEDA fingerprints

29 CONCLUSIONS The deep source charge (cracked oil charge) is very important in the Santos Basin due to the widespread presence of cracked oil Cracked oil is indicated by QDA. It cannot be indicated or correlated by biomarkers Three sources are indicated by QEDA, two marine and one lacustrine in both cracked and non-cracked oil. Without the application of QDA and QEDA the major charges to certain oil fields can be completely missed leading to incorrect basin models

30 CONCLUSIONS Correlation by application of the following methods can be accomplished for any oils isotopes of biomarkers (CSIA-B), with restrictions 2 diamondoid fingerprints (QEDA), without restrictions 3 diamondoid isotopes (CSIA-D), without restrictions

31 Acknowledgments The professional staff of Biomarker Technologies, Inc. IPEX and the ANP for Santos Basin oil samples Dr. Silvana Barbanti, IPEX Rio de Janeiro (currently Schlumberger) for cooperation on the Santos oil correlation project Dr. Jeremy Dahl, Laboratory for Materials and Energy Science, Stanford University, for collaboration in the development of diamondoid technologies

32 A special thanks to the BPSM member companies for their support of the program

33 Thank you! Obrigado! Gracias! धन यव द! شكرا لك! ありがとうございます! Danke! Merci! Asante! 謝謝!