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ENHANCED RESERVOIR
    CHARACTERISATION
          BASED UPON
BOREHOLE
IMAGES          SAADALLAH GEOCONSULTANT AS
                            A. SAADALLAH Dr.

&             Misjonsveien 39, N-4024 Stavanger Norway
              Tel. + (47) 51 52 62 65 (office)
DIPMETER      Email: kader@saadgeo.com
              website: www.saadgeo.com

DATA
WARNING !

THIS PRESENTATION WAS
PREPARED IN 2005

IT HAS TO BE UPDATED BY
INCLUDING NEW TOOLS (such as
those of Weatherford) AND OTHER
ELEMENTS OF INTERPRETAION
ENHANCED RESERVOIR
CHARACTERISATION BASED UPON
BOREHOLE IMAGES & DIPMETER
DATA



OVERVIEW
1 Introduction
2 Dipmeter Tools
3 Imaging Tools
4 Borehole Map
5 Stereographic Projections
6 From Raw Data to Geologically Interpretable Outputs
7 Basic Interpretation
8 Clastic Reservoirs
9 In Situ Stress Issue
10 Fractured Reservoirs
11 Key Features to keep in mind
12 Key References
INTRODUCTION
From Logging & Petrophysic
point of view

to

a Geologic Mapping of the
Borehole Wall concept
From Logging & Petrophysic point of view to a Geologic
Mapping of the Borehole Wall concept

Curve:
ONE value (Rock Propriety)

vs.

ONE Depth (MD)
From Logging & Petrophysic point of view to a Geologic
Mapping of the Borehole Wall concept
Curve: a value (Rock Propriety) vs. Depth (MD)




Dip needed very early in
Logging industry (Seismic not
yet performed or/and poor, Oil
goes up!)
From Logging & Petrophysic point of view to a Geologic
Mapping of the Borehole Wall concept
Curve: a value (Rock Propriety) vs. Depth (MD)
Dip needed very early in Logging industry (Seismic not yet
performed or/and poor, Oil goes up!)


Dip needs a set of at least 3
measurements of the SAME
FEATURE: Dipmeter tool: 4
curves
From Logging & Petrophysic point of view to a Geologic Mapping of
the Borehole Wall concept
Curve: a value (Rock Propriety) vs. Depth (MD)
Dip needed very early in Logging industry (Seismic not yet
performed or/and poor, Oil goes up!)
Dip needs a set of at least 3 measurements of the SAME FEATURE:
Dipmeter tool: 4 curves
Technology improvements: more data,
magnetometers, accelerometers, transmission
of data (pulse within mud) IMAGING
TOOLS: ca 100 000 measurements per Meter
MD: MAPPING OF THE BOREHOLE
WALL.
From Logging & Petrophysic point of view to a
Geologic Mapping of the Borehole Wall concept
Curve: a value (Rock Propriety) vs. Depth (MD)
Dip needed very early in Logging industry (Seismic
not yet performed or/and poor, Oil goes up!)
Dip needs a set of at least 3 measurements of the
SAME FEATURE: Dipmeter tool: 4 curves
Technology improvements: more data,
magnetometers, accelerometers, transmission of
data (pulse within mud) IMAGING TOOLS: 100
000 measurements per Meter MD: MAPPING OF
THE BOREHOLE WALL.
From1 Dip in 1 day (1969
Sidi Ferruch Algiers)
1250 Dips measured (2004) a fractured reservoir
From 1 Dip in 1 day (1969
Sidi Ferruch Algiers)
To
1250 Dips measured (2004
fractured reservoir)
From FEW to
THOUSANDS of
MEASUREMENTS
That’s
DIGITAL GEOLOGY
New ways of thinking,
managing data, processing,
interpreting…and more
and more data…in real
time …new challenges for
geoscientists
Logging History Mile Stones: 1927
      Figure 1.The first electric
      log was obtained Sept.
      27, 1927, on the
      Diefenbach 2905 well,
      Rig.No. 7,
      at Pechelbronn,Alsace,
      France.The resistivity
      curve
      was created by plotting
      successive readings.
Logging History Mile Stones: 1947
1941: logging took another major step forward with the
introduction of the Spontaneous-Potential
Dipmeter.

1947: This measurement was improved further with the
Resistivity Dipmeter

1952: Continuous Resistivity Dipmeter
Logging History Mile Stones:
Imaging Tools
1968 BHTV (BoreHole TeleViewer) Mobil Acoustic...

1986: FMS (Formation MicroScanner) Schlumberger Electric...

1991 FMI (Fullbore Formation Microscanner) Schlumberger...

1994 RAB (Resistivity at the Bit) LWD Schlumberger...

2001 OBMI (Oil Base MicroImager) Schlumberger...

NEXT: high resolution imaging LWD tools (technical issue to
transmit data while drilling solved: WO (2007??)

Followed by other logging companies: Baker Hughes, Halliburton
MAIN DIPMETER TOOLS
                                                                  Logging Company
                Main Technical
Tool Name                                          Resolution     Name & Mud
                Characteristics
                                                                  Environment
SHDT            8 microresistivity electrodes on
                                                                  Schlumberger’s tool
(Stratigraphi   4 pads (2 per pads)
                                                                  Water-base mud
c Dipmeter)     Sampling: 0.1 in
HEXDIP                                             Vertical
                6 microresistivity electrodes on                   Baker Hughes’ tool
(Hexagonal                                         resolution: 1-2
                6 pads                                             Water-base mud
Diplog)                                            cm
SED (Six
                6 microresistivity electrodes on                  Halliburton’ tool
Arm
                6 pads                                            Water-base mud
Dipmeter)
TOOL Example:
SED (Halliburton)
HIGH RESOLUTION IMAGING TOOLS
Electrical and Acoustic
of the main logging companies
                         in petroleum industry
 BAKER HUGHES:
    - STAR (electrical & acoustic)
    - CBIL

 HALLIBURTON:
    - XRMI (EMI)
    - CAST
 SCHLUMBERGER:
    - FMI (FMS)
    - UBI
Main Characteristics of Electrical Imaging Tools
Use electrical responses of the formation to create Images.
Pad-based Microresistivity (conduct. mud),
sensitive to poor pad contact. Depth of investigation: 1 in.
Resolution linked with electrical contrast:
Bedding ca. 1 cm; Fracture ca. 1 mm (Resistivity Contrast)

                         EMI             FMI            STAR
                  6 Pads, 2 rows      4 Pads & Flaps 6 Pads
Arm configuration                     2 X 12 Sensors 2 X 12 Sensors
                  25 Sensors
Sensors           150                 192            144
Coverage              58% of 8.5”      75% of 8.5”     56% of 8.5”
Logging Speed        1800 ft/hr       1800/1500 ft/hr 1200/2400 ft/hr
X-, Y-Spacing        0.2 in.           0.1-0.2 in.      0.1 in.
Main Characteristics of Acoustic Imaging Tools
Acoustic response of the formation to build up images
Rotating transducer (Transmitter-Receiver)
Ultras. pulse 250-500 kHz. Water- and Oil-based mud,
100% borehole coverage, sensitive to borehole shape,
Depth of investigation: 0, Travel Time and Amplitude Attenuation
Resolve feature down to 1 in.
                        CAST           UBI              CBIL
                   200 samples/rev 7.5 Rot /Sec     6 Rot/Sec
Measurements                       180 samples /rev 12 (STAR)
                                                    250 samples/rev

                                    1 in. 2100 ft/hr
Vertical Sampling 0.3 in            0.4 in 800 ft/hr    0.2 in
rate & Logg. speed 1200 ft/hr       0.2 in 400 ft hr    2400 ft/hr

Image Resolution                    0.4 in at 250 kHz
                                    0.2 in at 500 kHz
TOOL Example:
FMI (Schlumberger)
BOREHOLE MAP
BoreHoleMap
Borehole
Tool
Projection: Boreholemap
Tool within the Borehole: RB
Attitude of a plane in Space
Attitude of an axis in Space
Boreholemap representation: Sinecurve
Tadpole
BoreHoleMap: Orientation
Borehole Axis
DEVI: Deviation (inclination): Angle 00-90 Deg (from vertical to horizontal axis)
HAZI: Borehole axis azimuth: Angle 000-360 Deg (from N-000- to N -360 clockwise)
MD: Measured Depth
Tool Axis (Sonde Axis)
DEVI: Sonde Deviation: Angle 00-90 Deg (from vertical to horizontal axis)
Sonde DEVI = Borehole DEVI
P1AZ: Ref PAD (PAD1): Azimuth PAD1 = Angle 000-360 Deg from North (000) or
from the BOREHOLE HIGH SIDE clockwise

