MK - PGC-7
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Transcript of MK - PGC-7
Lesson-7: Oil-Oil
and Oil-Source Rock
Correlation (a)
Introduction to Petroleum Geochemistry
Further Readings
Bissada, K.K. et al, 1992, “Geochemical Inversion –
A Modern Approach to Inferring Source Rock Identity
from Characteristics of Accumulated Oil and Gas”,
Proc IPA Convention
Curiale, J.A., 1994, “Correlation of Oils and Source
Rocks – A Conceptual and Historical Perspective”,
AAPG Memoir 60, Chapter-15
Waples, D.W. and J.A. Curiale, 1999, ”Oil-Oil and
Oil-Source Rock Correlations”, AAPG Treatise
Handbook Vol 3, Chapter-8
Petroleum System:
Source Rock – Migration – Traps – Preservation
Processes:
Generation
Migration
Accumulation
Preservation
Elements:
Source Rock
Migration Route
Reservoir Rock
Seal Rock Trap
Petroleum System Definition
The essential ELEMENTS and PROCESSES and all genetically-related hydrocarbons that occur in petroleum shows and accumulations whose provenance is a single pod of active source rock
ELEMENTS
Source Rock
Migration Route
Reservoir Rock
Seal Rock
PROCESSES
Generation
Migration
Accumulation
Preservation Trap
AAPG
Oil and Gas Fields Distribution
Oil and Gas Fields Distribution
Why some fields contain gas?
Others only gas?
Which fields sourced from Talang Akar?
Any other source rocks?
Further exploration potential?
Genetic Relationship of Trapped Oil and Sources
Objectives
Genetic relationship of oil – source rock(s)
Group oils into genetic families and postulate potential mixing
Determine how many effective source rocks exist
Envisage migration pathways – thus opens up potential extension of current plays
Given in 3 lectures
Basic Concepts
Oil inherits certain properties of the source
rock thus oil can be genetically correlated to
its source rock
Two or more oil pools generated from same
source rock can genetically be correlated
A model may then be developed to infer
migration and trapping to allow searching for
additional pools to be found
Genetic Correlation
Oils can be correlated to source rock by comparing
parameters to the extractable organic matter
(bitumen) parameters that may lead to identification
of:
Organic Matter type of the source rock
Depositional Environment of the source rock
Maturity level of the source rock
Basic Concepts-1
Crude oil correlated with
other crude oils from
different fields and with
Rock Extracts (bitumen)
by comparing parameter
similarities
High similarities –
positive correlation
Low similarities –
negative correlation
Basic Concepts-2
When source rock
candidate NOT
AVAILABLE:
Crude oil correlated with
Other crude oils from
other fields by comparing
parameter similarities
Source rock facies and
maturity may be inferred
from biomarkers and
other properties
Correlation Techniques
Bulk Parameters
API Gravity
Sulfur Content
C15+ Compounds (Saturates, Aromatics, Resin/Asphaltenes)
Gas Chromatography:
Whole Oil
Saturates
Isotopes:
Carbon: 13C (mostly)
Hydrogen: D/H (Deuterium / Hydrogen) ratio
Sulfur: 34S/32S
Biomarkers (Molecular Fingerprinting)
API Gravity vs Sulfur Content
Both API and Sulfur content affected by maturity level
Presence of sulfur (>0.5 %wt) suggests marine environment
Low sulfur (< 0.5 %wt) – terrestrial sourced
High sulfur (>2 %wt) - carbonate sourced
Be careful with secondary sulfur
Australian Oil Samples
Cross plot of onshore and offshore oils from
the East Java Basin based on physical bulk
properties and pristane/phytane
Ternary Plot of Paraffins – Naphthenes – Aromatics
Ternary Diagram of Paraffins – Naphthenes and Aromatics+NSO
Possible Mixing of Source Rocks
Gas Chromatography
May be performed on:
Whole oil
Saturated Fractions
Light ends
Heavy ends
Petroleum and Petroleum Products
Schematic Diagram of
Gas Chromatography
• Saturates Fraction GC
• Whole oil GC
Gas Chromatogram of a high-wax oil of terrestrial origin with an odd carbon
preference (CPI) in the wax region and a high pristane–phytane ratio typical of
coaly or certain nearshore aquatic environments
Significant input of terrigenous organic matter is indicated by a bimodal n-alkane
distribution (a second mode in the wax region, from n-C23 to n-C31), a pristane–
phytane ratio greater than 2.0, and a strong odd-carbon n-alkane dominance from
n-C25 to n-C31
These features are characteristic of deltaic or lacustrine sourced oils (in this case
from Indonesia)
GC Analysis and Crude Alteration
Schematic of Oil & Gas Formation/Destruction
Organic Matter
(Kerogen) Bitumen
CO2
Oil/Gas Primary
Cracking
Wet
Gas
Dry
Gas
Pyrobitumen
Biodegradation
Secondary
Cracking
Secondary Cracking /
Thermal Cracking due to
deeper burial of the
accumulated oil
160 oC (320 oF)
Ro ~ 1.1%
200 oC (390 oF)
Ro ~ 1.5%
Gas Chromatograms of two oils from Wyoming. Both were sourced from the Permian Phosphoria Formation, but are reservoired in different fields
The bimodal distribution of n-alkanes in the top oil is consistent with a lower level of maturity than that of the unimodal oil at the bottom
Comparison of these oils using gas chromatography for the purpose of oil–oil correlation must be done with caution because of the maturity differences
Gas Chromatograms of saturated hydrocarbons from an immature extract of coaly organic matter (top) and an oil with a fairly high wax content believed to have been sourced from a similar facies (bottom)
Both show many of the same characteristics — high wax content, odd-carbon preference in the wax range, high pristane–phytane ratio—but maturity effects have changed many of the details
Immature Coaly Rock Extract
Oil
Mature vs Immature Oil GC
Thank you
for your attention