ICE 2022


Even though the first oil field of Venezuela (La Petrólia, 1882) was discovered in the Táchira Depression, located at the junction of the Venezuelan Andes with the Cordillera Oriental of Colombia, no liquid hydrocarbon discoveries have been made in the area ever since. However, since 1960 a major oil seep impregnating mio-pliocene conglomerates of the La Cope Formation has been exploited intermittently as asphalt mostly for road construction. (La Gotera Asphalt Mine). La Cope Formation was deposited as a product of the first uplift of the Andes. The unit was deposited unconformably on the nose and flanks of a large-scale anticline oriented N40° and plunging to the SW (Uribante High). However, this unit extended over a much larger area but was later affected by the main Andean orogeny and was partially eroded. A detailed analysis of the petrography of the sandstones and conglomerates as well as paleocurrents, indicate that these sediments were derived from the Uribante High. The La Cope Formation has a fluvial origin and is arranged in two members. The Lower Member is mostly conglomeratic and was deposited by braided rivers. The Upper Member is mostly composed by sand and clay and was deposited by high sinuosity meandering rivers. The asphalt accumulations are present in the northeastern portion of the Táchira Depression, where the Lower Member of the La Cope Fm rests directly above the unconformity on top of the Cretaceous Aguardiente Fm, which at the time was part of the Uribante High. It is believed that the conglomerates were charged with oil derived from the Cretaceous La Luna Formation that was generating oil at the time of deposition of the unit. This oil migrated directly into the conglomerates and moved for a short distance updip also impregnating the sandstones of the underlying mid Cretaceous Aguardiente Fm. The seal of the accumulation was formed by lateral facies changes, overbank shales, or eventually the muddier Upper Member. It is difficult to establish the ultimate size of this paleo-accumulation. The EUR reserves of the La Gotera mine are approximately 6.3 MMBO. A rough estimate of the total hydrocarbons in the outcrops of the La Cope Fm is in the order of 90 MMBO, however the original accumulation was orders of magnitude larger. This breached trap was probably the focus point for charge in the Táchira Depression, thus suggesting that a large portion of the hydrocarbons generated in the area have been lost.