A successful qualitative and quantitative integrated interpretation of Lower Miocene wells and seismic data in Salina del Istmo Basin, Mexico

What is it about?

The study area is located in mid to deep waters of the Salina del Istmo Basin where Repsol operates Block 29. The objective of this work is to integrate qualitative and quantitative interpretations of rock and seismic data in order to predict lithology and fluid of the Early Miocene prospects. The seismic expression of those prospects differs from age-equivalent well studied analogue fields in the US GOM basin due to the mineralogically very complex composition of abundant extrusive volcanic material. Offset well data (i.e. core, logs, cuttings) were used to discriminate lithology types and to quantify mineralogy. This analysis served as input for developing a new rock physics framework and perform Amplitude Versus Offset (AVO) modeling. The results indicate that the combination of intercept and gradient allows to discriminate hydrocarbon (AVO class II & III) versus non-hydrocarbon filled rocks (AVO class 0 & IV). Different lithologies within hydrocarbon bearing reservoirs cannot be discriminated as gradient remains negative for all rock types. However, AVO analysis allows to discriminate three different reservoir rock types in water bearing cases (AVO class 0, I, IV).

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Photo by Sarah Berriman on Unsplash

Photo by Sarah Berriman on Unsplash

Why is it important?

The conclusions of this paper were obtained during studies conducted in 2018–2019 and were used in prospect evaluation to select drilling locations leading to 2 wildcat discoveries drilled in 2020 in Block 29 (Polok and Chinwol).