Tools for subsurface analysis

Tools for subsurface analysis

1. GEOL 553 Lecture 3; Subsurface
Analysis
GEOL 553: GEOL 553: Marine SedimentsMarine Sediments
University of South CarolinaUniversity of South Carolina
Fall 2005Fall 2005
Professor Chris KendallProfessor Chris Kendall
EWS 304 EWS 304
[email protected] [email protected]
777.2410777.2410
The Tools of Subsurface AnalysisThe Tools of Subsurface Analysis

2. GEOL 553 Lecture 3; Subsurface
Analysis
The Tools of Subsurface AnalysisThe Tools of Subsurface Analysis
Well logsWell logs
Cores Cores
SeismicSeismic
Gravity & magneticsGravity & magnetics
Facies analysis of subsurface data Facies analysis of subsurface data
depends on tools which delimit of depends on tools which delimit of
surfaces and provide clues as to the surfaces and provide clues as to the
sediments they contain:sediments they contain:

3. GEOL 553 Lecture 3; Subsurface
Analysis
Well Logs Versus SeismicWell Logs Versus Seismic
Well logs Well logs
Great vertical resolution Great vertical resolution
Delimit bounding surfacesDelimit bounding surfaces
Establish lithology of sediments penetratedEstablish lithology of sediments penetrated
SeismicSeismic
Great lateral continuity and resolutionGreat lateral continuity and resolution
Define gross sediment geometryDefine gross sediment geometry

4. GEOL 553 Lecture 3; Subsurface
Analysis
Tools are Keys to Allostratigraphy
& Sequence Stratigraphy
AllostratigraphyAllostratigraphy: bounding : bounding
discontinuities including erosion discontinuities including erosion
surfaces, marine flooding surfaces, surfaces, marine flooding surfaces,
tuffs, tempestite, and/or turbidite tuffs, tempestite, and/or turbidite
boundaries etc. as time markersboundaries etc. as time markers
Sequence StratigraphySequence Stratigraphy: higher level : higher level
allostratigraphic model which interprets allostratigraphic model which interprets
depositional origin of sedimentary depositional origin of sedimentary
strata as products of "relative sea level strata as products of "relative sea level
changechange""

5. GEOL 553 Lecture 3; Subsurface
Analysis
The Tools of Subsurface Analysis
Well logsWell logs
SeismicSeismic
Facies analysis of subsurface data Facies analysis of subsurface data
depends on tools which delimit of depends on tools which delimit of
surfaces and provide clues as to the surfaces and provide clues as to the
sediments they contain:sediments they contain:

6. GEOL 553 Lecture 3; Subsurface
Analysis
Well Logs
Resistivity LogsResistivity Logs
Spontaneous Potential (SP) LogsSpontaneous Potential (SP) Logs
Gamma Ray LogsGamma Ray Logs
Neutron LogsNeutron Logs
Density LogsDensity Logs
Sonic (acoustic) LogsSonic (acoustic) Logs
Delimit of surfaces & identify sediments penetratedDelimit of surfaces & identify sediments penetrated

7. GEOL 553 Lecture 3; Subsurface
Analysis

8. GEOL 553 Lecture 3; Subsurface
Analysis

9. GEOL 553 Lecture 3; Subsurface
Analysis
Resistivity Logs
Measures resistance of flow of electric Measures resistance of flow of electric
currentcurrent
Is function of porosity & pore fluid in rockIs function of porosity & pore fluid in rock
 Frequently used to identify lithologyFrequently used to identify lithology
The most commonly used logs:The most commonly used logs:

10. GEOL 553 Lecture 3; Subsurface
Analysis

11. GEOL 553 Lecture 3; Subsurface
Analysis
Spontaneous Potential (SP) Logs
Measures electrical current in wellMeasures electrical current in well
Result of salinity differences between Result of salinity differences between
formation water and the borehole mudformation water and the borehole mud
Separates bed boundaries of permeable Separates bed boundaries of permeable
sands & impermeable shales.sands & impermeable shales.
Next most common logNext most common log

