basins fossil fuels and subsurface reservoirs

descrive the formation of fossil fuels in the subsurface

fossil fuels originate as biological material (algal material) accumulated in anoxic conditions

Def CCUS

carbon capture, utilization, storage \

• co2 is concentrated into a liquid

• pumped into subsurface reservoirs

\*\*which grain orientation will decrease the permeability of a rock

random fabric = better flow

increasing platy minerals + oriented fabric of particules = decrease

\*\*describe the accumulation of source rock for fossil fuels

biological material/algal material accumulates in anoxic conditions = high TOC (total organic carbon) rock

\*\*What was the cretaceous Castlegate Sandstone

a reservoir that was probably filled in the subsurface due to its high porosity and permeability but that has now been exhumed in Utah

\*\*def porosity vs permeability

porosity: how much spore space there is

permeability: how easy fluids can flow through the rock

\*\*define trap formations

any structural deformation that traps upward-migrating hydrocarbons with an impermeable change in lithology taht juxtaposes a reservoir and seal

**decreasing order of productive trap for:

• monocline

• antiform

• san-andreas fault

best: antiform

bof: monocline

bad: fault

describe the evolution of the western interior basin

\
cretaceous thrust-faults and foreland basin

proterozoic-jurassic strata

relative place of interrelated depozones with the foreland basin system

wedge top (weight) → foredeep → forebuldge (upward flexure)→ backbuldge

What are the seven petroleum systems events? •

source rock

reservoir rock

seal rock

overburden rock

preservation

trap formation

rock unit

Read and interpret a petroleum systems events graph. •

give the Timing of critical elements in formation of a petroleum system

Describe the characteristics of source rocks / reservoir rocks / seal rocks •

source rock: where the hydrocarbon form

• organic rich rock 1.8%

reservoir rock: high porosity and permeability, trapping properties (shallow = aquifer)

• porous sandstone, carbonate, fractured igneous/meta

seal rock: low porosity and permeability, impearmeable, creates traps (shallow = aquitard)

• evaporites, filled porosity sandstone/limestone, shale

What are the major types of traps. •

anticline, fault, salt = structural trap

stratigraphic, reef, unconformity = stratigraphical trap

Be able to evaluate whether a given scenario forms a good or bad trap •

How does subsidence result in extremely thick stratigraphic packages? •

accomodation is made for more deposition

What is a foreland basin and what are the parts of a foreland basin? •

accomodation made by the weigh of the belt

* wedge top → foredeep → forebuldge (up flexure) → backbuldge