By OGJ editors
HOUSTON, Jan. 4 -- Shell Venezuela SA is producing 25,000 b/d of light oil from Lower Cretaceous Cogollo carbonates at 16,400 ft in Urdaneta West field just west of Lake Maracaibo.
Matrix properties were found to control production rates and ultimate recovery, whereas the reservoir was long considered a fractured reservoir similar to others in the area, said Poppelreiter and others in a paper in the AAPG Bulletin for December 2005.
Matrix porosity ranges from 2% to 16% and averages 3%, and matrix permeability averages less than .01 md and ranges as high as tens of millidarcies.
A 26 ft thick oyster packstone present throughout the field yields economic production rates if porosity above 7% and permeability in the tens of millidarcies are encountered, the paper said.