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For contact information, please visit our website: www.weatherfordlabs.com Canada United States Norway United Kingdom Kazakhstan Brazil Mexico Trinidad.

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Presentation on theme: "For contact information, please visit our website: www.weatherfordlabs.com Canada United States Norway United Kingdom Kazakhstan Brazil Mexico Trinidad."— Presentation transcript:

1 For contact information, please visit our website: Canada United States Norway United Kingdom Kazakhstan Brazil Mexico Trinidad Venezuela Kuwait Libya Oman Saudi Arabia United Arab Emirates Iraq Australia India Malaysia Thailand New Zealand Indonesia Source Rock Geochemistry and Thermal Maturity Discussion of the Utica-Point Pleasant in the Northern Appalachian Basin Presented by: Dick Drozd

2 © 2009 Weatherford Laboratories. All rights reserved. Presentation Outline What are the important elements of a geochemical evaluation and why. Specific geochemical issues with the Ordovician section. Geochemistry of the Utica – Point Pleasant and equivalent units. Implications for exploration. Questions

3 © 2009 Weatherford Laboratories. All rights reserved. Significant Elements of Source Rock Evaluation 1.Organic Richness 2.Remaining Potential for Generation 3.Thermal Maturity 4.Kerogen Type All measurements are made on present-day as- received material Original condition most significant for exploration

4 © 2009 Weatherford Laboratories. All rights reserved. Total Organic Carbon (TOC) Solid organic material contained within a sample that can be subdivided into kerogen and bitumen. Total organic carbon determined by combustion of samples that have been treated with acid to remove inorganic carbon. Usually reported in units of weight fraction, TOC weight divided by sample weight.

5 © 2009 Weatherford Laboratories. All rights reserved. Why is TOC Important? TOC provides the carbon for hydrocarbons TOC provides increased porosity with increasing thermal maturation TOC provides adsorptive sites for hydrocarbons –To retain oil for cracking to gas –Storage of adsorbed gas

6 © 2009 Weatherford Laboratories. All rights reserved. Total Organic Carbon Guidelines Present day organic richness of source rock QualityTOC (wt%) Poor <0.5 Fair 0.5 to 1 Good 1 to 2 Very good 2 to 4 Excellent >4 Threshold Shale Gas Threshold Shale Oil The TOC Myth: “If I have high TOC, I have a good source rock.” (Dembicki, 2009)

7 © 2009 Weatherford Laboratories. All rights reserved. Programmed Pyrolysis Pyrolysis A chemical degradation reaction that is caused by thermal energy. (The term pyrolysis generally refers to an inert environment.) Temperature-Programmed Pyrolysis A pyrolysis during which the sample is heated at a controlled rate within a temperature range in which pyrolysis occurs.

8 © 2009 Weatherford Laboratories. All rights reserved. Source Rock Analyzer (SRA) Pyrolysis instrument that uses an FID detector and IR cells to measure: Available Hydrocarbon Content – S 1 Remaining Hydrocarbon Generation Potential – S 2 Organic Richness – TOC Thermal Maturity – T max

9 © 2009 Weatherford Laboratories. All rights reserved. Parameters Measured With Flame Ionization Detector (FID) - detects hydrocarbons only: –Volatile hydrocarbon content – S1 –Pyrolized hydrocarbons – S2 Tmax – Temperature of maximum S2 release With Infrared Detector – detects CO and CO 2 only: –CO 2 generated during pyrolysis – S3 –Total organic carbon (TOC) – S4

10 © 2009 Weatherford Laboratories. All rights reserved. Displayed Pyrogram 600 o C S1S1 S2S2 Tmax Temperature trace (nonisothermal at 25 o C/min) 300 o C Time (mins.) Yield S4S4 S3S3 Volatile Hydrocarbon Content Remaining Generative Potential Hydrogen CO 2 Generation Measure of TOC

11 © 2009 Weatherford Laboratories. All rights reserved. 11 Challenging to Measure Maturation parameters are indicative of the maximum paleo- temperature that a source rock has reached: Visual –Vitrinite reflectance (whole rock or kerogen concentrate) –Color indices (Conodonts, Zooclasts, bitumen) Chemical –Programmed Pyrolysis Tmax (chemical) Thermal Maturity

12 © 2009 Weatherford Laboratories. All rights reserved. Vitrinite Reflectance Vitrinite: a term (from coal petrography) for the jellified remains of higher plant tissues (post-Silurian) With increasing thermal alteration, vitrinite becomes more graphitic (condensed aromatic rings increase) and reflects more light Reflectance (%Ro) tracks kerogen maturity Other maturity measures expressed on vitrinite “scale”

