In-context interpretation: Avoiding pitfalls in misidentification of igneous bodies in seismic data

Abstract

In the past few decades, many exploration wells have been drilled into igneous rocks because of their similar seismic expressions to common exploration targets, such as carbonate mounds, sheet sands, and sand-prone sinuous channels. In cases in which interpreters cannot clearly delineate sedimentary features such as channels or fans, the interpretation may be driven primarily by bright spot anomalies, in which a poor understanding of the wavelet polarity may lead to an erroneous interpretation. Although many wells drilled into igneous rocks are based on the interpretation of 2D seismic data, misinterpretation still occurs today using high-quality 3D seismic data. To address this challenge, we analyze the seismic expression of andesitic volcanoes in the Taranaki Basin, New Zealand and use it to help understand misinterpreted igneous bodies in different parts of the world. Then, we develop an in-context interpretation workflow in which the seismic interpreter looks for key clues above, below, and around the target of interest that may alert the interpreter to the presence of igneous rocks.