Tim Carr - West Virginia University
2
"I am sitting inside the truck, watching a screen. The truck reels the tool back up out of the hole, slowly - more slowly than if you were reeling it in by hand - and foot by foot, the tool passes through all that dark mystery of time, emitting signals and picking up signals. I watch the tool's response to the formations it passes through on my screen, little green blips of radioactivity, and like an EKG, each blip indicates something . . .
I love to log wells. I’ve logged a thousand, and I still
find myself holding my breath when the tool first starts up out of the hole, when the electronic green lights begin to flicker and race. No one has ever before seen what I am seeing.”
OIL NOTES by Rick Bass 1989 Houghton Mifflin
Company/Seymour Lawrence. 3
Modified from SPWLA Website
PETROPHYSICS
PETROPHYSICS
GEOLOGY
DRILLING RESERVOIR
ENGINEERING
GEOPHYSICS
4
In the beginning …
5
Pechelbronn,
Alsace, France
September 5, 1927
SPWLA 6
7
Electrical
Acoustic or Sonic
Nuclear
Geometry Hole Diameter – Rugosity
Direction – Inclination
Temperature
Pressure
8
Wireline
Tubing/Pipe
MWD Measurement While Drilling
LWD Logging While Drilling
9
Single Curve
A Continuous Recording of a Geophysical Parameter along a Borehole
Suite or Group of Curves
Measured or Derived Parameters
Record
Physical (Paper)
Cyber (Raster – Digital)
Logging Tool (Sonde)
Process of Logging
10
11
12
13
Log Data to Assess Reservoir and Formations
Contracted to a Specialist Company Wireline Logs are made when drill-bit is
removed from the borehole Open-hole logs Cased-hole logs
Wireline Logging set-up Wireline Tool The Wire Winching Gear Data Analysis and Recording Equipment Data Processing and Transmission
Equipment 14
15
16
17
Drilling related measurements downhole and transmitted to the surface while drilling
MWD tools are conveyed downhole as part of bottom hole assembly (BHA).
MWD systems can take several measurements (eg., gamma ray, directional survey, tool face, borehole
pressure, temperature, vibration, shock, torque etc.
Telemetry for steering well
Results transmitted digitally mud pulser telemetry
18
Well logging tools conveyed into the well borehole downhole as part of the bottom hole assembly (BHA).
LWD tools work transmit measurement results to the surface via a drilling mud pulser Real Time Data Memory Data
Complete measurement results downloaded after MWD tools are pulled out of hole
LWD technology as replacement for wireline logging LWD widely used for drilling (geosteering), formation evaluation (especially for real time and high angle wells).
19
20
Wellbore Environment Logging Speed
Borehole Diameter
Borehole Rugosity
Borehole Orientation
Mud Properties
Invaded Zone
Formation Properties
Most modern boreholes are drilled using a rotary bit in a column of circulated mud
The drilling operation creates the borehole environment in which wireline logging measurements of the rocks will be made
21
Borehole size is set by the drill bit, but it is influenced by:
Changes in stress state
borehole breakout
induced fracturing
creep of salt
Chemical Reactions
swelling clays in shale
dissolution of salt
Drilling Process
spiral borehole
bit marks
What Do They Measure?
Size and shape of a recently drilled hole.
How Do They Work?
• Mechanical arms record hole size
• Hydraulic systems with calibrated
potentiometers.
How Are They Used?
• Hole size used to correct other logs
• Hole volume for cementing
• Lithologic information
•washouts indicative of formation
properties
• Stress field from hole break-out
24
Deep Induction
Deep Laterlog
Short
Normal
Micospherically
Focused
Microlog
Dipmeter/FMI
Gamma ray
Neitron
Density Sonic
1000
100
10
1
0.1 0.1 1 10 100 1000
Radius of Investigation (inches)
Ver
tica
l R
eso
luti
on (
inch
es)
Seismic
NMR
Spherically
Focused
25
Gamma Ray
Scintillation detector (similar to a Geiger counter) that measures the natural radiation from a formation
SP (spontaneous potential)
Measurement of the potential difference between the voltage in the wellbore and an electrode on the surface
For both logs:
Deflections to the right = Shale
Deflections to the left = Sand
Sh
ale
S
an
d
Sd
Gamma Ray
Shale Baseline
Porosity - Φ
Permeability - K, Krel
Lithology/Mineralogy
Fluid & Gas Saturations - Sw, Sg, So
Resistivity/Electrical Properties
Sonic Properties (e.g., Strength)
Bed Contacts & Thickness
Fractures (Size, Frequency, Direction)
In-situ Stress 27
The Heebner Shale
outcrop in
Lawrence:
a geiger counter
reading of “58”
28
Measurement of the natural radioactivity
Principal isotopes are Potassium-40, Uranium, and Thorium (K40, U, Th)
Isotopes concentrated in clays higher radioactivity in shale
Detectors count the number of gamma rays per unit of time
Recorded in “API Units” which is 1/200th of the calibrated, standard response.
