Simulating rapidly fluctuating CO2 flow into the Vedsted CO2 pipeline, injection well and reservoir

Vattenfall is considering the Danish coal fired power plant Nordjyllandsværket for a CO2 post combustion capture plant. Up to 1.8 million tones of CO2 per year will eventually be captured. Related storage option is investigated in the nearby onshore Vedsted Structure where a saline aquifer is found around 2 km depth with anticipated sufficient storage capacity and injectivity. A 24 km pipeline is predicted. The CO2 flow from the capture plant will fluctuate on a daily as well as hourly rate and sudden shut downs must be expected. Pipeline, wells and well completion must thus be designed such that a high level of fluctuation can be handled in the entire system. Here we present a study of transient variations in terms of pressure, temperature and phase. A reservoir model is used for studying effects in the formation near the well bore and a flow simulator for the pipeline and well. Special emphasis is made on results related to transient pressure behavior in the bottom hole of the well. The results point towards that high loads as well as shut downs and shorter periods without flow can be handled by the modeled system. For long periods of very low rates of CO2 problems arise with keeping high CO2 saturation in the near well reservoir and with phase changes in the pipeline and well; thus the design of the system must be further investigated.