Lesson 1 Geological Setting

8/7/2019 Lesson 1 Geological Setting

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Geologic Origin of

Reservoir Rocks

Courtesy


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Fundamentals of Geology

For those of you who want to enhanceyour geological background, UH hasan excellent Geosciences

Department.In the short term, you might review

the NASA web pagehttp://rst.gsfc.nasa.gov/Sect2/Sect2_1a.h(actually the entire site is good)
http://rst.gsfc.nasa.gov/Sect2/Sect2_1a.htmlhttp://rst.gsfc.nasa.gov/Sect2/Sect2_1a.html


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Rock Cycle

Courtesy NASA


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Rock Cycle

Courtesy USGS:// . . / / /http earthquake usgs gov learn glossary

rustDestroyed

rustCreated


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Plate tectonics

Courtesy Schlumberger


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Geologic Time Scale

Most reservoirs

Similar to,Tiab Table

. , .2 1 p 35


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Major Rock Classes

Primary

InterestForReservoirs


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Sedimentary Rocks areFormed in Horizontal Layers

which are Later Deformed andFaulted


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Seismic ExamplesSalt Dome

From Oilfield Review, .Jan 1993


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eismic ExamplesFaults

From Oilfield Review, .Jan 1993


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Modern Visualization

/ :123DI Geosigns Courtesy Shell International Exploration andProduction


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Modern Visualization

/ :123DI Geosigns Courtesy Shell International Exploration andProduction


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What makes a goodreservoir rock?

Space to hold hydrocarbons (porosity)that can flow into a well(permeability)

What else is needed for a goodpetroleum reservoir?Commercial quantities of hydrocarbons must

be ( )generated source and move( ) ( )migration into a confined volume trap(where they can be recovered drive

).mechanism

P i S di t R k


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Primary Sedimentary RockTypes in Reservoirs, Source,

and Traps Clastics composed of particles ofother rocks Sandstone reservoir

Shale source, trap, and increasinglyreservoir(!)

Non-clastic physical or chemicalsedimentation but not particles ofother rocks Carbonate reservoir

Evaporites removed from solution

by evaporation


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Approximate Distribution ofPetroleum Reservoirs

~59% Sandstone

~40% carbonates


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Sedimentation


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Sedimentary Rocks are foundin Sedimentary Basins

,Courtesy Jon Burger UH andChevron


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Sandstone Deposition

Rivers

Deltas

Deepwater Beach and Barrier Islands

Dunes


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Sedimentary Deposition ofSandstone by Water

Very complicated rules (


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R iv e r

Which way is downhill? Where are the biggrains?


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,Courtesy Jon Burger UH and

Chevron

Larger grains

Finer grains


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Deltaic

Larger grains Finer grains

Note the grain sizes? Why?,Courtesy Jon Burger UH and

Chevron


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eltaic Test

Plot grain sizes as a functionof depth


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Summary

Geological settings are rich in theirvariety but arise from relativelysimple physical rules, e.g., water

flows downhill Understanding the geological setting

for a reservoir provides valuable

insights about the reservoir, e.g.,permeability distribution

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Lesson 1 Geological Setting