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CSPGSEP4.PPT
1. CORPOVEN
CSPG-SEPM JOINT CONVENTION
SEDIMENTARY EVENTS AND HYDROCARBON SYSTEMS
CALGARY, JUNE 1997
Chemostratigraphic Correlation of the Source
Rock and definition of the La Luna-K/T(!)
Petroleum System In Southwestern Venezuela
ANGEL F. CALLEJÓN. Exploration Management, Corpoven S.A., Venezuela,
HENRY BRICEÑO, MARINO OSTOS, FRANKLIN YORIS, LITOS, Venezuela
SUHAS TALUKDAR, Core Laboratories, Houston
PDVSA
4. Thickness of the Studied Sections
VENEZUELA
20 KM
OUTCROPS
LA LUNA Fm.
NAVAY Fm.
EL CURITO
LAS DELICIAS
LA ORTIZA
EL CUITE
ESCANDALOSA
LA VUELTOSA
BOCONO
FAULT
N
COLOMBIA
THE ANDES FOOTHILL
190 m
189 m
426 m
614 m
890 m
250 m
5. • 342 SAMPLES COLLECTED AND ANALYZED FOR
ORGANIC AND INORGANIC PARAMETERS
• ORGANIC SPECIES : TOC, ROCK-EVAL PYROLISIS,
KEROGEN ORGANIC PETROGRAPHY
• INORGANIC SPECIES: Ca, Ti, V, Cr, Mn, Fe, Co, Ni,
Cu, Zn, Sr, Y, Nb, Mo, Ag, Cd, La, Ce, Hf, Ta, Th, U,
Na2O, MgO, AL2O3, SiO2, P2O5, K2O, TiO2, Cr2O3, MnO.
Analytical
6. Maturity of the Studied Sections
VENEZUELA
20 KM
N
EL CURITO
LAS DELICIAS
LA ORTIZA
EL CUITE
ESCANDALOSA
LA VUELTOSA
COLOMBIA OVERMATURE
THE ANDES FOOTHILL
EARLY MATURE
INMATURE
STA. BARBARA
SAN CRISTOBALBOCONO
FAULT
8. Chemical Accumulation Rate
Differences (CARD) Plots
Sampleorder(base-top)
(Al2O3 + SiO2) - CaO
1-9-19
0
30
60
90
120
Colón Fm.
Glauconitic Zone
Transition Zone
Ftanita del Táchira
Pelagic Facies
Capacho Fm.
8 m
26 m
106 m
60 m
La Luna Fm.
9. Siliciclastic vs. Carbonate
Accumulation
(Al2O3-SiO2)-CaO
Burguita Fm.
Quevedo Mb.
La Morita Mb.
0
-7 33
60
Ftanita
del
Tachira
Pelagic
Facies
-13
0
120
Capacho Fm.
Colon Fm.
17 1-19
0 Capacho Fm.
Las Delicias La Ortiza El Cuite
Sampleorder(base-top)
120
Fm. Colón
Ftanita
del
Tachira
Pelagic
Facies
Navay Fm.La Luna Fm.La Luna Fm.
10. Redox Conditions
Chemical Accumulation Rate Differences
(CARD)
Ni - V
100
-14 -7 -1-21
120
-28
0
12
Colon Fm.
Capacho Fm.Capacho Fm.
Colon Fm.
60
0
-19 -3
Burgüita Fm.
3-15
40110
00 0
Sampleorder(base-top)
Las Delicias La Ortiza La Vueltosa El Cuite El Curito
Navay Fm.La Luna Fm. Navay Fm. Navay Fm.La Luna Fm.
Early
Campanian
Early
Campanian
Late
Santonian
Late
Santonian
Early
Campanian
Late
Santonian
Early
Campanian
Late
Santonian
Early
Campanian
Late
Santonian
11. (Al2O3 + SiO2) - CaO
1-9-19
0
30
60
90
120
Zona de Transición
Ftanita del Táchira
Facies Pelágicas
8 m
26 m
106 m
60 m
-1-21 -11
Fm. Colón
FtanitadelTáchira
Fm. La Luna
FaciesPelágicas
Fm. Capacho
Ni - V
Sampleorder(base-top)
Comparison of Redox
Conditions and Mineralogy
12. Geochemical Correlation Between
Organic and Inorganic Parameters
Navay Fm. La Vueltosa Section
600
400
200
0
0.1 1 10
Zr / Ni
r2
= 0.9441
400
200
0
StratigraphicDistance(m)
0.1 10 1001
COT < 1
HI < 200
3
2
1
0
0.1 1 10 100
%COT
r2
= 0.9769
COT > 1
HI > 200
HI
13. Source Potential Index
DEMAISON AND HUIZINGA, (1991)
SPI = h (S1 + S2) ρ / 1000
SPI = The maximum quantity of
hydrocarbons that can be generated
within a column of source rock under one
square meter of surface area (in metric
tons of hydrocarbons / square meter)
h =
source
rock
thickness
(m)
1
m
eter
1 meter
14. VENEZUELA
20 KM
N
EL CURITO
LAS DELICIAS
LA ORTIZA
EL CUITE
ESCANDALOSA
LA VUELTOSA
COLOMBIA
THE ANDES FOOTHILL
EARLY MATURE
(0.6 %Ro)
Source Potential Index
SAN CRISTOBAL
6
10
8
7
2
STA. BARBARA
OVERMATURE0.6
INMATURE8
6
SPI VALUES
BOCONO
FAULT
0.6
16. La Luna-K/T (!) Petroleum System
Elements
RESERVOIR / REGIONAL SEAL
SOURCE ROCK / REGIONAL SEAL
RESERVOIR
RESERVOIR / SEAL PAIRS
RESERVOIR / SEAL PAIRS
RESERVOIR / SEAL PAIRS
RESERVOIR / SEAL
PARANGULA
GUAFITA
NAVAY
ESCANDALOSA
AGUARDIENTE
APON
RIO NEGRO
CARBONERA
OROCUE
BURGUITA
0 m
4000
3200
2400
1600
800
6200
5600
4800
PALEOCENE
EOCENE
MIOCENE
MIO-PLIOCENE
LOWER K
SANTO-CAMP
MAASTRICH.
