3d seismic interpretation of an early miocene succesion, offshore northwestern venezuela

PETROLEOS DE VENEZUELA

INTEVEP, S.A.

3D SEISMIC INTERPRETATION OF AN

EARLY MIOCENE SUCCESION, OFFSHORE

NORTHWESTERN VENEZUELA

A report prepared for:

The Institut Français du Petrole School and

Petróleos de Venezuela Exploration Management,

By:

B.S. Carlos Saavedra

August, 2010


INTEVEP, S.A.

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SUMMARY


INTEVEP, S.A.

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TABLE OF CONTENTS

Page

SUMMARY 2

LIST OF ILLUSTRATIONS 4

1. INTRODUCTION 6

1.1. Objective 6

1.2. Study area 7

1.3. Available data 8

1.4. Geological setting 8

2. METHODS 11

2.1. Reconnaissance study 11

2.2. Seismic to well ties 11

2.3. Horizon and fault interpretation 13

2.4. Seismic facies mapping 19

3. RESULTS AND DISCUSSIONS 20

3.1. Horizon EO 20

3.2. Horizon IM 26

3.3. Horizon EM 26

3.4. Seismic facies mapping 29

3.4.1. Unit A 29

3.4.2. Unit B 31

4. CONCLUSIONS AND RECOMMENDATIONS 34

REFERENCE LIST 36


INTEVEP, S.A.

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LIST OF ILLUSTRATIONS

Page

Figure 1. Sketch map of offshore northwestern Venezuela showing

the location of the area of the 3D Seismic survey (blue

rectangle), on which this study is based.

7

Figure 2. Geologic tectonic map of the northwestern Venezuela.

Major fold and fault trends and ages of outcropping units are

compiled from Muessig [2] and Macellari [3].

9

Figure 3. Stratigraphic Column of the Urumaco Trough and their

onshore lithostratigraphic equivalent. Note that the

Paleogene succession has not been clearly established in

the area.

10

Figure 4. Well A depth-TWTT relationship with linear depth scale.

Included are the caliper, gamma ray and impedance logs,

reflection coefficients, Traces from the Line 2448, and

synthetic seismogram.

12

Figure 5. Horizon EO interpreted along a 20 x 20 line/crossline grid.

The polygons in dark red indicate the borders of the blocks

of the Rafael Urdaneta Project.

14

Figure 6. Horizon EO autotracked throughout the entire seismic

survey using the ZAP! tool. This horizon was previously

interpreted along a 20 x 20 line/crossline grid. The abrupt

amplitude changes highlight trends of the main faults.

15

Figure 7. Results of the Edge attribute calculated from the Horizon

EO showed on Figure 6. The discontinuities in the map

indicate the direction of the main faults.

16

Figure 8. Fault heaves calculated for the Horizon EO interpreted

along a 20 x 20 line/crossline grid.

17


INTEVEP, S.A.

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Figure 9. Fault polygons for the Horizon EO. These polygons were

constructed from fault heaves showed on Figure 8.

18

Figure 10. Seismic Trace 4060 with the horizons interpreted in this

study.

21

Figure 11. Seismic Line 2600 with the horizons interpreted in this

study.

22

Figure 12. Arbitrary Line in the direction SW-NE showing the horizons

interpreted in this study.

23

Figure 13. Arbitrary Line in the direction NW-SE showing the horizons

interpreted in this study.

24

Figure 14. Structural map in TWTT (ms) of the horizon EO. 25

Figure 15. Structural map in TWTT (ms) of the horizon IM. 27

Figure 16. Structural map in TWTT (ms) of the horizon EM. 28

Figure 17. a) Seismic facies using the (A-B)/C notation for the

succession between horizons IM and EO. 17b-17e) Seismic

examples of the codes used in a).

30

Figure 18. a) Seismic facies using the (A-B)/C notation for the

succession between horizons EM and EO – IM. b-d)

Seismic examples of the codes used in a).