MD: Measured Depth
ORIENTATION of the BOREHOLE MAP
Y-AXIS:
   - Borehole High Side                     0 90 180 270 3600
   - Tool Frame




                               Y-Axis: MD
   - North
& MD

X- AXIS:
    - Borehole Perimeter
& Azimuthal                X-Axis: Azimuthal & Perimeter
ORIENTATION of the
      TOOL WITHIN the Borehole

Tool ROTATES (around the AXIS) its
EXACT position INSIDE the BOREHOLE
has to be known at EVERY measurement

RB: Relative Bearing:
Angle between the referenced-arm (P1AZ) and a fixed feature
(North,   High side of the Borehole) is recorded at
every measured point
AXIS ATTITUDE in SPACE:
Dip/Dip-Azimuth
Core Goniometry
               Methodology
1. - Projection of core-features
       onto a borehole map

2. - Projection of a planar-feature
       onto the borehole map (Fault…)

3. - Projection of a linear-feature of a surface
       onto the borehole map
       (Striation on Fault-Surface)
Projection of Core: Borehole Map
Orthogonal projection onto
a cylindrical surface = Borehole Map
            A reference line parallel
            to the core axis
            = master calibration line
               with the MD
            = Y-Axis
 Perimeter
 =2PR
 = 3600
 = X-Axis (cm & Deg)
Projection of a Planar-feature
    PR
                     DIP-AZIMUTH
         Sine curve TOP                PR




        Sine curve BOTTOM
        =DIP-AZIMUTH

          Perimeter
          =3600        900      1800         2700    360-00
          =2PR         PR/2      PR         3PR/2   2P R-0 cm

          DIP-AZIMUTH (cm or Deg)
          relative to the master calibration line
               Master Calibration Line
Projection of a Planar-feature
                             DIP

          Sine Curve
          Amplitude
            DZ

                         900      1800    2700    360-00
                         PR/2      PR    3PR/2   2P R-0 cm


                                   DZ
            Tang DIP =
                                Core Diameter
AXIS On Borehole Map
Fault Surface with Striation (Sandstone clast) in Shale
Projection of a Linear-feature
of a Surface onto the Borehole Map
                                      PR




           DZ


                      900     1800     2700    360-00
                     PR/2        PR   3PR/2

        Tang DIP =          DZ                2P R-0 cm
                     Diameter of the Core
         DIP-AZIMUTH of the line relative
         to the master calibration line
Projection of a Linear-feature
of a Surface onto the Borehole Map




                     900    1800     2700    360-00
                     PR/2    PR    3PR/2
                                            2P R-0 cm


         DIP-AZIMUTH of the LINE relative
         to the master calibration line
N (000Deg)
TADPOLE
               0 Deg                 90 Deg

                                       10/135 Deg



 W (270 Deg)                                  E (090 Deg)




  15/225 Deg
                       S (180 Deg)
STEREOGRAPHIC
PROJECTION
We are dealing

with DIP POPULATIONS

NOT with

INDIVIDUAL DIP
Analysing Dip Populations:
Stereographic Projections

SCHMIDT PROJECTION
Upper Hemisphere
Only ORIENTATION Matters
NOT the Spatial POSITION
UPPER HEMISPHERE
Vertical & Horizontal lines
Girdle of Lines
Vertical &
Horizontal

Planes
One Pop. Dipping
increasingly South:
GIRDLE
Schmidt
Net




Lines
Projection of a
Plane: Pole &
Cyclographic
Schmidt Net



       Planes
Schmidt Net
Unimodal
Population
Unimodal Population
Bimodal
Population
GIRDLE: Population Related to Fault
GIRDLE: FOLD
Compass Rose
                                                   360/0
                                  348.75                      011.25

                     326.25                                                  033.75
                                                                                             045
                                                   N-S
          315




                                                                 .S W
                                   N..N
                                   NN
                                                                                              056.25




                                                              E-S
                                       W-
                                        W-




                                                           N.N
                                                                               SW



                                          S..S
      303.75             NW
                            -S                                               E-



                                              EE
                              E                                            N

                 W.
                    NW                                                              .SW            078.75
 281.25                -E.                                                      E-W
                           SE                                              E. N


270            E-W                                                                    E-W              090

                                                                           W.
                           W                                                  NW
 258.75                W. S                                                     -E.
                 E. NE-                                                             SE             101.25

                                                                           NW
                                                            N..N
                                                            NN
                                           .SW




                             SW                                              -S
                                                                               E
                           E-                                                                   123.75
                                                                W-
                                                                 W-S




                         N
                                       E -S




        236.25
                                                                   S..SE
                                    N.N




                                                                      S




                                                                                          135
          225                                      N-S
                                                                                    146.25
                     213.75                                      168.75
                                    191.25
                                                   180
Dipping                       Striking                   Dipping                         Striking
348.75…011.25: N              E-W                        168.75…191.25: S                E-W
011.25…033.75: N.NE           W.NW-E.SE                  191.25…213.75: S.SW             W.NW-E.SE
033.75…056.25: NE             NW-SE                      213.75…236.25: SW               NW-SE
056.25…078.75: E.NE           N.NW-S.SE                  236.25…258.75: W.SW             N.NW-S.SE
078.75…101.25: E              N-S                        258.75…281.25: W                N-S
101.25…123.75: E.SE           N.NE-S.SW                  281.25…303.75: W.NW             N.NE-S.SW
123.75…146.25: SE             NE-SW                      303.75…326.25: NW               NE-SW
146.25…168.75: S.SE           E.NE-W.SW                  326.25…348.75: N.NW             E.NE-W.SW
168.75…191.25: S              E-W                        348.75…011.25: N                E-W
From RAW Data to

GEOLOGICALLY

Interpretable Outputs
Main Processes
Raw data, microresistivity measurements recorded by electrode tool,
need to be processed:
Speed correction,

Magnetic declination correction,

Depth shift offset (when it is needed)

Generation of image/dip logs.
Main Processes
Speed correction,
convert data, recorded vs. time into data vs. depth
&
correct depth offset due to oscillations along the axis tool.

Oscillations are caused by irregularities of the borehole or in fact due
to the none-constant speed of the tool while running the logs.

Generally, a sliding window of 10 ft is used for an average cable speed
of 1600 ft/hr.
SPEED CORRECTION: is applied
                                            to correct for erratic tool motion
                                  & convert data recorded in time to depth

             0   90   180   270    3600
                                                                                  T8

                                          T3
     0.2 in.

                                          T2                                     T2-7
                                                                                  2-7


                                          T1                                      T1
Y Axis: MD




                                          T0                                       T0

IN THEORY: Tool moves up the                      IN REALITY: Tool moves ERRATICALLY up
borehole recording measurement-sets               the borehole recording measurement-sets at
At regular timing (T0 – T3)                       regular timing (T0 – T3)
Main Processes
Magnetic declination correction,
applied to inclinometry measurements
recorded by the tool (relatively to the
magnetic North) to convert them to
Geographic North.
Main Processes
Depth shift offset (when it is needed)

Correlation of GR from another Run (Wireline Log) & GR from FMI

Geological Feature determined from other sources
Main Processes
Generation of images
Static normalised images (called Static Images):
computation carried out in a window covering all the
logged section.

Dynamically normalised images (called Dynamic Images):
sliding window (5 Ft).