13 © 2009 Weatherford Laboratories. All rights reserved. Problems Obtaining R o Maturities Properly identified vitrinite: –Primary –Recycled –Cavings –Mud additives Factors affecting accurate R o measurements: –Poor polish –Oxidized vitrinite –Inclusions (pyrite, bitumen, other macerals) Poor statistics (too few particles) Hunt, 1996, p. 515

14 © 2009 Weatherford Laboratories. All rights reserved. Calculated %Ro Values from Tmax Calculated values Jarvie et al., 2001 %VRo from Tmax = ( x Tmax) -7.16

15 © 2009 Weatherford Laboratories. All rights reserved. Issues with Tmax Anything that affects the peak shape will affect Tmax –Contamination from drilling mud may alter the S2 peak, –with high amounts of indigenous or migrated oil present, the oil part of S2 may exceed the kerogen S2 and Tmax will be too low, –at very high maturities, there is no S2 peak (flat) and Tmax is virtually random –dependent on kerogen type.

16 © 2009 Weatherford Laboratories. All rights reserved. Some S2 Pyrograms Tmax Tmax?

17 © 2009 Weatherford Laboratories. All rights reserved. 17 Vitrinite Reflectance (% Ro) scale for maturity assessment Immature<0.6% Ro Oil window % Ro Wet gas window % Ro Dry gas generation1.4-~2.2% Ro Dry gas preservation~2.2-~3.2% Ro Gas destruction>~3.2% Ro (?) Thermal Maturity Guidelines

18 © 2009 Weatherford Laboratories. All rights reserved. The TOC Myth: “If I have high TOC, I have a good source rock.” (Dembicki, 2009) Although a good source rock must have high TOC, not all organic matter is created equal. The more hydrogen associated with the carbon, the more hydrocarbon it can generate – particularly liquid hydrocarbons. Thus, we also need an indicator for the amount of hydrogen present in the organic matter (measured present day – projected into the past). KEROGEN TYPE From, Dembicki, H. (2009), Three common source rock evaluation errors made by geologists during prospect or play appraisals, AAPG Bulletin, v. 93, p

19 © 2009 Weatherford Laboratories. All rights reserved. Type III (HI=250) Type II (HI=420) Primary Hydrocarbon Generation Yields Type I (HI=810) Jarvie, unpublished data C1 C2-C4 C5-C14 C15+ Oil vs. Gas (Not secondary cracked products)

20 © 2009 Weatherford Laboratories. All rights reserved. Maceral composition is determined via petrographic (optical) analyses of pelletized samples or thin sections. Three Primary Maceral Groups. –Liptinite: Hydrogen-Rich –Vitrinite: Oxygen-Rich –Inertinite: Carbon-Rich Numerous macerals and sub- macerals in each maceral group. Fully characterize Kerogen Type via Maceral Composition and Programmed Pyrolysis. Maceral Group Macerals Organic Precursors Kerogen Type Liptinite Alginite I Fresh Water Algae I Alginite IIMarine AlgaeII Exinite Spores (Sporinite), Pollen II CutiniteLeaf CuticleII Resinite Resin, Tree Sap II Vitrinite Vitrinite, Psuedovitrinite Woody TissueIII Inertinite Semifusinite, Fusinite, Sclerotonite, etc. Reworked and/or Oxidized Material, Charcoal IV Kerogen Maceral Types

21 © 2009 Weatherford Laboratories. All rights reserved. Visual Kerogen Type Assessment Amorphous organic matter Type I: (oil prone) lacustrine algae Type II: (oil prone) marine algae

22 © 2009 Weatherford Laboratories. All rights reserved. Structured organic matter Type III: (gas prone) woody Visual Kerogen Type Assessment

23 © 2009 Weatherford Laboratories. All rights reserved. ca. 0.55% VRo Kerogen Quality Plot – Barnett Shale Example ca. 0.70% VRo ca. 0.85% VRo ca. 1.00% VRo ca. 1.50% VRo 25% 0.70%Ro 50% 0.85%Ro 75% 1.00%Ro 90% 1.50%Ro Samples as measured today, at present maturity!