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1. INTRODUCTION

The Gulf of Venezuela is located in northwestern Venezuela (Figure 1), bounded to the

west by the Guajira Peninsula, to the southwest by the Maracaibo Basin, to the south by

the Dabajuro block, to the southeast by the Falcón Basin, to the east by the Paraguaná

Peninsula, and opened to the north into the Caribbean Sea (e.g., Coronel,1969). This

physiographic feature covers an area of approximately 20,000 square kilometers.

In 2005, the Venezuelan Energy and Petroleum Ministry announced the beginning of the

Rafael Urdaneta Project. For this major Project, the northwestern offshore area of

Venezuela was divided into 29 operational blocks, of which 18 are in the Gulf of

Venezuela. Pre-auction expectations for oil and gas from previous studies in the Gulf of

Venezuela were estimated at 7 millions of barrels (MMBls) and 22 trillion cubic feet

(TCF), respectively. The immediate goal of the project is to produce natural gas for

Venezuela’s domestic market, which has a current deficit of 1.5 million cubic feet per

day.

Within the framework of the Rafael Urdaneta Project, the CARDON IV block, located in

the eastern part of the Gulf of Venezuela, was licensed to two operators who have

successfully drilled 2 exploratory wells in a carbonate reservoir. The discovery could

contain 8-10 TCF of recoverable natural gas reserves and sizable amounts of

condensates.

1.1. Objective

In order to increase our geological knowledge about the recent discovery, this

contribution focuses on the 3D seismic interpretation of the Early Miocene succession

within which the carbonate reservoir was developed.


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1.2. Study area

The study area is located in the western portion of the Cardon IV block. It covered

511,74 square kilometers. This area was imaged by a 3D seismic survey, on which this

work is based (Figure 1).|

Figure 1. Map of northwestern Venezuela showing the geographic and seismic location

of the study area. The light-gray polygons indicate operational blocks for the Rafael

Urdaneta Project.


INTEVEP, S.A.

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1.3. Available data

To carry out this study, it was disposed of a 3D seismic data volume, which was

acquired in 2007 and encompasses 716 square kilometers with 511,74 square

kilometers in the western portion of the Cardon IV Block. This volume consists of

poststack migrated seismic data in 8-bit format. Data from two wells: A and B (Figure 1),

were also available. Wells A and B are renamed because of confidential reasons. Both

seismic and well data were loaded in the Landmark's OpenWorks [1] suite for their

subsequent interpretation.

1.4. Geological setting

The study area is located at the north border of a northwest-trending depression known

as Urumaco Trough (Figure 2). This depression was created as a result of the

extensional subsidence developed in a pull-apart zone during the Paleogene oblique

collision of the Caribbean and South American plates [2, 3]. The continuous

convergence accentuated the subsidence of the Urumaco Trough throughout the

Neogene. Thus, it became a receptacle for a thick pile of post-Eocene sediments that in

its central parts could exceed 27000 feet [4]. Northward Urumaco Trough, seismic data

have showed the presence of several structural highs where the average thickness of

the post-Eocene sediments is of the order of 13000 feet [5].

In general, the sedimentary succession of the eastern Gulf of Venezuela overlies an

allochthonous basement, which was emplaced during the Paleogene compressive

phase. It consists mainly of Late Cretaceous metasediments [6]. Above this basement, it

is believed that a marine succession was deposited during the Early to Middle Eocene.

These deposits were unconformably overlain by Late Eocene to Oligocene sediments,

which were better developed in the central parts of the Urumaco Trough. Towards the

structural highs only a reduced Paleogene section was deposited.


INTEVEP, S.A.

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By correlation with the surrounding onshore areas, it is believed that sedimentation in

the Urumaco Trough during the Early Miocene started with shelf deposits of the Agua

Clara Formation and the subsequent progradation of the Cerro Pelao deltaic complex

which was followed by the transgression of the Querales shales. During the Middle to

Late Miocene a major phase of inversion took place in the onshore Falcon basin,

resulting in the uplift of the Falcon anticlinorium and the subsequent rapid basinward

progradation of the deltaic facies of the Socorro Formation [4]. According to Audemard

[7] this tectonic inversion could be still active. The rest of the stratigraphic column

(including the Urumaco and Codore formations), was accumulated during a continuous

bathymetric decline until reach the current water depth (Figure 3).

