Highlights
The Raya Prospect is defined as a structural high against an east-west fault within the Zorritos Formation, the primary reservoir in the basin, with a combined 46km2 structural and stratigraphic trap with shales overlying the Zorritos Unconformity providing a regional seal1 (Figure 2).
The Company notes that results from the adjacent Delphin and Barracuda wells confirm the presence of oil charge in the area and, in order to determine resevoir quality, has conducted Quantitative Interpretation (QI) studies of the seismic data covering the Raya prospect.
eSeis Inc., a leading Houston-based QI company, has provided LithSeis and Amplitude Versus Offset (AVO) volumes over the entire 3D data set.
The LithSeis cube, although uncalibrated by well data, is a pre-stack seismic-based petrophysical analysis that yields lithology, porosity, and possible hydrocarbon fill. In the LithSeis section (Figure 3b), yellow colours are interpreted to represent porous sandstones, with red reflectors interpreted to represent very high porosity and/or where hydrocarbons are present. In this case, several layers of high porosity at the top of potential reservoir zones (such as layer SC 1) are evident.
The AVO sections illustrate the responses of seismic reflections to increasing angles of offset and uses a colour bar to differentiate between the five commonly recognised classes of AVO responses; in this area, Class 2 or Class 3 responses are of particular interest as they may be indicative of a hydrocarbon- filled reservoir (either gas or oil).
The highly encouraging culmination of these analyses are the mapped responses of LithSeis and AVO across the SC 1 layer (Figure 4). The strong and consistent LithSeis response suggests the presence of a highly porous sandstone fairway running NE-SW across the Raya prospect, potentially derived from one of the feeder systems identified during field mapping.
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