24 © 2009 Weatherford Laboratories. All rights reserved. Measured present day: TOC Volatile Hydrocarbons Remaining Potential Kerogen Type Thermal Maturity “Magic” is a set of calculations described in the literature but too long for this presentation. Yield a set of yield estimates. Estimation of Yields Original: TOCo Total Potential Kerogen Type Partitioning gas/oil MAGIC Barnett Shale (Oil)

25 © 2009 Weatherford Laboratories. All rights reserved. Early Paleozoic age, therefore no primary Type III organic matter present Maturity - no vitrinite – Substitute: –Zooclasts reflectance (chitinozoans, scolecodonts, etc.) or bitumen reflectance –Conodont color Original Kerogen Type – Original hydrogen index (HIo) –Primary organic matter marine –Contribution from reworked/ recycled organic matter likely low, –Contribution of oxidized organic matter unknown –Over large geographic area & depositional settings variations likely (measured HIo 200 to 650) Utica / Point Pleasant & Equiv. Rocks

26 © 2009 Weatherford Laboratories. All rights reserved. Stratigraphy

27 Utica & Point Pleasant Thickness

28 © 2009 Weatherford Laboratories. All rights reserved. Structure on Top of the Trenton

29 © 2009 Weatherford Laboratories. All rights reserved. Source Rock Maturation Status

30 © 2009 Weatherford Laboratories. All rights reserved. Utica Undifferentiated Point Pleasant Collingwood Cobum Antes Cobourg Lindsay Point Pleasant Equivalents

31 © 2009 Weatherford Laboratories. All rights reserved. Two papers in the 1990’s Cole et al and Drozd & Cole examined the petroleum systems in Ohio. Conclusions: Oil in Ohio classified into three families –Group 1 found in Cambrian, Ordovician and some Silurian reservoirs, fingerprint characteristics of Early Paleozoic organic matter, and heavy carbon isotopes, –Group 2 found in some Silurian and Devonian to Pennsylvanian reservoirs, variable but distinct fingerprint characteristics, and intermediate carbon isotopes, –Group 3 found in a few Berea reservoirs similar to Group 2 in fingerprint pattern, but with light carbon isotopic composition. Source-Oil Correlation –Group 1 oils from Point Pleasant Shale, –Group 2 oils from facies of Ohio Shale, hence variable characteristics, –Group 3 oils from Sunbury Shale. Source Rock – Oil Correlation

32 © 2009 Weatherford Laboratories. All rights reserved. Contour Map – TOCo Utica / Pt Pleasant

33 © 2009 Weatherford Laboratories. All rights reserved. Contour Map – Ro Equiv Pt Pleasant

34 © 2009 Weatherford Laboratories. All rights reserved. Contour Map – NOC

35 © 2009 Weatherford Laboratories. All rights reserved. Comparison of Pt Pleasant to Other Shale Plays TOC (wt%) TOCo (wt%) Maturity (%Ro eq) OhioPt Pleasant Attractive MichiganCollingwood OntarioLindsay OntarioLindsay OntarioLindsay OntarioLindsay OhioUtica PAUtica Barnett (Oil) Eagle Ford (Oil) Geneseo/Burkett There is some variability in TOC in OH, similar to Collingwood in MI. Average maturity very different. “Selected” samples can have much higher TOC than cuttings. Utica in PA may include Pt Pleasant facies; much more mature. Other shale oil plays.

36 © 2009 Weatherford Laboratories. All rights reserved. Our understanding of the kinetic of the Point Pleasant kerogen is very limited due in part of lack of appropriate samples (low maturity but similar facies to producing area) Therefore, maturity guides may not be as appropriate as we would like. Ongoing Thoughts

37 © 2009 Weatherford Laboratories. All rights reserved. Kerogen Type Determines Timing/Rates of Conversion %Ro Tmax ( o C) Type II Type II-OS Type III Type I

38 © 2009 Weatherford Laboratories. All rights reserved. Our understanding of the kinetic of the Point Pleasant kerogen is very limited due in part of lack of appropriate samples (low maturity but similar facies to producing area) Therefore, maturity guides may not be as appropriate as we would like. Product expectation (heavier oil, light oil, condensate, wet gas) is also less certain than preferred. Variation in properties across a play is always an issue when the play is new, because we have yet to fully measure parameters needed to obtain a basic understanding of the detailed rock characteristics. Ongoing Thoughts

39 © 2009 Weatherford Laboratories. All rights reserved. The first step in our successful development of the Eagle Ford Shale play was to “prove the rocks”. (Richard Stoneburner, COO, Petrohawk Energy)

40 © 2009 Weatherford Laboratories. All rights reserved. Questions?


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