Pyrolysis and TOC Identification of Tight Oil Sweet Spots TALK OUTLINE

Transcription

1 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

2 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 Graham USA #1-15 Jacob Huber #1 Angus Kennedy #F32-24D Caroline E. Peck #2 Well NGS # Well Name Hagen #1-13 Dobrinski #18-44 Texel #1-15 Long #1-01H Location of 8 wells analyzed from North Dakota, Williston Basin 2

3 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

4 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 = 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

5 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

6 Formation Tops in the Analyzed Wells Upper (ft.) (ft.) Lower (ft.) Texel # Dobrinski # ft. Hagen # Catherine E. Peck # Angus Kennedy #F32-24D Jacob Huber # Graham USA # Long #1-01H Graham USA #1-15 Well Upper Shale Member

7 Jacob Huber #1 Well Lower Angus Kennedy #F32-24-P Well Upper Lower

8 Catherine E. Peck #2 Well Lower Hagen #1-13 Well Lower

9 Dobrinski #18-44 Well Upper Lower Texel #21-35 Well Upper Depth (ft) Lower

10 Long 1-01H Well Upper Lower 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, , , , 9151, , 9155, 9156, , 9164, , <1.00 Sandy 9142, 9143, , , , , 9153, , , 9160, , , 9141, 9142, , , 9152, , , , Silty >1.60 Shaly 10

11 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.) TOC (wt. %); range (0.35) (0.82) OSI; range (88) (132) S2 (mg HC/g rock); range (0.56) (0.94) Inferred Lithofacies Sandy Hydrogen Index of Lower ; range Sandy (108). Roe of Lower ; (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 (0.35) (0.47) (115) (630) (0.61) (1.36) Sandy (108). Roe of Lower ; (1.01) Silty (712). Roe of Lower ; (0.61) 11

12 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 (0.29) (44) (0.13) Sandy (200). Roe of Lower ; (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 ii. Hydrogen Index of about

13 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, 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 and Hydrogen Index of about

14 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 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 and p 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 LeFever, J. A., 2009, Montana-North Dakota? Member Play, North Dakota Geological Survey. North Dakota Geological Survey, 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