hints to students for simple understandings_dileep p allavarapu

1. Science Behind Logging
Dileep.P.Allavarapu
dpa.taeching@gmail.com /or
motherindia.energy@gmail.com
9703070878

2. Role of Different Disciplines
Logging play any important role in exploration and production industry?
Can be comparable with other techniques ?
Really logging is a replacement of core recovery and analysis?
Cost effective ?

3. EACH DISCIPLINE HAS ITS OWN IMPORTANCE & ROLE in E&P
RESERVOIR MODELING
OPEN HOLE LOGGING
(RES, POR, LITH LOGS)
-LWD/WL
MUD LOGGING
CORE ANALYSIS
DRILLING
& LOGGING
STATIC MODEL
INTERPRETATION MODEL
& UNCERTAINITY
CERTAINITY
CORE ANALYSIS
3D & VSP
GEOLOGY
& SEISMIC
CASED HOLE /PL LOGGING
(cement eval,flow rate ,fluid
Tests)
-WL
INJUCTION DATA
FLUID STUDIES
DYNAMIC MODEL
FLUID STUDIES
4D

4. observations
OPEN HOLE LOGGING
(RES, POR, LITH LOGS)
-LWD/WL
MUD LOGGING
CORE ANALYSIS
CASED HOLE /PL
LOGGING
(cement evaluation ,
flow rate ,fluid Tests)
-WL
INJUCTION DATA
FLUID STUDIES
DRILLING
&LOGGING operations
Interrelated operations
completions
DRECTIONAL DRILLING
CORE RECOVERY
PIPING & CASING
OIL TUBING
(packers arrangement)
PERFORATING
WELL CLEANING
(gravel packing , acid
injunctions, compressions)
INJUCTIONS

5. Few things about Logging
Well ,log ,logging,………?
Log interpretation.

6. Logging : the process of continuous recording of parameters w.r.to depth that is to
obtain comprehensive information about formations in the bore hole by lowering
the tool
Log: the record that contains obtained and required basic information about the
parameters in the bole

7. Don’t miss understand……..
logs (product)
logging (process)
open
hole
cased
hole
LWD , WL ,….. Production well
logging…..
open
hole
cased
hole
Production well
Lithology ,Porosity ,Resistivity, ….
Other miscellaneous
Sonde: Combination of lowering tool,
Bore Hole/Well :Source of parameters/formation,
Bore Hole Environment:Distrubed –Undisturbed condition of Bore Hole,
Before production
(Stage of Reservoir /Field/Basin)
In production
(Stage of Production)
Well: Discovery(Wild cat),Exploratory ,Development
Well: Production(Recovery),Injection

8. Log Presentation
Lithology logs
SP,GR along with
CALIPER, BIT SIZE
Lithology:
(shale ,sand ,…)
Porous –permeable beds
(no of ,thickness)
Shale volume
Resistivity logs
Porosity logs
Focused(latro) ,
Non focused types
of NormalInduction
Sonic ,Neutron,
Density
Resistivity :
Formation water
& True resistivity
Saturation
MHI
Permeability indication
Porosity :
Effective porosity
Type of fluid
Contacts
(GSC,GOC,OWC,GWC)
Uncompacted

9. Stages of Interpretation
UNDERSTANDING LOG
STUDY THE LOG RECORD
(to take proper action in any stage of interpretation )
HEADer- MAINfo- TAILer,…. DISPLAY INFORMATION .
TOOL SKETCH ,
CALIBRATION ,
PERFORMANCE & REMARKS ………
MARK THE INTERESTED ZONES
QUICK LOOK
INTERPRETATION
(to take the readings )
POROUS –PERMEABLE ZONES :
WATER /HC BEARING ,OTHER RESERVOIR ROCK UNITS
TAKE READINGS & LIST OUT THE INERPRETATION FORMULA
(to calculate the interpretation parameters)
GR , SP , CALIPER, RESTIVITY ,MICRO RESISTIVITY,
NEUTRON ,BULK DENSITY ,SONIC TRANSIT TIME
DETAILED
INTERPRETATION

10. GR FOR IGR
SP/RESISTIVITY &NEUTRON
RESISTIVITY FOR Rt
FOR
Rw
NEUTRON , BULK DENSITY ,SONIC TRANSIT TIME FOR
CALIPER, MICRO RESISTIVITY FOR
FOR
φe
k indication
S w, S hc, S movable , PAY= S movable * φe
Aim of logging: Calculation of
S
Hc
*
φ
Preparation of a PARA LOG
Why a log analyst limited his aim to
e
in each reservoir rock unit &
S hc × φ e
?
Log analyst can do but accuracy …..because cant estimate exact S hc = (1-S hr)
need help of core analyst of viscosity ,permeability ….