Scale in the range white-yellow-brown-dark :
white-yellow: minimum conductivity
To
brown-dark: maximum conductivity.
QC: Depth Match, Static & Dynamic Images
Geological Features: Bed Boundary, Bedding
QC: Depth Match, Static & Dynamic Images
Geological Features: Bed Boundary, Bedding
                                        Dynamic Image
QC: Depth Match, Static & Dynamic Images
Geological Features: Bed Boundary, Bedding
                          Static Image   Dynamic Image
QC: Depth Match, Static & Dynamic Images
Geological Features: Bed Boundary, Bedding
                          Static Image   Dynamic Image

        Calipers
QC: Depth Match, Static & Dynamic Images
Geological Features: Bed Boundary, Bedding
                          Static Image   Dynamic Image
                   GR

        Calipers
QC: Depth Match, Static & Dynamic Images
Geological Features: Bed Boundary, Bedding
                          Static Image   Dynamic Image
                   GR

        Calipers




RHOB
QC: Depth Match, Static & Dynamic Images
Geological Features: Bed Boundary, Bedding
                          Static Image   Dynamic Image
                   GR

        Calipers




RHOB



NPHI
PROCESSING of
      DIPMETER
              DATA
Measurements
recorded by pads
during the run
Represented by
resistivity curves
specific to each
pad
are correlated
during
the process
(spikes)
Correlation
process will fit a
plane & compute
its dip/dip-
azimuth
Processing Dipmeter Data:
-1 m sliding window (1600 ft/hr average cable speed
- Corresponding step: 0.5 m
- Search angle 70 Deg
Processing Dipmeter Data:
-1 m sliding window (1600 ft/hr average cable speed
- Corresponding step: 0.5 m
- Search angle 70 Deg
                             Max. Search
   Window      Step length   Angle relative   Computed log
                                                              Comments
 length (cm)      (cm)        to borehole        name
                                  Deg.
                                                             Computed log
                                                                 used for
                                              Hex100X50X8     interpret dips
    100            50             80
                                                   0         stored in a new
                                                                log named
                                                             INTERPR100

     60            30             60          Hex60X30X60

     20            10             40          Hex20X10X40
Dip Log:
Computed Dips Only
High & Low Confidence
Noise
Poor Data Intervals
From Atlas of Borehole Imagery Ed L.B. Thompson Aapg 2000
QUALITY CHECK
From LOADING
   To
      FINAL INTERPRETATION
QC: Depth Match, Static & Dynamic Images
Geological Features: Bed Boundary, Bedding
                          Static Image   Dynamic Image
                   GR

        Calipers




RHOB



NPHI
Other Points:
Repeat Section (200 ft MD)

Tool Rotation (less than one turn per 30 ft)

Slip-Stick Behaviour

Raw data in original format (LIS, DLIS)
Field Print (orientation, Pad#, Magnetic
Declination Value, Correction (Not Done)
IF Orientation
Don’t Fit with Previous Field Model ?
Comparison with OTHER RUNS
Geology is the BEST QC

Tool has picked the “wrong” North?

Rotation of the Dip Log, around the borehole axis
(Same Methodology as in Core Goniometry)

Assume the Same Error during all the RUN
ROTATION
Vertical Borehole
DIP remains the Same

DIP-Azimuth Changes
ROTATION
Deviated Borehole
BASIC

INTERPRETATION
INTERPRETATION:
3 Steps

1: Collecting Geologic Data

2: Analysing Dip Populations

3: Correlating Geologic Features
INTERPRETATION Step 1
Collecting Geologic Data
-1) Diptype Listing
-2) Image Quality
-3) Zonation Based on Image Fabric
Highlighting:

-4) Lithology (Sedimentology) Facies
-5) Deformation Facies
DIPTYPE LISTING:
3 Geologic Surface Types:

-1) Sedimentologic
-2) Structural
-3) In Situ Stress Features
Identification of Geological Features
Picked out directly from images &/or inferred
Sedimentological features:
- Bedding planes Structural-Dip, Paleo-Horizontal Dip
- Cross-bedding     Paleo-Transport Directions, Deposi-
- Unconformities tional environments
- Image facies      Help define reservoir units
Tectonic features:
- Faults:           Fault-block rotation, strike-slip component
- Fractures:        Fracture analyses of reservoir:
                    Fracture population characterisation, fracture
                    densities, Maximum fracturing directions
- In-situ Stress features:      Breakout, Tensile Fractures
In Horizontal wells:      syncline & anticline structures,
                          younging direction, Bedding-plane-correlation
                          to constrain reservoir zonation
SEDIMENTOLOGIC Features
Listing PARTICULAR to a RESERVOIR

Related to data from other sources (Cores,
Petrophysics, Seismic, Field Studies) to help
CORRELATE
QC: Depth Match, Static & Dynamic Images
 Geological Features: Bed Boundary, Bedding
                           Static Image    Dynamic Image
                    GR

         Calipers




RHOB



NPHI




                            Bed Boundary
FMI
QC: Depth Match, Static & Dynamic Images
 Geological Features: Bed Boundary, Bedding
                           Static Image    Dynamic Image
                    GR

         Calipers




RHOB



NPHI




                                            Bedding
                            Bed Boundary
FMI
Foreset, Foreset Boundary & Cross Bedding

            Calipers

                        GR

                                             Foreset Boundary




                                                         Cross
          RHOB
                                                         Bedding

                        Foreset




                                                   Bed Boundary
           NPHI




FMI
Shale Bedding, SS Bedding & Heterolithic Bedding

          Calipers    GR




          RHOB


          NPHI




                                                        Shale
                                                        Bedding




                                                     SS
                                                     Bedding




                                                    Heterolithic
                                                    Bedding

FMI
TECTONIC Features
Listing PARTICULAR to a RESERVOIR

Related to data from other sources (Cores,
Petrophysics, Seismic, Field Studies) to help
CORRELATE
Part of a Diptype List (Fractured Reservoir)

Diptype Name,
(Correspondent
Geological Notion),
                          Description & Correlation with Geological
colour used in plots                                                      Comments
                          Feature
and Fig., and
Illustration (Go to Fig
#)


                          Narrow or large, and discrete resistive or
FAULT                     conductive anomaly displayed along a sub-
                          planar feature cutting sedimentologic planes.   Fault is differentiated from
(Fault), Red              Also, a clear cut off the bulk resistivity,     Fracture.
GoToFig11                 highlighting a plane considered as a fault
                          plane.


                                                                          The current bedding planes are
BEDDING                   Change in the bulk conductivity along a         generally parallel to bed boundary
(Bedding),                planar boundary at the lowest scale of the      and regularly repeated in the bed or
                          image, i.e. centimetre scale. Regularly         layer.
Green                     repeated planar features corresponding to       Confusion sometimes with Shale
GoToFig12                 current bedding planes.                         Bedding, Bed Boundary and
                                                                          Stylolite
Fault, Bedding, BedBoundary
m MD, Vertical Well, Scale: V=H   FMI processed &
                                  interpreted with
                                  Recall
FMI
      Fault
      Examples of
      Geological Features
      Interpreted as a
      probable
      Reverse Fault
      Bedding plane
      in the Hangingwall Block

          Minor Fault

      The same Bedding plane
      in the Footwall Block

           Reverse Minor Fault
           with a ca 15 cm throw
From Atlas of Borehole Imagery Ed L.B. Thompson Aapg 2000
HORIZONTAL WELLS
Younging Direction in Horizontal Well
         Younging Direction            Cross section
TD
                                       of anticline
                                       drilled by a
                                       Horizontal Well



       Upward           Downward   Younging direction
                                   inferred from
                                   the shape of
                                   the sine curve

Outward direction   Inward direction
Bedding Plan Correlation: a methodology to
help define reservoir units
                             -INTERVAL without fault
      Younging Direction
                             picked out

                             -SHORT interval

                             - A BEDDING PLANE ,
                             bounding reservoir units
                             picked and choosen as
                             STRATUM GUIDE

                             - Locations where Stratum
                             guide is cut
                                DOWNWARD
                             or UPWARD
To be Performed Carefully!   are picked out
Bull’s eye structure in Borehole Images
  Borehole high side       of Horizontal Well:


 Inward direction         Inward direction

= Anticline structure

Or                        Outward direction


= Inflexion of the well-track (concave profile)
Wood-Grain structure in Borehole Images
  Borehole high side     of Horizontal Well:


