Seismic inversion for the Vaca Muerta shale of the Neuquen Basin, Argentina

Abstract

The Vaca Muerta Shale in the Neuquen Basin of Argentina is a world class shale reservoir still in the early stages of development. With thickness of 500 m, TOC of up to 14% and estimated recoverable reserves of 16 billion barrels of oil and 308 TCF of gas (EIA, 2015), the Vaca Muerta is extremely promising geologically. However, a lack of investment in infrastructure still makes oil and gas development more expensive in Argentina than in incomparable US shale plays. Geophysical techniques can help improve the understanding of the Vaca Muerta and reduce uncertainty, making substantial investments to reduce cost through large scale development less risky. A 3D-3C multicomponent seismic survey was acquired in the Neuquen Basin in 2016. This survey is the first known 3D multicomponent survey acquired over the Vaca Muerta and can help determine if multicomponent seismic data adds value for development of wells landed in the Vaca Muerta Shale. Challenges were experienced both in the acquisition and processing of this survey and are discussed to help future projects avoid these pitfalls. The acquisition was designed for P-waves and was azimuth limited at far offsets since shots were, in general, in the North. Azimuths and offsets were limited even more due to receiver dropouts in the South. A comparison of seismic inversion products for P-impedance, S-Impedance and density between the new multicomponent survey, a legacy 3D seismic survey, and a modern wide-azimuth survey over the same area are used to illustrate how the acquisition of the new survey changed our understanding of the reservoir properties in this area. The new multi-component survey P-wave inversion results show improvement over the legacy 3D seismic data inversion results. However, the challenges in acquisition and processing lead to less than ideal converted wave seismic volumes and the potential inversion improvement from adding converted wave data is not seen in this case. This research demonstrates the importance of high quality acquisition and processing in multicomponent seismic projects. While the value of multicomponent seismic could not be fully demonstrated with this dataset, other operators can learn from the issues this project encountered to improve future multicomponent seismic programs and more fully realize the value of multicomponent seismic data.