Petroleum System of the Barinas Basin: a 2D/3D Basin Modeling Approach Rojas Iliana (PDVSA-INTEVEP)

Petroleum System Of The Barinas Basin: A 2D/3D Basin Modeling Approach Rojas Iliana (PDVSA-INTEVEP)

This paper was selected for presentation by an ALAGO Technical Committee following review of information contained in an abstract submitted by the author(s).

Abstract Caribbean Deformation Front to the North and Arco de The study area is located towards the North of the Caribbean Merida to the South (Figure 1). Deformation Front; specifically where the structures of

Sipororo, La Yuca and Barrancas oils fields are located, near the Barinas Traditional oil Fields. From a structural point of view, the area of interest is bounded by the following structural features: Bocono Fault Northward, Arco de El Baul East, Caribbean Deformation Front to the North and Arco de Merida to the South and have been studied with the aim build

3D/2D basin model using 3D Temis and some 2D lines (2D Venezuela Temis), with the purpose of determining the different elements (crude oils /source rock, reservoirs, seals and traps) and processes (maturity, migration, transformation ratio, generated and expelled hydrocarbon volume) by the source rocks and South America their contribution with charge of the proposed exploration opportunities in the area, in order to integrate and update previous studies in the Barinas Basin. The methodology developed was first to evaluate the Barinas Basin geochemical characteristics of the crude oils and rocks. Then, Figure 1. Location map of the studied area showing the main from geological-structural model proposed in the area, was structural elements. built a geochemical modeling 2D and 3D as a result of the interpretation performed on 2D (15.520 km) and 3D (1.350 The sedimentary column covers ages from km2) surveys. The results model 2D/3D suggest two possible Cretaceous to Recent age. It includes mainly: Basamento, intervals for generation and expelling potential hydrocarbons Aguardiente, Escandalosa (reservoir), Navay (source rock), of Cretaceous age: the Quevedo and La Morita Members of Burguita, Gobernador (reservoir), Masparrito, Paguey (seal), Navay Formation were identified in the Northwest of the study Parangula and Rio Yuca formations. Four major tectonic area, which were active in the Miocene and currently at levels events led to the current basin: Pre-rift during Paleozoic, rift equivalent to maturity phase of maximum generation of liquid and drifting during Jurassic and early Cretaceous, Passive hydrocarbons (1.3% Ro).These hydrocarbons have migrated margin during the Cretaceous and active margin from vectors a Northwest-Southeast direction, towards the Barinas Cenozoic to the recent with the development of a flexural Basin. Thus, according to the result of this model and Mass Basin and the foreland basin (Figura 2). AGE PETROLEUM OPER PALEOENVIRONMENTS FORMATION / MERBER SYSTEM GEODYNAMIC Balance the opportunities displayed on the study area, have PERIOD/EPOC NAME C T NI NM NE BS ELEMENTS

QUATERNARYCUATERNARIO ALUVIONES

n n

t t

a a f

PLIOCENE f i

received enough volume of oil from these Cretaceous source PLIOCENO RIO YUCA YUCA i

l l

e . e

p p d

MIOCENO d

n MIOCENO PARANGULA n U

MIOCENE PARANGULA U Basin Foreland A rocks (Miocene generation) (5035.31 MMBLS) and its lateral A OLIGOCENEOLIGOCENO

O O TARDIO S

I I LATE equivalent La Luna Formation (generation in the Eocene), PAGUEY Flexural Basin,

R R

A A

Foreland type I I A

C C N MASPARRITO N

E MEDIO

R directly or through remigration oil that was accumulated in the R

E E MIDDLE

O Active margin (Cenozoic to TERTIARY

EOCENE B T E R C I A R I R O I A TI R C E O R I R C A ETI EEOCENO EEOCENO GOBERNADOR R Barinas fields. Molecular parameters have allowed C the recent) TEMPRANOEARLY Caribbean, Napas de Lara, corroborating the crude oils Northem Barinas and traditional Merida Arc PALEOGENEPALEOCENO MAASTRICHTIANMAASTRICHTIENSE BURGUITA D Barinas areas have mainly marine origin with some Beginning of the Uplift E contribution of terrestrial organic matter and different levels of F CAMPANIENSE G H LOWERTEMPRANO QUEVEDO I maturity and biodegradation. CAMPANIAN A J Passive Margin TO K (During the CONIACIANCONIACIENSECONIACIENSE NAVAY L SR M Cretaceous)

