Spatiotemporal wave propagation of the shale oil and gas development in the Marcellus Shale in the past one century and a half

Abstract

ABSTRACT Dense shale oil and gas extraction activities have a long history in the Marcellus Shale and the investigation of their evolution draws increasing interest. The spatiotemporal analysis of these shale oil and gas extraction activities is essential to understand their evolution in space-time, and important for the estimation of their historical impacts on local environments and communities. These shale oil and gas extraction activities formed numerous scattered hot spots, and it demands tremendous efforts to trace them over time. This particular issue then challenges the conventional spatiotemporal analysis approaches which are effective for single or limited spatiotemporal objects. This study models the spatiotemporal developments of the shale oil and gas extraction activities as wave propagation. By using the wave representation, the complicated transmission of these shale oil and gas extraction activities is automatically traced within a sub-space-time as free propagation. To implement the proposed wave model, density surfaces of active wells from 1868 to 2018 were estimated annually. A 15-year focal statistic filter was applied to the density curve at each location to identify temporal objects. The waves were formed from temporal objects using a spatiotemporal expansion algorithm while maximally allowing 1 gap year. Finally, comprehensive attributes were derived for each wave. The results indicate that chaotic and fragmentary waves propagated at the western and northern edges of the Marcellus Shale. In contrast, large and simple wave propagation occurred in the middle of the Marcellus Shale. The propagation of large waves has a southward general trend, the trend follows the Appalachian region’s mountainous topography. Different types of drilling activities show diversified wave propagation patterns and the conventional gas wells formed the most chaotic wave propagation. The wave representation is successfully applied to the evolution of the shale oil and gas extraction activities, and this study also develops a comprehensive set of attributes to depict the wave. The scattered hot spots of dense shale oil and gas extraction activities are automatically assembled in waves. These concrete and detailed attributes of the waves are effective in summarizing the general spatiotemporal evolution pattern of chaotic and fragmentary spatiotemporal objects, e.g., the dense shale oil and gas extraction activities in this case. The developed method is also transferable and applicable to the evolution of other geographic phenomena, which may comprise of either limited or numerous spatiotemporal objects.