 Inward direction         Inward direction

= Syncline structure

Or                        Outward direction



= Inflexion of the well-track (convex profile)
From Atlas of Borehole Imagery
Ed L.B. Thompson Aapg 2000
From Atlas of Borehole Imagery
Ed L.B. Thompson Aapg 2000
Cross Bedding, Closed Fracture
m MD, Vertical Well, Scale: V=H   FMI processed &
                                  interpreted with Recall
FMI processed &
Discontinuous & Continuous                    interpreted with
                                              Recall
            m MD, Vertical Well, Scale: V=H
Fractures
IN SITU STRESS
 CHARACTERISATION
Tensile Fractures (Images)
Borehole Breakout (Images)
Borehole Breakout (Calipers)
Constrain the entire Population
Determination of the SHmax Direction
From Atlas of Borehole Imagery Ed L.B. Thompson Aapg 2000
Borehole Breakout (from Calipers)
Criteria to Constrain

1) Tool Rotation < 30 Deg

2) Caliper Difference > 0.5 in

3) Smaller Cal > BS-1.5 in

4) Bigger Cal > BS

5) Avoid Key Seat ovality (angle
   > 15 Deg)
SHmax
Determination :
Plotting All to Get
Global Picture
QUALITY IMAGE ZONATION

Poor Intervals are flagged
IMAGE FABRIC ZONATIONS

Image Fabric might be related to Geological
  Features… Interference of tool behaviour (&…)
  Zonation Uncertainty…calibrated, correlated…

Zonation Helps define reservoir features:

1)Highlighting Matrix (Sedimentologic, Lithology):
  Thinly Bedded, Nodular, Vuggy…matrixes

2) Highlighting Deformation Facies (Stylolite
  Associated Fractures, Fracture Zone 1…)
LITHOLOGY ZONATION
Highlighting Matrix (Sedimentologic, Lithology):
 Thinly Bedded, Nodular, Vuggy…matrixes
Example of Image Fabric Zonation
                             Highlighting Matrix Characteristic

Zonation Name & Colour
used to flag the          Description & Correlation with
                                                                                     Comments
corresponding interval,   Geological Features and Events
and Illustration (Fig)

                                                                        This layer might be rich in
                                                                        clay, shale, fine grain that
Thinly Bedded             Interbedded matrix with thinly bed including might be a horizontal barrier to
Matrix (Red)              cross bedding. It is possible to pick every 5 fluid displacement.
GoToFig11                 cm a bedding surface.                         It can be used to determine the
                                                                        Paleohorizontal dip if
                                                                        necessary.

                                                                            The resistive spots are
                          Conglomerate-shaped matrix with resistive        considered as tight or close
                          nodules. This might be related to                therefore not used by fluids as
                          conglomerates or not, it has to be calibrated    porosity.
Nodular Matrix            with other data sources (cores, mud logs,        On the contrary, the “matrix”
(Green) GoToFig12         field studies…). Resistive nodules might be      between the resistive spots is
                          related to some anisotropic proprieties of the   conductive so it is considered
                          matrix or to some tight features.                as actual/potential significant
                                                                           porosity
Zonation Highlighting Sedimentology
m MD, Vertical Well, Scale: V=H
FMI processed &
interpreted with Recall




Image Fabrics:
Thin Bedded
&
Bioturbed
Vuggy Matrix
Important Features:


Isolated              Intersected by
Interconnected        Deformed Zones
Size (Relatively)
Up Grading
Down Grading
(Correlation
with Flooding
Surfaces)
Scale




Rudist Shuaiba (Cr)
Bu Hasa Field (Abu
Dhabi)
DEFORMATION FACIES
ZONATION
(Stylolite Associated Fractures, Fracture Zone 1…)
Example of Zonation Highlighting
      Deformation Features, Stylolite & Karstic Associations, and Poor Images
Zonation Name &
Colour used to flag
                      Description & Correlation with
the corresponding                                                                   Comments
                      Geological Features and Events
interval, and
Illustration (Fig)

Poor Image            Image is of poor quality, high to moderate
                                                                       Poor quality of image correspond
(Red)                 uncertainty in the interpreted features of the
                                                                       often to washout intervals
GoToFig11             flagged interval.

                                                                       This zone, subhorizontal might play a
                                                                       positive role in draining fluids
                      Tiny Fractures (up to 20 cm vertical-length)     horizontally.
                      sub perpendicular to Stylolite surface,          Such feature is known as used by fluid
Stylolite             occurring in the lower side, or upper side or    paths in some carbonate reservoirs.
Associated            both sides of the stylolite surface. Fractures   It might be considered as “pipe-layer”
                      are striking in all azimuths (radial) or in      parallel to the Stylolite surface.
Fractures             particular azimuths: it is not clear.            If crossed by Fracture Zone or
(Green)               Sometimes a couple of stylolite surfaces         Fractured/Cataclastic zone this might
GoToFig12             with their associated fractures are close        increase the draining propriety.
                      enough to constitute a Stylolite Zone            The question is about the role
                                                                       regarding vertical path of fluids:
                                                                       obstacle or drain?
FMI (Processed &
Stylolite Associated Fractures    Interpreted with Recall)

m MD, Vertical Well, Scale: V=H
INFERRED Features

By Analysing Dip Populations
Examples:
Girdle: Inferred faults
Bimodal: Unconformities
Paleohorizontal dip
Structural Dips: Per Units,
Logged Section
Structural Dip & / or Paleo-Horizontal Dip: ?
“...Dips with constant magnitude and azimuth in a low energy environment
can be selected. They correspond to the groups of beds, whose bedding planes have not
undergone any biogenic or tectonic alteration. It can reasonably be assumed that these
beds were deposited on nearly horizontal surfaces and that their present dips are the
result of tectonic stresses” Tire de Serra, O. 1985, “Sedimentary environments from
wireline logs”.

   I call it: PALEO-HORIZONTAL DIP
  “By Structural dip is intended the “general attitude of beds”. It is the dip that would
  be measured at outcrop. It is usually the dip seen on seismic reflectors, themselves a
  generalisation. It avoids any sedimentary structures of any size and is generally
  considered to represent the depositional surface which also is considered to be
  horizontal.” Tire de Rider, M. H. 1996 “The geological interpretation of well logs”


   I call it: STRUCTURAL DIP
The way I see it, and use it in my interpretation:


PALEO-HORIZONTAL DIP
Paleo-Horizontal Dip, as is suggested by the name, is the dip of bedding planes that
were originally deposited horizontally. Low energy sediments such as shale, planktonic
sediments and coals, in specific conditions, can be assumed to be deposited
horizontally.
Such bedding planes may be used to infer tectonic events such as uplift, tilting or fault
block rotation.

STRUCTURAL DIP
Structural dip is restricted to the mean dip of a lithological formation that can be used
in geological (structural) cross-section, or related to a specific marker that can be
correlated to a seismic one, avoiding detailed sedimentological structures at small
scale. The dip and associated dip-azimuth can be used to infer the geometry of the
units, for structural purposes at rather bigger scale, no matter what its genetic origin,
or what events the unit has previously undergone.
Paleo-Horizontal Dip: Interval of Low Energy Deposits
Paleo-Horizontal Dip: Whole Dip-type Population
of Low Energy Deposits
Structural Dip: Several Dip-type Populations: Bed
Boundary, ...
PALEOHORIZONTAL DIP Implemented to Rotate Out Dips




                                       After Rotation


                   Before Rotation
CROSS

        BEDDING
(After Gareth, G.; 2000, in PESGB Newsletter)
Terminology used in FMI image interpretation
                         Track-tadpole presentation

Foreset Boundary


Cross-Bedding Planes



Foreset Boundary




Foreset Boundaries
&                         Cross-section presentation
Cross- Bedding
are Parallel (Planar
Cross Bedding)?

= SS   Bedding
PALEOCURRENT

  DIRECTIONS
Paleocurrent directions: ONE DIRECTION
                         in
                         ONE SET
Paleocurrent directions: DIRECTIONS
                         in
                         ONE SET
PALEOCURRENT DIRECTIONS

GLOBAL
          RESULTS
Paleocurrent directions: Global Results




                   Major Minor
Cross Bedding
 Interval Method
 Whole Pop.

SS Bedding
 Interval Method
 Whole Pop.