11. Interpretation parameters
Rt
Φ N, Φ D
R w ,Ro, Rsh
V sh
Φ eff
Sw
S hc
Archie’s 2nd equation
Indonesian ’s equation
(Archie's 1st equation about formation factor)
DEPTH
Rw
Rt
Φ eff
SW
S Hc
S Hc × Φ eff

13. Sand Stones:
Log Analyst:
Composition (Sand Stone)
Framework of Quartz and Feldspar
Grains(Majority)/
Other Fragments (Non Majority)/
Cement (Quit Limited))
Processing Engineer:
Matrix (Sand Stone)
K-Na, Ca Al Si3 O8
Si O2

14. Shales: Frame work ,Matrix, Cement are Clay Minerals
( Kaolinite,Montmorilllonite,Illite)
Minute percentage of Non Clay Minerals.
90% Clay Minerals
K Feldspar derived Radio Active K rich clays
Rain water derived U,Th Br salts
K (12%),U Th (<500ppm)
Laminar (separate layers of fine grains)
Dispersed (spreaded clusters of fine grains in coarse grains)
Structural (distribution mixture of fine grains in coarse grains)
Which shale effects the formation more? Why?
Dispersed(assumptions become wrong;cant locate cluster and estimate its
distribution beyond well surroundings) >Structural>Laminar
Salt : 100% NaCl (general) or 0-10% KCl +90-100%NaCl (rare)
Brazile wells shows high gama in salt formations because of KCl presence ,in past
north brazilen sea having more KCl salt

15. Why anhydrate or gypsum are tops of salt(local gravity high)?
During evaporation of sea water more saturate solution of NaCl formed and precipitated,
still some minerals remain finally precipitated at top of the salt ,
at the end of the evaporation react with H2O form anhydrate or gypsum.

19. Chemical Sources:
NEUTRON
SOURCE
Neutron sources
Gamma sourceso Cesium(Cs137) produce a steady flux of gamma
rays at 662 KeV
ENERGY
LEAVING
SOURCE
106
NEUTRON ENERGY (e V)
o Am241-Be9 : emits neutrons with mean energy
of 4.2 MeV.
oz Californium(Cf252) : emits neutrons with mean
energy of 2.35 MeV.
104
102
10 eV
Electrical Generators:
This device produces 14 MeV neutrons by accelerating
deuterium ions into a tritium target
(up to 125,000 V DC).
APPROX.
EPITHERMAL
ENERGY
REGION
1
.4 eV
AVERAGE
THERMAL
ENERGY .
025 EV
CAPTURE
01
1
10
TIM E ( µ s )
100

20. Energy state
Range
Interaction
high
>0.5Mev
Inelastic scattering
medium
0.5ev-0.5Mev
Elastic scattering
low
<0.5ev
Thermal capture
Energy state
Range
Interaction
high
>2Mev
Pair production
medium
0.5Mev-0.5Mev
Compton scattering
low
<0.5Mev
PEE
Remark
Remark

21. Why R proportional to l /A ?
RMS velocity of free(week bonded )electron
Collision of energized surface electron with unenergized electron
Week bonded
Strong bonded
v v
vvv
v
me
If Area increased, no:
electrons come to contact
with electrode is increased
Energy transmission as velocity exchange

22. ELECTRICAL LOGGING TOOLS
Conventional Electrical survey Tools
Non-Conventional Electrical survey Tools
natural
artificial
artificial
artificial
SP
Normal
Resistivity
& Micro Resistivity
(focused, non focused)
Induction
(short, long)
Lateral
RADIO ACTIVE LOGGING TOOLS
Conventional Radio Active Tools
Non-Conventional Radio Active Tools
natural
artificial
artificial
GR
Neutron
Density
(Compensation)
Dual energy, Litho , GR-Spectroscopy
SONIC LOGGING TOOLS
Conventional Sonic Tools
Non-Conventional Sonic Tools
artificial
artificial
Sonic
(Compensation)
Long spread , Depth derived ,Array, Wave sonic, Dipole
MISCELLANEOUS LOGGING TOOLS
(BH Conditions)
Temperature ,Pressure…… Formation testers
(BH Geometry )
Caliper,Dipmeter,…

