Estimating the required underground natural gas storage capacity in Brazil from the gas industry characteristics of countries with gas storage facilities

摘要

The Brazilian energy sector has undergone significant changes in recent decades. In particular, consumption and production of natural gas have intensified, and more infrastructures for its transport and importation have been built. In addition, recent discoveries (such as the huge natural gas volumes located in offshore fields) and new research into unconventional deposits indicate a rise in Brazil's proven natural gas reserves in the near future. However, Brazil lacks the geological or underground storage facilities to support its rapidly expanding gas industry, as well as important tools for meeting fluctuating demand and production and improving supply security. To assess the required storage capacity for Brazil, it is useful to analyze the international experience, clarifying the development of several aspects of the gas industry in gas storing nations. To this end, we investigated the relationships between storage and various characteristics of the gas sector by linear regression analysis. The research, conducted on all 38 countries with operational underground natural gas storage, evaluated the extent to which storage capacity is affected by proven reserves, production, consumption, infrastructure, total gas imports and exports, and the use of natural gas as a percentage of total national energy consumption. A very strong relationship emerged between underground natural gas working storage capacity and gas consumption (R~2 = 0.8825) and gas infrastructure (R~2 = 0.9130). Another important relationship was identified between storage and gas production volume (R~2 = 0.8239). The remaining aspects did not significantly affect the development of gas storage activity. We estimated the deviations between the values calculated by the linear regression equations and those reported in the technical literature. The errors varied from 89.1%, when all 38 countries were involved, to 31.4%, considering the 13 nations with the highest working gas storage capacities. The average deviation was significantly higher for the 12 nations with little storage capacity (as high as 288%); excluding these 12 countries, the average error reduced to 37.4%. Thus, the equations obtained by the correlations more accurately predicted the outcome in countries with higher storage capacity. The large deviations for countries such as Argentina, China, and Sweden are discussed. Finally, the required storage for the Brazilian gas sector was determined at two intervals: (i) 0.34-9.22 billion m~3, based on the error of 89.1%, and (ii) 1.98-6.70 billion m~3, based on the deviation of 37.4%. It is important to mention that high errors were expected, since gas storage depends on factors such as geology and demand seasonality, which were not considered in this work, but which could be analyzed in future researches.