STRATIGRAPHIC CORRELATION

CAIRO UNIVERSITY
FACULTY OF ENGINEERING
PETROLEUM ENG. DEPARTMENT
PRE - M.SC. CLASS 2012-2013
SUBSURFACE GEOLOGY
Submitted To
Dr. : Abdulaziz Mohammed Abdulaziz

12/3/2013
Presented By
Mohammed Abdulmajeed Esmail
OUTLINES
1. Introduction.
2. Stratigraphic units
3. Space-time concept in correlation
4. Facies factor in correlation & Correlation markers
5. Magnitude of correlations
6. Factors controlling correlation investigations (FCCI)
7. Time & cost, Quality of personnel
8. Methods of subsurface correlation
9. Stratigraphic maps and correlation
10. Conclusions.

INTRODUCTION
INTRODUCTION
What is Stratigraphy ?
Stratigraphy is the branch of geology that deals
with all rock strata forming the Earths crust to
organize them in Space and time.
Bio-stratigraphic unit:
a body of rock which is defined and characterized
by its fossil content.
Unconformity
It means a missing in time record via a break in
sedimentation and or erosion.


INTRODUCTION
Benefits of Stratigraphy
Displays the vertical and lateral distribution of
rock strata and their interrelationship.
Displays the stratal geometry, lapout and missing
intervals
Contributes in building static model
Contributes in field evaluation and reserve
estimation
Contributes in locating development and
appraisal wells

INTRODUCTION
Importance of Correlation of stratigraphic
Correlation of stratigraphic units permits
establishment of formational sequences,
evaluation of contemporaneous and non-
contemporaneous deposits, recognition of
unconformities, reconstruction of paleotectonic
fabrics, and delineation of sedimentation
patterns.

STRATIGRAPHIC UNITS
STRATIGRAPHIC UNITS
Before the correlation of deposits is attempted, it
is essential that stratigraphic units be defined
accurately.
Schenck and Muller (1941) recommended that
continued use be made of three types of
stratigraphic units as a basis for correlation
(1)lithogenetic (rock),
(2) time-stratigraphic (time-rock), and
(3) time.

STRATIGRAPHIC UNITS
Figure 1. Time-stratigraphic unit.
STRATIGRAPHIC UNITS
Figure 2. Relationship of time-stratigraphic and lithogenetic units
STRATIGRAPHIC UNITS
Biozones play a major role in establishing
boundaries of time-stratigraphic units.

STRATIGRAPHIC UNITS
Figure 3. Biostratigraphic zonation
SPACE-TIME CONCEPT IN
CORRELATION
SPACE-TIME CONCEPT IN CORRELATION
Such variables as composition, texture, color,
porosity, permeability, thickness, and
paleontology must be evaluated through time and
along the space components in order to establish
the contemporaneity or non-contemporaneity of
deposits.

SPACE-TIME CONCEPT IN CORRELATION
Figure 4. demonstrates the lateral and vertical variations of three lithologies (facies) in
space within a time-stratigraphic unit.
FACIES FACTOR IN
CORRELATION
FACIES FACTOR IN CORRELATION
"when two deposits of the geologic column
have been found to hold pretty much the same
organisms, it has been assumed that the two
deposits have synchronous relations. It is equally,
if not more valid, to assume that the two deposits
were laid down under similar environments and
may actually be somewhat different in age . . .".

CORRELATION MARKERS
CORRELATION MARKERS
The recognition and the definition of lithologic,
paleontologic, and seismic markers in controlled
stratigraphic sequences are of utmost importance
in all correlation work.

These markers, including limestone, bentonite,
coal or lignite, anhydrite, concretions,
chert,

CORRELATION MARKERS
Figure 5. Marker beds
MAGNITUDE OF
CORRELATIONS
MAGNITUDE OF CORRELATIONS
Correlations may be of local, regional, inter-
regional, or of intercontinental magnitude.
Local correlations, for example, within an oil field
or in a small depositional basin, range from
simple to complex.
Regional correlations between basins of large
provinces, such as the Rocky Mountain Province.

MAGNITUDE OF CORRELATIONS
Interregional correlations, as between sections of
the Gulf, Pacific, and Atlantic coasts, can be
determined only approximatelymainly on the
basis of paleontology.
Intercontinental correlations involve those
between continents.

