Pyrolysis and TOC Identification of Tight Oil Sweet Spots Albert Maende* and W. David Weldon, Wildcat Technologies, LLC, Humble, TX, United States. TALK OUTLINE Formation area of study Type of data, analytical method and interpretation framework Previous work Identification of Sweet Spots Conclusions 1
Formation Area of Study Formation Members Lower Shale; deep marine organic rich Member; epicontinental calcareous, dolomitic siliciclastic that is variously mottled, bioturbated and laminated Upper Shale; deep marine organic rich Drilled Wells & Area of Study 8 wells that were drilled through the Mississippian Devonian (Paleozoic) Formation within Williston Basin in North Dakota; originated as continental shelf but became intracratonic and has structures that reflect trends of the Rocky Mountain province (Gerhard et. al., 1982) Area of Study Well NGS # Well Name 8474 2618 607 1405 Graham USA #1-15 Jacob Huber #1 Angus Kennedy #F32-24D Caroline E. Peck #2 Well NGS # Well Name 11617 8177 5088 16637 Hagen #1-13 Dobrinski #18-44 Texel #1-15 Long #1-01H Location of 8 wells analyzed from North Dakota, Williston Basin 2
Type, Source of Data and Analytical Method Type of Data Pyrolysis, TOC and Carbonate Carbon Source of Data Pyrolysis and TOC data published by North Dakota Geological Survey HAWK TM Pyrolysis, TOC and Carbonate Carbon (CC) measurements Analytical Method Dried drill cuttings ground using a mortar and pestle Weighed to about 100 mg on a 4 decimal place balance Analyzed for their S1, S2, S3, Tmax, TOC and CC measurements on the HAWK TM Pyrolysis and TOC instrument Analyzed Parameters Pyrolysis, TOC and Carbonate Carbon Parameters S1 free oil (mg hydrocarbons/g rock) S2 kerogen yield (mg hydrocarbons/g rock) S3 pyrolyzed CO 2 (mg CO 2 /g rock) Tmax - Temperature ( C) at maximum generation of hydrocarbons from pyrolysis Carbonate Carbon (inorganic carbon) wt. % Total Organic Carbon (TOC) wt. % 3
Pyrolysis Indices Interpreted Pyrolysis Indices Hydrogen Index; S2/TOC x 100 (mg HC/g TOC) Oxygen Index; S3/TOC x 100 (mg CO 2 /g TOC) Oil Saturation Index (OSI); S1/TOC x 100 Vitrinite Reflectance equivalent (Roe); Roe = 0.018 x Tmax 7.16 (Jarvie, 2012) Interpretation Framework Compilation of pyrolysis, TOC and CC data plus indices in graphical plots Evaluation in a lithofacies framework Previous Work Upper Shale Lithofacies 5 - Siltstone Lithofacies 4 - Parallel Interbeds of Dark Grey Shale and Buff Silty Sandstone Lithofacies 3 - Sandstone Lithofacies 2 - Parallel Interbeds of Dark Grey Shale and Buff Silty Sandstone Lithofacies 1 - Siltstone Lower Shale Member Lithofacies of the Member (LeFever, 2009) (Hess, 2011) Wireline logs from 2 Formation Fields 4
Previous Work Isopach Map of the Member Isopach Map of the Lower Shale W M Mountrail max thickness ~ 60 ft. W M Mc Mountrail max thickness > 50 ft. County M Mountrail W Williams Mc - Mckenzie Mc (LeFever, 2009) Previous Work Hydrogen Index Map of the Formation Thickest API Gravity of Formation Oils (Kuhn et. al., 2009) 5
Formation Tops in the Analyzed Wells Upper (ft.) (ft.) Lower (ft.) Texel #21-35 10160.00 10172.00 10169.00 10247.00 10248.00 10263.00 Dobrinski #18-44 8629.00 8638.50 8638.58 8661.50 8661.90 8668.00 ft. Hagen #1-13 10363.60 10375.00 10376.00 10406.00. Catherine E. Peck #2 10770.75 10793.92 10794.58-10815.83 Angus Kennedy #F32-24D 10508.67 10521.67 10522.0 10573.83 10574.00 10599.83 Jacob Huber #1 9801 9825.58 9826.08 9836.75 Graham USA #1-15 10369 10372 10374 10378 10379 Long #1-01H 9138 9171.5 Graham USA #1-15 Well Upper Shale Member 0.00 1.00 2.00 0 200 400 600 6
Jacob Huber #1 Well Lower 0 20 40 60 80 100 0 200 400 600 800 Angus Kennedy #F32-24-P Well Upper Lower 0 20 40 60 80 0 200 400 600 800 7
Catherine E. Peck #2 Well Lower 0 10 20 30 0 100 200 300 400 500 Hagen #1-13 Well Lower 0 5 10 15 20 0 200 400 600 8
Dobrinski #18-44 Well Upper Lower 0 50 100 150 0 500 1000 1500 Texel #21-35 Well Upper Depth (ft) Lower 0 20 40 60 80 0 200 400 600 800 9
