Tim Carr - West Virginia University

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3 GEOGRAPHIC EXTENT OF PETROLEUM SYSTEM A Trap Trap Trap A STRATIGRAPHIC EXTENT OF PETROLEUM SYSTEM Petroleum accumulation Top of oil window Bottom of oil window Overburden Seal Reservoir Source Underburden Tim Carr - West Virginia University

4 Elements Source Rock Migration Route Reservoir Rock Seal Rock Trap Processes Generation Migration Accumulation Preservation 4

5 1. Define prospect elements 2. Estimating trap volume 3. HC Presence & Type 4. Assessment 5. Risk Modified from ExxonMobil 5

6 1. Define prospect elements 2. Estimating trap volume 3. HC Presence & Type 4. Assessment 5. Risk Plumbing To Connect the Container to the Kitchen Correctly Placed Wells A Container From Which Oil & Gas Can Be Produced A Kitchen Where Organic Material Is Cooked Courtesy of ExxonMobil 6

7 ... Characterizing the type, history and origin of petroleum Predict Oil Quality Gama DensityResistivity Determine Ageof Oils Heavy Oil Lite Oil Gas Generation Rate Coaly SourceModel Leakage 10my SourceRockPrediction 0my Seal Reservoir Petroleum Charge Acumulation Petroleum Migration Sequence Stratigraphy SourceRock MigrationPathways 7

8 Questions for Exploration Geologist Does the rock have sufficient organic matter? Is the organic matter capable of generating? Has this organic matter generated petroleum? Has the generated petroleum migrated out? Is the organic material oil-prone or gasprone? Are there sufficient trap volumes 8

9 Kerogen Types Type 1 Type 2 Type 3 9

10 Tissot & Welte,

11 After Tissot & Welte,

12 Expulsion of oil and gas from low-permeability source rocks (shale-coal). Most major accumulations originated in source rocks with total organic carbon (TOC) >2.5 weight percent During generation (katagenesis) and primary migration, bitumen resides in pore space including fractures of the matrix. Primary migration accompanies peak generation 12

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14 Petroleum System Hydrocarbon Generation GEOGRAPHIC EXTENT OF PETROLEUM SYSTEM A Trap Present-Day Trap Trap A STRATIGRAPHIC EXTENT OF PETROLEUM SYSTEM Petroleum accumulation Top of oil window Bottom of oil window Overburden Seal Reservoir Source Underburden Magoon and Dow,

15 Draupne Shale organic rich serves as a source rock Heather Shale Sognefjord Shale both organic poor Fault Leak Point Oil Spill Point Facies Change Brent Sandstone acts as a reservoir Courtesy of ExxonMobil HC Generation & Expulsion oil & gas from the Draupne, gas from coals in the Brent HC Migration into Brent carrier beds and up faults HC Fill & Spill late gas displaces early oil 15

16 Driving Force Resisting Forces Phase Behavior Rates of migration Efficiency Long distance migration 16

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19 Movement from source to trap Along carrier bed As separate hydrocarbon phase (mostly) 19

20 Wetting q <90 o Nonwetting q >90 o 20

21 Pnw r Pnw Pnw Pw h Pw h Pw h Free Water Level Pnw=Pw Pw * Pw * Pw * Water Pw-Pnw = (r w -r nw ) h g 21

22 (after Berg, 1975) 22

23 (after Berg, 1975) 23

24 (Modified from Schowalter, 1979) 24

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29 England, Mann & Mann,

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31 England, Mann & Mann,

32 5 Km 32

33 England, Mann & Mann,

34 1. Define prospect elements 2. Estimating trap volume 3. HC Presence & Type 4. Assessment 5. Risk Modified from ExxonMobil 34

35 Exploration s Ultimate Goal is to Answer Four Questions: Where to Drill? What to Expect? How Certain? How Profitable? Location & Depth HC Volumes & Type Chance of Success (Risk) Economics Courtesy of ExxonMobil 35

36 A Kitchen Where Organic Material Is Cooked Source Organic-Rich Rocks, usually shale - coal Temperature & Pressure Conditions that Result in Oil & Gas Generation Courtesy of ExxonMobil 36