Figure 2. Simplified geologic map of the northwestern Venezuela. Major fold and fault

trends and ages of outcropping units are compiled from Muessig [2] and Macellari [3].

Note that Cardon IV block is located at the north border of the Urumaco Trough.


INTEVEP, S.A.

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Figure 3. Stratigraphic Column of the Urumaco Trough and their onshore

lithostratigraphic equivalent. Note that the Paleogene succession has not been clearly

established in the area.


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2. METHODS

The method used to analyze the Early Miocene succession in this study involved the

following stages:

2.1. Reconnaissance study

This stage consisted of an initial scrolling through the seismic volume. The data was

examined line to line, trace to trace, and from top to bottom at large steps. The objective

of this initial scrolling was to assess the overall structural and stratigraphic styles in the

target succession.

2.2. Seismic to well tie

Once the stratigraphic objectives have been identified in the initial reconnaissance

stage, the following step was to tie target seismic reflectors to well data via synthetic

seismograms, which were constructed in the SynTool application of OpenWorks [8]. For

each well, an impedance log and reflection coefficients were generated from the sonic

and density profiles. The acoustic impedance log as a function of depth was then

converted into a log as a function of two-way travel time (TWTT) using the time - depth

relation derived from the check shot survey of each well. The reflection coefficients

calculated from the impedance log were convolved with a seismic wavelet to produce a

synthetic seismic trace, which was then compared with the real seismic at the well site

looking for a good visual match. In order to choose the appropriate wavelet, I used three

methods: autocorrelation, Ricker and SeisWell [1], selecting that that best match the

actual seismic. Figure 4 illustrates the relationship between the impedance log,

reflection coefficients, seismic traces, and synthetic trace for the well A.


INTEVEP, S.A.

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Fig

ure

4. W

ell

A d

ep

th-T

WT

T r

ela

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ip w

ith lin

ea

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ave

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tch

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ea

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ic b

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een

180

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nd

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00

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= t

op

of E

arly M

ioce

ne

, IM

= t

op

of

ca

rbo

nate

re

se

rvo

ir,

EO

= t

op

of E

oce

ne/O

ligo

ce

ne

, A

B=

Aco

ustic B

ase

men

t.


INTEVEP, S.A.

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2.3. Horizon and fault interpretation

Following the calibration of the wells to the seismic data, the horizon interpretations

were carried out, starting with a line close to a well calibrated. The horizon picking was

preferably made by signal consistent automatic extraction of minimum, maximum or zero

crossing surfaces (“autotracking”), whenever was possible, especially in those areas of

good lateral continuity and well-defined seismic character. Otherwise, the manual

picking was necessary, especially in those areas where stratigraphic discontinuities

were detected.

The interpretation involved three horizons (Figure 4), which according to preliminary

biostratigraphic analysis correspond to: the top of the Oligocene-Eocene succession

(horizon EO), the top of the Early Miocene succession (horizon EM), and a third horizon

within the Early Miocene succession corresponding to the top of the carbonate

development (horizon IM). The interpretation of the acoustic basement (horizon AB) was

not made for the purpose of this internship report.

The horizons were interpreted along a 20 x 20 line/crossline grid (i.e., 250 m x 250 m,

Figure 5), and then autotracked throughout all the seismic survey using the ZAP! tool of

SeisWork (Figure 6). The resulting horizon helped to highlight the main trend of the

discontinuities present in the horizon. These discontinuities were also identified with the

use of edge-detection algorithms which allowed the direct illumination of faults (Figure

7). The identification of the main trend of faults was useful in determining the direction of

their interpretation, which has to be perpendicular to strike of the structures.

The faults were interpreted along a 20 x 20 line/crossline grid. Their identification was

helped by the use of time slices coming from a coherence (similarity or dissimilarity)

cube built in the PostStack/PAL application of OpenWorks [9]. The faults were then

interpolated using the Triangulate tool of SeisWork [1]. Once the faults were


INTEVEP, S.A.

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triangulated, the fault heaves were obtained (Figure 8) and the fault polygons

constructed (Figure 9).

