Ucayali Basin Research Articles

Hydrocarbon Potential of Amazon Basins of Colombia, Ecuador, and Peru: ABSTRACT

The Oriente, Ucayali, and Madre de Dios basins in the Amazon drainage of Colombia, Ecuador, and Peru are members of a series of large asymmetric depressions between the Andean cordillera and the Guiana and Brazilian shields. They are separated from one another by basement arches and have areas of 458,000, of 200,000, and of 95,000 sq km, respectively. The area is topographically low, covered by heavy rain forest, traversed by many huge tributaries of the Amazon and is sparsely populated. From early Paleozoic time until the Maestrichtian, seas repeatedly invaded the area, depositing a variety of sediments, but mostly calcareous and silicate clastic deposits. At the beginning of the Tertiary, dominantly marine deposition gave way to nonmarine deposition, reflecting the Andean orogeny and topographic development of the Andes Mountains. The depositional cycle of major importance for hydrocarbons took place in the Cretaceous. A complete marine cycle of miogeosynclinal sedimentation is represented with a maximum thickness of 2,500 m, but it thins and becomes sandier toward the east. Although the cycle consists mainly of sands and shales, limestones and sandy limestones are important potential reservoirs. Most prospective structures in the basin are anticlines, generally fau t-bounded and steeper on the east. Salt domes and other diapiric structures are also present. Amplitude of structures and intensity of deformation decrease eastward. The formation of structures and the migration and entrapment of hydrocarbons appear to have occurred at various times in the Tertiary. The state of exploration in the Colombian part of the Oriente basin is well advanced with low-undiscovered potential. In Ecuador, although the peak of exploration activity has been passed, the future potential may be substantial. In Peru exploration drilling in the Oriente basin already has discovered reserves on the order of 400 million bbl of oil. On the basis of these facts and on information from Colombia and Ecuador, the total potential of the Oriente basin is estimated to be 25 to 35 billion bbl. About 20 wildcats have been drilled in the Ucayali basin with the discovery of two small oil End_Page 1463------------------------------ fields and an undeveloped, but potentially large gas field. From these results, and estimates for the Oriente basin, the Ucayali basin has an estimated potential of 5 to 10 billion bbl. In addition, Paleozoic sediments also have some potential. Favorable conditions are known to exist and oil seeps are present in the Madre de Dios basin, the least known of the three. A potential of 3 to 8 billion bbl is estimated. The total estimated potential for the three basins is about 40 billion bbl. End_of_Article - Last_Page 1464------------

BINÓ STYLE CERAMICS FROM IPARIA

Over fifteen years have passed since Donald Lathrap initiated his pioneer investigation into the prehistory of the Ucayali basin in the tropical forests of eastern Peru. During this time, Lathrap and his students have documented a ceramic chronology which extends from the Early Tutishcainyo style of the second millenium B.C. to the ceramics of the present occupants of the Ucayali, the Shipibo and Conibo.*

The Mabaruma Phase: A Return to the More Probable Interpretation

In a recent publication Evans and Meggers have accused me of reinterpreting their work in an erroneous manner on two separate occasions (Evans and Meggers 1964). In one instance (Lathrap 1963a), I suggested that the Machalilla complex of Coastal Ecuador might be a member of the same ceramic tradition which also gave rise to Early Tutishcainyo and Late Tutishcainyo in the central Ucayali Basin in Peru. In the other case (Lathrap 1964), I offered what appeared to me to be a more reasonable seriation of the excavated levels of the Mabaruma phase of northwestern British Guiana and suggested that the age of the Mabaruma phase had been underestimated by a large factor.