Petroleum Prospectivity of the Southwestern Nicaraguan Rise (Colombian Caribbean) Based on Regional Integration of Seismic and Well Data

Carvajal Arenas, Luis Carlos; Mann, Paul; Saunders, Mike

The southwestern Nicaraguan Rise (SWNR) represents a vast (213,000 km2), underexplored part of the Caribbean where, since the early 1980s only two exploratory wells have been drilled to shallow depths (<2 km). To reevaluate the prospectivity of this area, we have used 2,500 km of vintage 2-D seismic data acquired in the early 1980s and 3,000 km of high-resolution, deep-penetration 2-D seismic data acquired in 2007. The 2007 data is tied to the two existing exploration wells and two ODP wells drilled in 1996 containing a complete set of logs and paleo ages. We have also integrated our interpretation with previous work by Bowland (1993) using UT lines from the early 1980s that effectively expands our study area to cover a 621,000 km2 area of the SWNR and Colombian basin in offshore Costa Rica and Nicaragua. Results include: 1) All three areas share a common Caribbean oceanic plateau basement erupted over a broad area in Turonian time (~90 Ma); 2) The late Cretaceous-Paleocene interval (84 m) overlying basement is a pelagic calcarenite-dolomite with TOC values as high as 10% in DSDP wells drilled in the 1970s in the Venezuelan basin, and this interval thins against numerous basement seamounts and highs reflecting continued igneous extrusions during the late Cretaceous; 3) The Middle Eocene-Middle Miocene interval varies widely in thickness (500-650 m) partly in response to its infilling of a rough, magmatically-controlled seafloor; these localized basins range in depth from 3,000 m to 8,000 m; this Cenozoic unit contains known source rocks from wells drilled in Nicaragua with TOC>2 and S2>5; this unit is also known to be mature with a fair to very good generation potential (for both gas and oil); sandstone within this unit, mainly derived from Central America, may also act as reservoirs; and 4) Middle Miocene to Holocene rocks are shallow water carbonate caps or peri-platform deposits with potential porosity and reservoir potential.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013