12. GEOL 553 Lecture 3; Subsurface
Analysis

13. GEOL 553 Lecture 3; Subsurface
Analysis
Gamma Ray Logs
Records radioactivity of a formationRecords radioactivity of a formation
Shales have high gamma radioactive responseShales have high gamma radioactive response
Gamma ray logs infer grain size (and so Gamma ray logs infer grain size (and so
subsequently inferred depositional energy)subsequently inferred depositional energy)
Gamma ray logs are most commonly used logs Gamma ray logs are most commonly used logs
for sequence stratigraphic analysisfor sequence stratigraphic analysis
Another common logAnother common log

14. GEOL 553 Lecture 3; Subsurface
Analysis

15. GEOL 553 Lecture 3; Subsurface
Analysis

16. GEOL 553 Lecture 3; Subsurface
Analysis
After Harris & Saller 1999

17. GEOL 553 Lecture 3; Subsurface
Analysis
Neutron Logs
Measures porosity of formationMeasures porosity of formation
Uses quantity of hydrogen presentUses quantity of hydrogen present
Measures lithology when used with Density Measures lithology when used with Density
LogLog
Another common logAnother common log

18. GEOL 553 Lecture 3; Subsurface
Analysis
Density Logs
Measures formation’s bulk densityMeasures formation’s bulk density
Used as a porosity measureUsed as a porosity measure
Differentiates lithologies with Neutron LogDifferentiates lithologies with Neutron Log
Used with Sonic Logs to generate synthetic Used with Sonic Logs to generate synthetic
seismic traces to match to seismic linesseismic traces to match to seismic lines
A common logA common log

19. GEOL 553 Lecture 3; Subsurface
Analysis
Sonic (Acoustic) Logs
Measures of speed of sound in formationMeasures of speed of sound in formation
Tied to porosity and lithologyTied to porosity and lithology
Used with Density Logs to generate Used with Density Logs to generate
Synthetic Seismic traces to match to Synthetic Seismic traces to match to
Seismic linesSeismic lines
Another common logAnother common log

20. GEOL 553 Lecture 3; Subsurface
Analysis

21. GEOL 553 Lecture 3; Subsurface
Analysis

22. GEOL 553 Lecture 3; Subsurface
Analysis
The Tools of Subsurface Analysis
Well logsWell logs
SeismicSeismic
Facies analysis of subsurface data Facies analysis of subsurface data
depends on tools which delimit of depends on tools which delimit of
surfaces and provide clues as to the surfaces and provide clues as to the
sediments they contain:sediments they contain:

23. GEOL 553 Lecture 3; Subsurface
Analysis
Seismic
Define geometries of genetic reflection Define geometries of genetic reflection
packages that envelope seismic sequences packages that envelope seismic sequences
and systems tractsand systems tracts
 Identify bounding discontinuities on basis Identify bounding discontinuities on basis
of reflection termination patterns and of reflection termination patterns and
continuitycontinuity
Seismic stratigraphic interpretation Seismic stratigraphic interpretation
used to:used to:

24. GEOL 553 Lecture 3; Subsurface
Analysis
Seismic Boundaries
Toplap termination Toplap termination
Truncation of sediment surface Truncation of sediment surface
 Often channel bottomOften channel bottom
Termination below discontinuity, or Termination below discontinuity, or
upper sequence boundaryupper sequence boundary ::
Onlap over surfaceOnlap over surface
 Downlap surfaceDownlap surface
Above a discontinuity defining lower Above a discontinuity defining lower
sequence boundary:sequence boundary:

25. GEOL 553 Lecture 3; Subsurface
Analysis
Seismic Boundaries
Below Boundary - Toplap terminationBelow Boundary - Toplap termination

26. GEOL 553 Lecture 3; Subsurface
Analysis
Seismic Boundaries
Below Boundary -Below Boundary - Truncation of surfaceTruncation of surface