Long 1-01H Well Upper Lower 0 20 40 60 80 100 120 140 160 180 200 0 200 400 600 800 1000 Interpretation of Interpreted Lithofacies for Member in Long 1-05H Well on the basis of Pyrolysis Data Depth (ft.) S2 (mg HC/g rock) Interpreted Lithofacies 9138, 9140, 9140.5, 9141.5, 9142.5, 9151, 9151.5, 9155, 9156, 9150.5, 9164, 9164.5, 9168.5-9170 <1.00 Sandy 9142, 9143, 9143.5, 9146 9147.5, 9150.5, 9152.5, 9153, 9155.5, 9156.5 9159, 9160, 9165 9168, 9170.5 9171.5 9138.5 9139.5, 9141, 9142, 9144 9145.5, 9148 9150, 9152, 9153 9154.5, 9157.5, 9160.5 9161, 9163 9163.5 1.00 1.60 Silty >1.60 Shaly 10
Interpreted Interpreted Sweet Spots in the Member Well Name (NGS No.) Graham USA #1-15 (8474) Catherine E. Peck #2 (1405) Formation Member Member Inferred Sweet spot; Depth (ft.) 10374-10376 10770-10793 TOC (wt. %); range 0.28 0.46 (0.35) 0.57 0.93 (0.82) OSI; range 54 146 (88) 89 149 (132) S2 (mg HC/g rock); range 0.33 0.86 (0.56) 0.50 1.25 (0.94) Inferred Lithofacies Sandy Hydrogen Index of Lower ; range Sandy 47 180 (108). Roe of Lower ; 0.81 0.98 (0.92) Interpreted Interpreted Sweet Spots in the Member Well Name (NGS No.) Formation Inferred Sweet spot; Depth (ft.) TOC (wt. %); range OSI; range S2 (mg HC/g rock); range Inferred Lithofacies Hydrogen Index of Lower ; range Hagen #1-13 (11617) Long 1-01 H (16637) Member Member 10363-10373 8138 9171.5 0.22 0.49 (0.35) 0.22 0.76 (0.47) 100 129 (115) 374 791 (630) 0.30 1.08 (0.61) 0.46 2.89 (1.36) Sandy 80 134 (108). Roe of Lower ; 0.83 1.07 (1.01) Silty 464 827 (712). Roe of Lower ; 0.51 0.74 (0.61) 11
Interpreted Non Oil Productive Member Well Name (NGS No.) Formation ; Depth (ft.) TOC (wt. %); range OSI; range S2 (mg HC/g rock); range Inferred Lithofacies Hydrogen Index of Lower ; range Dobrinski #18-44 (8474) Member 8638-8661 0.10 0.80 (0.29) 0 298 (44) 0 1.91 (0.13) Sandy 20 607 (200). Roe of Lower ; 0.31 0.62 (0.48) Identification of Sweet Spots Sweet Spots indicative of Member Productive Oil Intervals Oil Saturation Index Values exceeding 100 Over a continuous multi-depth interval not just single streaks Sandy lithofacies At locations with Member that overlies: i. Lower Shale of Roe 0.90 1.00 ii. Hydrogen Index of about 100 12
Some Exceptions Long 1-01H Well The productive oil depth interval differs in that: Roe of underlying Lower is barely mature (0.61) Hydrogen Index of the underlying Lower averages 712 Inferred to be migrated oil Conclusions Formation Tops Upper, and Lower Formation Tops can be picked on the basis of their pyrolysis and TOC data Using Pyrolysis and TOC to pick Formation Tops is similar to using wireline logs Using Pyrolysis data, the lithofacies can also be identified in terms of: Relative sandy, silty and shaly tendencies on the basis of S2 values; S2 values of <1.00, 1.00 1.60 and >1.60 mg HC/g rock Sweet Spots marking productive oil intervals Oil Saturation Index values >100 over a continuous multi-depth interval Locations where overlies Lower of Roe 0.90 1.00 and Hydrogen Index of about 100 13
Acknowledgements/Questions I am grateful to Wildcat Technologies for sponsoring my participation at this landmark conference and I wish to also say thank you to URTeC conference organizers for inviting me. Thank you for listening to me and please let me have your questions. References HESS, 2011, Westward Expansion of the Oil Resource Play in North Dakota, Tight Oil from Shale Plays, World Congress 2011. Jarvie, D. M., 2012, Shale Resource Systems for Oil and Gas: in J. A. Breyer, ed., Shale Reservoirs Giant Resources for the 21 st Century: AAPG Memoir 97, p 69 87 and p.89 119. Gerhard, L. C., S. B. Anderson, J. A. LeFever and C. G. Carlson, 1982, Geological Development, Origin, and Energy Mineral Resources of Williston Basin, North Dakota: AAPG Bull. v.66, No. 8, p. 989 1020. LeFever, J. A., 2009, Montana-North Dakota? Member Play, North Dakota Geological Survey. North Dakota Geological Survey, 2011. Kuhn, P. H., R. di Primio and B. Horsfield, 2009, Inconsistency of Hydrocarbon Generation Potential and Production Data, The Play of North Dakota, 7 th Petroleum Geology Conference Queen Elizabeth II Conference Center, London. 14