24th World Gas Conference The Global Energy …members.igu.org/html/wgc2009/papers/docs/wgcFinal00514.pdfadjacent plates (Pindell et al,1995) In the Caribbean region (northeast Colombia,

The Gas Potential of the Sub Andean Basins 24th World Gas Conference, 5-9 October 2009

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24th World Gas Conference The Global Energy Challenge: Reviewing the Strategies for Natural Gas

Buenos Aires, 5 - 9 October 2009

THE GAS POTENTIAL OF THE SUB-ANDEAN BASINS; THE CURRENT EXPLORATION STATUS AND THE FUTURE

PROSPECTIVITY AS AN ENERGY RESOURCE FOR THE REGIONAL MARKET

Authors: Marcelo Rosso*, Patricio Malone*, Gustavo Vergani*

*Geoscience Department, PLUSPETROL SA.

Keywords: Sub-Andean basins; non-associated Gas, basin, Exploration

Abstract

This paper aims to review the Gas potential of the Sub-Andean basins in South America. Based on the exploration work carried out and the gas fields already discovered, the authors assess the remaining potential of this energy resource in the region. Due to the particular geological characteristics of the Intracratonic and the Active and Passive margin basins of South America, they are not included within the scope of this study. The sub-Andean Basins cover an area of about 2.6 million km2 extending south from Venezuela to Tierra del Fuego in the southernmost part of Argentina and Chile. These basins contain about 4% and 9 % of the total world gas and oil proven reserves respectively. This paper briefly describes the Petroleum Systems in place, the exploration maturity of the Sub-Andean Basins and the possibilities for new exploration. Finally, a succint description of the main challenges the industry is facing in the region for the gas prospection, the necessary exploration works to be carried out and the present status of the gas as an energy supply for the southern cone is given.


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GEOLOGICAL SETTING: The South America basement (Pre-Cambrian) outcrops in the entire central region of the continent encompassing eastern and northern Brazil, Paraguay, Uruguay, southern Venezuela, eastern Colombia, Ecuador, Perú, Bolivia and central-southern Argentina. The deposition of the sedimentary cover started in the early Paleozoic infilling the intracratonic basins. In the pericratonic basins the deposition occurred as a sedimentary prism flanking the platform. In most of the basins the sedimentary infill extended to the Cenozoic period and many of them were subject to intensive erosion and tectonic processes. The sub-Andean basins cover a surface of about 2,580,000 km2 extending in the western part of South America for more than 8,000 km (Fig.1). The geological history of these basins is closely related to the plate tectonics.

Fig.1 South America Sedimentary Basins The formation of the South Atlantic margins resulted from the breakup of the Gondwana supercontinent. (Franke et al, 2006). The South American continent separated from Africa moving to the west in a clockwise movement entering in collision with the Pacific plates. The final opening of the South Atlantic took place in Lower Cretaceous. The opening occurred diachronously rejuvenating from South to North and may be described as a successive northward unzipping of the Gondwana rift zones (Jackson et al, 2000). Several Triassic and Jurassic extensional basins were tectonically affected and evolved together with the volcanic arc in the Active Margin (Fig. 2). During the Tertiary the tectonic development of the Andean chain led to the formation of a fold and thrust belt and a segmented foreland basin that extends along the western Active Margin (Bally et al, 1980).This fold and thrust belt (”Cordillera de los Andes”) deformed and inverted the original architecture of the pre-existing rifts and marginal basins.


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Fig. 2 South America Sedimentary Basins (modified from IHS-Bally classification)

Each basin has its own tecto-sedimentary complexity. Some of them have an active magmatic arc and are recognized by some authors as backarc or forearc basins depending on their position relative to the volcanic arc. Much of the length of the Andean chain has been the site of magmatism during Mesozoic and Cenozoic time and its is useful to think of the Andes as an evolving arc system controlled by the motion of South America relative to the mantle and the adjacent plates (Pindell et al,1995) In the Caribbean region (northeast Colombia, Venezuela and Trinidad & Tobago) the basins have a very complex tectonic framework due to the presence of transform dextral faults trending west-east (and where the oceanic crust is involved) forming the Caribbean folded belt (Cordillera de la Costa, Perez Mejía et al, 1980). The Austral basin in the southernmost part of South America is also deformed by tectonic movements between the South America and Scotia plates (Ghiglione et al, 2005). Since Tertiary times most of the sub-Andean basins share a common structural style forming the foreland basins with a folded and thrusted belt and an undisturbed area (platform) towards the old craton. A foredeep or trench could be recognized nearby the folded belt (associated to the subduction plate boundary of the Active Margin). The development of these trenches and the subsidence of the underlying foreland sediments have a significant impact on the hydrocarbon generation. Pre-Andean Mesozoic marine source rocks reached generative maturity for oil and gas because tectonic loading and burial by thick synorogenic clastics sequences as well the compressive deformation that defines the structural style for the trapping mechanism.

ACTI

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METHODOLOGY About 70 % of the total sub-Andean basins area remains in a moderately to immature exploration stage. Most of these basins have proven petroleum systems but different exploration maturity and hydrocarbon richness. Considering the different petroleum systems (Magoon et al, 1994) and for practical purposes the sub-Andean basins were divided in three major regions for their description: 1) North, 2) Central and 3) South (Fig.3). The Creaming Curve is a useful tool to analyze the reserve additions by basin by year on a cumulative basis. This graph allows perceiving the exploration maturity of the basins and the evolution of the geological concepts (play) tested in time. Each region encompasses more than one basin and may include several petroleum systems. By consolidating two or more basins in one creaming curve the methodology could mask the reality. For example, while one basin has been adding reserves over the years there has not been reserve addition in the other. In this case the consolidated creaming curve shows a reserve addition anyway. These deviations are explained in the text when appropriated. Another issue is when a basin is shared by two countries. Although the geology does not recognize political boundaries the exploration activity could be unequal in both sides (for example due to different fiscal terms or the exploration strategy followed by each country). These issues are also clarified when analyzing the exploration maturity of the basins. When making the statistics of the hydrocarbon richness, exploration drilling density and seismic density a weighted formula was used to obtain an average of all the group of basins within a specific region. Some basins have offshore extensions with little exploration activity. Nevertheless, the statistics for the basins were made considering the whole surfaces. The following is an example of the formula used to obtain the average hydrocarbon richness: EUR: Estimated Ultimate Recovery of Proven + Probable reserves (2P): ((EUR Basin A / Basin A Surface km2) + (EUR Basin B / Basin B Surface km2) + (…Basin n….)) / (Basin A+B+..n ..Surface); see Appendix “A”). It is believed that the results obtained give the perception of the exploration maturity of each region with considerable certainty.

Fig.3 Su-Andean Regions Subdivision


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PETROLEUM SYSTEMS AND EXPLORATION MATURITY: The South America basins contain 9% and 4.2% of the total proven world oil & gas reserves respectively (Fig. 4). The proven hydrocarbon reserves are 122 billion barrels of oil (BBO) and 264 trillion cubic feet of gas (TCF).

