Tim Carr - West Virginia University
Exploration s Ultimate Goal is to Answer Four Questions: Where to Drill? What to Expect? How Certain? How Profitable? Location & Depth HC Volumes Chance of Success (Risk) Economics
A Rube Goldberg View of a Hydrocarbon System 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
A Kitchen Where Organic Material Is Cooked Source Organic-Rich Rocks, usually shales Temperature & Pressure Conditions that Result in Oil & Gas Generation
A Container From Which Oil & Gas Can Be Produced Reservoir Porous & Permeable Rock Suitable for Production Most Commonly Sandstones & Carbonates Trap 3-D Configuration that Pools the Oil & Gas Structural and/or Stratigraphic Traps Seal Rocks that Prevents Leakage from the Trap Most Commonly Shales and Evaporites Top Seals & Lateral Seals
Plumbing To Connect the Container to the Kitchen Migration From source (shales) to porous reservoirs Strata-Parallel Component (sand & silt layers) Cross-Strata Component (faults, fractures)
Depth (km) 0 2 4 6 8 Oil & Gas Generation Window Gas Generation Window No More HC Generation Source Reservoir Trap & Seal Migration Gas & Oil Courtesy of ExxonMobil L 2 - Basics of Prospecting
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?
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
Unconsolidated products of Weathering & Erosion Loose sand, gravel, silt, mud, etc. Transported by rivers, wind, glaciers, currents, etc. Sedimentary Rock: Consolidated sediment 11
Sedimentary rocks are formed by the lithification of inorganic and/or organic sediments, or as chemical precipitates. There are two types of sedimentary rocks: Detrital (=Clastic) and Chemical Detrital sedimentary rocks form when existing parent rock material is weathered, fragmented, transported, and deposited in layers as unconsolidated sediment that undergoes lithification (e.g., compaction, cementation, dewatering) to form sedimentary rocks. Chemical sedimentary rocks are formed by a variety of processes and are divided into inorganic, and biochemical or organic chemical sedimentary rocks. Inorganic chemical rocks form from chemicals that are dissolved in a solution, transported, and chemically precipitated out of solution. Biochemical or organic sedimentary rocks form when plant or animal material is deposited and lithified. Those classified as biochemical chemical generally involve some form of fossilization or the accumulation of fossilized organism or organism remains, such as shell fragments. Organic rocks that are classified as clastic, involve the deposition of plant material and formation of peat and coal deposits. The physical, chemical, or biological changes that occur during the lithification of sedimentary rocks are described by process collectively referred to as diagenesis. 12
http://www.dnr.sc.gov/geology/images/rockcycle-pg.pdf 13
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Φ =41.73 e z/8197 ft Φ =41.73 e z/2498 m Schmoker and Halley, 1982 16
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Well rounded Well sorted Quartz sandstone Good Reservoir! Bimodal rounding Poorly sorted Lithic sandstone Poor Reservoir! 19
Black Shale Source rocks (fine grain, muddy, very low energy environ., high organic productivity) Reservoir Seal and Barriers Porous Sandstone Reservoirs (coarse grain, high energy environment, organic poor) 20
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Matt Miller 23
Braided Meandering 24
Atkinson et al., 1988 25
Atkinson et al., 1988 26
Braided Stream Meandering Stream 27
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Time 29
Kimberley, Australia National Geographic Photo 30
Sandstone Mudstone 31
NOAA 32
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USGS 35
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Garrison et al. 2013 38
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AAPG Memoir 72 40
Monterey Bay Aquarium Research Institute 41
Indiana University 42
Fans 43
Made of Calcium Carbonate or Mg -Ca Carbonate Precipitated from seawater Mostly by organisms (biochemical) algae, shells, corals In some cases chemically (inorganic) Diagenesis Important Aragonite Calcite Calcite Dolomite Limestone _ aragonite or calcite (CaCO 3 ) Dolostone _ dolomite (Ca,Mg (CO 3 ) 2 ) 44
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Carbonate Reefs 46
Carbonate Reefs 47
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Geoexpro vol.9, 2013 Leduc Reef, Alberta, Canada 50
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Chalk Fields in the North Sea produce from fractured chalk White Cliffs of Dover, UK 52
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Ghawar, Saudi Arabia 54
Take Home Ideas Exploration Process must evaluate all the components of the Petroleum System The vertical stacking of sedimentary rocks reflects the lateral change of the sedimentary system Lithification (Diagenesis) Dewatering, Compaction, Cementation, etc. Detrital Systems Importance of Depositional Energy for Sorting Importance of Continuity Carbonate Systems Biologic Influence Chemically Susceptible - Diagenesis Economic Potential is the Bottom Line 55
Assignments Reading for this week Chapter 3, Selley Read Today in Energy for Friday (2/6) at http://www.eia.gov/ Be Prepared to Discuss in Class - Thursday Discussion Leader Antonella Recchia Exercise passed-out Due on Friday (2/13). Wednesday (2/11) No Class. 56
Assignments Reading for this week Chapter on Sedimentary Environments from Earth Systems History textbook. See website Reading for next week Ch. 5, pp. 191-206, Selley Read Today in Energy at http://www.eia.gov/ Be Prepared to Discuss in Class Quiz closes at Noon Monday (2/10) 57