Keywords: oil, generation, expulsion, migration, entrapment, O

C CONIACIENSE CONIACIANA

CONIACIENSETURON.TARDIO CRETACEOUS geochemical, structural. T TO UPPERA LA MORITA N

E TURONIANTURON.TARDIO

C MIDDLE TURONIAN O Deepeding of the passive TURON. MEDIO P TO LOWERA ESCANDALOSA R margin during Introduction CENOM.TEMPRANOCENOM.TEMPRANO R CENOMANIAN S ofseparation of South LOWER CENOM.TEMPRANO and North America CENOMANIANA TO T The study area, is located towards the North of the Caribbean AGUARDIENTE UPPERALBIENSE ALBIAN TARDIO Deformation Front; specifically where the structures of ALBIENSEALBIENSE TEMP.TEMP. LOWERA ALBIAN Post “Rift” (Early NEOCOMIENSE Sipororo, La Yuca and Barrancas oils fields are located, near Cretaceous) PRE-CRETACEOUSPRE-CRETACEO BASAMENT BASAMENTO = Erosi “Rift” (During Jurassic) the Barinas Traditional oil Fields. The UTM area coordinates Erosion T= Transitional NM= Medium Neritic BS= Batial C= Continental NI= Neritic Internal NE= External Neritic boundaries are: Xmax = 410000, Xmin = 335,000, Ymin = Modified from: Meza M. (2000) 910,000 and Ymax = 990,000. From a structural point of view, Figure 2. Stratigraphic column type of the Barinas sub-basin the area of interest is bounded by the following structural and the main elements of the petroleum system (Reproduced features: Bocono Fault Northward, Arco de El Baul East, and modified from Lisbeth Meza, 1995). 2 ROJAS ILIANA

The development of the model presented was in this Results and Discussion paper done mainly from the 2D/3D seismic data (seismic The results were divided in two ways: The Petroleum System transects and map in depth), key wells available and the Elements and the Petroleum System Processes. interpreted stratigraphic framework interpreted from this data. Key tops formations were identified, as well as eroded Petroleum System Elements thicknesses, formation ages, lithology of each interpreted Crude Oils / Source Rock sequence and geochemical parameters of the source rock such: The crude oils Northem Barinas and traditional Barinas areas total organic richness, effective thickness and type of kerogen. have mainly marine origin (carbonate and/ or shale) with some contribution of terrestrial organic matter and different levels of Objective maturity to increase from Southwest to Northeast in the study Building a 3D/2D basin model using 3D Temis and some 2D area. The biodegradation can be interpreted in different levels, lines (2D Temis), with the purpose of determining maturity, ranging from high in the seeps studied, to moderate and low, migration, transformation ratio, generated and expelled in some cases as presented of the Barinas fields (figure 5). hydrocarbon volume by the source rocks and their H contribution with charge of the proposed exploration opportunities in the area, in order to integrate and update O previous studies in the Barinas Basin. D K AA A M B 3 T AB Methodology AC F The methodology developed was first to evaluate the geochemical characteristics of the crude oils and rocks. Then, Z Y from geological-structural model proposed in the area, was built a geochemical modeling 2D and 3D as a result of the 2 interpretation performed on 2D (15,520 km) and 3D (1,350 km2) surveys (figure 3,4). 1

1.- Evaluation of the geochemical Figure 5. General Characteristics of the crude oils and seep characteristics of crude oils and rocks oils of Barinas area: the origin, maturity and biodegradation.

9. - Extraction of 2D section to validate geometry, 2D-3D 2.- Building of structural geometry model run and maps (time ms) From previous studies, the main hydrocarbon source thermal calibration rock is represented by Navay Formation, which is constituted

by La Morita and Quevedo Members, for Barinas Basin.

