Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Application of sequence stratigraphic reinterpretation of Lower Lagunillas Member to further development of Bloque IV, Lake Maracaibo, Venezuela

Conference ·
OSTI ID:471921
Discovered in 1955, the Lower Lagunillas Member reservoir of the Miocene Lagunillas Formation of Bloque IV of the Bachaquero field was and was originally estimated to contain 2 billion barrels of oil. This reservoir interval has traditionally been interpreted to have been deposited in a delta plain setting and to comprise three reservoir subdivisions that were developed as a single drainage unit. Sedimentological interpretation of four cored wells has led to the development of a new model of deposition in tidally influenced lower delta plain and delta front settings. This model is supported by Fourier Transform Infrared (FTIR) measurement of illite concentrations and prompt neutron capture boron measurements that are indicative of a brackish water depositional setting. The conceptual geological model has been used to guide correlation of wireline logs from 46 wells in the central part of Bloque IV and to provide a high-resolution sequence stratigraphic model of the Lower Lagunillas reservoir. Eleven genetic layers are identified that are separated by locally developed intraformational seals into up to eight drainage units. High permeability, tidally influenced channel-fill sands have acted as preferential conduits for gas influx, leaving bypassed oil in lower quality sands that were deposited as lagoonal deltas and bars. This reservoir model has been supported by re-examination of production data and by openhole measurements in a recent infill well and cased-hole logging of two other wells in the study area. The new model will form the basis for redevelopment of the Lower Lagunillas reservoir to further increase recovery from this mature field.
OSTI ID:
471921
Report Number(s):
CONF-961003--
Country of Publication:
United States
Language:
English