SOURCE: ; O&G JOURNAL, JAN.2009

4.2 %

TOTAL 6,254 TCF

264 TCF 9%

TOTAL 1,342 BBO

122 BBO

WORLD GAS PROVEN RESERVES (TCF) WORLD OIL PROVEN RESERVES (BBO)

SOURCE: ; O&G JOURNAL, JAN.2009

4.2 %

TOTAL 6,254 TCF

264 TCF 9%

TOTAL 1,342 BBO

122 BBO

WORLD GAS PROVEN RESERVES (TCF) WORLD OIL PROVEN RESERVES (BBO)

Fig. 4 World Oil& Gas Proven Reserves - South America Percentages of the Total Reserves

(Oil & Gas Journal Jan, 2009) About 90% and 95% of South America’s oil and gas reserves respectively, are in the sub-Andean basins. The remaining 10% and 5% of oil and gas reserves are located mainly in Brazil’s Atlantic margin basins and in Argentina’s intracratonic basins. The aim of this paper is to review the gas potential of these basins where so far most of the known proven gas reserves are located and to assess the gas reserves and resources able to supply the South American market. Brazil has 12.6 BBO and 12.9 TCF of proven oil and gas reserves respectively. About 90% of these reserves concentrated in three basins: Santos, Campos and Espirito Santo (Fig.5). A significant amount of contingent resources (SPE/WPC/AAPG/SPEE) of oil and gas were recently reported in the offshore Brazil. Nevertheless, the gas in Brazil has today some economic limitations. According to Cedigaz (CNR48/12/10) Brazil was flaring by February 2009 about 8.1 million cubic meters per day of natural gas from its offshore platforms. Gas in Brazil has to compete with hydroelectric plants. When they operate normally the gas-fuelled power plants have to shut down. Gas price and dropping demand due to global crisis and competition with hydroelectricity may delay the challenges of building a massive pipeline system to reach the gas fields located about 300 km away from the coast. However, it is believe that offshore LNG is an almost inevitable choice in the long term. Due to the special offshore logistics (i.e. water depths and distance to the coast), reserve assessment uncertainties, commerciality for a full gas development and the special geological conditions, the Atlantic margin basins are not included within the scope of this study. Argentina has two other producing basins (Golfo San Jorge and Northwest Cretaceous) but both are not included in this paper within the sub-Andean domain. Although important for Argentina these basins’ have no impact on the South America regional gas market. The Golfo San Jorge basin has 2 TCF and 2 BBO 2P (Proven+Probable) reserves. Its remaining gas reserves equals


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to 15 months of the country’s current gas consumption. The Cretaceous basin has 27 MMBO (million barrels oil) and 63 BCG (billion cubic feet gas) of remaining 2P reserves.

Fig. 5 Location of Brazil and Argentina producing basins not included in the sub-Andean study SUB-ANDEAN REGIONS 1. NORTH REGION The North region corresponds to the basins located in Perú, Ecuador, Colombia, Venezuela and Trinidad & Tobago. This region has two main petroleum systems (Magoon et al, 1994):

• a) Tertiary source rocks charging Tertiary reservoirs. • b) Upper Cretaceous rocks sourcing Cretaceous and Tertiary reservoirs.

1a. TERTIARY SYSTEM This system is gas prone and encompasses the Tobago, Lower Guajira, Lower Magdalena and Falcon basins (Fig.6). For this group the 2P remaining reserves are estimated in 283 MMBO and 15.3 TCF of gas Appendix “A”).


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Fig. 6 Sub-Andean North Region – Tertiary-Tertiary System The Tobago basin lies in the Venezuela and Trinidad & Tobago offshore; the Lower Guajira extends almost 70% in the Colombia and Venezuela offshore. Both basins are in an immature exploration stage with a combined 2P gas reserves of 13.2 TCF. The source rocks are Oligocene to Miocene in age. The gas has a biogenic origin and is accumulated in structural and combined traps. About 25 % of the surface of the Lower Magdalena and Falcon basins extend to the offshore. Although the petroleum system is primarily gas some oil is present in Falcon basin. The source rock (Oligocene-Miocene) is marine to swampy environments in origin. The hydrocarbon generation is thermal in the deepest part of the troughs (i.e. Urumaco and La Vela bay). The reservoir consists in limestone (i.e. Agua Clara Formation) and sandstone rocks (i.e. Cienaga de Oro and Porquero Formations). The remaining 2P oil and gas reserves are of about 137 MMBO and 2 TCF respectively. The Creaming Curve (Fig. 7) for the Tertiary system basins clearly shows that the source rock is mainly gas prone. No oil reserves addition was made since the 70s’ onwards. The gas volumes have a sharp increase from the 70s’ to early 80s’ due to the discoveries made in the Venezuela and T&T offshore (Mariscal Sucre complex, Hibiscus) and remained almost flat for a period of 20 years until the discoveries made in Block 22 (Cassra Field) and La Creciente discovery (Lower Magdalena) took place.

L. MAGDALENA BASIN

LOWER GUAJIRABASIN

FALCON BASIN TOBAGO BASIN

TERTIARY-TERTIARYSYSTEM

L. MAGDALENA BASIN

LOWER GUAJIRABASIN

FALCON BASIN TOBAGO BASIN

TERTIARY-TERTIARYSYSTEM


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Fig. 7 Creaming Curve by Time – Tertiary -Tertiary System

The hydrocarbon richness and the total sub-Andean area that covers the Tertiary system are shown in Fig.8.

Fig. 8 Hydrocarbon Richness – Tertiary-Tertiary System

LA CRECIENTE

Source: modified from IHS

RES

ERVE

S M

MB

OE

YEAR

CASSRA

SUCRE

MARISCAL SUCRE

(DRAGON-EJILLONES-PATAO)

KK

CHUCHUPA-BALLENA

LA VELA

CICUCO-EL DIFICILCUMAREBO

STRATIGRAPHIC PINCHOUTS-FAULTED STRUCTURES-ANTICLINE TRAPS

STRUCTURAL DOMES-STRATIGRAPHIC TRAPS

STRIKE-SLIP FAULTS ANTICLINESREVERSE FAULTS TRAPS

HIBISCUS

OilO & GO & G & C LA CRECIENTE


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MB

OE

YEAR

CASSRA

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MARISCAL SUCRE

(DRAGON-EJILLONES-PATAO)

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CHUCHUPA-BALLENA

LA VELA

CICUCO-EL DIFICILCUMAREBO

STRATIGRAPHIC PINCHOUTS-FAULTED STRUCTURES-ANTICLINE TRAPS

STRUCTURAL DOMES-STRATIGRAPHIC TRAPS

STRIKE-SLIP FAULTS ANTICLINESREVERSE FAULTS TRAPS

HIBISCUS

OilO & GO & G & C

NORTH REGION BASINS: TERTIARY SourceNORTH REGION BASINS: TERTIARY Source

8 %8 %

% OF TOTAL SUB ANDEAN BASINS AREA% OF TOTAL SUB ANDEAN BASINS AREA

N° of OIL FIELDS: N° of OIL FIELDS: 2929

N° of GAS FIELDS:N° of GAS FIELDS:4141

TOTAL FIELDS :TOTAL FIELDS : 7070

AVERAGE HC RICHNESS :AVERAGE HC RICHNESS :

2,321 Barrels / km2,321 Barrels / km22

100 MMCFG / km100 MMCFG / km22

NORTH REGION BASINS: TERTIARY SourceNORTH REGION BASINS: TERTIARY Source

8 %8 %


N° of OIL FIELDS: N° of OIL FIELDS: 2929


TOTAL FIELDS :TOTAL FIELDS : 7070





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1b. CRETACEOUS-CRETACEOUS -TERTIARY SYSTEM This petroleum system was divided in two sub-regions to avoid the risk of masking the real hydrocarbon potential of the basins by averaging the statistics.

• i) Northeast sub-region basins: Maracaibo, Eastern Venezuela,Trinidad • ii) Southwest sub-region basins: Upper&Middle Magdalena, Llanos, Putumayo,Marañon

1b.i) NORTHEAST SUB-REGION The Northeast sub-region basins are shown in Fig.9.

Fig. 9 Northeast sub-region basins Due to the large reserves of Maracaibo, Eastern Venezuela and Trinidad basins (containing about 86 % and 59 % of the sub-Andean 2P remaining oil and gas reserves respectively) they were included in one sub-region (Northeast) and analyzed separately from the rest. The basins of this sub-region present exceptional geological conditions. A world-class source rock, very effective regional seals and the presence of reservoirs with excellent petrophysical properties coexist in order to generate one of the richest hydrocarbon regions of the world. The main source rocks belong to Tigre and Querecual Formations (and equivalents La Luna-Guavinita Formations), Upper Cretaceous in age. These source rocks charged sandstone reservoirs like the Mirador and Carbonera Formations (Eocene-Miocene) and the Merecure Group – Lagunillas and Oficina Formations (Oligocene to Lower Miocene). Limestone rocks are good reservoirs in some local areas like in the Maracaibo basin (i.e. Colón Formation). The Creaming Curve (Fig. 10) shows a rapid reserve addition from the early 30s’ to the late 50s’, period when heavy-oil belt and most of the “easy oil” was discovered. From 1960 onwards the reserve addition per year was significantly lower (plateau) in comparison with the former cycle exhibiting the curve a mature exploration stage.