Heterolithic
 Whole Pop.
PALEOCURRENT

DIRECTIONS
               Vs

    GEOLOGIC TIME
Ex. 1: SAME       DIRECTION
Paleocurrent directions are stacked up from
bottom to top:
-Bottom (Dark Blue)
-Middle of the unit (Green)
-Top (Yellow)
Ex. 2:       CYCLE
Re-Considering the previous example (Global
Result)
Paleocurrent directions: Global Results




                   Major Minor
Cross Bedding
 Interval Method
 Whole Pop.

SS Bedding
 Interval Method
 Whole Pop.

Heterolithic
 Whole Pop.
Paleocurrent Directions (from O to 360 Deg)

N

W
S

E
N



                                                          Geological
                               Cycle                      Time
                                           Northerly
                                           Paleocurrent
Final Result: Distinct Stacked Paleocurrent cycles



                                                     N
                                                         N




 W
W-SW




        S     S
PaleoHorizontal Dip Implemented to
Constrain Fault Block Rotation
PaleoHorizontal Dip Implemented to
Constrain Fault Block Rotation
Unconformity from Bimodal Bedding
Population: whole section
Unconformity from Bimodal Bedding
Population: Upper Unit
Unconformity from Bimodal Bedding
Population: Lower Unit
Geometry
of the
whole
section
INFERRING
GEOLOGIC
FEATURES:
FAULTS



Fault
Pattern
FAULT: Picked & Constrained (girdle) 1of2
FAULT: Picked & Constrained (girdle) 2 of 2
Constraining a Normal Fault with Roll Over 1of 2
Constraining a Normal Fault with Roll Over 2 of 2
Key References
Overview To Linked In
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Overview To Linked In