27. GEOL 553 Lecture 3; Subsurface
Analysis
Seismic Boundaries
ChanneledChanneled
Surface Surface
– – Below Below
BoundaryBoundary

28. GEOL 553 Lecture 3; Subsurface
Analysis
Seismic Boundaries
Over Boundary - Onlap onto surfaceOver Boundary - Onlap onto surface

29. GEOL 553 Lecture 3; Subsurface
Analysis
Seismic Boundaries
Over Boundary- Downlap onto surfaceOver Boundary- Downlap onto surface

30. GEOL 553 Lecture 3; Subsurface
Analysis

31. GEOL 553 Lecture 3; Subsurface
Analysis

32. GEOL 553 Lecture 3; Subsurface
Analysis

33. GEOL 553 Lecture 3; Subsurface
Analysis

34. GEOL 553 Lecture 3; Subsurface
Analysis
Sequence Stratigraphy
Surfaces of erosion & non-deposition (sequence Surfaces of erosion & non-deposition (sequence
boundaries)boundaries)
Flooding (trangressive surfaces [TS] &/or Flooding (trangressive surfaces [TS] &/or
maximum flooding surfaces [mfs]) & high stand maximum flooding surfaces [mfs]) & high stand
condensed surfacescondensed surfaces
Subdivision & interpretation of sedimentary Subdivision & interpretation of sedimentary
record using a framework surfaces seen in record using a framework surfaces seen in
outcrops, outcrops, well logs, & 2-D and 3-D seismicwell logs, & 2-D and 3-D seismic. .
Include:Include:
This framework used to predict the extent This framework used to predict the extent
of sedimentary facies geometry, lithologic of sedimentary facies geometry, lithologic
character, grain size, sorting & reservoir character, grain size, sorting & reservoir
qualityquality

35. GEOL 553 Lecture 3; Subsurface
Analysis
Tools Define Bounding Surfaces
Relative time framework for Relative time framework for
sedimentary successionsedimentary succession
Better understanding of inter-Better understanding of inter-
relationship of depositional settings & relationship of depositional settings &
their lateral correlationtheir lateral correlation
These surfaces subdivide sedimentary rockThese surfaces subdivide sedimentary rock &
provide:-provide:-
Conceptual models follow that link the
processes that formed the sediments and
enable the prediction of their gross geometries

36. GEOL 553 Lecture 3; Subsurface
Analysis
Sequence geometries are subdivided and Sequence geometries are subdivided and
defined bydefined by
Maximum Flooding Surfaces (mfs) Maximum Flooding Surfaces (mfs)
Transgressive Surfaces (TS) Transgressive Surfaces (TS)
Sequence Boundaries (SB)Sequence Boundaries (SB)
Define how vertical succession or stacking Define how vertical succession or stacking
patterns of unconfined sheets are arranged patterns of unconfined sheets are arranged
Prograde (step seaward) Prograde (step seaward)
Retrograde (step landward) Retrograde (step landward)
Aggrade (build vertically)Aggrade (build vertically)
Sheets and unconfined lobes may containSheets and unconfined lobes may contain
Non-amalgamated bodiesNon-amalgamated bodies
Amalgamated, multi-storied bodiesAmalgamated, multi-storied bodies
Incised topographic fill of valleysIncised topographic fill of valleys
Unconfined but localized lobes from point & Unconfined but localized lobes from point &
multiple up dip sourcesmultiple up dip sources
Unconfined but localized build ups (carbonates)Unconfined but localized build ups (carbonates)
Hierarchy of Geometries