MARACAIBO BASIN

EASTERN VENEZUELA.

TRINIDAD BASIN

CRETACEOUS -CRETACEOUS-TERTIARY SYSTEM

MARACAIBO BASIN

EASTERN VENEZUELA.

TRINIDAD BASIN

CRETACEOUS -CRETACEOUS-TERTIARY SYSTEM


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A significant change in the curve’s tendency could be caused by different reasons like the discovery of new exploration concepts, a political issue that could stimulate or deteriorate the exploration activity and the use of new exploration technologies. In this Creaming Curve an example of a new exploration concept successfully tested is the discovery of Furrial field during the early 80s’ in the fold belt of the Eastern basin.

Fig. 10 Creaming Curve by Time – Cretaceous-Tertiary System There is no reserve addition for almost 25 years (from late 50s’ to early 80s’). Some of the explanations for this could be political (creation of CORPOVEN in 1960, the mandatory relinquishments of the foreign operators’ concessions in 1969 and the hydrocarbon nationalization in 1976) or operational (possible concentration of the activity in the production of the giant fields already discovered). For several years, like other countries in the region, the exploration for gas was discouraged in Venezuela. The hydrocarbon richness of the Northeast sub-region is summarized in Fig. 11. It shows a dramatic difference when compared with all other sub-Andean basins. With an average hydrocarbon richness of 472,032 barrels of oil /km2 and 853 MMCF of gas/km2 concentrated in about 12% of the total sub-Andean surface, these basins are by far the most prolific in the region.

SURFACE STRUCTURALTRAPS IN BOTH BASINS

ROTATED NORMAL FAULT& BASIN MARGIN PINCH OUTS(HEAVY OIL ORINOCO BELT)

OFICINA PLAY

THRUST BELT EASTERN BASINSTRUCTURAL TRAPS

FURRIAL

TIA JUANA,LA PAZ, LAGUNILLAS, BACHAQUERO MENE,SANTA BÁRBARA, QUIRIQUIRE

JUSEPIN, CARABOBO, OFICINA CENTRAL

LAMA, CEUTA,CENTROJOBO, MELONES, MORICHAL Oil

O & GOilO & GO & G & C

YEAR

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(MM

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SURFACE STRUCTURALTRAPS IN BOTH BASINS

ROTATED NORMAL FAULT& BASIN MARGIN PINCH OUTS(HEAVY OIL ORINOCO BELT)

OFICINA PLAY

THRUST BELT EASTERN BASINSTRUCTURAL TRAPS

FURRIAL

TIA JUANA,LA PAZ, LAGUNILLAS, BACHAQUERO MENE,SANTA BÁRBARA, QUIRIQUIRE

JUSEPIN, CARABOBO, OFICINA CENTRAL

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O & GOilO & GO & G & C

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MARACAIBO & EASTERN VENEZUELA BASINS


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NORTH REGION BASINS: CRETACEOUSNORTH REGION BASINS: CRETACEOUS--TERTIARY SYSTEMTERTIARY SYSTEM

N° of OIL FIELDS:N° of OIL FIELDS: 466466

N° of GAS FIELDS:N° of GAS FIELDS: 8585

TOTAL FIELDS:TOTAL FIELDS: 551551

AVERAGE HC RICHNESSAVERAGE HC RICHNESS ::



12 %% OF TOTAL SUB ANDEAN BASINS AREA% OF TOTAL SUB ANDEAN BASINS AREA

NORTH REGION BASINS: CRETACEOUSNORTH REGION BASINS: CRETACEOUS--TERTIARY SYSTEMTERTIARY SYSTEM




AVERAGE HC RICHNESSAVERAGE HC RICHNESS ::



12 %

Fig. 11 Hydrocarbon Richness – Cretaceous -Tertiary System

Most of the gas reserve in this sub-region is associated to oil and therefore it is difficult to market the gas without attempting against the reservoirs performance and good production practices. This issue will be discussed in a more detail way further on in this paper. 1b.ii) SOUTHWEST SUB-REGION The Southwest sub-region encompasses the Upper & Middle Magdalena, Llanos Orientales, Putumayo and Marañon basins (Fig.12).

Fig. 12 Southwest sub-region basins

UPPER MAGDALENA BASIN

MIDDLE MAGDALENA BASIN

LLANOS – BARINAS – FOOTHILLBASINS

PUTUMAYO BASINS

MARAÑÓN BASINSCRETACEOUS-CRETACEOUS

SYSTEM

UPPER MAGDALENA BASIN

MIDDLE MAGDALENA BASIN

LLANOS – BARINAS – FOOTHILLBASINS

PUTUMAYO BASINS

MARAÑÓN BASINSCRETACEOUS-CRETACEOUS

SYSTEM


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This sub-region covers 32 % of the sub-Andean basins. Although with a larger surface with respect to the Northeast sub-region, in terms of hydrocarbon content it is not as rich as the previous one (Fig. 13). The EUR 2P reserves for this sub-region are 22 BBO and 18 TCF gas.

Fig. 13 Hydrocarbon Richness – Cretaceous-Cretaceous System This group of basins has about 9.6 BBO and 3.3 TCF of the 2P remaining reserves (6 % and 1.1 % of the total oil and gas reserves of the sub-Andean basins respectively). The Southwest sub-region clearly is a more oil prone region than a gas one.

Fig. 14 Creaming Curve by Time – Cretaceous-Cretaceous System

YEARSource: modified from IHS

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Oil and Gas

Oil and Gas and Cnd

MARAÑON – PUTUMAYO - U & MIDDLE MAGD.- LLANOS

FOLDED BELTOVERTHRUSTED ANTICLINES

FORELAND STRIKE SLIP FAULTSTRUCTURE RELATED

HINTERLAND DRAPE ANTICLINES

CUSIANA.CUPIAGUA

GUAFITA, CAÑO LIMON

SINCO, APIAY, SACHA,SUSHUFINDI, ISHIPINGO,CORRIENTES

LA CIRAVELAZQUEZ

SANTOS

OilO & GO & G & C

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MARAÑON – PUTUMAYO - U & MIDDLE MAGD.- LLANOS

FOLDED BELTOVERTHRUSTED ANTICLINES

FORELAND STRIKE SLIP FAULTSTRUCTURE RELATED

HINTERLAND DRAPE ANTICLINES

CUSIANA.CUPIAGUA

GUAFITA, CAÑO LIMON

SINCO, APIAY, SACHA,SUSHUFINDI, ISHIPINGO,CORRIENTES

LA CIRAVELAZQUEZ

SANTOS

OilO & GO & G & C




NORTH REGION BASINS: CRETACEOUSNORTH REGION BASINS: CRETACEOUS-- CRETACEOUS SYSTEMCRETACEOUS SYSTEM





32 %









32 %






32 %


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The Creaming Curve (Fig. 14) indicates a significant difference with respect to the northern Venezuela basins. The exploration activity begins later in the 40s’ and since the oil discoveries made in Putumayo and Marañon on the early 70s’ the plateau seems to be not reached. Although the curve tends to flatten in the 90s’ the exploration is far from being mature (especially in Barinas and Putumayo basins). The lack of reserve additions from the year 2000 onwards seems to be more related to other issues (environmental, social and political) than to exploration play exhaustion. 2. CENTRAL REGION The Central region has a distinctive geological condition relative to the other sub-Andean regions. The petroleum system is Paleozoic in age and is mainly gas prone. The Central region (Fig.15 and 16) extends from the Ucayali-Madre de Dios basins (southeast Peru, Disalvo et al, 2008, Aleman et al, 2008) to the Chaco-Tarija basins (eastern Bolivia and northern Argentina; Cruz et al, 2008; Vergani et al, 2008). The presence of the gas prone Paleozoic sediments makes this zone of singular interest for the gas exploration. The presence of giant non-associated gas fields occurs in this region with fields like Ramos (Argentina), San Alberto (Bolivia) and Camisea (Perú). Due to the gas prone conditions of the Central region more technical details are given in the “Gas Prospectivity in the Central Region” topic in this paper.

