Neutron ng Example #2
Listed below are the FDC log bulk densities and SN? log apparent limestone porosities for
different zones. Assuming that, if porous, the formation is liquid-ﬁlled and that its matrix
consists of no more than two minerals, determine t

Gamma Ray Log
Outline
Background Information Review
Principle of GR Log
GR Response to typical formation
Unit of Measurement
Uses of Gamma Ray Log
Review
Shale
Background Information Review
1. What is shale?
A fine grained, thinly laminated or fissile, de

Water Resistivity
Determination
Water Resistivity
The resistivity of a brine is dependent on:
1. viscosity, (a function of temperature)
2. ionic concentration
3. ion charge and size
Rw of NaCl
solutions
Example Point
200 degrees F
20000 ppm NaCl
0.11 ohmm

Chapter 4
Reserve Estimation
Water Resistivity Determination
Outline
Definitions
Reserve
Cutoff
Net Pay
Oil-in-place and Reserve Estimation
Method to determine Rw
Definitions
1. What is Petroleum Reserve?
Reserves are those quantities of petroleum

Rock Characteristics and Electricity
Properties
Types of Permeability
Absolute permeability
Pore spaces are 100% saturated with the same fluid.
Effective permeability
The permeability of a flowing phase that does not saturate 100% of
the rock.
Relati

Chapter 7.
Density & Pef Logs
(Gamma Ray Absorption Log)
Outline
Porosity calculation from densities
Principle of Density Logs
Bulk Density Logs
PEF Log (Photoelectric Effect)
Summary
Why density is important?
Finding out what is in the formation
Gas Dete

Chapter 3.
Borehole Environments and Caliper
Logging
Borehole Environments
Borehole Fluid and Invasion
Mud Circulation and Mud Properties
Invasion
Borehole size & shape (Caliper Log)
Temperature
Pressure
The fluid circulation system
Mud
pump
Stand
p

Chapter 10
Clean Formation Interpretation
(Porosity and Lithology)
Quantitative log analysis
1942: Gus Archie, Shell, publishes at the SPE meeting in
Dallas.
Tortuosity factor
Formation water resistivity
Water saturation
1
n
a Rw
Sw =
R m
t
Formatio

Electrical Resistivity of Rocks
Ohms law describes the relationship between resistance, voltage
and current.
The resistance consists of two parts: material and geometry
In logging we use resistivity rather than resistance.
A material with a resistivity of

Sonic Logs (Acoustic Logs)
Outline
Principle of Sonic Logs
Types of Sonic Log tools
Interpretation of Sonic Logs
Example
Summary
Sonic Logs (Acoustic Logs)
Sonic Tools are based on
the measurement of the
velocity and amplitudes of
the sonic body waves in

Formation Evaluation
Lecture I
Austen Cain
[email protected]
MW 10-11:30
F 9-10
Course Requirement
Uses of Well Log and Reading for a Practical Well Log
Rock propertiesPermeability, Porosity, Saturation and Resistivity
Archie Equations
Wellbore Environ

Neutron Logs
Review
Goals
Calculate water/oil saturation
Find porosity
Find lithology
Other info
Question: How to reach to these
goals?
-We have Archis equation but we need Rw
-Need to find Rw (know-how to find Rw)
-Need to find Rt (Know-how to find Rt)

Resistivity Logs
The objective is to investigate the
presence of hydrocarbons and its quantity!
First used in mining industry to obtain
quantitative and qualitative information
pertaining the type and structure of
subsurface
The first resistivity log
wa

Resistivity Logs Example #1
Attached is a log over a series of sands and shales, please answer the following questions.
1. For the depths specified by the dashed red line, read the Deep (RILD), the Medium
(RILM), and the Shallow (RSFL) curves.
Deep (RILD)

Density Log Example #1
Using the log given on the following page, answer the following questions:
1. For the intervals in the table given below, calculate the density porosities for each
matrix type (Sandstone, Limestone, and Dolomite).
:2!" =L8$
(mums r?

you WSTANDO FF
Resistivity Correction Example #2:
. 1. What is the Corrected Resistivity if given a 2” standoff in a 16" well, with an Rnl1 = 0.2
JAN; and a RILD = 34 ohm*m?
0351;” -‘v B‘low‘na Ski’s °" Faﬁ‘ z
r.
1'22“.- Es“ Wt °“ ms 3»
+ 31:“
000 A
4

FLUID minaon COiZV-CCTLW
Resistivity Correction Example #1:
1. From the log below, read the deep, shallow and medium resistivity at 10305 feet and 10400
feet.
2. Find inyasion diarrletéer, corrected Rt and Rxo using tornado charts as

v“
Nell)" "a; RD =
U”?
Resistivity Logs Example #2
For the SP/Resitivity log given below, perform the follwoings:
1. Based on your resistivity log, where do you think is your clean water bearing zoneﬁ"Ith 2 46:? ad
Why? “an :5 59,?nral'lon Sou-ween s
ﬁé C

Density Example #2
1. Using the log given on page 2, answer the following questions (Use PE, Density, and
get help from GR):
a. What is the dominant lithology in the log?
-—=: ?e4a\uto?fouahl1 3 dnA {[6, Low Cam/"mi
woolA inﬂlfcpbl'ﬂ 0L dﬂmlﬁahtl: “of” D

Density Log Example #3
1. The log given on the following page is from a well in Texas. The density porosity is
given in the log assuming the matrix density is 2.71. Determine the bulk density
and lithology for formationsBand C. ﬁagﬁomlﬁ & = LO
10‘s?) _
/

Sonic Log Example #3
Using the log given on the following page, answer the following questions:
1. For the intervals in the table given below; calculate the porosities, for each matrix
type (Sandstone, Limestone, Dolomite, and Anhydrite), using the Sonic

Sonic Log Example #2
The log on the following page presents the electrical and sonic logs obtained in shale/ sand
sequence. The electric log shows three thick sands, the bottom sand is water hearing. The
two upper sands contain gas zone in top section.
1.

Sonic Log Example #1
Using the log given on the following page, answer the following questions:
1. For the intervals in the table given below; calculate the porosities for each matrix type
(Sandstone, Limestone, Dolomite, and Anhydrite), using the Sonic L

Neutron Log Example #1
This figure given below is a neutron log in which the tool has been calibrated by
limestone pit. Tabulate the porosity for the indicated zones, if your formation is
limestone, sandstone, or dolomite separately.
SEE; m H": Mculmn qu’

SP & GAMMA RAY EXAMPLE
1. The figure below is a log over a series of sands and shales. Assuming that Zone B is a clean water
bearing zone, determine the following.
trﬁﬁ—n—A'u—_-"
.T_-_—-'-'Mg-_-_-a“
"“ ' nan.
T‘H—E—"Tﬂ
Cl
Tl'"“"'"}l
)
I'
\
9
i
f
I
)
x
I

Chemical Analysis to Determine Rw Example:
1. Determine the Rw (in ohm*m) at a temperature of 200°F, given the following:
Equivalent
Concentration
(ppm)
Multiplier Concentration
(ppm)
25,000
2,000
lg: 66— Hr“, lolal a? \‘on COV‘Cﬂ‘hahms am

XII.
SONIC (ACOUSTIC) LOGS
A. Principle of Sonic Logs
It is a porosity log that creates an acoustic signal and measures
the amount of time that it takes (interval transit time) for the
compressional sound wave (P-wave) to travel through a given
formation