8.-- 3D block building (maps Geological Model 3.- Building of structural loading in the Block Build ) maps (depth) The figures 6 show the TOC variation and Ro for the

Quevedo and La Morita Members. The general trends for both 7.- Constructions of 4 and 5. - Exporting, reviewing and thematic maps (TOC, editing the depth structural maps of them increase from Southeast to Northwest. kerogen index and thermal Basin Modeling in the Map Editor model)

Quevedo Member 6.- Building the lithology TOC Original Maturity maps and the lithology index maps TOC (%) Ro (%)

Figure 3. Methodology used for the petroleum system G analysis of the Barinas Basin using a 2D-3D Basin Modeling. H AD I Ñ J O D KA

N AK AK AL AL Q Study area G Q AC F AE AM AM 10.534 Km 2 R W W X P H R X AN AF AN AG Z Y I J Ñ AH O D K L M LEGEND AI N AJ 3D Merged

3D Block P

Study area

2D Seismic

10 Km

Figure 4. Location map of the available seismic data (2D and

3D). PETROLEUM SYSTEM OF THE BARINAS BASIN: A 2D/3D BASIN MODELING APPROACH 3

La Morita Member TOC Original Maturity TOC (%) Ro (%)

G G

H H AD AD

I I J Ñ Ñ J O O D K D K A A N AK NAK AL AL Q AC AC F AE Q F AE AM W WAM P X R P R AF AN X AG AF AG AN Z Y Z Y AH AH

AI AJ AI AJ

Figure 6 .TOC and maturity trends in the Quevedo and Morita Figure 8 Thickness variation of the Formation Paguey in the Member. Barinas Traditional Area to the North, where the red line represents the depth lines, the blue one lines in time, time lines Reservoirs and the different colors (yellow, medium and strong) (Taken The gobernador and Escandalosa Formations have been from ANKA et al, 1998). identified as the main reservoirs in the Barinas Traditional Field. In the Gobernador Formation sandstones of Middle Traps Eocene age, have porosities between 9 to 18 % and Escadalosa The main structure of the Barinas Basin occurred during the Formation between 2 and 10% in areas already drilled. Middle Eocene. This period of deformation generated new inverse structures and also produced the inversion of some The figures 7 show the general trend of the thickness previous normal faults, with subsequent recovery activity reservoir, for the Gobernador and Escandalosa formations, the during the Late Middle Miocene (The Venezuelan Andes higher thickness are observed in the central part of the study Uplifting), generated structural styles represented by highs area and the lower to the North. associated with inverse faults reactivated and Neogene age faults. There are two (2) big groups of older alignments: (1) Gobernador Formation Escandalosa Formation The alignment direction (Northeast-Southwest), driven by the A B Boconó Fault in the Andes and (2) The economic basement

LA YUCA LEGEND (Feet) LA YUCA LEGEND (Feet) heritage in the East-West direction, which left its remains well BARRANCAS BARRANCAS marked in the Barinas Traditional Area with a variety of

BORBURATA structural traps that give rise to numerous opportunities BORBURATA identified. LAS LOMAS TORUNOS

CAIPE TORUNOS OBISPO CAIPE OBISPO

MAPORAL MAPORAL SMW BEJUCAL SINCO BEJUCAL SINCO MINGO MINGO PAEZ 100 Km 10 km 0 10 km PAEZ 10 Km

Figure 7. Total thickness variation for the Gobernador (A) and Escandalosa Formations (B) (From Re-Exploration Barinas 2009 Project).

Seals Figure 9. Traps Eocene (Compresion Napa de Lara) and The regional seal characterized by shales intervals of the Oligocene- Miocene (Compresion y Transpresion). Paguey Formation of Late Eocene age which is responsible of the retention of hydrocarbons in the area is represented mainly Petroleum System Processes by with thicknesses varying from 1100´, in the Barinas To simulate the processes of maturity, generation, expulsion, Traditional Area, to 5000´to the North, where Sipororo, La migration and entrapment of oil in the North area of Barinas Yuca and Barrancas structures are located (Figure 8)(ANKA and Barinas traditional, Temis 2D and 3D (Beicip Franlab ®) et al ,1998). programs were used. The following results describe the obtained products of 2D lines and 3D block to define the location of clearly source rocks, the amount of Hc generated 4 ROJAS ILIANA

(mass balance) and the direction of migration of these hydrocarbons toward the proposed structures in the area.

