Fractured Basement: New Exploratory Target in La Concepción Field, Western Venezuela

Porras, Jesus S.¹, Elmer Ferro², Carla E. Castillo³, Vanessa I. Machado⁴, Luis A. Ochoa¹, Nelson E. Chirinos¹ (1) PDVSA - Empresa Mixta Petrowayuu, Maracaibo, Venezuela (2) Petrobras Energía S. A, Caracas, Venezuela (3) PDVSA-Empresa Mixta Petrowayuu, Maracaibo, Venezuela (4) PDVSA- Empresa Mixta Petrowayuu, Maracaibo, Venezuela

In Western Venezuela, production from naturally fractured basement has been known for decades. Since El Totumo, Limon and giant Mara-La Paz oilfields discoveries in the early twentieth century, new commercial oil production from basement had not been reported in years. In the 1960-decade, unsatisfying results were obtained searching for oil from basement in El Mojan, Sibucara, Los Lanudos, and La Concepcion fields. In La Concepcion field, evidence in some wells suggested the existence of basement as a producing reservoir. However, a combination of factors including: operational problems that impeded production testing, the experience of having dry basement in some former wells and the insignificant production obtained in the only well where basement was proved -when compared to its Cretaceous production- prevented further pursuit of basement as a commercial target.

Nevertheless, it was not until 2004 when commercial production from basement was obtained through well C310, initially producing at 4600 bopd. Further drilling continued basement development; well C313 was completed in July 2004, producing 3915 bopd, and well C314 was completed in November 2004, producing 3714 bopd. Recently, in 2006, well C325 confirmed basement production too.

This paper aims to describe the main characteristics of fractured basement in La Concepcion field. Also, it is intended to evaluate the reservoir under a new perspective, in order to determine its potential, after exploration, and further studies and analyses. As a result, additional opportunities could be obtained, and as a consequence, hydrocarbons reserves would be increased.