29
30
6590
6610
6630
6650
6670
6690
6710
6730
6750
6770
6790
59
00
61
00
63
00
65
00
67
00
69
00
71
00
73
00
75
00
77
00
79
00
81
00
83
00
85
00
87
00
89
00
91
00
93
00
95
00
97
00
99
00
10
10
0
10
30
0
0
50
100
150
200
250
300
350
400
450
500
550
600
Wellbore Top of MarcellusTop of Target Base of TargetOnondaga Top of PurcellTop of Cherry Valley Gamma15 per. Mov. Avg. (Top of Cherry Valley)
DIP PROFILE
McCue 28-10H
NWSE
De
pth
(T
VD
)
Measured Depth
Ga
mm
a
Overall Dip = ~0.44° ; Required Inclination = 90.44°
~0.5 ~0.1
31
32
The SP log records the electric potential between an electrode pulled up a hole and a reference electrode at the surface.
This potential exists because of the electrochemical differences between the waters within the formation and the drilling mud.
The potential is measured in millivolts on a relative scale only since the absolute value depends on the properties of the drilling mud.
33
The Spontaneous Potential (SP) tool
E = -K log (aw/amf)
K is f(Temperature)
34
35
36
Marine Flooding Surface
Marine Flooding Surface
Marine Flooding Surface
37
38
39
Well logs give us detailed information at the location of the borehole
If there are several wells in an area, we can correlate stratigraphic units between them
The correlation is based on ‘characteristics’ of the well log responses – like a fingerprint
Often we select a datum – a correlation horizon that is registered to a common depth (flattened)
There are two main ‘philosophies’ used in well log correlation:
Correlate based on lithologic units - Lithostratigraphy
Correlate based on assume time lines – Chronostratigraphy
Which is Better? A matter of heated debate!!
AAPG©1990 reprinted with permission of the AAPG
whose permission is required for further use.
Well A Well D Well C Well B
Coastal Plain Sandstones and Mudstones
Shallow Marine Sandstones
Shelf Mudstones Van Wagoner et al., 1990
Here the correlation is based on common lithologic units
Well A Well D Well C Well B
Datum
Coastal Plain
Nearshore Sands
Shelf Mudstones
Van Wagoner et al., 1990
AAPG©1990 reprinted with permission of the AAPG
whose permission is required for further use.
Here the correlation is based on an interpretation of time-equivalent stratal packages – i.e., parasequences
Well A Well D Well C Well B
Coastal Plain
Shelf Mudstones
Van Wagoner et al., 1990
AAPG©1990 reprinted with permission of the AAPG
whose permission is required for further use.
Index
Fossil
Chronostratigraphy
Lithostratigraphy
Perhaps not for finding a field
BUT
It can impact:
- estimates of reserves
- development plans
- enhanced recovery
Based on Van Wagoner et al., 1990
Based on Van Wagoner et al., 1990
AAPG©1990 reprinted with permission of the AAPG
whose permission is required for further use.
A D
C B
A D
C B
Logs are Important for Evaluating the Subsurface History – Schlumberger Brothers (1927)
Borehole Environment - Resolution
Reservoir Evaluation
Geosteering
Correlation Lithostratigraphic
Chronostratigraphic
Geologic Interpretation Lithology
Facies
Sequence Stratigraphy
45
46
Assignments
Reading for this week Ch. 3.2, Selley
Discuss Test on Wednesday Read Today in Energy for Tuesday (3/10) at
http://www.eia.gov/
Be Prepared to Discuss in Class - Wednesday
Discussion Leader – Andrew Hamilton
Top Related