  • 1. ENHANCED RESERVOIR CHARACTERISATION BASED UPON BOREHOLE IMAGES SAADALLAH GEOCONSULTANT AS A. SAADALLAH Dr. & Misjonsveien 39, N-4024 Stavanger Norway Tel. + (47) 51 52 62 65 (office) DIPMETER Email: kader@saadgeo.com website: www.saadgeo.com DATA
  • 2. WARNING ! THIS PRESENTATION WAS PREPARED IN 2005 IT HAS TO BE UPDATED BY INCLUDING NEW TOOLS (such as those of Weatherford) AND OTHER ELEMENTS OF INTERPRETAION
  • 3. ENHANCED RESERVOIR CHARACTERISATION BASED UPON BOREHOLE IMAGES & DIPMETER DATA OVERVIEW
  • 4. 1 Introduction 2 Dipmeter Tools 3 Imaging Tools 4 Borehole Map 5 Stereographic Projections 6 From Raw Data to Geologically Interpretable Outputs 7 Basic Interpretation 8 Clastic Reservoirs 9 In Situ Stress Issue 10 Fractured Reservoirs 11 Key Features to keep in mind 12 Key References
  • 6. From Logging & Petrophysic point of view to a Geologic Mapping of the Borehole Wall concept
  • 7. From Logging & Petrophysic point of view to a Geologic Mapping of the Borehole Wall concept Curve: ONE value (Rock Propriety) vs. ONE Depth (MD)
  • 8. From Logging & Petrophysic point of view to a Geologic Mapping of the Borehole Wall concept Curve: a value (Rock Propriety) vs. Depth (MD) Dip needed very early in Logging industry (Seismic not yet performed or/and poor, Oil goes up!)
  • 9. From Logging & Petrophysic point of view to a Geologic Mapping of the Borehole Wall concept Curve: a value (Rock Propriety) vs. Depth (MD) Dip needed very early in Logging industry (Seismic not yet performed or/and poor, Oil goes up!) Dip needs a set of at least 3 measurements of the SAME FEATURE: Dipmeter tool: 4 curves
  • 10. From Logging & Petrophysic point of view to a Geologic Mapping of the Borehole Wall concept Curve: a value (Rock Propriety) vs. Depth (MD) Dip needed very early in Logging industry (Seismic not yet performed or/and poor, Oil goes up!) Dip needs a set of at least 3 measurements of the SAME FEATURE: Dipmeter tool: 4 curves Technology improvements: more data, magnetometers, accelerometers, transmission of data (pulse within mud) IMAGING TOOLS: ca 100 000 measurements per Meter MD: MAPPING OF THE BOREHOLE WALL.
  • 11. From Logging & Petrophysic point of view to a Geologic Mapping of the Borehole Wall concept Curve: a value (Rock Propriety) vs. Depth (MD) Dip needed very early in Logging industry (Seismic not yet performed or/and poor, Oil goes up!) Dip needs a set of at least 3 measurements of the SAME FEATURE: Dipmeter tool: 4 curves Technology improvements: more data, magnetometers, accelerometers, transmission of data (pulse within mud) IMAGING TOOLS: 100 000 measurements per Meter MD: MAPPING OF THE BOREHOLE WALL.
  • 12.
  • 13.
  • 14. From1 Dip in 1 day (1969 Sidi Ferruch Algiers)
  • 15. 1250 Dips measured (2004) a fractured reservoir
  • 16. From 1 Dip in 1 day (1969 Sidi Ferruch Algiers) To 1250 Dips measured (2004 fractured reservoir)
  • 17. From FEW to THOUSANDS of MEASUREMENTS That’s DIGITAL GEOLOGY
  • 18. New ways of thinking, managing data, processing, interpreting…and more and more data…in real time …new challenges for geoscientists
  • 19. Logging History Mile Stones: 1927 Figure 1.The first electric log was obtained Sept. 27, 1927, on the Diefenbach 2905 well, Rig.No. 7, at Pechelbronn,Alsace, France.The resistivity curve was created by plotting successive readings.
  • 20. Logging History Mile Stones: 1947 1941: logging took another major step forward with the introduction of the Spontaneous-Potential Dipmeter. 1947: This measurement was improved further with the Resistivity Dipmeter 1952: Continuous Resistivity Dipmeter
  • 21. Logging History Mile Stones: Imaging Tools 1968 BHTV (BoreHole TeleViewer) Mobil Acoustic... 1986: FMS (Formation MicroScanner) Schlumberger Electric... 1991 FMI (Fullbore Formation Microscanner) Schlumberger... 1994 RAB (Resistivity at the Bit) LWD Schlumberger... 2001 OBMI (Oil Base MicroImager) Schlumberger... NEXT: high resolution imaging LWD tools (technical issue to transmit data while drilling solved: WO (2007??) Followed by other logging companies: Baker Hughes, Halliburton
  • 22. MAIN DIPMETER TOOLS Logging Company Main Technical Tool Name Resolution Name & Mud Characteristics Environment SHDT 8 microresistivity electrodes on Schlumberger’s tool (Stratigraphi 4 pads (2 per pads) Water-base mud c Dipmeter) Sampling: 0.1 in HEXDIP Vertical 6 microresistivity electrodes on Baker Hughes’ tool (Hexagonal resolution: 1-2 6 pads Water-base mud Diplog) cm SED (Six 6 microresistivity electrodes on Halliburton’ tool Arm 6 pads Water-base mud Dipmeter)
  • 24. HIGH RESOLUTION IMAGING TOOLS Electrical and Acoustic of the main logging companies in petroleum industry BAKER HUGHES: - STAR (electrical & acoustic) - CBIL HALLIBURTON: - XRMI (EMI) - CAST SCHLUMBERGER: - FMI (FMS) - UBI
  • 25. Main Characteristics of Electrical Imaging Tools Use electrical responses of the formation to create Images. Pad-based Microresistivity (conduct. mud), sensitive to poor pad contact. Depth of investigation: 1 in. Resolution linked with electrical contrast: Bedding ca. 1 cm; Fracture ca. 1 mm (Resistivity Contrast) EMI FMI STAR 6 Pads, 2 rows 4 Pads & Flaps 6 Pads Arm configuration 2 X 12 Sensors 2 X 12 Sensors 25 Sensors Sensors 150 192 144 Coverage 58% of 8.5” 75% of 8.5” 56% of 8.5” Logging Speed 1800 ft/hr 1800/1500 ft/hr 1200/2400 ft/hr X-, Y-Spacing 0.2 in. 0.1-0.2 in. 0.1 in.
  • 26. Main Characteristics of Acoustic Imaging Tools Acoustic response of the formation to build up images Rotating transducer (Transmitter-Receiver) Ultras. pulse 250-500 kHz. Water- and Oil-based mud, 100% borehole coverage, sensitive to borehole shape, Depth of investigation: 0, Travel Time and Amplitude Attenuation Resolve feature down to 1 in. CAST UBI CBIL 200 samples/rev 7.5 Rot /Sec 6 Rot/Sec Measurements 180 samples /rev 12 (STAR) 250 samples/rev 1 in. 2100 ft/hr Vertical Sampling 0.3 in 0.4 in 800 ft/hr 0.2 in rate & Logg. speed 1200 ft/hr 0.2 in 400 ft hr 2400 ft/hr Image Resolution 0.4 in at 250 kHz 0.2 in at 500 kHz
  • 29. BoreHoleMap Borehole Tool Projection: Boreholemap Tool within the Borehole: RB Attitude of a plane in Space Attitude of an axis in Space Boreholemap representation: Sinecurve Tadpole
  • 30. BoreHoleMap: Orientation Borehole Axis DEVI: Deviation (inclination): Angle 00-90 Deg (from vertical to horizontal axis) HAZI: Borehole axis azimuth: Angle 000-360 Deg (from N-000- to N -360 clockwise) MD: Measured Depth Tool Axis (Sonde Axis) DEVI: Sonde Deviation: Angle 00-90 Deg (from vertical to horizontal axis) Sonde DEVI = Borehole DEVI P1AZ: Ref PAD (PAD1): Azimuth PAD1 = Angle 000-360 Deg from North (000) or from the BOREHOLE HIGH SIDE clockwise MD: Measured Depth
  • 31.
  • 32.
  • 33. ORIENTATION of the BOREHOLE MAP Y-AXIS: - Borehole High Side 0 90 180 270 3600 - Tool Frame Y-Axis: MD - North & MD X- AXIS: - Borehole Perimeter & Azimuthal X-Axis: Azimuthal & Perimeter
  • 34. ORIENTATION of the TOOL WITHIN the Borehole Tool ROTATES (around the AXIS) its EXACT position INSIDE the BOREHOLE has to be known at EVERY measurement RB: Relative Bearing: Angle between the referenced-arm (P1AZ) and a fixed feature (North, High side of the Borehole) is recorded at every measured point
  • 35.
  • 36.
  • 37. AXIS ATTITUDE in SPACE: Dip/Dip-Azimuth
  • 38. Core Goniometry Methodology 1. - Projection of core-features onto a borehole map 2. - Projection of a planar-feature onto the borehole map (Fault…) 3. - Projection of a linear-feature of a surface onto the borehole map (Striation on Fault-Surface)
  • 39. Projection of Core: Borehole Map Orthogonal projection onto a cylindrical surface = Borehole Map A reference line parallel to the core axis = master calibration line with the MD = Y-Axis Perimeter =2PR = 3600 = X-Axis (cm & Deg)
  • 40. Projection of a Planar-feature PR DIP-AZIMUTH Sine curve TOP PR Sine curve BOTTOM =DIP-AZIMUTH Perimeter =3600 900 1800 2700 360-00 =2PR PR/2 PR 3PR/2 2P R-0 cm DIP-AZIMUTH (cm or Deg) relative to the master calibration line Master Calibration Line
  • 41. Projection of a Planar-feature DIP Sine Curve Amplitude DZ 900 1800 2700 360-00 PR/2 PR 3PR/2 2P R-0 cm DZ Tang DIP = Core Diameter
  • 42. AXIS On Borehole Map Fault Surface with Striation (Sandstone clast) in Shale
  • 43. Projection of a Linear-feature of a Surface onto the Borehole Map PR DZ 900 1800 2700 360-00 PR/2 PR 3PR/2 Tang DIP = DZ 2P R-0 cm Diameter of the Core DIP-AZIMUTH of the line relative to the master calibration line
  • 44. Projection of a Linear-feature of a Surface onto the Borehole Map 900 1800 2700 360-00 PR/2 PR 3PR/2 2P R-0 cm DIP-AZIMUTH of the LINE relative to the master calibration line
  • 45.
  • 46. N (000Deg) TADPOLE 0 Deg 90 Deg 10/135 Deg W (270 Deg) E (090 Deg) 15/225 Deg S (180 Deg)
  • 48. We are dealing with DIP POPULATIONS NOT with INDIVIDUAL DIP
  • 49. Analysing Dip Populations: Stereographic Projections SCHMIDT PROJECTION Upper Hemisphere
  • 50. Only ORIENTATION Matters NOT the Spatial POSITION
  • 57. Projection of a Plane: Pole & Cyclographic
  • 58. Schmidt Net Planes
