Zusammenfassung der Ressource
LECTURE 17
- PETROLEUM SYSTEM
- Elements
- Source rock
- reservoir rock
- SEAL
rock
- prevent migrate
of H/C through
reservoir + force
H/C accum. in
trap
- low
permeability,
non-porous,
small pore
throats - trap H/C
- Types
- Fine-grained rocks
- siltstones, shales, mudstones
- cappillary seal (completely seal)
- susceptible to breaching by fracturing
- may be source rocks as well as seal rocks
- Clay smear/fault
gouge in fault zone
- capillary seal
- may provide fault seals
- Evaporites
- non-permeable
- self-sealing (ductility) -
high sealing integrity
- Modes
- cap seals
- Potential
depends
- Capacity
- max. capillary
pressure/
column height
- displacement
pressure
- pressure required to form
a filament of mercury
through pore space
- Capillary pressure vs. buoyancy
- capillary increase-column height
increase-buoyancy increase at top of
reservoir-H/C invade seal through large
pore where cap. pressure is lower
- upward migrate
H/C driven by
buoyancy
(density
difference betw.
fluids) oppose
cap.pressure
- Migration
change
depth+shape
reservoir
- Buoyancy press.
> displacement
press - seal leak
- geometry (seal closure)
- thickness +
areal extend
- Seal intergrity
- Mechanical properties, lithological+
structural homogeneity, ductility
- fault seals
- Types
- Damage
- processes (grain crushing)-
membrane seal (limestone)
- sand:sand windows
across fault due
- shale gouge
- ductile shale beds
either side of fault
entrained in fault zone
- cataclasis
- grains breaks+crushes
-fine grained gouges
-loss pores
- cementation
- fluid flow along once
permeable fault
- Juxtaposition
- fault juxtaposes
sealing rock again
reservoir rock-
juxtaposition fault seal
- sand:sand high risk,
sand:seal low risk
- Reactivation
- fault reactivate after trap
charged-high risk H/C migrate
along active fault zone
- stick-slip-stick
- fault seal valving with periodic pore
pressure rise then fluid release
- Quality
- Good (perfect)- capillary seal
- Poor- rate seal
- Overburden rock
- Processes
- trap formation
- H/C migration
- H/C accum..
- trap&H/C preservation
- H/C generation