CONIACIAN
CENOMANIAN
Editor's Notes
Good mornig ladies and gentlemen
The results you are going to see today are part of a multidisciplinary effort to improve the knowledge on the hydrocarbon habitat in this area.
The study area is located in the most south western part of the barinas-apure basin which is characterized by the production of high quality oils in the traditional barinas fields and in the la victoria and guafita fields near the venezuelan - colombian border.
The geology of the area is structurally complex and includes from volcaniclastic rocks of the jurasic to molassic sediments of mio-pliocene age.
The upper cretaceous rocks of the La Luna formation and its equivalent, the Navay formation, considered the source rock of the petroleum in the Maracaibo and Barinas-Apure basins, were studied in several outcrops in the southwestern part of the apure-barinas basin to help on the definition of the petroleum system operating in this area.
The La Luna Formation was defined as a sequence of fine grained sediments deposited in a restricted basin in the northern border of the southamerican plate. This formation is represented by a continous sedimentation of shales and calcareous mudstones known as the pelagic facies, which grades upsection into a more siliceous facies grossly represented by cherty sediments so called the ftanita del táchira member in the studied outcrops
The thickness of La Luna in this area is about 200 meters but as you move south, towards the source of sediments, the La Luna Formation changes its lithological composition to the more siliciclastic Navay Formation. To the base of the Navay Formation it is possible to recognize a shalley section, La Morita member which is in turn overlain by interbedded mudstones and ftanites of the Quevedo Mmember.
Here the thickness of the Navay Formation varies between for houndred and nine houndred meters
As part of the corpoven’s exploration effort, three hundred and forty two samples were collected in sections where the la luna and navay formations crops out and were characterized from their organic and inorganic content.
The analytical results were integrated on a chemostratigraphy basis using multivariant statistics and correlation both vertically and laterally between the studied sections
Besides this several oil seeps and oils from two wells were collected and geochemically characterized
The maturity of the studied source rocks in outcrops varies from inmature (indicated as yellow dots) to over mature (in red color), as Las Delicias section, to mature rocks as in the La Ortiza section (in green color).
Additionally seeps were colected and geochemically characterized in order to correlate them with the organic extracts from the potential source rocks in the area.
Using Statistical Factor Analisys, Three geochemical associations were determined:
A Clastic Association wich include elements present into the siliciclastic mineral fraction;
An Organic Assocition with metals usually fixed in the organic matter;
An finally a Carbonatic Association made up by the elements of calcareous minerals.
The elements of each association were studied and correlated between stratigraphic sections
Using the card plots we could stablish relationship between the siliciclastic sedimentation represented by shales and ftanites and carbonate sedimentation.
Most of the studied sections show an unique maximun in the sedimentation of carbonates and the change in the slope of the curve marks the precise moment where the siciliclastic sedimentation became more important compared to the carbonatic one.
A similar situation occurs with the oxidation reduction conditions during the sedimentation process, we can see an unique maximum in the reduction conditions and again the change in the slope marks the change in the redox conditions of the environment from an anoxic cycle to a more dysaerobic cycle.
This main event is syncronous in the area and occurred during the early campanian.
In the La Vueltosa section we interpreted the age of this event based on the chemostratigraphic information
As I mentioned before, the segments with the same dip, limited by those changes, correspond to relatively homogenoeus intervals, these segments or cycles overlap lithologic changes and are related to mayor geologic events.
In this case in the Ortiza section the mineralogical change appears later than the change in the redox conditions.
We use the geochemical correlations of some elements to stablish a relationship between organic and inorganic parameters in order to define the organic potential of sections with low organic data but good enough inorganic data.
We select the La Vueltosa section as an example to show these correlations between Total Organic Carbon, Hydrogen Index and the ratio of circonium over nickel (siliciclastic input over organic input).
Based on these geochemical correlations we could estimate the effective thickness of the source rock for any inmature studied section with low organic data.
The use the Source Potential Index, as defined by Gerard Demaison and Bradley Huizinga, permit us to compare the potential quality of the source rocks in the area .
As I show you before, in sections with low quantity of organic data we use some of the inorganic parameters you saw before to obtain a rough estimate of the SPI values.
Previous to this study the Navay formation was not considered as a good source rock for the oils potentially generated in the area.
Despite of the change in the sedimentaion facies and on the shown results of the Source Potential Index, the Navay formation is considered now an oil prone source rock in the studied area. Its quality disminished as you move to the northeast limit of the studied area.
Using several standard organic geochemical parameters, including biomarker analysis, we correlate the seeps and bitumen impregnations in the area
Here we show an example of this correlation based on a triangular plot of the C27, C28, C29 regular steranes.
Other geochemical parameters confirm a similar correlation between the seeps and the bitumen of the La Luna and Navay formations
A detailed study of the petrophysical properties of the sandstones in the shown outcrops and in others not mentioned here show the presence of potential reservoirs and seals for the area.
The main targets are Aguardiente and Escandalosa sandstones and limestones of the cretaceous and the tertiary Guafita formation.
Some minor entrapments appear possible in other fromation and inside the molassic sediments.