  • 65. Compass Rose 360/0 348.75 011.25 326.25 033.75 045 N-S 315 .S W N..N NN 056.25 E-S W- W- N.N SW S..S 303.75 NW -S E- EE E N W. NW .SW 078.75 281.25 -E. E-W SE E. N 270 E-W E-W 090 W. W NW 258.75 W. S -E. E. NE- SE 101.25 NW N..N NN .SW SW -S E E- 123.75 W- W-S N E -S 236.25 S..SE N.N S 135 225 N-S 146.25 213.75 168.75 191.25 180 Dipping Striking Dipping Striking 348.75…011.25: N E-W 168.75…191.25: S E-W 011.25…033.75: N.NE W.NW-E.SE 191.25…213.75: S.SW W.NW-E.SE 033.75…056.25: NE NW-SE 213.75…236.25: SW NW-SE 056.25…078.75: E.NE N.NW-S.SE 236.25…258.75: W.SW N.NW-S.SE 078.75…101.25: E N-S 258.75…281.25: W N-S 101.25…123.75: E.SE N.NE-S.SW 281.25…303.75: W.NW N.NE-S.SW 123.75…146.25: SE NE-SW 303.75…326.25: NW NE-SW 146.25…168.75: S.SE E.NE-W.SW 326.25…348.75: N.NW E.NE-W.SW 168.75…191.25: S E-W 348.75…011.25: N E-W
  • 66. From RAW Data to GEOLOGICALLY Interpretable Outputs
  • 67. Main Processes Raw data, microresistivity measurements recorded by electrode tool, need to be processed: Speed correction, Magnetic declination correction, Depth shift offset (when it is needed) Generation of image/dip logs.
  • 68. Main Processes Speed correction, convert data, recorded vs. time into data vs. depth & correct depth offset due to oscillations along the axis tool. Oscillations are caused by irregularities of the borehole or in fact due to the none-constant speed of the tool while running the logs. Generally, a sliding window of 10 ft is used for an average cable speed of 1600 ft/hr.
  • 69. SPEED CORRECTION: is applied to correct for erratic tool motion & convert data recorded in time to depth 0 90 180 270 3600 T8 T3 0.2 in. T2 T2-7 2-7 T1 T1 Y Axis: MD T0 T0 IN THEORY: Tool moves up the IN REALITY: Tool moves ERRATICALLY up borehole recording measurement-sets the borehole recording measurement-sets at At regular timing (T0 – T3) regular timing (T0 – T3)
  • 70. Main Processes Magnetic declination correction, applied to inclinometry measurements recorded by the tool (relatively to the magnetic North) to convert them to Geographic North.
  • 71. Main Processes Depth shift offset (when it is needed) Correlation of GR from another Run (Wireline Log) & GR from FMI Geological Feature determined from other sources
  • 72. Main Processes Generation of images Static normalised images (called Static Images): computation carried out in a window covering all the logged section. Dynamically normalised images (called Dynamic Images): sliding window (5 Ft). Scale in the range white-yellow-brown-dark : white-yellow: minimum conductivity To brown-dark: maximum conductivity.
  • 73. QC: Depth Match, Static & Dynamic Images Geological Features: Bed Boundary, Bedding
  • 74. QC: Depth Match, Static & Dynamic Images Geological Features: Bed Boundary, Bedding Dynamic Image
  • 75. QC: Depth Match, Static & Dynamic Images Geological Features: Bed Boundary, Bedding Static Image Dynamic Image
  • 76. QC: Depth Match, Static & Dynamic Images Geological Features: Bed Boundary, Bedding Static Image Dynamic Image Calipers
  • 77. QC: Depth Match, Static & Dynamic Images Geological Features: Bed Boundary, Bedding Static Image Dynamic Image GR Calipers
  • 78. QC: Depth Match, Static & Dynamic Images Geological Features: Bed Boundary, Bedding Static Image Dynamic Image GR Calipers RHOB
  • 79. QC: Depth Match, Static & Dynamic Images Geological Features: Bed Boundary, Bedding Static Image Dynamic Image GR Calipers RHOB NPHI
  • 80. PROCESSING of DIPMETER DATA
  • 81. Measurements recorded by pads during the run Represented by resistivity curves specific to each pad are correlated during the process (spikes)
  • 82. Correlation process will fit a plane & compute its dip/dip- azimuth
  • 83.
  • 84. Processing Dipmeter Data: -1 m sliding window (1600 ft/hr average cable speed - Corresponding step: 0.5 m - Search angle 70 Deg
  • 85. Processing Dipmeter Data: -1 m sliding window (1600 ft/hr average cable speed - Corresponding step: 0.5 m - Search angle 70 Deg Max. Search Window Step length Angle relative Computed log Comments length (cm) (cm) to borehole name Deg. Computed log used for Hex100X50X8 interpret dips 100 50 80 0 stored in a new log named INTERPR100 60 30 60 Hex60X30X60 20 10 40 Hex20X10X40
  • 86. Dip Log: Computed Dips Only High & Low Confidence Noise Poor Data Intervals
  • 87. From Atlas of Borehole Imagery Ed L.B. Thompson Aapg 2000
  • 88. QUALITY CHECK From LOADING To FINAL INTERPRETATION
  • 89.
  • 90.
  • 91.
  • 92.
  • 93.
  • 94.
  • 95.
  • 96.
  • 97. QC: Depth Match, Static & Dynamic Images Geological Features: Bed Boundary, Bedding Static Image Dynamic Image GR Calipers RHOB NPHI
  • 98. Other Points: Repeat Section (200 ft MD) Tool Rotation (less than one turn per 30 ft) Slip-Stick Behaviour Raw data in original format (LIS, DLIS) Field Print (orientation, Pad#, Magnetic Declination Value, Correction (Not Done)
  • 99. IF Orientation Don’t Fit with Previous Field Model ? Comparison with OTHER RUNS Geology is the BEST QC Tool has picked the “wrong” North? Rotation of the Dip Log, around the borehole axis (Same Methodology as in Core Goniometry) Assume the Same Error during all the RUN
  • 100. ROTATION Vertical Borehole DIP remains the Same DIP-Azimuth Changes
  • 102.
  • 103.
  • 105. INTERPRETATION: 3 Steps 1: Collecting Geologic Data 2: Analysing Dip Populations 3: Correlating Geologic Features
  • 106. INTERPRETATION Step 1 Collecting Geologic Data -1) Diptype Listing -2) Image Quality -3) Zonation Based on Image Fabric Highlighting: -4) Lithology (Sedimentology) Facies -5) Deformation Facies
  • 107. DIPTYPE LISTING: 3 Geologic Surface Types: -1) Sedimentologic -2) Structural -3) In Situ Stress Features
  • 108. Identification of Geological Features Picked out directly from images &/or inferred Sedimentological features: - Bedding planes Structural-Dip, Paleo-Horizontal Dip - Cross-bedding Paleo-Transport Directions, Deposi- - Unconformities tional environments - Image facies Help define reservoir units Tectonic features: - Faults: Fault-block rotation, strike-slip component - Fractures: Fracture analyses of reservoir: Fracture population characterisation, fracture densities, Maximum fracturing directions - In-situ Stress features: Breakout, Tensile Fractures In Horizontal wells: syncline & anticline structures, younging direction, Bedding-plane-correlation to constrain reservoir zonation
  • 109. SEDIMENTOLOGIC Features Listing PARTICULAR to a RESERVOIR Related to data from other sources (Cores, Petrophysics, Seismic, Field Studies) to help CORRELATE
  • 110. QC: Depth Match, Static & Dynamic Images Geological Features: Bed Boundary, Bedding Static Image Dynamic Image GR Calipers RHOB NPHI Bed Boundary FMI
  • 111. QC: Depth Match, Static & Dynamic Images Geological Features: Bed Boundary, Bedding Static Image Dynamic Image GR Calipers RHOB NPHI Bedding Bed Boundary FMI
  • 112. Foreset, Foreset Boundary & Cross Bedding Calipers GR Foreset Boundary Cross RHOB Bedding Foreset Bed Boundary NPHI FMI
  • 113. Shale Bedding, SS Bedding & Heterolithic Bedding Calipers GR RHOB NPHI Shale Bedding SS Bedding Heterolithic Bedding FMI
  • 114. TECTONIC Features Listing PARTICULAR to a RESERVOIR Related to data from other sources (Cores, Petrophysics, Seismic, Field Studies) to help CORRELATE
  • 115. Part of a Diptype List (Fractured Reservoir) Diptype Name, (Correspondent Geological Notion), Description & Correlation with Geological colour used in plots Comments Feature and Fig., and Illustration (Go to Fig #) Narrow or large, and discrete resistive or FAULT conductive anomaly displayed along a sub- planar feature cutting sedimentologic planes. Fault is differentiated from (Fault), Red Also, a clear cut off the bulk resistivity, Fracture. GoToFig11 highlighting a plane considered as a fault plane. The current bedding planes are BEDDING Change in the bulk conductivity along a generally parallel to bed boundary (Bedding), planar boundary at the lowest scale of the and regularly repeated in the bed or image, i.e. centimetre scale. Regularly layer. Green repeated planar features corresponding to Confusion sometimes with Shale GoToFig12 current bedding planes. Bedding, Bed Boundary and Stylolite
  • 116. Fault, Bedding, BedBoundary m MD, Vertical Well, Scale: V=H FMI processed & interpreted with Recall
  • 117. FMI Fault Examples of Geological Features Interpreted as a probable Reverse Fault Bedding plane in the Hangingwall Block Minor Fault The same Bedding plane in the Footwall Block Reverse Minor Fault with a ca 15 cm throw
  • 118. From Atlas of Borehole Imagery Ed L.B. Thompson Aapg 2000
  • 120. Younging Direction in Horizontal Well Younging Direction Cross section TD of anticline drilled by a Horizontal Well Upward Downward Younging direction inferred from the shape of the sine curve Outward direction Inward direction
  • 121. Bedding Plan Correlation: a methodology to help define reservoir units -INTERVAL without fault Younging Direction picked out -SHORT interval - A BEDDING PLANE , bounding reservoir units picked and choosen as STRATUM GUIDE - Locations where Stratum guide is cut DOWNWARD or UPWARD To be Performed Carefully! are picked out