Figure 5. Horizon EO interpreted along a 20 x 20 line/crossline grid. The polygons in

dark red indicate the borders of the blocks of the Rafael Urdaneta Project.


INTEVEP, S.A.

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Figure 6. Horizon EO autotracked throughout the entire seismic survey using the ZAP!

tool. This horizon was previously interpreted along a 20 x 20 line/crossline grid. The

abrupt amplitude changes highlight trends of the main faults. The polygons in dark red

indicate the borders of the blocks of the Rafael Urdaneta Project.


INTEVEP, S.A.

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Figure 7. Results of the Edge attribute calculated from the Horizon EO showed on

Figure 6. The discontinuities in the map indicate the direction of the main faults. The

polygons in dark red show the borders of the blocks of the Rafael Urdaneta Project.


INTEVEP, S.A.

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Figure 8. Fault heaves calculated for the Horizon EO interpreted along a 20 x 20

line/crossline grid. The polygons in dark red indicate the borders of the blocks of the

Rafael Urdaneta Project.


INTEVEP, S.A.

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Figure 9. Fault polygons for the Horizon EO. These polygons were constructed from

fault heaves showed on Figure 8. The lines in dark red indicate the borders of the blocks

of the Rafael Urdaneta Project.


INTEVEP, S.A.

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Finally, the fault polygons were superimposed to the interpreted horizons to generate

the structural maps in TWTT for each horizon. In this stage, the abrupt amplitude

changes were in great part corroborated to correspond to the presence of faults.

However, those areas with amplitude contrasts but without faults were reinterpreted to

verify the possible presence of faults initially unrecognized.

2.4. Seismic facies mapping

In order to map the distribution of the seismic characteristics of the seismic stratigraphic

units (sensu Zampetti et al. [10]) recognized in this work, I used the A-B/C mapping

approach proposed by Ramsayer [11]. The basic elements of the technique include

observations of the geometric relations of the upper boundary (A), the geometric

relations of the lower boundary (B) and the internal reflection character (C) of a seismic

sequence, which are abbreviated and plotted on a map as (A-B)/C. This technique

allows interpreters to make inferences about the character of the reflection termination

patterns and their meaning within the depositional framework of a determined area.


INTEVEP, S.A.

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3. RESULTS AND DISCUSSIONS

Three seismic horizons were selected to analyze the Early Miocene succession in the

study area. They correspond, from base to top, to: 1) the top of the Oligocene –Eocene

succession, which is identified as EO and colored in orange on the seismic data; 2) the

top of the carbonate reservoir, which is identified as IM and colored in magenta on the

seismic data; and 3) a horizon near the transition Early Miocene – Middle Miocene,

which is identified as EM and colored in dark green on the seismic data. These horizons

define two the seismic stratigraphic units: Unit A (between horizons EO and IM) and Unit

B (between horizons EM and EO/IM). Figures 10 to 13 show different sections across

the seismic volume, with the horizons interpreted in this contribution.

3.1. Horizon EO

This horizon is represented by a reflector of good continuity and moderate to high

amplitude. It shows a strong contrast of acoustic impedance caused by the lithologic

changes between the overlying Miocene rocks and the underlying clastic and

metamorphic rocks. In general, the interpretation of this event is facilitated by their good

continuity, except towards the borders of the seismic volume, where the quality of

seismic data is poor. Figure 14 shows the structural map in TWTT of this horizon.

The main structural feature interpreted for this event is a structural high elongated in a

NW-SE direction, which occupies the central part of the study area. This high shows a

steeper dip in the southwestern flank and gentler dip in the northeastern flank. A series

of normal faults is affecting this reflector, many of which extend down into the Paleogene

succession. These normal faults can be grouped into two main families according to

their orientation: one with a dominant NW strike direction and a preferential dip to the

SW, and other with a dominant NNW strike direction and a preferential dip to the W.


INTEVEP, S.A.

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Fig

ure

10

. S

eis

mic

Tra

ce

40

60

with

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ns i

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n;

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top

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ca

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ir;

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= t

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n E

arly M

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ne

– M

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. T

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ote

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est.

