A Case Study of CO2Sequestration Potential of a Saline Aquifer in Qatar

Abstract

CO2 is one of the byproducts of natural gas production in Qatar. High rate of natural gas production in Qatar has led to significant amounts of CO2 production. Release of CO2 into the atmosphere may be harmful from the global warming standpoint. Recent increase in CO2 concentration in atmosphere due to burning of fossil fuels and deforestation may be one of the main causes for acceleration in global warming. Since fossil fuels will be a critical component of world energy supplies for the coming decades, methods for disposal of CO2 that do not involve long residence of CO2 in the atmosphere should be studied. One of these methods is injection of CO2 in underground saline aquifers. It is generally believed that saline aquifers provide the largest potential for CO2 sequestration. However, the effort required to screen and select saline aquifers for safe and long-term storage is significant. It is also important that screened CO2 storage sites are exploited to their full potential. In this work, we studied CO2 sequestration potential in Qatar's Aruma aquifer. Aruma aquifer is a saline aquifer in the southwest of Qatar. It occupies an area of about 1985 km2 on land, which is approximately 16% of Qatar's area. We developed a compositional model for CO2 sequestration in the Aruma aquifer. Our model is based on available log data and flow test data from the Qatar Department of Agricultural and Water Research. We modeled CO2 injection at a constant rate for a period of 30 years and monitored the CO2 propagation for 200 years. We identified a suitable CO2 injection rate to keep pore pressure below formation fracturing pressure. We also studied water production at some distance from CO2 injection wells as a possible way to control pore pressure. This method resulted in significant increase in CO2 sequestration potential of the Aruma aquifer. The water produced from this aquifer is less saline than seawater and could provide a good water source in the desalination process. The main source of current Qatar's water usage is desalination of seawater.