MAGNITUDE OF CORRELATIONS
Paleontology is the primary basis for these
correlations.
In general, it may be said that the greater the
distance between stratigraphic sections, the more
difficult and uncertain the correlation.

FACTORS CONTROLLING
CORRELATION INVESTIGATIONS
(FCCI)
FCCI
Some of the more critical factors controlling the
solution of correlation problems are the following:

1. Lateral Continuity of Deposits
The more uniform the lithology and paleontology
of a stratigraphic sequence, the less difficult the
correlation of surface and subsurface units.

FCCI
2. Structural Complexity of Section
In areas where the section is highly folded and
faulted, and unconformities are present,
correlations are frequently complicated-at least,
until a normal stratal sequence has been
established

3. Availability of Basic Data
In some areas stratigraphic data are extremely
meager or absent. In such cases the geologist is
greatly handicapped and must bide his time until
data become available.

TIME & COST
TIME AND COST
Some oil companies follow an ultraconservative
attitude in their stratigraphic programs and make
every attempt to reduce or even eliminate coring,
taking ditch samples, or running an electrical log.

On the other hand, many companies spend great
sums in obtaining basic stratigraphic information.

QUALITY OF PERSONNEL
QUALITY OF PERSONNEL
For one to become familiar with the various
methods of correlation; their uses and limitations,
requires time, experience, and integrated
reasoning.
A company having young, inexperienced
geologists must expect correlation errors.

METHODS OF SUBSURFACE
CORRELATION
METHODS OF SUBSURFACE
CORRELATION
All methods and techniques listed in next Figure
are applicable to correlating subsurface
stratigraphic units; but to apply any one of them
out their limitations generally initiates poor
results.

METHODS OF SUBSURFACE
CORRELATION
Figure 6. Procedures applied in correlation of strata
STRATIGRAPHIC MAPS AND
CORRELATION
STRATIGRAPHIC MAPS AND
CORRELATION
During the past 10 years, great advances have
been made in presenting stratigraphic data in the
form of contour maps.
The philosophy of preparing stratigraphic maps is
based on the idea that any stratigraphic variable
(color, texture, composition, thickness, etc.) that
can be expressed numerically can be contoured.

To initiate construction of a series of stratigraphic
maps, the following procedure is recommended.

STRATIGRAPHIC MAPS AND
CORRELATION
Measure, describe, and sample, in detail, surface
and subsurface sections; define the boundaries
of stratigraphic units and establish their lateral
equivalents; prepare the following maps: isopach,
which is the basis for all subsequent stratigraphic-
type maps; lithofades, including clastic and non-
clastic (percentage or ratio) ; biofades
(percentage or ratio of variables) ; and tectofades
and paleogeographic.
When these maps are completed; then comes the
stage of integration and interpretation of the data.
STRATIGRAPHIC MAPS AND
CORRELATION
After proper integration of such maps, much may
be learned of the tectonic and sedimentation
history of the region.

These maps could not have been prepared until
fundamental stratigraphic units had been defined
and correlated.
STRATIGRAPHIC MAPS AND
CORRELATION
Figure 7. Isopach and sand-shale for the Dakotan and Coloradoan rocks
DIFFICULTIES OF
CORRELATION
DIFFICULTIES OF CORRELATION
Some of the more common difficulties
encountered in correlation work are:
(1) discontinuity of stratigraphic units
(2) structural complexity
(3) lateral variations in thickness, lithology, and
paleontology
(4) poor development or absence of marker beds
(5) presence of unrecognized unconformities
DIFFICULTIES OF CORRELATION
(6) multiplicity of lithogenetic and time-stratigraphic
nomenclature
(7) erroneously compiled data
(8) lack of experienced personnel assigned the
problem.
CONCLUSION
CONCLUSION
Stratigraphic units
Space-time concept in correlation
Facies factor in correlation & Correlation markers
Magnitude of correlations
Factors controlling correlation investigations (FCCI)
Time & cost, Quality of personnel
Methods of subsurface correlation
Stratigraphic maps and correlation
Difficulties of correlation

REFERANCE
Subsurface Geology in Petroleum Exploration; edited by
John D. Haun and L. W. LeRoy, Colorado School of Mines
Golden, Colorado 1958