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ile t

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M is s

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wn

conco

rda

nt.

?


INTEVEP, S.A.

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Fig

ure

11

. S

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mic

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e 2

60

0 w

ith

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terp

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d in t

his

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ue

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ark

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ms).

?


INTEVEP, S.A.

23

Fig

ure

12

. A

rbitra

ry L

ine

in

th

e d

ire

ction

SW

-NE

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ho

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in

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ure

10

. N

ote

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e in

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M is c

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ve

Pa

leoge

ne

de

pre

ssio

ns.


INTEVEP, S.A.

24

Fig

ure

1

3.

Arb

itra

ry L

ine

in

th

e d

ire

ction

N

W-S

E sh

ow

ing

th

e horizo

ns in

terp

rete

d in

th

is stu

dy.

Th

e

ho

rizo

n n

om

en

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an

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lor

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the

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ha

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se

d i

n F

igure

10

. N

ote

the

ab

rup

t in

cre

ase

in

th

ickn

ess o

f th

e ye

llow

su

cce

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rds N

W,

wh

ich

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a

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cia

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w

ith

n

orm

al

gro

wth

fau

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oote

d i

n t

he

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ene

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n.

Th

e b

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uccessio

n p

inch

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ut

ag

ain

st

the

ho

rizon

EO

both

to

wa

rds N

W a

nd

SE

.


INTEVEP, S.A.

25

Figure 14. Structural map in TWTT (ms) of the horizon EO.


INTEVEP, S.A.

26

3.2. Horizon IM

This horizon is represented by a reflector of good continuity and moderate amplitude. In

great part of the interpreted area, this horizon is characterized by a strong lithologic

contrast between the underlying carbonates and the overlying clastic rocks. However,

towards southwest the interpretation required more effort due to the weak contrast of

acoustic impedance and the poor seismic image present there. The interpretation of this

event was also facilitated by the baselap terminations observed against the reflector

(Figures 10 to 13). Figure 15 shows the structural map in TWTT of this horizon.

Towards north and northeast the horizon IM pinches out against the horizon EO,

following the trend outlined by the NW-SE elongated structural high of the horizon EO

(Figure 14). Towards southwest the horizon IM shows a steep dip. Many normal faults

affecting this horizon show a NW direction akin to that of the underlying horizon EO.

3.3. Horizon EM

Seismically, this reflector presents truncation in certain areas of the survey, which helps

in their interpretation (Figures 11 to 13). However, there are parts of the seismic volume

where upper terminations are conformable. In general, the contrast of acoustic

impedance is moderate and the continuity is regular. It is probably as a result of

lithologic changes more subtle than in the preceding seismic reflectors. Figure 16 shows

the structural map in TWTT of this horizon.

The horizon EM shows a gentle dip towards the south. It is curt by a series of normal

faults, many of which show a dominant NW-SE strike direction and a preferential dip to

the SW, while others show a NNW strike direction. They are both similar to the

orientations of the older horizons. Faults with a NW orientation, as evidenced by the

cross-cut relationships, are shown to be younger than the faults with NNW orientation.


INTEVEP, S.A.

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Figure 15. Structural map in TWTT (ms) of the horizon IM.


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Figure 16. Structural map in TWTT (ms) of the horizon EM.


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3.4. Seismic facies mapping

For purpose of this contribution, two seismic stratigraphic units were recognized: Unit A

(between horizons EO and IM) and Unit B (between horizons EM and EO/IM). These

units were analyzed by the “A-B-C” mapping approach [11]. Due to limitations imposed

by the seismic data, it was not possible to construct individual maps at the scale of

depositional systems tracts, thus the facies map of the units A and B represent major

depositional trends.

3.4.1. Unit A

The Figure 17 shows the seismic facies interpreted for the Unit A (carbonate

succession). It is noted that this Unit is partially imaged by the 3D seismic volume. This

succession is mainly represented by concordant and parallel internal reflectors, which

vary from straight to slightly wavy and are characterized by moderate amplitude and

moderate to good continuity. The Unit thins towards the north-northeast margins, where

sigmoidal facies become evident and the reflectors baselapping against the horizon EO

(Figures 10-12). Towards the southwest the Unit shows a steep dip accompanied by the

presence of divergent and chaotic facies.