37. GEOL 553 Lecture 3; Subsurface
Analysis

38. GEOL 553 Lecture 3; Subsurface
Analysis
Sequence geometries are subdivided and Sequence geometries are subdivided and
defined bydefined by
Maximum Flooding Surfaces (mfs) Maximum Flooding Surfaces (mfs)
Transgressive Surfaces (TS) Transgressive Surfaces (TS)
Sequence Boundaries (SB)Sequence Boundaries (SB)
Define how vertical succession or stacking Define how vertical succession or stacking
patterns of unconfined sheets are arranged patterns of unconfined sheets are arranged
Prograde (step seaward) Prograde (step seaward)
Retrograde (step landward) Retrograde (step landward)
Aggrade (build vertically)Aggrade (build vertically)
Sheets and unconfined lobes may containSheets and unconfined lobes may contain
Non-amalgamated bodiesNon-amalgamated bodies
Amalgamated, multi-storied bodiesAmalgamated, multi-storied bodies
Incised topographic fill of valleysIncised topographic fill of valleys
Unconfined but localized lobes from point & Unconfined but localized lobes from point &
multiple up dip sourcesmultiple up dip sources
Unconfined but localized build ups (carbonates)Unconfined but localized build ups (carbonates)
Hierarchy of Geometries

39. GEOL 553 Lecture 3; Subsurface
Analysis

40. GEOL 553 Lecture 3; Subsurface
Analysis
Sequence geometries are subdivided and Sequence geometries are subdivided and
defined bydefined by
Maximum Flooding Surfaces (mfs) Maximum Flooding Surfaces (mfs)
Transgressive Surfaces (TS) Transgressive Surfaces (TS)
Sequence Boundaries (SB)Sequence Boundaries (SB)
Define how vertical succession or stacking Define how vertical succession or stacking
patterns of unconfined sheets are arranged patterns of unconfined sheets are arranged
Prograde (step seaward) Prograde (step seaward)
Retrograde (step landward) Retrograde (step landward)
Aggrade (build vertically)Aggrade (build vertically)
Sheets and unconfined lobes may containSheets and unconfined lobes may contain
Non-amalgamated bodiesNon-amalgamated bodies
Amalgamated, multi-storied bodiesAmalgamated, multi-storied bodies
Incised topographic fill of valleysIncised topographic fill of valleys
Unconfined but localized lobes from point & Unconfined but localized lobes from point &
multiple up dip sourcesmultiple up dip sources
Unconfined but localized build ups (carbonates)Unconfined but localized build ups (carbonates)
Hierarchy of Geometries

41. GEOL 553 Lecture 3; Subsurface
Analysis

42. GEOL 553 Lecture 3; Subsurface
Analysis
Sequence geometries are subdivided and Sequence geometries are subdivided and
defined bydefined by
Maximum Flooding Surfaces (mfs) Maximum Flooding Surfaces (mfs)
Transgressive Surfaces (TS) Transgressive Surfaces (TS)
Sequence Boundaries (SB)Sequence Boundaries (SB)
Define how vertical succession or stacking Define how vertical succession or stacking
patterns of unconfined sheets are arranged patterns of unconfined sheets are arranged
Prograde (step seaward) Prograde (step seaward)
Retrograde (step landward) Retrograde (step landward)
Aggrade (build vertically)Aggrade (build vertically)
Sheets and unconfined lobes may containSheets and unconfined lobes may contain
Non-amalgamated bodiesNon-amalgamated bodies
Amalgamated, multi-storied bodiesAmalgamated, multi-storied bodies
Incised topographic fill of valleysIncised topographic fill of valleys
Unconfined but localized lobes from point & Unconfined but localized lobes from point &
multiple up dip sourcesmultiple up dip sources
Unconfined but localized build ups (carbonates)Unconfined but localized build ups (carbonates)
Hierarchy of Geometries

