Induced earthquake damage assessment methodology for potential hydraulic fracturing sites: Application to Manaus, Brazil

Abstract

The number of seismic events induced by the exploitation of unconventional oil and gas reservoirs has escalated considerably in the last decade. This has raised concerns in several sectors of society, and in consequence, research efforts have been launched to ascertain the risk associated with induced seismicity. This article presents a procedure to quantify potential damages caused by induced seismicity to the built infrastructure of a region. The technique adapts the probabilistic seismic hazard analysis framework to the features of induced seismicity. The risk is then evaluated by the probability of exceeding economic loss. Estimates of potential injuries or loss of life caused by buildings’ interior components are fundamental policymaking inputs, but were not considered in this initial study which is focused on assessing direct damage. In a future study, however, these factors will be addressed. The procedure is applied in a case study in Manaus, a city located on a large shale gas basin which is potentially exploitable. The results of the study indicate that the tectonic parameter (b) of the adjusted Gutenberg–Richter model is a governing driver in the loss analysis. Two damage mitigation strategies are proposed: one that limits volume injected setting loss thresholds and other that restricts injection locations based on damage modeling estimates. Insights from the case study emphasize that these type of activities should be avoided near urban areas where seismic standard anticipates low natural seismicity, and with a high proportion of poorly built residential infrastructure. The study contributes to the literature a technique to inform the decision-making associated with establishing unconventional oil and gas exploitation projects that is applicable to several places and situations.