Fig. 15 Central Region – Location Map


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Fig. 16 Central Region The Central region covers about 34 % of the sub-Andean sedimentary basins and most of the prospectable surface remains immature with one NFW per 566km2 in Chaco to one NFW per 27,317km2 in Madre de Dios basin. There is a significant distance gap between the two gas provinces of Chaco and Ucayali (> 1,200 km), with almost no drilling exploration works in Madre de Dios and Beni basins (Fig16). Therefore, when the hydrocarbon richness and the exploration maturity of these huge regions are analyzed it is necessary to do it carefully (Figs. 17 and 18).

Fig. 17 Hydrocarbon Richness – Paleozoic System

BENI BASIN

MADRE DE DIOS BASIN

UCAYALI BASIN

CHACO BASIN

PALEOZOIC-CRETACEOUS-TERTIARYSYSTEM

1,250 km

BENI BASIN

MADRE DE DIOS BASIN

UCAYALI BASIN

CHACO BASIN

PALEOZOIC-CRETACEOUS-TERTIARYSYSTEM

1,250 km

N° of OIL FIELDS:N° of OIL FIELDS: 6969AVERAGE HC RICHENESS:AVERAGE HC RICHENESS:



% OF TOTAL SUB ANDEAN BASINS AREA % OF TOTAL SUB ANDEAN BASINS AREA

34 %



N° of OIL FIELDS:N° of OIL FIELDS: 6969AVERAGE HC RICHENESS:AVERAGE HC RICHENESS:



% OF TOTAL SUB ANDEAN BASINS AREA % OF TOTAL SUB ANDEAN BASINS AREA

34 %




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Only the gas fields of the Chaco foothills (Bolivia & NW Argentina) and the southeast of Ucayali basin (Perú) contribute with about 16 % (41 TCF) of the remaining proven gas reserves of South America. To analyze the Creaming Curve of this region (Fig.18) it is necessary to do so considering some details. Although the exploration activity started in the 20s’ with some shallow exploration success (i.e. Bermejo and Tranquitas fields, Paleozoic-Tertiary system), the first positive peak is observed in the early 70s’ when the National Oil Companies (NOC) carried out surface geology works and started drilling in the foothills. The second peak occurred during the 70s’ with discoveries made in deeper horizons in Bolivia and Argentina (i.e. Vuelta Grande and Ramos fields, Paleozoic-Paleozoic system). The third peak is associated to discoveries made in the 80s’ in Ucayali (i.e. San Martin & Cashiriari, Paleozoic-Cretaceous system). These discoveries were made in the Amazon, a very sensitive area. They could be put on-stream almost 25 years later when an international consortium, through an international bidding process put these fields on stream in 2004 after a three year fast track E&P process. If the Ucayali basin is not considered there is a flat period for the Chaco basin with more than 20 years of no significant reserve addition. In the 90s’ this situation change with the discoveries of San Alberto and Margarita. This increase of reserves was the result of a change in the hydrocarbon policy in Bolivia. A significant foreign capital influx on exploration took place as a result of the capitalization process of YPFB, the National Oil Company, and stimulated by the presence of a mature gas market in Argentina and a potential large gas market in southern Brazil. Since mid-2000s’ the curve tends to flatten again due to a lack of reserve addition in Chaco basin (change in contractual terms, environmental difficulties and native communities issues of Bolivia). The tendency of the curve is offset by additional discoveries made in the “Great Camisea” area (Kinteroni).

Fig. 18 Creaming Curve by Time – Paleozoic System

0

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ANTICLINES AND COMBINED TRAPS-LENSES RESERVOIRS

RIO GRANDEVUELTA GRANDECAMPO DURÁN - MADREJONES

FOLDED BELT OVERTHRUST ANTICLINES

SAN MARTIN

MARGARITA

OIL +GAS+C

GAS+C

OIL

UCAYALI UCAYALI -- CHACO BASINSCHACO BASINS


RAMOS

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- SAN ALBERTO

OilO & GO & G & C

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GAS+C

OIL



RAMOS

CASHIRIARI

KINTERONI

PAGORENI

- SAN ALBERTO

OilO & GO & G & C


16

3. SOUTH REGION The South region (Fig19) includes three producing basins of Argentina: Cuyo, Neuquén and Austral. The three basins have distinctive geological characteristics. They cover 15 % of the total sub-Andean basins surface (Fig.20).

Fig. 19 South Region They have only 1.6% (1.5 BBO) and 6% (19 TCF) of the total sub-Andean oil and gas 2P remaining reserves respectively.

Fig. 20 Hydrocarbon Richness – Triassic-Jurassic-Cretaceous Source

15 %







% OF TOTAL SUB ANDEAN BASINS AREA

15 %







% OF TOTAL SUB ANDEAN BASINS AREA


17

Fig. 21 Creaming Curve by Time – Triassic, Jurassic & Cretaceous Source

The consolidated creaming curve (Fig.21) shows advanced exploration maturity for these basins with low oil reserve additions since the late 70s’. However, for the gas curve there is an interesting upward tendency due to gas discoveries made in Austral and Neuquén basins in the early 80s’. The curves tend to flatten from the mid-90s’ onwards implying that the known oil targets in the basins a very mature. This tendency could change if a new geological concept could be successfully tested (i.e. the deeper Tertiary turbidites in the western flank of the Austral basin foredeep where the potential targets are overlying the deeper Lower Cretaceous source rock currently in the “gas window” generation. This sector of the basin is in an immature exploration stage with one NFW per 1000 km2. The Neuquén basin primary source rocks are the marine Upper Jurassic shales of Vaca Muerta Formation. Secondary source rocks are the Lower Jurassic (Los Molles Formation) and the Lower Cretaceous shales of the Agrio Formation. The basin has several targets for both, oil and gas, but it has been subject of an intensive exploration and production campaigns since the early 20s’. The basin today is in a very mature exploration phase for the known exploration plays. In the Cuyo basin the lacustrian shales of Cacheuta Formation is a very prolific oil prone rock. The main reservoirs are sandstones of Barrancas Formation (Jurassic) and Papagayos Formation (Upper Eocene); (Bogetti et al,2002; Zencich et al, 2005). The basin is currently in a very mature exploration stage and it is difficult to find new plays because the limited extension of the source rock and the exceptional hydrocarbon trapping conditions.