The figures 10, shows the 3D block and the location of the 2D lines. These NW-SE direction lines were selected to represent the structural basin evolution, which generally can be divided into 3 areas: One located to the North of the Caribbean Deformation Front, where the Sipororo, La Yuca Figure 12 Thermal Calibration of temperature and maturity and Barrancas structures are located. Second, located between for B and A wells, showing a similar tendency between the the Deformation Front and the Caribbean Neogene Syncline measured data from wells and those calculated by the foothills where Las Lomas and Guasimitos structures were program. located. Finally, the third structure is located to the South, in the Traditional Barinas Fields. The results model 2D/3D suggest two possible

intervals for generation and expelling potential hydrocarbons

of Cretaceous age: the Quevedo and La Morita Members of

Navay Formation were identified in the Northwest of the study

area, which were active in the Miocene and currently at levels G equivalent to maturity phase of maximum generation of liquid H hydrocarbons (1.3% Ro) , as shown in graphics (Age My Vs%

J Ñ Ro) of Figures 13 and 14. In contrast, to the Southeast, is now O D at the beginning of the oil generation window. This is due to K M B S E the Upper Eocene-Oligocene and Miocene have the biggest V F thickness of rocks, while thickness is smaller in the Southeast

area, in the Traditional Fields of Barinas. These hydrocarbons R X Z Y have migrated vectors a Northwest-Southeast direction,

towards the Barinas Basin.

NW SE

Figure 10. 3D block, the location of 2D lines (1 and 2) and (%Ro) Ro interpreted faults in the structural model of the area, showing Age (Ma) the deeper part of the basin to the NW (warm colors) and the 1 shallower to the SW (cold colors) as well as the 3 stages that ~1.3% Ro represent the structural evolution of the basin.

• Thermal maturity (Where yellow color indicates immature zones (0.1 to 0.6% Ro) Thermal Calibration and the green one the oil zones (% Ro 0.7a 1.3)).

This transect (figure 11) allowed to verify thermal calibrations Figure 13 Transect 2D (NW-SE), showing the thermal by comparing the trend obtained from measured data of maturity variation and the graph showing the evolution in time temperature and vitrinite reflectance of wells. So, it is possible (Age My Vs% Ro) for transect 1, NW-SE. to say according to figures 12 that the obtained calibration was successfully, since the measured data from wells and those calculated by the program are very similar.

G H NW TOR-1XA CAI-1XB SE J Ñ D K A E M B S Q T V F W R X 1 Z Y

• Thermal maturity 2D section NW-SE

Figure 11 Thermal Maturity variation. Yellow color indicates Figure 14. 3D view of maturity evolution (Quevedo Member immature zone (0.1 to 0.6% Ro) and the green one the oil zone %Ro) (% Ro 0.7a 1.3). PETROLEUM SYSTEM OF THE BARINAS BASIN: A 2D/3D BASIN MODELING APPROACH 5

According to the analysis show in the 2D sections modeling done by the team EFAI 2009. and in the 3D block, have been identified two active source rocks in the study area: Quevedo and La Morita member. The The basin modeling EFAI 2009 was made through a figure 15, shown the productivity of these rocks in terms of transect located West of the transect considered in this study, the hydrocarbons generated. Indicating that the crude oils from even when it overlaps with the covered area of the 3D model, Barinas Basin were generated from these two source rocks it has the special property to extend to the North of the (Miocene generation) with its lateral equivalent La Luna outcrops area of the Santo Domingo River. Simulations show Formation (generation in the Eocene), directly or through the history of the basin structure and evolution of thermal remigration oil that was accumulated in the Barinas fields. maturity of source rock intervals (Figure 16). It is possible to visualize that during the Middle Eocene (46 My), the These results could verify the mass balance depocente of the basin was located to the Northeast of the area conducted in the area, in which the rocks for the Navay where the ranges of Cretaceous age of maturity reached levels formation have a volume of hydrocarbons generated about equivalent of thermal generation of petroleum. This situation 5035.31 MMBLS, a value greater than the amount of oil in continued until the Middle Miocene, when subsequently, with place (POES) calculated for the 14 oil fields in Barinas about the “Uplift of the Andes” and the inversion of the basin, the 4027.035 MMBLS; which is the product of the ratio between generation and maturity process was extended Southward the recoverable reserves (cumulative production + remaining from the basin. reserves) and the recovery factor (FR). These results are only C D E considering the area of hydrocarbon generation located NW of F the study area (figure 15).

