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Organic matter and hydeocarbon potentialpptx
1. Rock Eval Pyrolysis: A Tool for Reservoir
Characterization and Hydrocarbon Potentiality
Estimation
Dr Subhashree Mishra
Scientist
CSIR-NIO
2. Duration of the internship: 1st January, 2022 – 28th February, 2022
Topics to be covered:
· What is source and reservoir?
· What are the geological controls for hydrocarbon generation?
· Types of hydrocarbons?
· Organic matter in marine sediments
· A brief introduction to Rock Eval Pyrolysis
· Principles and Applications of Rock Eval Pyrolysis
Presentation: 28/02/2022
5. • The Carbon content of kerogen increases with increasing
temperature.
• 3 phases of transformation of OM to HCs:
1.Diagenesis
2.Catagenesis
3.Metagenesis
• Kerogen is intermediate product formed during diagenesis.
• Source rock: which contains OM and is capable to generate the
hydrocarbons.
• Reservoir rock: which can hold the hydrocarbons in pores and
fractures.
• Cap rock: An impermeable rock which don’t allow the
hydrocarbons to escape from the reservoir rock.
8. • Organic Matter: organisms (plant or animal) dies, normally
oxidized but under exceptional conditions like sudden burial its
preserved in basins (Terrestrial and Marine).
Kerogen/Organic matter
• Organic matter is divided into:
Labile OM
Refractory OM
• Components of OM in sediments – Proteins, Carbohydrates,
Lipids, Lignins.
• Bitumen is a low-grade of crude oil which is composed of
complex, heavy hydrocarbons.
• Kerogen is complex mixture of hydrocarbon compounds
insoluble in water or organic solvent.
• Dead plants/animals + Time + Temp + Pressure = Kerogen.
• Elementally kerogen consists of C, H & O with minor amounts
of N & S.
9. • According to the Van
Krevelen diagram, Kerogens
can be classified based on the
ratios of H/C and O/C.
• The classification includes:
Δ Type I Kerogen (algae)
- Higher H:C ratio than others.
- The organic compounds are typically
lipids.
Δ Type II Kerogen (Spores, pollens,
cuticles)
- Intermediate H:C ratio.
- Consist mostly of planktons.
Δ Type III Kerogen
(Humic kerogen/Land plants)
-Generally from humic
materials.
-H:C ratio very low.
Δ Type IV Kerogen
- Rarest kerogen type
- Consist of inert particles
Types of Organic matter
Tissot and Welte, 1989
10. Macerals
• Microscopically identifiable constituents of kerogen are
called macerals.
• Three primary macerals group: Vitrinites/Huminite;
Liptinites; Inertinites
1 2 3 4 5
11. Evolution of organic matter from photosynthesis, through
the oil and gas windows, to post methane generation.
Bohacs et al., 2013
16. TOC and Rock Eval Pyrolysis
• S3 – CO/CO2 generated from the kerogen during thermal cracking of the
kerogen
• Tmax - temperature at which the maximum amount of hydrocarbons are
generated, which is a measure of thermal maturity of the organic matter
• Hydrogen index (HI) = (S2*100)/TOC and Oxygen index (OI) =
(S3*100)/TOC
• Production Index (PI) = S1/(S1+S2), denoting ratio of free hydrocarbons to
total hydrocarbons.
• Hydrocarbon generating potential (PY) = S1 + S2 is the measurement of total
pyrolytic hydrocarbon yield.
• Total organic carbon (TOC) content (wt.%) – is determined
by oxidation of the residual organic carbon under air
environment at temperature above 600 °C.
• S1 – free hydrocarbons (small chain lipids) released at
temperatures of about 300 °C.
• S2 - hydrocarbons generated by thermal cracking of the
organic matter in the rock samples at temperature of 300-
550 °C.
22. ROCK-EVAL 6 APPLICATIONS
• Mineral carbon determination (PyroMiNC):
improved characterization of marly/carbonate
source rocks; detection of carbonate types (e.g., siderite, calcite,
dolomite); Enhanced characterization of hydrocarbons in
carbonate reservoirs; possible correction of matrix effects.
• Oxygen indices:
Impact on source rock facies analysis;
Impact on the knowledge of source rock
Preservation conditions
• Improved measurements of TOC and Tmax:
Better analysis of type III source rocks;
Better analysis of heavy bitumen in reservoirs (tar-mat studies);
Better characterization of coals
Better characterization of recent sediments
• Source rock characterization
• Reservoir geochemistry, and environmental studies
• Quantification and typing of hydrocarbons in contaminated soils
31. • The presence of organic-additives in drilling mud can adversely affect both
TOC and Rock-Eval data. Multiple washing can remove the bulk of the
additives.
• Oil-based mud (OBM) generally comes under the S1 measurement, but
polymeric organic material based on glycol and similar additives is less
volatile and tends to produce a precursor to the S2 peak. Inspection of
pyrograms is therefore always recommended.
• If oil or other organic mud additives are known to have been used, this
contamination of source rocks is best removed by solvent extraction prior
to the TOC and Rock-Eval analyses, so that more reliable TOC, S2, S3, HI,
OI and Tmax values can be obtained.
Potential problems