Chapter 18: Carbonate Platform Seismic Sequence Attributes, Maracaibo Basin, Venezuela
T. Chris Stiteler, Fernando J. Chacartegui, Orlando J. Ortega, Robert W. Scott, Izaskun Azpiritxaga, Chris K. Taylor, 1997. "Carbonate Platform Seismic Sequence Attributes, Maracaibo Basin, Venezuela", Carbonate Seismology, Ibrahim Palaz, Kurt J. Marfurt
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A sequence stratigraphic evaluation of Cretaceous platform carbonates was conducted in the Lake Maracaibo region of Venezuela. The study was part of a larger multidisciplinary project in which cores, logs, a 3-D seismic survey, and well test data from the Cretaceous carbonate section were analyzed. Carbonate platform stratigraphy was interpreted to be tabular shaped and consists of alternating cycles of subparallel strata with intermittent shale beds at maximum-flooding intervals. Primary porosity is poorly developed in grain-rich facies, but secondary porosity is well developed in grain-rich facies in the vicinity of fault-associated fractures.
The seismic interpretation was conducted on a 3-D survey acquired in Lake Maracaibo. The seismic responses of the platform carbonates were divided into two types: a shallower section character in which some of the larger scale cycles/sequences and lateral changes in rock properties were interpreted with reasonable constraint, and a deeper section response composed mainly of “false stratigraphy” that appears to be stratigraphically controlled but is actually caused by side lobes and subtle changes in structure. The interpretation was also complicated by the weak seismic response of the platform carbonate section. A systematic interpretation method was proposed to help the interpreter distinguish between seismic events due to stratigraphic changes and those due to other effects. Keys to successful interpretation involve use of core data, seismic modeling, and 3-D seismic data that are calibrated to well control.