National and Global Petroleum Assessment

Assessment of Continuous Oil and Gas Resources of the 

Maracaibo Basin Province of Venezuela and Colombia, 2016

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2017–3011

March 2017 Printed on recycled paper

Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable 

mean continuous resources of 656 million barrels of oil and 5.7 trillion cubic feet of gas in the Maracaibo Basin Province, 

Venezuela and Colombia.

Introduction

The U.S. Geological Survey (USGS) completed an assessment of undiscovered, technically recoverable continuous oil and 

gas resources within the Maracaibo Basin Province of Venezuela 

and Colombia (fig. 1). The Maracaibo Basin Province is a structurally complex region encompassing approximately 58,000 square 

kilometers between the Sierra de Perijá and Cordillera de Mérida, 

with the northern boundary generally placed at the Oca-Ancón 

fault (Mann and others, 2006). More than 30 billion barrels of conventional oil have been produced from the basin, which ranks it as 

one of the top petroleum-producing basins in the world. Organicrich shales of the Upper Cretaceous La Luna Formation are the 

main petroleum source rock, and La Luna shales have reached 

adequate thermal maturity for oil and gas generation throughout much of the basin (Talukdar and others, 1986; Talukdar and 

Marcano, 1994; Escalona and Mann, 2006). The purposes of this 

study are (1) to estimate the volumes of recoverable continuous 

oil and gas remaining in La Luna Formation source rocks following two phases of petroleum generation and expulsion and (2) to 

postulate the presence of gas resources in low-permeability (tight) 

sandstones. Although the La Luna Formation is mapped as being 

partly in the gas generation window, little information is available 

on potential gas resource distribution and the possible presence of 

gas resources remaining in the La Luna source rock or in deeply 

buried, tight sandstones.

Total Petroleum System and Assessment Units

For the Maracaibo Basin Province, the USGS defined a 

La Luna Continuous Total Petroleum System (TPS) and the 

La Luna Continuous Oil Assessment Unit (AU), the La Luna 

Continuous Gas AU, and the Maracaibo Tight Gas AU within 

this TPS. The major risk for the occurrence of recoverable continuous oil and gas in these AUs is retention of recoverable gas 

within the source rocks following migration. The geologic model 

proposed in this study is for some portion of the oil and gas to 

have been retained in the La Luna Formation source rock and for 

gas to potentially have migrated into tight sandstones, although 

the presence of tight sandstones is highly uncertain.

Assessment input data for each assessment unit are shown 

in table 1. Well drainage areas, estimated ultimate recoveries, 

and success ratios are taken from U.S. shale-oil, shale-gas, and 

tight-gas analogs.

Undiscovered Resources Summary

The USGS quantitatively assessed undiscovered, technically recoverable continuous oil and gas resources within the 

La Luna Continuous TPS of the Maracaibo Basin Province, 

Venezuela and Colombia (table 2). For continuous resources, 

the total mean resources are 656 million barrels of oil (MMBO) 

with an F95–F5 range from 111 to 1,632 MMBO; 5,713 billion 

cubic feet of gas (BCFG), or 5.7 trillion cubic feet of gas, with 

an F95–F5 range from 208 to 17,128 BCFG; and 127 million 

barrels of natural gas liquids (MMBNGL) with an F95–F5 

range from 8 to 362 MMBNGL. 

Figure 1. Location of the Maracaibo Basin Province and the three 

continuous assessment units (AUs) defined in this study.

!

–73° –72° –71°

11°

10°

9°

8°

Lago de Maracaibo

CARIBBEAN SEA

Cúcuta

Mérida

San Cristóbal

VENEZUELA

COLOMBIA

COLOMBIA OCA-ANCÓN FAULT

CORDILLERA DE MÉRIDA

SIERRA DE PERIJÁ

Maracaibo

Trujillo

Source: U.S. Department of the Interior National Park Service VENEZUELA

Map

area

ATLANTIC 

OCEAN

PACIFIC

OCEAN

COLUMBIA

SOUTH

AMERICA

0 25 50 MILES

0 25 50 KILOMETERS

EXPLANATION

Maracaibo Basin Province

La Luna Continuous Oil AU

La Luna Continuous Gas AU

Maracaibo Tight Gas AU
ISSN 2327-6916 (print) ISSN 2327-6932 (online) https://doi.org/10.3133/fs20173011

For the La Luna Continuous Oil 

AU, the mean estimates are 656 MMBO 

with an F95–F5 range from 111 to 

1,632 MMBO, 1,314 BCFG of associated 

gas with an F95–F5 range from 208 to 

3,389 BCFG, and 53 MMBNGL with an 

F95–F5 range from 8 to 137 MMBNGL. 

