Subsurface Structural Trap

• talk about how we find oil

• simulation to plan the drilling of a well

Today’s Activity

but before we start …..

Petroleum Geology

• 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?

Seismic

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

Migration of Oil

driven by buoyancy

Trapped Oil

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

Seismic Line B

Seismic Line C

Combining Seismic Lines for 3d

Seismic Line A - Solution

Seismic Line B

Seismic Line C – No Trap!