37 Plumbing To Connect the Container to the Kitchen Migration From source (shale) to porous reservoirs Strata-Parallel Component (sand & silt layers) Cross-Strata Component (faults, fractures) Courtesy of ExxonMobil 37

38 A Container From Which Oil & Gas Can Be Produced Reservoir Porous & Permeable Rock Suitable for Production Most Commonly Sandstone & Carbonate Trap 3-D Configuration that Pools the Oil & Gas Structural and/or Stratigraphic Traps Seal Rocks that Prevents Leakage from the Trap Most Commonly Shale and Evaporite Top Seals & Lateral Seals Courtesy of ExxonMobil 38

39 Timing Did the Trap form before HC Migration began? Fill & Spill Has HC Generation Exceeded Trap Volume? Has there been Spillage from Trap to Trap? Where is the Oil? Preservation Has Oil been degraded in the reservoir - thermal cracking or biodegradation? 39

40 1. Early Charge: Some Oil, Minor Gas 2. Peak Charge: Significant Oil, Some Gas 3. Late Charge: No Oil, Significant Gas Trap B Oil Spills Up Fault Gas Cap Displaces Oil Trap A Synclinal Spill Point Fault Leak Spill Point Oil Spilled from Trap A to Trap B Courtesy of ExxonMobil 40

41 Given the geologic framework and the results of our data analysis, our next task is to analyze and assess viable prospects: Analyze prospect elements Source, Migration, Reservoir, Trap, Seal Consider the most-likely scenario Consider other cases - the range of possibilities Assess the prospect What volumes of HCs can we expect? Will it be oil or gas? Risk the Prospect What is our level of confidence that all the prospect elements work? 41

42 Draupne Shale organic rich serves as a source rock Heather Shale Sognefjord Shale both organic poor Fault Leak Point Oil Spill Point Facies Change Courtesy of ExxonMobil Brent Sandstone acts as a reservoir HC Generation & Expulsion oil & gas from the Draupne, gas from coals in the Brent HC Migration into Brent carrier beds and up faults HC Fill & Spill late gas displaces early oil 42

43 Alpha Beta Sea Water Oil Fill & Spill Overburden Seal Oil Migration Reservoir Source Basement Oil Generation 18 Ma Courtesy of ExxonMobil 43

44 Alpha Beta Sea Water Oil Migration Overburden Seal Oil Migration Reservoir Source Basement Oil Generation 10 Ma Courtesy of ExxonMobil 44

45 Alpha Beta Sea Water Oil Migration Overburden Seal Oil & Gas Migration Reservoir Source Basement Oil Generation Present Gas Generation Courtesy of ExxonMobil 45

46 Alpha Beta Oil Oil 18 Ma Map of the Reservoir Unit Courtesy of ExxonMobil 46

47 Alpha Beta Oil Oil Map of the Reservoir Unit 10 Ma Courtesy of ExxonMobil 47

48 Alpha Beta Gas Oil Oil Map of the Reservoir Unit Present Courtesy of ExxonMobil 48

49 Identify Opportunities Acquire Seismic Data Interpret Seismic Data Capture Prime Areas Process Seismic Data Assess Prospects Drill Wildcats Failure Success Confirmation Well Courtesy of ExxonMobil 1. Volume 2. HC Type 3. Assessment 4. Risk Drop Area Uneconomic Success Development 49

50 Take Home Ideas Primary Migration Secondary Migration Direction & Magnitude Hydrocarbon Buoyancy Hydrostatic Fluid Flow & Buoyancy - Hydrodynamic Migration Paths and Timing Critical Capillary Pressure Pore Size Dependent Seal Competency Trap Size and Fill Amount Filling Fluid (Oil, Gas or Water) Fill and Spill Seal Failure 50

51 Assignments Reading for this week Jacobson, Petroleum Source Rocks p England et al. Migration Source to Trap, p Read Today in Energy for Thursday (2/19) at Be Prepared to Discuss in Class - Wednesday Discussion Leader Sean Kotter Quiz on Friday 2/20 Open at 1:00pm Closes on 2/23 at 11:00am Test on Friday 2/27 51