LECTURE 14

LECTURE 14

HYDROCARBON TRAPS
1. a trap consists of volume of porous and permeable reservoir rock which is partially/completely enclosed by sealing rocks/pressure barriers
2. Types
  1. Stratigraphic traps
    1. Channel traps
    2. Pinchout traps
    3. Change in rock type
      1. high risk (difficult identify rock types
    4. Turbidite mound traps
    5. Onlap traps
    6. Reef traps
    7. Unconformity traps
  2. Structural traps
    1. created by deformation of rocks. Concave-down pockets hold reservoir.
    2. Salt dome
      1. antiforms+other traps assoiciated with salt domes
      2. deformation caused by salt movement-form many traps surround and overlying
    3. Combination of fault and fold trap
      1. common, higher risk (fault leak)
    4. Deformations
      1. Folding
        antiformal trap
        represent by closed contour,4-way dip closure (pericline)
        most common, easy to find, low risk
        bed of reservoir rock (overlain by seal rock) is folded into antiform-beds dip away from crest on both side-form antiform traps
      2. Faulting
        fault trap
        shale gouge-shale smeared along fault plane by displacement
        rare, higher risk (fault seal/leak)
  3. Combination of structural+stratigraphic traps
GEOMETRIC ELEMENT
1. Crest
  1. highest(shallowest) inside closed contour
2. Lowest closing contour (LCC)
  1. deepest contour that still close. max. depth hcarbon can accmulation
3. Vertical Closure
  1. Crest-LCC: max. gross vertical column of hydrocarbon trap can hold
4. Area closure
  1. Area of LCC: max. area of an accumulation in a trap
5. Spill point
  1. trap filled to LCC then further hydrocarbon will migrate through spill point
  2. lie on LCC where contour start open
6. Stacked reservoirs
  1. alternating reservoirs+seals in trap-multiple accumulation

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	Created by Hoa Truong almost 9 years ago