RES

ERVE

S (M

MB

OE)

YEAR

OIL +GAS+C

GAS+C

OIL

-COMBINED TRAPS & OVERTHRUST ANTICLINES

-STRATGRAPHIC TRAPS

-PINCHOUTS AGAINST PALEOHIGHS FLANKS

-OVERTHRUST ANTICLINES

ALONG WEST FOLDED BELT

-FORELAND ANTICLINES -STRIKE SLIP RELATED STRUCTURE ALONG BASIN FLANKS

CHIHUIDO LAS SALINAS-EL PORTONTRAPIAL

LOMA DE LA LATA

PUEST HERNANDEZCAÑADÓN ALFA-AGUADA PICHANA

DORSAL DE HUINCUL

BARRANCAS, LA VENTANA, VIZCACHERAS


MEDANITO-ENTRE LOMAS-CHIHUIDO SIERRA NEGRA, POSESION

RES

ERVE

S (M

MB

OE)

YEAR

OIL +GAS+C

GAS+C

OIL

-COMBINED TRAPS & OVERTHRUST ANTICLINES

-STRATGRAPHIC TRAPS

-PINCHOUTS AGAINST PALEOHIGHS FLANKS

-OVERTHRUST ANTICLINES

ALONG WEST FOLDED BELT

-FORELAND ANTICLINES -STRIKE SLIP RELATED STRUCTURE ALONG BASIN FLANKS

CHIHUIDO LAS SALINAS-EL PORTONTRAPIAL

LOMA DE LA LATA

PUEST HERNANDEZCAÑADÓN ALFA-AGUADA PICHANA

DORSAL DE HUINCUL

BARRANCAS, LA VENTANA, VIZCACHERAS


MEDANITO-ENTRE LOMAS-CHIHUIDO SIERRA NEGRA, POSESION


18

SUB-ANDEAN REGIONS: Exploration Drilling Density Fig. 22 is a cake diagram showing the total sub-Andean basins surface divided in four portions. Each portion is a percentage of the total sedimentary surface representing the level of exploration maturity. These four levels were established based in the exploration drilling density :

VERY MATURE < 100 km2 per NFW MATURE 100 to 500 km2 per NFW MODERATELY MATURE 500 to 1000 km2 per NFW IMMATURE > 1000 km2 per NFW

Fig. 22 Exploration Maturity based on Drilling Density About 61 % of the total sedimentary surface of the sub-Andean is in an immature to moderately mature exploration stage (i.e. Madre de Dios basin has 1 NFW per 27,317 km2)

Fig. 23 Exploration Maturity-Sub-Andean Basins

27%

34%

7%

32%V ERY MA TURE

MA TURE

MODERA TELY MA TURE

IMMA TURE

S

SUB-ANDEAN BASINS: Exploration Maturity% OF TOTAL SEDIMENTARY SURFACE

27%

34%

7%

32%V ERY MA TURE

MA TURE

MODERA TELY MA TURE

IMMA TURE

S

SUB-ANDEAN BASINS: Exploration Maturity% OF TOTAL SEDIMENTARY SURFACE


19

In Fig 23 all the basins were plotted based on the previous criteria and shows that the Paleozoic source in the Central region is the less explored of the whole sub-Andean basins. GAS ASSOCIATED vs. GAS NON- ASOCIATED The Fig. 24 shows that most of the oil reserves are located in the North region. When considering the gas reserves the situation is more balanced and the Central region acquires a significant share. This fact has an important meaning when considering the exploration immaturity of the Central region (Fig 23).

Fig. 24 Oil & Gas Remaining Reserves Distribution in the sub-Andean Regions (Source: IHS data base)

The North region has 66% (194 TCF) of the total remaining gas reserves in the sub-Andean basins. To break down the total gas reserves in associated and non-associated gas was important to understand which percentage of the total is “free gas”. This percentage has an impact on the availability to supply gas to the consumption market. The associated gas is one of the reservoir energy mechanisms. It is not easy to put the associated gas on-stream without deteriorating the reservoir performance. A field-by-field analysis was made to discriminate the “free gas” fields from the gas associated to oil fields This analysis shows that the “free gas” reserve percentage in the sub-Andean basins is about 40% (118 TCF) of the total remaining 2P gas reserves.

SOUTHERN SECTORCENTRAL SECTOR

OIL

SOUTHERN SECTOR

REMAINING RESERVES P1+P2REMAINING RESERVES P1+P2OIL & GAS DISTRIBUTION BY REGIONSOIL & GAS DISTRIBUTION BY REGIONS

NORTHERN SECTOR96 %

1.6 %2.4 %

CENTRAL SECTOR

6 %28 %

66 %NORTHERN SECTOR

GAS

295 TCF96 BBO

SOUTHERN SECTORCENTRAL SECTOR

OIL

SOUTHERN SECTOR

REMAINING RESERVES P1+P2REMAINING RESERVES P1+P2OIL & GAS DISTRIBUTION BY REGIONSOIL & GAS DISTRIBUTION BY REGIONS

NORTHERN SECTOR96 %

1.6 %2.4 %

CENTRAL SECTOR

6 %28 %

66 %NORTHERN SECTOR

GAS

295 TCF96 BBO


20

Fig. 25 shows the distribution of the EUR gas reserves in the sub-Andean basins. The Maracaibo, Eastern Venezuela and Trinidad & Tobago basins account for 60% of the total EUR (275 TCF, Appendix “A”, IHS data base source).

Fig. 25 Remaining (P1+P2) Gas Distribution Sub Andean Basins When the “free gas” 2P remaining reserve (118 TCF) is discriminated by basin there is a significant change in the gas volumes distribution.

Fig. 26 Remaining 2P Non-Associated Gas Reserves

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

EastVenezuela

Basin

ChacoBasin

MaracaiboBasin

Trinidad &TobagoBasins

NeuquenBasin

AustralBasin

UcayaliBasin

Llanos-BarinasBasin

LowerGuajiraBasin

EUR Free Gas

EUR Associated Gas

EUR FREE AND ASSOCIATED GAS BY BASIN

ESTIMATED ULTIMATE RECOVERY GAS RESERVES (P1+P2)

TOTAL GAS EUR: 434 TCF (FREE GAS: 30%)

TCF

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

EastVenezuela

Basin

ChacoBasin

MaracaiboBasin

Trinidad &TobagoBasins

NeuquenBasin

AustralBasin

UcayaliBasin

Llanos-BarinasBasin

LowerGuajiraBasin

EUR Free Gas

EUR Associated Gas

EUR FREE AND ASSOCIATED GAS BY BASIN

ESTIMATED ULTIMATE RECOVERY GAS RESERVES (P1+P2)

TOTAL GAS EUR: 434 TCF (FREE GAS: 30%)

TCF

-

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

Chaco Basin TrinidadBasin

UcayaliBasin

EastVenezuela

NeuquenBasin

AustralBasin

Rest Basins(10)

Low erGuajiraBasin

Maracaibo

Remaining Free Gas (TCF)

REMAINING NON-ASSOCIATED GAS RESERVES (P1+P2) - TCF

38 %

16 %

54% OF THE NON-ASSOCIATED GAS IS IN THE PALEOZOIC SOURCE SYSTEM

TCF

-

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

Chaco Basin TrinidadBasin

UcayaliBasin

EastVenezuela

NeuquenBasin

AustralBasin

Rest Basins(10)

Low erGuajiraBasin

Maracaibo

Remaining Free Gas (TCF)

REMAINING NON-ASSOCIATED GAS RESERVES (P1+P2) - TCF

38 %

16 %

54% OF THE NON-ASSOCIATED GAS IS IN THE PALEOZOIC SOURCE SYSTEM

TCF


21

The main gas volumes shift from the North region to the Central region (Fig. 26). Two of the four basins located in the Central Region (Chaco and Ucayali) have 54 % of the “free gas” reserves. The other two (Madre de Dios and Beni) remain under explored. Note that Venezuela produces about 3 BCF of gas per day. When considering the country’s consumption it has a deficit of about 32 BCF per year. Venezuela is the third gas producer in South America after Argentina and Trinidad & Tobago (source: BP Statistical Review of World Energy, June 2009). This gas shortage between production and consumption has geological and technical explanations but the critical one is that almost 90 % of the Venezuela’s Maracaibo and Eastern basins 2P remaining gas reserves are associated to oil. The production of the associated gas reduces dramatically the oil recovery and accelerates the declining of the mature fields. Venezuela consumes more than 60 % of the produced gas re-injecting it to maintain reservoir pressure. GAS POTENTIAL OF THE CENTRAL REGION: PALEOZOIC SYSTEM The Central region is a promising province for gas exploration due the quality of the petroleum system in place, the structural characteristics and the tectonic history. A review of the main known gas occurrences in this segment of the foreland thrust and folded belt of the sub-Andean region follows.

Fig 27 Central Region Basins This region encompasses the basins with the Paleozoic petroleum system, which extends from the Contaya Arch (Perú) to the Michicola Arch (North Argentina), Fig. 27. The chart in Fig. 28 summarizes the chronostratigraphy of the four basins with the main reservoirs and source rocks distribution.