In terms of stratigraphic interpretation, particularly in the determination of the

depositional environments, the dominant parallel patterns at the topographic high

suggest a relatively uniform rate of sedimentation in platform interior positions. The

sigmoidal geometry and baselap terminations suggest progradation at the platform

margins. The divergent and chaotic configurations in areas of low topography indicate a

basinward deposition with an increase in muddier fabrics.


INTEVEP, S.A.

30

Fig

ure

17

. a

) S

eis

mic

fa

cie

s u

sin

g t

he

(A

-B)/

C n

ota

tion

fo

r th

e s

ucce

ssio

n b

etw

ee

n h

orizon

s I

M a

nd

EO

. 17

b-1

7e

) S

eis

mic

exa

mp

les o

f th

e c

od

es u

se

d in

a).

). R

ed

arr

ow

s in

dic

ate

se

ism

ic t

erm

ina

tio

ns.


INTEVEP, S.A.

31

In general, the Unit A reveals the development of an isolated carbonate platform with a

dome-shaped external geometry, which nucleated in a faulted structural high. Smaller

thicknesses variations along normal faults confirm their control during carbonate

deposition (Figures 17b, 18d). The continuous character of internal reflectors of Unit A

suggests that this buildup could be composed of laterally extensive stratiforms

sequences. However, it is premature to further establish the geometry of internal

subunits without available core samples that allow the determination of the

paleobiological communities that built the succession. This is due to the fact that many

ancient fauna are extinct today and there is few knowledge of the architecture of their

depositional environments.

Onlapping (Figures 10-12) against the top of Unit A is consistent with a regional flooding

event associated with the continuation of the subsidence of the Paleogene extension [3].

This relative rise of sea level was probably the cause of the demise of the platform.

Seismic evidence of exposure was not found at this stage of the study, which suggest

that exposure events were either absent or too short to produce seismically

recognizable signatures.

Since the point of view of the exploration for hydrocarbon, the interpretation of Unit A

extends the platform southward Cardon IV Block, which open the possibility to

investigate the Urumaco I block looking for a better definition the southern end of this

buildup.

3.4.2. Unit B

The Figure 18 shows the seismic facies interpreted for the Unit B. This succession is

mainly represented by divergent seismic facies, which baselapping against the horizon

EO or the top of Unit A. There is a west-east trending area, where the internal


INTEVEP, S.A.

32

configuration of the seismic unit becomes oblique progradational, showing areas with


INTEVEP, S.A.

33

Fig

ure

18

. a

) S

eis

mic

fa

cie

s u

sin

g t

he

(A

-B)/

C n

ota

tion

fo

r th

e s

ucce

ssio

n b

etw

een

ho

rizo

ns E

M a

nd

EO

– IM

. b

-d)

Se

ism

ic e

xa

mp

les o

f th

e c

od

es u

se

d in

a).

Re

d a

rro

ws in

dic

ate

se

ism

ic t

erm

ina

tio

ns.


INTEVEP, S.A.

34

clear truncation or toplap terminations, and baselap at the lower boundary. In general,

reflections in this units show a moderate to good continuity and strong to weak

amplitudes. The unit thinning above and against the structural highs, becoming thicker

toward the Paleogene depressions (Figures 10-12).

The possible origin of the erosional truncation at the top of this unit could be related to

the early stages of deformation and inversion at the end of the Early Miocene inferred in

the surrounding Falcon Basin [12].


INTEVEP, S.A.

35

4. CONCLUSIONS AND RECOMMENDATIONS

Detailed seismic analysis of a 3D data set from an Early Miocene succession offshore

western Venezuela has shown a well defined carbonate build-up, which was developed

in a faulted structural high elongated in a NW-SE direction. This carbonate platform is

mainly characterized by parallel internal reflectors at the platform interior with prograding

facies at the margins. It was recognized the possibility of the platform extension

southward of the study area.