  • 122. Bull’s eye structure in Borehole Images Borehole high side of Horizontal Well: Inward direction Inward direction = Anticline structure Or Outward direction = Inflexion of the well-track (concave profile)
  • 123. Wood-Grain structure in Borehole Images Borehole high side of Horizontal Well: Inward direction Inward direction = Syncline structure Or Outward direction = Inflexion of the well-track (convex profile)
  • 124. From Atlas of Borehole Imagery Ed L.B. Thompson Aapg 2000
  • 125. From Atlas of Borehole Imagery Ed L.B. Thompson Aapg 2000
  • 126. Cross Bedding, Closed Fracture m MD, Vertical Well, Scale: V=H FMI processed & interpreted with Recall
  • 127. FMI processed & Discontinuous & Continuous interpreted with Recall m MD, Vertical Well, Scale: V=H Fractures
  • 128. IN SITU STRESS CHARACTERISATION Tensile Fractures (Images) Borehole Breakout (Images) Borehole Breakout (Calipers) Constrain the entire Population Determination of the SHmax Direction
  • 129. From Atlas of Borehole Imagery Ed L.B. Thompson Aapg 2000
  • 130. Borehole Breakout (from Calipers) Criteria to Constrain 1) Tool Rotation < 30 Deg 2) Caliper Difference > 0.5 in 3) Smaller Cal > BS-1.5 in 4) Bigger Cal > BS 5) Avoid Key Seat ovality (angle > 15 Deg)
  • 131. SHmax Determination : Plotting All to Get Global Picture
  • 132. QUALITY IMAGE ZONATION Poor Intervals are flagged
  • 133. IMAGE FABRIC ZONATIONS Image Fabric might be related to Geological Features… Interference of tool behaviour (&…) Zonation Uncertainty…calibrated, correlated… Zonation Helps define reservoir features: 1)Highlighting Matrix (Sedimentologic, Lithology): Thinly Bedded, Nodular, Vuggy…matrixes 2) Highlighting Deformation Facies (Stylolite Associated Fractures, Fracture Zone 1…)
  • 134. LITHOLOGY ZONATION Highlighting Matrix (Sedimentologic, Lithology): Thinly Bedded, Nodular, Vuggy…matrixes
  • 135. Example of Image Fabric Zonation Highlighting Matrix Characteristic Zonation Name & Colour used to flag the Description & Correlation with Comments corresponding interval, Geological Features and Events and Illustration (Fig) This layer might be rich in clay, shale, fine grain that Thinly Bedded Interbedded matrix with thinly bed including might be a horizontal barrier to Matrix (Red) cross bedding. It is possible to pick every 5 fluid displacement. GoToFig11 cm a bedding surface. It can be used to determine the Paleohorizontal dip if necessary. The resistive spots are Conglomerate-shaped matrix with resistive considered as tight or close nodules. This might be related to therefore not used by fluids as conglomerates or not, it has to be calibrated porosity. Nodular Matrix with other data sources (cores, mud logs, On the contrary, the “matrix” (Green) GoToFig12 field studies…). Resistive nodules might be between the resistive spots is related to some anisotropic proprieties of the conductive so it is considered matrix or to some tight features. as actual/potential significant porosity
  • 136. Zonation Highlighting Sedimentology m MD, Vertical Well, Scale: V=H FMI processed & interpreted with Recall Image Fabrics: Thin Bedded & Bioturbed
  • 137. Vuggy Matrix Important Features: Isolated Intersected by Interconnected Deformed Zones Size (Relatively) Up Grading Down Grading (Correlation with Flooding Surfaces)
  • 138. Scale Rudist Shuaiba (Cr) Bu Hasa Field (Abu Dhabi)
  • 139. DEFORMATION FACIES ZONATION (Stylolite Associated Fractures, Fracture Zone 1…)
  • 140. Example of Zonation Highlighting Deformation Features, Stylolite & Karstic Associations, and Poor Images Zonation Name & Colour used to flag Description & Correlation with the corresponding Comments Geological Features and Events interval, and Illustration (Fig) Poor Image Image is of poor quality, high to moderate Poor quality of image correspond (Red) uncertainty in the interpreted features of the often to washout intervals GoToFig11 flagged interval. This zone, subhorizontal might play a positive role in draining fluids Tiny Fractures (up to 20 cm vertical-length) horizontally. sub perpendicular to Stylolite surface, Such feature is known as used by fluid Stylolite occurring in the lower side, or upper side or paths in some carbonate reservoirs. Associated both sides of the stylolite surface. Fractures It might be considered as “pipe-layer” are striking in all azimuths (radial) or in parallel to the Stylolite surface. Fractures particular azimuths: it is not clear. If crossed by Fracture Zone or (Green) Sometimes a couple of stylolite surfaces Fractured/Cataclastic zone this might GoToFig12 with their associated fractures are close increase the draining propriety. enough to constitute a Stylolite Zone The question is about the role regarding vertical path of fluids: obstacle or drain?
  • 141. FMI (Processed & Stylolite Associated Fractures Interpreted with Recall) m MD, Vertical Well, Scale: V=H
  • 142. INFERRED Features By Analysing Dip Populations
  • 143. Examples: Girdle: Inferred faults Bimodal: Unconformities Paleohorizontal dip Structural Dips: Per Units, Logged Section
  • 144. Structural Dip & / or Paleo-Horizontal Dip: ? “...Dips with constant magnitude and azimuth in a low energy environment can be selected. They correspond to the groups of beds, whose bedding planes have not undergone any biogenic or tectonic alteration. It can reasonably be assumed that these beds were deposited on nearly horizontal surfaces and that their present dips are the result of tectonic stresses” Tire de Serra, O. 1985, “Sedimentary environments from wireline logs”. I call it: PALEO-HORIZONTAL DIP “By Structural dip is intended the “general attitude of beds”. It is the dip that would be measured at outcrop. It is usually the dip seen on seismic reflectors, themselves a generalisation. It avoids any sedimentary structures of any size and is generally considered to represent the depositional surface which also is considered to be horizontal.” Tire de Rider, M. H. 1996 “The geological interpretation of well logs” I call it: STRUCTURAL DIP
  • 145. The way I see it, and use it in my interpretation: PALEO-HORIZONTAL DIP Paleo-Horizontal Dip, as is suggested by the name, is the dip of bedding planes that were originally deposited horizontally. Low energy sediments such as shale, planktonic sediments and coals, in specific conditions, can be assumed to be deposited horizontally. Such bedding planes may be used to infer tectonic events such as uplift, tilting or fault block rotation. STRUCTURAL DIP Structural dip is restricted to the mean dip of a lithological formation that can be used in geological (structural) cross-section, or related to a specific marker that can be correlated to a seismic one, avoiding detailed sedimentological structures at small scale. The dip and associated dip-azimuth can be used to infer the geometry of the units, for structural purposes at rather bigger scale, no matter what its genetic origin, or what events the unit has previously undergone.
  • 146. Paleo-Horizontal Dip: Interval of Low Energy Deposits
  • 147. Paleo-Horizontal Dip: Whole Dip-type Population of Low Energy Deposits
  • 148. Structural Dip: Several Dip-type Populations: Bed Boundary, ...
  • 149. PALEOHORIZONTAL DIP Implemented to Rotate Out Dips After Rotation Before Rotation
  • 150. CROSS BEDDING
  • 151. (After Gareth, G.; 2000, in PESGB Newsletter)
  • 152. Terminology used in FMI image interpretation Track-tadpole presentation Foreset Boundary Cross-Bedding Planes Foreset Boundary Foreset Boundaries & Cross-section presentation Cross- Bedding are Parallel (Planar Cross Bedding)? = SS Bedding
  • 154. Paleocurrent directions: ONE DIRECTION in ONE SET
  • 157. Paleocurrent directions: Global Results Major Minor Cross Bedding Interval Method Whole Pop. SS Bedding Interval Method Whole Pop. Heterolithic Whole Pop.
  • 158. PALEOCURRENT DIRECTIONS Vs GEOLOGIC TIME
  • 159. Ex. 1: SAME DIRECTION Paleocurrent directions are stacked up from bottom to top: -Bottom (Dark Blue) -Middle of the unit (Green) -Top (Yellow)
  • 160. Ex. 2: CYCLE Re-Considering the previous example (Global Result)
  • 161. Paleocurrent directions: Global Results Major Minor Cross Bedding Interval Method Whole Pop. SS Bedding Interval Method Whole Pop. Heterolithic Whole Pop.
  • 162. Paleocurrent Directions (from O to 360 Deg) N W S E N Geological Cycle Time Northerly Paleocurrent
  • 163. Final Result: Distinct Stacked Paleocurrent cycles N N W W-SW S S
  • 164. PaleoHorizontal Dip Implemented to Constrain Fault Block Rotation
  • 165. PaleoHorizontal Dip Implemented to Constrain Fault Block Rotation
  • 166. Unconformity from Bimodal Bedding Population: whole section
  • 167. Unconformity from Bimodal Bedding Population: Upper Unit
  • 168. Unconformity from Bimodal Bedding Population: Lower Unit
  • 171. FAULT: Picked & Constrained (girdle) 1of2
  • 172. FAULT: Picked & Constrained (girdle) 2 of 2
  • 173. Constraining a Normal Fault with Roll Over 1of 2
  • 174. Constraining a Normal Fault with Roll Over 2 of 2