Consequence Modeling of Hypothetical Releases From Carbon Dioxide (CO2) Transport Pipelines

Abstract

Reducing carbon emissions is increasingly becoming a priority to combat climate change. Carbon capture, utilization, and storage (CCUS) is one of the primary approaches to help combat carbon emissions in the oil and gas and other industries. These technologies involve capturing the CO2 from combustion, refining, or other types of industrial activities, then transporting that CO2 to another location where it can be utilized or stored underground or below the sea floor. Pipelines are one of the primary transportation methods, and as more CCUS operations start to come online, more pipelines will be built or converted from transporting hydrocarbons to transporting CO2. Like most products transported by pipeline, there are risks associated with CO2 transport. However, these risks are quite different from those of hydrocarbon transport. CO2 is not flammable and is less toxic. The primary risk associated with a release of a large quantity of CO2 is the displacement of oxygen that can cause an asphyxiation hazard. Direct exposure to cooled CO2 liquid or gas can cause irritation or even frostbite. CO2 releases into water can harmfully alter the water pH level. Due to these risks, it is necessary for operators to understand the potential consequences of an accidental loss of containment. This paper will review an approach for consequence modeling used for the potential conversion of service from crude oil transport to CO2, for a confidential pipeline operator. This will include an overview of the modeling tools used, the inputs and assumptions incorporated, the range of hypothetical release scenarios considered (including full-bore ruptures and smaller leaks) and overview of the results. This assessment was used to answer a variety of questions asked to evaluate whether this conversion was a viable project. This included determining the potential impact area from a worst-case discharge, what receptors are at risk, and identifying optimal operational considerations (i.e. valve type and placement, leak detection requirements, etc.). This approach for consequence modeling for CO2 pipelines can be used to help ensure safety during the coming energy transition.