The seismic terminations patterns recognized are shown to be in concordance with the

regional geologic framework known for the area. Thus, the onlapping against horizons

EO and IM is associated with continuation of the subsidence of the Early Eocene

extension; while the erosional truncation at the transition of the Early Miocene – Middle

Miocene is thought to reflect the first pulses of the Middle Miocene Inversion recorded in

the surrounding onshore Falcón basin. However, given the little geologic knowledge of

the offshore area, eustatic effects could not be discarded.

Two main systems of normal faults were identified: one with a N-S (older) and other with

a NW-SE (younger) striking direction. Many of these faults extend down into the

basement and terminate upward at Quaternary levels, affecting the development of the

section under study, as evidenced by the thickness variations along these faults.

Contingent upon the availability of 3D seismic volume at 16 or 32 bits and information of

core sedimentological analysis (currently in progress), It would be highly valuable to

propose a detailed model for the evolution of the studied platform to better constrain

geological processes affecting, controlling and modifying the growth and demise of the

platform.


INTEVEP, S.A.

36

Clearly, this study will be object of a deeper analysis, which will involve the interpretation

of other key horizons, the time to depth conversion, and the facies seismic analysis of

the entire sedimentary succession.


INTEVEP, S.A.

37

REFERENCE LIST

[1] Landmark graphics Corporation, SeisWorks/3D User Guide. Houston, TX, USA,

2004.

[2] Muessig, K. W., Structure and Cenozoic tectonics of the Falcón basin,

Venezuela, and adjacent areas, in W. E. Bonini, R. B. Hargraves, and R.

Shagam, (eds.), The Caribbean-South American plate boundary and regional

tectonics: GSA Memoir 162, 1984, p. 217-230.

[3] Macellari, C., Cenozoic sedimentation and tectonics of the southwestern

Caribbean pull-apart basin, Venezuela and Colombia, in A. Tankard, S. Suarez,

and H. Welsink, (eds.), Petroleum basins of South America: AAPG Memoir 62,

1995, p. 757–780.

[4] Quiroz, L., and Jaramillo, C., Stratigraphy and sedimentary environments of

Miocene shallow to marginal marine deposits in the Urumaco Trough, Falcon

Basin, western Venezuela, in Sanchez-Villagra, M., Aguilera, O., and Carlini, A.

A., (eds.), Urumaco and Venezuelan Palaeontology, the Fossil Record of the

Northern Neotropics: Indiana University Press, Bloomington, 2010, 296 p.

[5] Coronel, G. R., A geological outline of the Gulf of Venezuela: 7th World

Petroleum Cong., Mexico, Proc., 1967, v. 2, p. 799-812.

[6] Audemard, F.E., Tectonics of Western Venezuela. Ph.D. Thesis. Rice University,

Houston, TX, USA, 1991, 245 pp.


INTEVEP, S.A.

38

[7] Audemard, F. A., Bousquet, J-C., and Rodríguez, J. A., Neotectonic and

Paleoseismicity studies on the Urumaco fault, northern Falcón basin,

northwestern Venezuela. Tectonophysics, 308, 1999, p. 23-35.

[8] Landmark graphics Corporation, SynTool User Guide. Houston, TX, USA, 2004.

[9] Landmark graphics Corporation, PostStack Family User Guide. Houston, TX,

USA, 2004.

[10] Zampetti, V., Schlager, W., Konijnenburg, J-H. and Everts A-J., Architecture and

growth history of a Miocene carbonate platform from 3D seismic reflection data;

Luconia province, offshore Sarawak, Malaysia. Marine and Petroleum Geology

21, 2004, p. 517–534.

[11] Ramsayer, G. R., Seismic Stratigraphy, A Fundamental Exploration Tool:

Offshore Technology Conference Proceedings, Vol. 3, 1979, p. 1859–1867.

[12] Gorney, D., Escalona, A., Mann, P., The Bolivar Group, 2007. Chronology of

Cenozoic tectonic events in western Venezuela and the Leeward Antilles based

on integration of offshore seismic reflection data and on-land geology. American

Association of Petroleum Geologists Bulletin 91, 2007, p. 653–684.

3d seismic interpretation of an early miocene succesion, offshore northwestern venezuela

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