Subsurface Structural Trap
• talk about how we find oil
• simulation to plan the drilling of a well
Today’s Activity
but before we start …..
• reservoir rock
• trap
• source rock
• seal
• migration of oil
Fundamentals of Petroleum Exploration
Oil is stored pores between the grains in sandstones and other "reservoir" rocks
Rivers Transport Sand and Mud
Core showing channel sands
Making a Structural Trap
Cedar Mesa Sandstone, SE Utah
Originally Horizontal Beds ….
…sometimes get folded• topography accentuates strike and dip
Folds and Faults make TRAPS
- faults represent brittle rock deformation
Subsurface Geology(how do we see underground?)
•core
•seismic
•logs
• source rock
• migration of oil
• reservoir rock
• trap
Fundamentals of Petroleum Exploration
How do we see below the surface?
A
B
A B
Casper Arch Thrust, Central Wyoming
Seismic Acquisition and Processing
Subsalt Imaging
4-DReservoir Monitoring
4-D Seismic and Reservoir Modeling
4-D Seismic
Difference Update-1995
Base-1983
A
B
A B
Casper Arch Thrust, Central Wyoming
Fundamentals of Petroleum Accumulation
Source Rock
Reservoir Rock
Migration
Trap
Putting it all together …..
Original Horizontal Layers
Mountain Building - Compression
Build a structural trap
Deformed Reservoir
Source
driven by buoyancy
Will folding in one direction be an effective trap?
Plate Tectonics Deforms/Folds
Rocks
Really need folding in two directions…
And that dome needs to be buried & covered with a seal!
Available Data
• Interpreted Seismic Lines– needed to determine if you have a trap
• Well-log Lithology– needed for determining whether you have a
reservoir rock (sandstone) and a seal – determine potential source rock (shale)
• Geochemical Analysis– determine if a potential source rock has
generated oil
Instructions
• divide into teams of 3 or 4 explorationists
• your budget is $330,000
• purchase data
• analyze data to choose a spot to drill
Prices
• Seismic Lines– Line A - $100,000– Line B - $75,000– Line C - $75,000
• Well-log Lithology– Well 1 - $25,000– Well 2 - $35,000
• Geochemical Analysis– Well 1 - $5,000– Well 2 - $5,000
Seismic Line A
Shale
Shale
ShaleSandstone
Sandstone
Sandstone
Limestone
Combining Seismic Lines for 3d
Seismic Line A - Solution
Seismic Line C – No Trap!