22

Fig 28 Central Region – Chronostratigraphic Chart with main Reservoirs and Source Rocks In Ucayali basin (Perú) the source system is Carboniferous Ambo Group. The source rock recognized is Type II/III (mainly gas prone, Disalvo et al, 2008). The Silurian-Devonian marine sediments of the Cabanillas Group with high thermal maturity might contribute with an early gas generation in the region. The main reservoirs are fluvial and eolian sandstones (Permian-Cretaceous in age). The main traps are huge anticlines generated during Neogene period (Fig. 29). Most of the hydrocarbons generated in Paleozoic rocks in this basin are reservoired in Cretaceous clastics. The Madre de Dios basin is separated from the Ucayali by the Manu Arch. This basin extends from the Andean region to the adjacent plains in the SE Perú and NW Bolivia. The basin has the same petroleum system as Ucayali and besides a more complete interval of the Silurian-Devonian source rocks. These marine shales seem to be extending with almost no interruption up to North Argentina. In spite of the scarce subsurface data some source rocks (marine Type I/III) were recognized. Of especial interest is the Upper Devonian rocks considered as a ”world class source rock” with total organic content (TOC) up to 16% (average 2 to 4%) and more than 200 m in thickness. The main reservoirs are Paleozoic and Jurassic-Cretaceous clastic rocks. The trapping mechanism is associated to the folded and thrusted belt of the Andean region. Towards the east, the foreland is less deformed and a more stratigraphic component for the potential traps could be expected.


23

Towards the South and separated by the Madidi Arch extends the Beni basin (Zubieta, 2008). The petroleum system is related to marine Carboniferous to Permian sequences (Retama and Copacabana Formations, Fig.28) along the folded belt. The Devonian source rocks are present to the east of the folded region (Tequeje and Tomachi Formations). The subsurface data in this basin is scarce and scattered. The Liquimuni x-1 wildcat (Fig.33) drilled potential source rocks (Carboniferous-Permian). Rocks with medium to moderate generation capability are recognized in outcrops samples. The potential of the eastern part of the basin is speculative since no wells were drilled. The reservoirs are sandstones of Beu and Eslabón Formations (Jurassic-Cretaceous) and fractured Paleozoic reservoirs. The folded belt in this zone generates huge potential traps in thrust anticlines (Neogene in age). The structural style is related to thin-skinned belts. To the East of the basin, like in Madre de Dios, the platform is less deformed and the chance to find suitable accumulations are on stratigraphic traps. The Chapare High (nearby Santa Cruz de la Sierra) separates de Beni basin from the Chaco (Chaco-Tarija ) basin. This basin extends to the South up to the Michicola Arch in Argentina. After Ucayali this is the next gas-producing province in the Central region. The source rocks are transgressive marine Devonian shales (Los Monos Formation) of moderate TOC but large volumes of rocks in the gas window (kerogene Type I/III). The main reservoirs are Devonian fractured quartzites (Huamampampa Formation). However, Carboniferous, Cretaceous and Tertiary rocks are secondary reservoirs. The traps are anticlines associated to a thin skin tectonics style. Hydrocarbon exploration to date shows the fundamental structural control over the hydrocarbons habitat in Ucayali and Chaco basins respectively (Figs. 29 and 30).

Fig 29 NE-SW Seismic Line Showing the Compressive Tectonics (Camisea Field)


24

Fig. 30 Geological Cross Section-Chaco Basin PROSPECTIVE RESOURCES Ucayali has 12 hydrocarbon discoveries (Fig.31). The basin does not have the minimum amount of fields to make a good analysis to estimate the remaining undiscovered field size and resources with a statistical methodology. Madre de Dios (Fig.32) and Beni (Fig.33) are both frontier basins. Chaco (Fig.34) has historical information to apply statistical techniques to assess basin resources and yet-to-find estimates. For the first three basins the estimated prospective resources are based on works and studies carried out by Pluspetrol’s geoscientists with knowledge in the drilling history, regional geology and hydrocarbon systems of the basins. The Ucayali basin (Fig.31) has a total of 12 fields. The Upper Ucayali has 7 fields (EUR 2P reserves are 136 MMBO and 387 BCF).The main field is Aguaitía. The first discovery in the basin was the Agua Caliente Field (EUR 15 MMBO, 1939). Only small accumulations were discovered up-to-now in the North Ucayali in anticlines associated with basement involved deformation. The South Ucayali (Urubamba sub-basin) has 4 fields (plus a recent discovery under appraisal, Kinteroni) fields with EUR reserves of about 12 TCF trapped in young anticlines associated with detached faults (Fig.29). These fields are under production and development status since 2004. The Ucayali basin still has several untested anticlines and sub-basins with prospective resources estimated at about 15 TCF. The total depth (TD) to reach the targets is between 2,000 to 4,000 meters. The possibility to obtain a very good seismic image in the Lower Ucayali is an advantage with respect to other sub-Andean basins. In most of the sub-Andean basins the seismic information is almost useless (poor to very poor quality) and the exploratory drilling is based on conceptual geological models (Fig.30).


25

Fig 31 Ucayali Basin – Discoveries and Exploration Status (2P Reserves)

The Madre de Dios basin (Fig. 32) comprises a largely undeformed southward-dipping foreland ramp in the North and a thin belt of foothills structures in the South-Southwest (Mathalone et al, 1995)

Fig 32 Madre de Dios Basin –Discoveries and Exploration Status (2P Reserves)

Camisea Fields

19 TCF P1+P2

Surface:160,621 km2

1 NFW per 3,278 km2

1 km seismc line per 4.3 km2

AguaitíaEUR: 75 MMBO

382 BCFG

100 kmCamisea Fields

19 TCF P1+P2

Surface:160,621 km2

1 NFW per 3,278 km2

1 km seismc line per 4.3 km2

AguaitíaEUR: 75 MMBO

382 BCFG

100 km100 km

100 km

Surface:273,174 km2

1 NFW per 27,317 km2

1 km seismc line per 21 km2

Candamo (1998)EUR: 2TCF

Pando (1991)EUR: 1MMBO – 10 BCFG

100 km100 km100 km

Surface:273,174 km2

1 NFW per 27,317 km2


Candamo (1998)EUR: 2TCF

Pando (1991)EUR: 1MMBO – 10 BCFG

Pacific Ocean Chaco

Michicola Arch

Chapare High

Beni

MadidiArch

Ucayali

Madre de Dios

ContayaArch

Manu Arch

CORDILLERA ORIENTAL

CORDILLERA OCCIDENTAL

Pacific Ocean Chaco

Michicola Arch

Chapare High

Beni

MadidiArch

Ucayali

Madre de Dios

ContayaArch

Manu Arch

CORDILLERA ORIENTAL


Pacific Ocean Chaco

Michicola Arch

Chapare High

Beni

MadidiArch

Ucayali

Madre de Dios

ContayaArch

Manu Arch

CORDILLERA ORIENTAL


Pacific Ocean Chaco

Michicola Arch

Chapare High

Beni

MadidiArch

Ucayali

Madre de Dios

ContayaArch

Manu Arch

CORDILLERA ORIENTAL


Agua Caliente


26

The detached thrust faulted (trending northwest-Southeast) and folded traps are restricted to the west-southwest part of the basin on a fringe of about 50-60 km width and about 500 km long. The basin is huge and the drilling density is one exploration well per 27,317 km2. The well Candamo 1x tested gas in Cretaceous and Paleozoic. It was drilled on surface anticline. The prospective resources for the folded belt are estimated in about 10 TCF. The Madre de Dios foreland (most of the eastern section) with a thin Cretaceous section is little deformed. The Pando x-1 well (1991, Bolivia) reached basement and tested oil in Devonian sandstones. Due to the scarce subsurface data no resources assessment was made for the foreland region where the potential for oil is high although the trapping should be more stratigraphic. The Beni basin (Fig.33) is located towards the South of Madre de Dios and develops completely in Bolivia territory where it is known as “Sub-Andino Norte”.