43. GEOL 553 Lecture 3; Subsurface
Analysis

44. GEOL 553 Lecture 3; Subsurface
Analysis
Sequence geometries are subdivided and Sequence geometries are subdivided and
defined bydefined by
Maximum Flooding Surfaces (mfs) Maximum Flooding Surfaces (mfs)
Transgressive Surfaces (TS) Transgressive Surfaces (TS)
Sequence Boundaries (SB)Sequence Boundaries (SB)
Define how vertical succession or stacking Define how vertical succession or stacking
patterns of unconfined sheets are arranged patterns of unconfined sheets are arranged
Prograde (step seaward) Prograde (step seaward)
Retrograde (step landward) Retrograde (step landward)
Aggrade (build vertically)Aggrade (build vertically)
Sheets and unconfined lobes may containSheets and unconfined lobes may contain
Non-amalgamated bodiesNon-amalgamated bodies
Amalgamated, multi-storied bodiesAmalgamated, multi-storied bodies
Incised topographic fill of valleysIncised topographic fill of valleys
Unconfined but localized lobes from point & Unconfined but localized lobes from point &
multiple up dip sourcesmultiple up dip sources
Unconfined but localized build ups (carbonates)Unconfined but localized build ups (carbonates)
Hierarchy of Geometries

45. GEOL 553 Lecture 3; Subsurface
Analysis
Ebb Ooid Delta - UAE

46. GEOL 553 Lecture 3; Subsurface
Analysis
Delta Mouth Bar - Kentucky
Note Incised SurfaceNote Incised Surface

47. GEOL 553 Lecture 3; Subsurface
Analysis
Channel – Gulf Coast
Note Incised SurfaceNote Incised Surface

48. GEOL 553 Lecture 3; Subsurface
Analysis
Flood Deltas & Channels - Kty

49. GEOL 553 Lecture 3; Subsurface
Analysis
Tidal
Channels
Khor
al
Bazam
-
UAE

50. GEOL 553 Lecture 3; Subsurface
Analysis
Tidal, Storm or Tsunami Channel
Note Incised SurfaceNote Incised Surface

51. GEOL 553 Lecture 3; Subsurface
Analysis
Tsunami Load & Drape - Kty
Note Uniform Thickness of LayerNote Uniform Thickness of Layer

52. GEOL 553 Lecture 3; Subsurface
Analysis
Clastic Sequence Stratigraphic Hierarchies

53. GEOL 553 Lecture 3; Subsurface
Analysis
Channels & Shelves
C
h
a n
n
e l
C
h
a n
n
e l
S
h
e
l
f
S
h
e
l
f
Both have unique processes & Both have unique processes &
structures that can be used to structures that can be used to
identify their settingidentify their setting

54. GEOL 553 Lecture 3; Subsurface
Analysis
Tools Enable Sequence Stratigraphic
Analysis
Subdivision of section into sequences, Subdivision of section into sequences,
parasequences and beds.parasequences and beds.
Link conceptual models with mix of Link conceptual models with mix of
components of the individual sequence, components of the individual sequence,
parasequence or beds parasequence or beds
Use these to explain the depositional Use these to explain the depositional
setting in terms of their lithology, grain setting in terms of their lithology, grain
size, sedimentary structures, contacts size, sedimentary structures, contacts
character (gradational, abrupt) etccharacter (gradational, abrupt) etc
This analysis involvesThis analysis involves

55. GEOL 553 Lecture 3; Subsurface
Analysis
Sequence
Stratigraphic
Analysis

56. End of the Lecture
Can it be supper Can it be supper
time?time?

57. GEOL 553 Lecture 3; Subsurface
Analysis

58. GEOL 553 Lecture 3; Subsurface
Analysis

59. GEOL 553 Lecture 3; Subsurface
Analysis
Unconfined Flow - Not in a Channel
Unique ProcessesUnique Processes
Flow is in all directions Flow is in all directions
No lateral boundaries, only upper and lower No lateral boundaries, only upper and lower
boundaries boundaries
Velocity changes: high to low Velocity changes: high to low
Sediment responsesSediment responses
Decrease in grain size: Fining outward Decrease in grain size: Fining outward
(coarse to fine)(coarse to fine)
Erosional/sharp/gradational contacts Erosional/sharp/gradational contacts
Accretion: Downstream, upstream and Accretion: Downstream, upstream and
vertical vertical
Decrease in sedimentary structures away Decrease in sedimentary structures away
from source from source
GeometriesGeometries
Sheets Sheets
Thin in direction of flow Thin in direction of flow