23. M
M
SP tool
A
A
M
N
Normal Device
Lateral Device

24. Archie's Both Equations : Archie's experiment concludes an empirical
relationship between resistivity of the water bearing formation and
water, pore volume it contain and also water saturation.
If Sw = 1 ,
means water-bearing formation
Resistivity of water
Resistivity of waterbearing formation
Formation factor
Water saturation

25. Volume of Shale: The percentage of shale present in the rock unit
Response in the
zone of interest
Shale
Clean formation
Indonesian Equation

26. GR: The record of count rate of Natural GAMMA as a result of emission from RADIO ACTIVE
MINERALS present in the ROCK UNITS
RADIO ACTIVE MINERALS are more in the CLAYS & SHALES
GR infer the LITHOLOGY whether rock unit is having CLAYS & SHALES or not
In the first /each run (lowering tool), first track (left side of log paper)
0-100 API (10intervels)
along with CALIPER,BIT SIZE , SP.
GR
around 30 -SAND
up to 50 -SAND SHALE
up to 80 -SHALE SAND
up to 100- SHALE
more than 100-CLAY
Volume of Shale
DEPTH GR
Vsh
END

27. SP: The record of voltage variation
as a result of electrolytic conduction due to salinity
variation between fluids present in the ROCK UNITS
electrolytic conduction is more across porous –permeable rock unit
SP infer the LITHOLOGY whether rock unit is having porous& permeable SAND or not
In the first /each run (lowering tool), first track (left side of log paper)
0-100 units (10intervels)
along with CALIPER,BIT SIZE ,GR.
SP +Ve : R mf <R w : Shale Base Line is in left side of Sand Deflection Line
SP in the same well either +Ve or –Ve :
crossover indicates the presence of HYDROCARBON
END

28. OR
K=61+0.133T°F
R we to R w
conversion chart
DEPTH
SSP
K
10 ˆ(SSP/K)
Rwe R w
END

29. BIT SIZE : size of the drill-bit used
CALIPER: size of the drilled hole
Grater than BIT SIZE : absence of permeable rock units / factures
Less than BIT SIZE : presence of permeable rock units /MUD CAKE
RESISTIVITY : Apparent resistivity of the formation
(can calculate true resistivity by using at least three apparent resistivity values )
Using Resistivity Tool: in saline muds , good contact between annulus electrode and BH wall.
Using Induction Tool : in non saline muds
In the first run (lowering tool), first track (middle of log paper)
0.2-2000 units (log scale)
Configuration :
App resistivity = (Geometrical factor × Observed voltage difference)/ Sending current
Characteristic charts used to calculate true resistivity from apparent resistivity
END

30. DLL MSFL Invasion
Correction charts
DLL MSFL LOG RECORD
(R t / R LLD )× R LLD = R t
DEPTH
LLD
LLS
MSFL
LLD/LLS
LLD/MSFL Rt/LLD
Rsh = Rt in shale
RO = Rt in WBZ
Rt
END

31. NEUTRON: The count rate of back scattered neutron/gamma as a result of energizing rock
units with neutrons (source: Am Be -16 curie)
Sending neutron lose total energy and collapse into the nuclei of HYDROGEN and release a
Gamma
Response α Hydrogen Index
In the first run (lowering tool), third track (right side of log paper)
0.54 - -0.06 (10intervels)
along with SONIC ,DENSITY.
NEUTRON :
Gas < Oil <Water in sand
Sand < Shale (bounded water)
Correction for shale:
Φ Nc = ΦN-(Vsh× ΦN in shale)
Neutron Porosity
Φ N = ΦN
calibration
corrected
END

32. DENSITY : The count rate of back scattered gamma as a result of energizing rock units with
gammas (source : Cs 137)
Sending gamma undergone Compton Scattering
no of collisions α no of electrons in rock unit ρe
ρb = 1.0704 ρe + 0.1883
In the first run (lowering tool), third track (right side of log paper)
2.8 -1.8 (10intervels)
along with SONIC ,NEUTRON.
DENSITY:
Gas < <Oil <Water in sand
Correction for shale:
Φ Dc = ΦD-(Vsh× ΦD in shale)
END

33. Effective Porosity: Volume of interconnected pores
Neutron Correction for shale:
Φ Nc = ΦN-(Vsh× ΦN in shale)
Density Correction for shale:
Φ Dc = ΦD-(Vsh× ΦD in shale)
DEPTH
Φ N cal
Φ NC
ρb
φD
φDC
Φeff
END