Fig.33 Beni Basin – Main Discoveries and Exploration Status (2P Reserves)

A few exploration wells were drilled in the basin. The western fringe associated with the folded and thrust belt is in continuity with Madre de Dios and Chaco basins. This region is the most interesting zone for gas prospection. Long and steep anticlines develop with a very impressive topographic relief. The Eva Eva Sur x-1 wildcat was drilled on an anticline structure reaching at bottom hole depth Paleozoic (TD 5,829m), Oil and gas was tested in Eslabón Formation (Upper Cretaceous) with prospective resources of about 1 MMBO and 0 .5 BCF gas. It is estimated that about 10 TCF of prospective resources could be discovered in the folded belt of Beni. The logistics is very difficult, and to acquire seismic is a real challenge in this region. The eastern part (foreland) is considered less prospectable due to the absence of potential Paleozoic rock (by erosion close to the foothills). The Chaco basin (south Bolivia and north Argentina) is the more explored basin in the Central region (Fig.34).

100 km

Surface:154,376 km2

1 NFW per 7,351 km2


EUR:1MMBO – 500 MMCFG(2001)

EUR:1MMBO – 500 MMCFG(2004)100 km100 km

Surface:154,376 km2

1 NFW per 7,351 km2




Pacific Ocean Chaco

Michicola Arch

Chapare High

Beni

MadidiArch

Ucayali

Madre de Dios

ContayaArch

Manu Arch

CORDILLERA ORIENTAL


Pacific Ocean Chaco

Michicola Arch

Chapare High

Beni

MadidiArch

Ucayali

Madre de Dios

ContayaArch

Manu Arch

CORDILLERA ORIENTAL



27

Fig.34 Chaco Basin – Discoveries and Exploration Status (2P Reserves)

Almost all the discovered fields are associated to anticlines in the fold and thrust belt and in the foothills. More than 300 exploration wells were drilled in the basin in different drilling campaigns but only about of 100 reached the deeper Devonian main target (30 % of these last wells resulted in significant gas discoveries in the Devonian). As mentioned before the seismic data is almost useless to have a good subsurface image. Presence of complex geology, difficult topography, lateral velocity changes and anticlines with vertical limbs are some of the main reasons for the poor seismic definition in depth. Extensive field works, geological modeling, balanced structural cross sections (Fig. 30) are some of the main tools used by the geoscientists to carry out the exploration. The sub-Andean thrust belt is a thin-skinned system (Dunn et al, 1995) with two main detachment levels (Silurian and Devonian in age). The primary source rock is Los Monos Formation. The tight surface folds are currently producing oil; the broad deeper structures associated with Silurian detachment (Kirusillas Formation) remain poorly explored. These deeper almost untested structures have the potential for large gas accumulations. To the geological risk it should be added the challenge to drill to depths between 4000 to 6000m. Most of the times several and costly side tracks drilling operation are necessary to correct the drilling trajectory and reach the deeper targets. There are several structural alignments in the Chaco basin that remains untested. Potential sub-thrust structures (with reservoir repetitions in depth) are very common (i.e. Ramos Field Fig. 35), Aguaragüe, San Pedrito in Argentina or San Alberto, Sábalo and Margarita in Bolivia). The potential prospective resource in this basin is estimated in 35 TCF.

100 km

Surface:284,672 km2

1 NFW per 566 km2


61 OIL FIELDS70 GAS FIELDS

100 km

Surface:284,672 km2

1 NFW per 566 km2


61 OIL FIELDS70 GAS FIELDS

Pacific Ocean Chaco

Michicola Arch

Chapare High

Beni

MadidiArch

Ucayali

Madre de Dios

ContayaArch

Manu Arch

CORDILLERA ORIENTAL


Pacific Ocean Chaco

Michicola Arch

Chapare High

Beni

MadidiArch

Ucayali

Madre de Dios

ContayaArch

Manu Arch

CORDILLERA ORIENTAL



28

Fig.35 Chaco Basin – Arbitrary Seismic Line West-East Ramos Field-Deep Exploration (NW Argentina)

GAS CONSUMPTION IN SOUTH AMERICA: Fig. 36 shows the gas consumption in South America until year 2025. The average consumption growth for the region was estimated at about 7% per year. For the forecast was considered the previous 5 years consumption level of each country (source: BP Statistical Review of World Energy, June 2009). At this rate in 17 years the countries hereby considered will consume about 157 TCF.

Fig. 36 South America – Main Countries Gas Consumption Forecast

TD= 5700 mbsl

Ramos xp-1012

-9000 mrnm

TD= 5700 mbsl

Ramos xp-1012

-9000 mrnm

W E

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

2008

2010

2012

2014

2016

2018

2020

2022

2024

TCF

BOLIVIAVENEZUELAPERUCOLOMBIACHILEBRAZILARGENTINA

TOTAL GAS CONSUMED: 157 TCF

AVERAGE GROWTH:

7%

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

2008

2010

2012

2014

2016

2018

2020

2022

2024

TCF

BOLIVIAVENEZUELAPERUCOLOMBIACHILEBRAZILARGENTINA

TOTAL GAS CONSUMED: 157 TCF

AVERAGE GROWTH:

7%

RAMOS DEEP WELL


29

Please note the rate of growth is pushed up by Perú, the new gas player in the region. Without Peru, the region’s average gas consumption falls from 7 % to 5 % per year. The Peruvian government strategy is to change the country’s energy matrix they had in 2003 (7 % gas and 69 % oil before Camisea development) to an energy matrix with 34 % gas and 33 % oil in a 20 years term. This strategy implies an estimated gas consumption growth of about 20 % per year consuming their current proven reserves by 2023. Peru estimates that about 60 % of their proven reserves will be consumed by their local market and the remaining 40 % by export (LNG). The Ucayali basin has significant 2P reserves (19 TCF gas) and about 15 TCF of prospective resources. If Perú could transform these resources into reserves in the short term, it would be able to supply any extra gas to the regional market Fig. 37 shows a scenario assuming that each country will consume its own currently proven published reserves. By 2012 Chile is the first country consuming all its proven reserves. Argentina consumed 1.57 TCF/yr (eq. 4.3 BCF/day) in 2008. With a rate of consumption growing at 5 % per year the country will need about 3.6 TCF/yr (eq. 10 BCF/day) in 2025. By 2016 Argentina consumed all its reserves and should be a net gas importer. In the case of Bolivia this country consumed about 100 BCF/day plus 400 BCF/day exported to Argentina and Brazil (2008). For Bolivia it was estimated a rate of growth per year of about 3%. The gas exported from Bolivia to Argentina and Brazil was considered when analyzing these last two countries consumption otherwise both countries should be in a negative position earlier in the graph (Fig.37). Venezuela is the only case where it was followed the criteria of “Free Gas” reserves availability already explained in this paper. The goal of this exercise is to illustrate the gas market situation in South America and to show the impact on the main gas consumers if no more reserves are added in the region.

Fig.37 Proven (2008) gas consumption until reserve exhaustation by Country until 2025.