Assessment input data—

Continuous assessment units (AUs)

La Luna Continuous Oil AU La Luna Continuous Gas AU

Minimum Mode Maximum Calculated

mean Minimum Mode Maximum Calculatedmean

Potential production area of AU (acres) 800 1,000,000 6,200,000 2,400,267 1,200 1,000,000 6,000,000 2,333,733

Average drainage area of wells (acres) 40 80 120 80 80 120 160 120

Success ratios (%) 10 50 90 50 10 50 90 50

Average EUR (MMBO, oil; BCFG, gas) 0.02 0.04 0.1 0.043 0.1 0.3 1 0.337

AU probability 1.0 0.9

Assessment input data—

Continuous assessment units (AUs)

Maracaibo Tight Gas AU

Minimum Mode Maximum Calculated

mean

Potential production area of AU (acres) 1,200 2,000,000 4,100,000 2,033,733

Average drainage area of wells (acres) 40 120 200 120

Success ratios (%) 10 50 90 50

Average EUR (BCFG) 0.1 0.3 1 0.337

AU probability 0.5

Table 1. Key assessment input data for three continuous assessment units in the Maracaibo Basin Province, Venezuela and Colombia.

[AU, assessment unit; %, percent; EUR, estimated ultimate recovery per well; MMBO, million barrels of oil; BCFG, billion cubic feet of gas. Well drainage areas, 

EURs, and well success ratios are taken from U.S. shale-oil, shale-gas, and tight-gas analogs. The average EUR input is the minimum, median, maximum, and 

calculated mean. Shading indicates not applicable]

Total petroleum system 

and assessment units (AUs)

AU

probability

Accumulation 

type

Total undiscovered resources

Oil (MMBO) Gas (BCFG) NGL (MMBNGL)

F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 F5 Mean

La Luna Continuous Total Petroleum System

La Luna Continuous Oil AU 1.0 Oil 111 528 1,632 656 208 1,027 3,389 1,314 8 41 137 53

La Luna Continuous Gas AU 0.9 Gas 0 2,230 8,173 2,923 0 43 168 59

Maracaibo Tight Gas AU 0.5 Gas 0 223 5,566 1,476 0 2 57 15

Total undiscovered continuous resources 111 528 1,632 656 208 3,480 17,128 5,713 8 86 362 127

Table 2. Assessment results for three continuous assessment units in the Maracaibo Basin Province, Venezuela and Colombia.

[MMBO, million barrels of oil; BCFG, billions of cubic feet of gas; MMBNGL, million barrels of natural gas liquids. Results shown are fully risked estimates. For 

gas accumulations, all liquids are included under the NGL (natural gas liquids) category. F95 represents a 95-percent chance of at least the amount tabulated; other 

fractiles are defined similarly. Fractiles are additive under the assumption of perfect positive correlation. Shading indicates not applicable]

F95–F5 range from 0 to 5,566 BCFG 

and 15 MMBNGL with an F95–F5 range 

from 0 to 57 MMBNGL. For gas accumulations, zeros at F95 reflect the chance 

that gas might not exist in the AU, and 

the geologic AU probability (risk) was 

estimated to be less than one.

Mean estimates for the La Luna 

Continuous Gas AU are 2,923 BCFG 

with an F95–F5 range from 0 to 

8,173 BCFG and 59 MMBNGL with an 

F95–F5 range from 0 to 168 MMBNGL. 

Mean estimates for the Maracaibo 

Tight Gas AU are 1,476 BCFG with an 

References Cited

Escalona, Alejandro, and Mann, Paul, 2006, An overview of the petroleum system of Maracaibo Basin: American Association of Petroleum Geologists Bulletin, v. 90, no. 4, p. 657–678.

Mann, Paul; Escalona, Alejandro; and Castillo, M.V., 2006, Regional geologic and tectonic setting of the Maracaibo supergiant basin, 

western Venezuela: American Association of Petroleum Geologists Bulletin, v. 90, no. 4, p. 445–477.

Talukdar, S.C., and Marcano, Fernando, 1994, Petroleum systems of the Maracaibo Basin, Venezuela, in Magoon, L.B., and Dow, W.G., 

eds., The petroleum system—From source to trap: American Association of Petroleum Geologists Memoir No. 60, p. 463–481.

Talukdar, S.C.; Gallango, Oswaldo; and Chin-A-Lien, Marcel, 1986, Generation and migration of hydrocarbons in the Maracaibo Basin, 

Venezuela—An integrated basin study: Organic Geochemistry, v. 10, nos. 1–3, p. 261–279.

For More Information

Assessment results also are available at the USGS Energy Resources Program website 

at http://energy.usgs.gov.

Maracaibo Basin Province Assessment Team

Christopher J. Schenk, Marilyn E. Tennyson, Tracey J. Mercier, Stephanie B. Gaswirth, 

Kristen R. Marra, Phuong A. Le, Janet K. Pitman, Michael E. Brownfield, Sarah J. Hawkins, 

Heidi M. Leathers-Miller, Thomas M. Finn, and Timothy R. Klett