34. Φ N RT
GR
20
97
24
24
78
23
22
69
25
28
72
26
30
52
23
Will get
Rt =100
Sand Stone
Matrix Point
∆t = 48,
φN =0 ,
ρb =2.65
ΦN = 0
10
20
30
40
50
Choose
Φ=20
END

35. now mark the point φ=20,Rt=156.25
& draw the 80% saturation line
Rw=4.878
now replace the 0.64 by
0.36,0.16,0.04 …..to get the
60%,40%,20%,…… saturation lines
Sw =80% =0.8
Rt = 100/0.64
= 156.25
END

36. SW =1=100%
Red Points
GR=23-30
Blue Points
GR=30-40
Yellow Points
GR=40-50
END

37. Sw=0.8=80%
END

38. Ro =F Rw
Rt= F Rwa
Different Trend
HC indication
Main Trend
Rwa line WBZ

39. 50 = φ DC
-10
0
10
20
30
40
GAS
-10
0
10
20
30
40
50= φ NC

40. Indonesian Equation
S HC = (1-SW)
DEPTH
Rw
Rt
Φ eff S W
S Hc
S Hc × Φ eff
END

41. Here our goal need more data from
ROCK PHYSICS LABORATORY,
so it limited to
S hc × φ e

42. GSC
GOC
WOC

43. Lithology
GR
Rt
φN
Sand Stone ( more
compacted & dry )
Less=25
Less clay
minerals
More=1000
SiO2 insulator / no
electrolytic
conduction
Less<10
More=2.6
No fluid / no H2 Closed grain
packing
Sand Stone ( less
compacted & wet)
Less=25
Less clay
minerals
Less<100
Saltwater
conductor /
electrolytic
conduction
More=10-30
Having H2
Moderate=2.1
(30% H2O=1
/70% SiO2
=2.6)
Having oil
Less=25
Less clay
minerals
Moderate >100-700
Oil insulator
(at least 5times of
R0 )
More=10-30
Having H2
(less than
water zone)
Moderate=1.9
(less than
water zone)
Having gas
Less=25
Less clay
minerals
More >700
Gas insulator
(at least 5times of
More=10-30
Having H2
(less than oil
Less =1.8
Having water
ρb

44. Lithology
GR
Rt
φN
ρb
Sand-Shale ( more
compacted & dry )
Less=30-50
More or
less clay
minerals
More<100
Dry clay insulator
,bounded water in
composition / not
much electrolytic
conduction
Less=20
No fluid /
bounded water
H2
More=2.5
Closed grain
packing
(30%shale
=2.3,70%sio2=2
.6)
Sand-Shale ( less
compacted & wet)
Less=30-50
More or
less clay
minerals
Less<50
Wet clay
conductor / more
electrolytic
conduction
More=20-40
Having H2
Moderate=2.2
(20% H2O=1
,50% SiO2 =2.6
30%Shale 1.82.6)
Having oil
Less=30-50
More or
less clay
minerals
Moderate >100-700
Oil insulator
(at least 5times of
R0 )
More=20-40
Having H2
(less than
water zone)
Moderate=1.8
(less than
water zone)
Having gas
Less=30-50
More or
less clay
minerals
More >700
Gas insulator
(at least 5times of
oil zone )
More=20-40
Having H2
(less than oil
zone)
Less =1.7
Having water

45. Lithology
GR
Rt
φN
ρb
Shale ( more
compacted & dry )
More =80-100
More clay
minerals (80%)
More<50
Dry clay insulator
/ not much
electrolytic
conduction
Less=30-40
No fluid /
bounded water
H2
More=2.3
Closed grain
packing
Shale ( less
compacted & wet)
More =80-100
More clay
minerals
Less<10
Wet clay
conductor
/ more electrolytic
conduction
More=40-50
Having H2
Moderate=1.9
(30%
H2O=1,70%
shale=2.3)
,
More >100(120)
More clay
minerals
More<50
Dry clay insulator
/Less<10
Wet clay
conductor
Less=30-40
More 2.4
Having water
Clay

46. Dileep.P.Allavarapu
dpa.taeching@gmail.com /or
motherindia.energy@gmail.com
9703070878
Contact any Institution
Dept. of Mathematics, MGR Junior College
Dept. of Chemistry, LAMP Degree College
Dept. of Geophysics , Andhra University
Logging Base ,ONGC –Rajahmundry Asset
Oil and Gas Deliveries, Infotech Enterprises Limited
Gravity Observatory , Gravity Group-NGRI
Seismological Observatory, Warna Canal Division-MERI
UV Physics Academy
Analog IAS Academy