-80

-60

-40

-20

0

20

40

60

80

100

120

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

TCF

BOLIV IA

V ENEZUELA

PERU

COLOMBIA

BRA ZIL

A RGENTINA

CHILE

2008

2012

Chi

le

2016

Arge

ntin

a

2018

Bra

zil

Cum.Deficit: 61 TCF-80

-60

-40

-20

0

20

40

60

80

100

120

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

TCF

BOLIV IA

V ENEZUELA

PERU

COLOMBIA

BRA ZIL

A RGENTINA

CHILE

2008

2012

Chi

le

2016

Arge

ntin

a

2018

Bra

zil

Cum.Deficit: 61 TCF


30

No doubt that the recent gas discoveries in Santos basin of Brazil will have a significant impact on the gas scenario in the southern cone. Brazil is carrying out several studies aimed at proving the commercial viability of floating liquefaction vessel (FLNG, capable of producing 2.5 million tonnes per annum of liquefied natural gas) in the pre-salt cluster of that basin. According to Petrobras sources deploying an FLNG vessel with 10 million cubic meters per day of gas would be a first stage. However it is expected that the system could not be operational before 2015. The balance between supply and demand for gas is complex due to Brazil’s heavy reliance on unpredictable hydroelectric power. However, Petrobras is planning a third regasification terminal (1.9 million tones per annum with construction to begin by 2011). Fig. 38 shows the gas distribution and main gas facilities in South America and the way some countries are planning and preparing themselves to tackle with the gas supply “bottle neck” in the southern cone of South America.

Fig. 38 South America - Regional Pipelines - LNG & Regasification Facilities The USA consumes about 23 TCF per annum and the forecast for 2025 indicates an additional consumption of 4 TCF/year. It is expected that most of the Caribbean gas will be dedicated to that huge market. Trinidad is already exporting the LNG to the USA and Peru will be doing so in the near future. The southern cone excess in the supply was the main driver to develop good regional gas connectivity in the late 90s’. Now due to the fall of Argentina’s reserves the region is reaching an inflection point concerning the future energy matrix of each country.

TRINIDAD Y TOBAGOTRINIDAD Y TOBAGO

PARAGUAY

PERU

BOLIVIA

CHILE

ECUADOR

COLOMBIA

VENEZUELA

BRASIL

Santa CruzSanta Cruz

San Pablo

Punta Arenas

Santiago

Concepción

LimaLima

Bahía Blanca

Pisco Brasilia

Fortaleza

REGIONAL GAS PIPELINES,Liquefaction and

Regasification Plants

LNG - LIquefaction

LNG - Regasification

Montevideo(Under study)

REFERENCES

8 MM m3/(2008)

14 MM m3/d(2009)

7 MM m3/d( ? )

(Under study)10 MM m3/d

Vessel8 MM m3/d

(2008)

10 MM m3/d(2009)

5,5 MM m3/d(2010)

18 MM m3/d(2010-11)

URUGUAY

Buenos Aires

ARGENTINA

Montevideo

Bahia de Guanabara

Pecem

Quinteros

Mejillones

60 MM m3/d

Project Sucre(Under study)

SUDAMERICANO (Suspended)

SUDAMERICANO (Alternative to LNG ?)

GASNEA (Under Re-Evaluation)

GAS PIPELINES

Puerto Ordaz

GAS PIPELINES

TRINIDAD Y TOBAGOTRINIDAD Y TOBAGO

PARAGUAY

PERU

BOLIVIA

CHILE

ECUADOR

COLOMBIA

VENEZUELA

BRASIL


San Pablo

Punta Arenas

Santiago

Concepción

LimaLima

PERU

BOLIVIA

CHILE

ECUADOR

COLOMBIA

VENEZUELA

BRASIL


San Pablo

Punta Arenas

Santiago

Concepción

LimaLima BRASIL


San Pablo

Punta Arenas

Santiago

Concepción

LimaLima

Bahía Blanca

Pisco Brasilia

Fortaleza

REGIONAL GAS PIPELINES,Liquefaction and

Regasification Plants

LNG - LIquefaction

LNG - Regasification

Montevideo(Under study)

REFERENCES

8 MM m3/(2008)

14 MM m3/d(2009)

7 MM m3/d( ? )

(Under study)10 MM m3/d

Vessel8 MM m3/d

(2008)

10 MM m3/d(2009)

5,5 MM m3/d(2010)

18 MM m3/d(2010-11)

URUGUAY

Buenos Aires

ARGENTINA

Montevideo

Bahia de Guanabara

Pecem

Quinteros

Mejillones

60 MM m3/d

Project Sucre(Under study)

SUDAMERICANO (Suspended)

SUDAMERICANO (Alternative to LNG ?)

GASNEA (Under Re-Evaluation)

GAS PIPELINES

Puerto Ordaz

GAS PIPELINES


31

In the next 5 years it will be critical the gas supply for some countries. Significant investment efforts and careful planning must be carried out in partnership with all the actors (Governments, National Oil & Gas companies, International and Domestic O&G Companies). It is necessary to move gas projects forward today to help ensure economic growth and secure the energy required by today’s people and future generations that will follow us. Public technical papers and companies’ reports put emphasis on the natural gas as the fastest primary energy component. “If the 20th century was the Age of Oil, then the 21st century is poised to become the Age of Natural Gas. The LNG, gas-to-liquids and long-distance pipeline projects that are under way will help diversify the world’s energy portfolio…” (Blackwell J., Chevron, World Energy 2008). CONCLUSIONS The Central Region of the Sub Andean basins is unexplored. From Ucayali’s gas fields (southeast Perú) to the northern Chaco fields (Bolivia) there is a distance of more than 1200 km with very little exploration activity and subsurface exploration data. Being the gas prone Paleozoic system present all along the Central region it is difficult to believe that hydrocarbon accumulations are only present in the northern (Ucayali) and southern (Chaco) extremes of this huge Central region. It is estimated that there are more than 70 TCF of gas Undiscovered Prospective Resources in the Central region. Geological conditions for petroleum generation (gas prone predominant) and favorable structural conditions to secure the trapping mechanism are present in the Central Region. More than geological conditions to explain the poor exploration activity in this region there are some key issues to overcome:

• Technology (complex geology interpretation and poor seismic subsurface image) • Deep wells (difficult and expensive drilling works) • Complex logistics (Amazon Jungle) implies to work onshore as offshore projects • Sensitive Environment • Native Communities • Lack of Infrastructure • Drug gangs, Terrorism

However, through a strong and aligned partnership (Government, Local Communities and Industry) all these negative factors could be overcome and projects could be put online efficiently. A good example of this is the development of Camisea field in the Peruvian Amazon jungle. After more than 20 years of having “sleeping gas reserves” the field was put on-stream in 2004 after a three-year fast track effort carried out jointly by the government and the industry. Perú a former energy importer country changed to an energy exporter and a consumer of cleaner fluid, In USA the gas is a commodity since the mid-80s’. Before the government fixed the price but at a value that did not rewarded the companies to invest in exploration and capital intensive projects. To think in developing a similar process in South America today sounds unrealistic due to the different energy policies followed by the South American governments. However to work jointly in the gas interconnectivity will be critical. Each country could secure their gas supply from different sources and will help in developing a more transparent gas price. These prices could then be less influenced by local scenarios and closer to the international ones. In this case the typical price volatility of a commodity should be accepted. Anyway, the advantage of energy integration surpasses the risk involved. To promote the gas exploration and change the fallen tendency in the proven reserves the governments should act now. To transform probable and possible resources in proven reserves is


32

not an easy process. It takes time and a lot of money. Any regulatory and fiscal terms must be able to tackle the rise in demand for energy. While some Sub Andean countries have clear and transparent contractual terms attracting the industry to invest in their countries others change the “rules of the game” constantly. The governments should be more creative to attract the industry to invest in exploration risk. This is not an easy task in a very competitive market where the companies have several options in the international arena. It is necessary to overcome the political uncertainties and to respect the contractual and fiscal terms of the contracts awarded. These negative factors cause significant delays in the energy development. At the same time they deny the people rights to a better life condition. This is a challenge that sooner or later the Sub Andean countries have to face. ACKNOWLEDGMENTS The authors would like to express their gratitude to Pluspetrol SA for the support and authorization to prepare this paper. The authors want to express their gratitude to reviewers Marcelo Arteaga and Nino Barone. We thank María Silvia Castro for drafting the figures and several colleagues at Pluspetrol for their comments and suggestions.


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24th World Gas Conference The Global Energy …members.igu.org/html/wgc2009/papers/docs/wgcFinal00514.pdfadjacent plates (Pindell et al,1995) In the Caribbean region (northeast Colombia,

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