Marañon Basin Petroleum Systems The Marañon Basin is one of the sub-Andean basins of Peru. Located in the northeastern jungle of the upper Amazonas hydrographic system, it is the largest Peruvian sedimentary basin, occupying an area of 350,800 km2. It extends from the eastern sub-Andean foothills in the west through the easternmost Amazon River in the Peruvian territory to Brazil in the east. The Marañon Basin is bordered by the sub-Andean fold-thrust belt in the west and southwest and by the Contaya Arch in the south, which separates it from the Ucayali Basin. Its northern, northeastern, and southeastern boundaries are marked by the international borders of Ecuador, Colombia, and Brazil, respectively (Figure 1.1). Geologically however, the Marañon Basin is part of a larger sub-Andean basin that extends into the Oriente Basin in Ecuador and the Putumayo Basin in Colombia. Hydrocarbon exploration in the Marañon Basin began with the spudding of the Marañon 1X well by Texaco in 1955. Texaco drilled two additional wells in the same structure, (Marañon 22X and Marañon 110X) between 1956 and 1957, and another (Yurimaguas 1X) in southwestern part of the basin in 1958. All four wells were dry holes. After a 23 year absence in drilling activity, the Corrientes oil field was discovered during PeruPetro’s first phase of exploration in 1971. Continued exploration has resulted in discovery of a number of oil fields. Exploration and drilling activity in the basin has increased since initiation of the privatization of PeruPetro. |
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A total of 103 wildcat wells were drilled in the basin as of 2001 (Table 1, PARSEP 2002 data). Of these, oil was produced or tested in 38 wells and oil shows were present in 9 wells. Figure 1.2 shows the recoverable reserves assigned to the main Marañon Basin oil fields with their discovery dates. The total reserves are 734 MMBO, of which 62% is in Cretaceous Vivian reservoirs and 37% in Cretaceous Chonta reservoirs (Mathalone and Montoya, 1995). PeruPetro (2003) estimated the total official proven, probable, and possible oil reserves of the Marañon Basin as of December 31, 2001 at 190 MMBO, 100.5 MMBO, and 711.5 MMBO, respectively. Probable and possible gas reserves were estimated at 39.6 BCF and 56.5 BCF, respectively. PeruPetro (2003) also estimated on the basis of potential prospects an unrisked potential oil reserve of 13,581 MMBO and an additional risked potential oil reserve of 3,672 MMBO. There is no charge for this report. |
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Contact Rick Schrynemeeckers, Managing Director: Call: 1-281-681-8811 |
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