Generated HC Liquid Kg/m 2 G G H H J Ñ J Ñ D (a) Generation of hydrocarbons area in Eocene- Oligocene ages K M A B D E K A S E B Q T M C D E S F Q T V F R F V X R W Z W Z Y X Y

1.400 PROD. ACUM (MBLS) 1.200 RES. REMAN. (MMBLS) TOTAL GENERATED LIQUID HYDROCARBONS POES (MMBLS) 1.000 (MIOCENE KITCHEN)

800 (b) Generation of hydrocarbons area in Miocene age (Fm. Navay) : 5.035,51 MMBLS MMBLS 600 Figure 16. Hydrocarbons of Generation areas in the Barinas 400

200 Basin. (a) Generation of hydrocarbons area of Eocene- ACUMULATED PRODUCTION : 735,16 MMBLS 0 REMAINING RESERVES : 1.002,22 MMBLS Oligocene age. (b) Generation of hydrocarbons area of CAIPE SINCO SILVAN OBISPO ESTERO PALMITA BEJUCAL MAPORAL TORUNOS RECOVERABLE RESERVES : 1.737,38 MMBLS SILVESTRE LASLOMAS HATO VIEJO HATO PAEZMINGO Miocene age. (Taken from Schneider 2009). BORBURATA CAMPOS TOTAL POES: 4.027,03 MMBLS Figure15. Hydrocarbons generated (kg/m 2) by the Quevedo Conclusions and La Morita members of the Navay Formation, in cold Crude oils from Northern Barinas and Traditional colors the lowest values and warm colors the highest, at the Barinas areas have mainly marine origin (carbonate same time histogram of the area of cumulative production and / or shale) with some contribution of terrestrial Barinas Traditional, remaining reserves and POES in MMBL organic matter. (Production data taken from Re-Exploration Barinas 2009 Crude oils from the study area have different levels Project). of maturity and biodegradation. According to the estimated data obtained from the Two possible intervals for generation and expelling simulations, it has been determined the migration efficiency of potential hydrocarbons of Cretaceous age were about 80%, which is a very high value, considering the losses identified in the Northwest area, for both the of hydrocarbons by primary and secondary migration. This Quevedo and La Morita Members of Navay high value is a result of the following equation: EM (%) = 100 Formation. (POES / HG) where; EM: migration efficiency, POES: The maturity evolution map in terms of rate of original oil in place and HG hydrocarbons generated, and can transformation in the area, shows the existence of a be explained by the low estimation of hydrocarbons generated, possible kitchen in the Northwest area, responsible for this study. The hydrocarbon generation area is limited to for the crude oils found in Traditional Area of covered the 3D model, being necessary to consider the Barinas. volumes generated by the intervals corresponding to the La The two proposed source rocks in the study area Luna Formation located further North in the study area, correspond to Quevedo and La Morita of Navay beyond the extend of the 3D model, as evidenced by the basin Formation facies, according to this model (Mass 6 ROJAS ILIANA

Balance), have a good capacity of generation to Ponencia Presentada en el V Congreso Geológico provide enough volumes of oil to the structures and Venezolano, Caracas: Colegio de Ingenieros de Venezuela. prospects of Barinas. p. 789-815. The migration vectors have a Northwest-Southeast Schneider F., (2009). “Estudio integrado de los sistemas petroliferos de Venezuela Occidental”. Sintesis Version direction towards Barinas Basin. 4.0. Petróleos de Venezuela y Beicip Fralab. Informe The petroleum system proposed in this study for the interno. Barinas area, is considered an active and efficient Vipa, (2000 ). “Visión integrada del potencial petrolífero system, due to the evidence of hydrocarbon presence de Venezuela” . Petróleos de Venezuela, Informe interno. during drilling and evaluation of drilled wells in the area. Acknowledgments First let PDVSA-INTEVEP by presenting this work and to Recommendations Mr. Frederic Schneider for their assistance in the same Since the migration model appears to be very sensitive to changes in porosity, permeability, capillary pressure and reservoir pressure data, it is recommended to incorporate to this study, new drilling data when it is available, in order to gradually improve approaches obtained from this study. To improve lithologic maps and characterization of different faults in order to have a better estimation of migration processes in the new 3D survey in the area. To characterize more effectively the risk of occurrence of hydrocarbon exploration prospects with the use of the basin modeling tool and subsequent calibration with the geochemical characterization of the crude oils present in the area. To do better estimation of the migration efficiency in the basin, in order to assess the prospectivity associated with the new proposal opportunities.

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