Oil recovery and cooling for underground salt cavern oil storage: Insights from coupled flow and thermal model

Abstract

Petroleum reserve in salt caverns is paying more attention to oil cooling to prevent dissolved gas release from heated crude oil. This work introduced a method for oil recovery in conjunction with cooling, along with a matching flow and heat transfer model taking changes in crude oil thermophysical parameters into consideration. An average error of 3.43% was observed between the model results and filed monitoring data. It was found that after being cooled by the heat exchanger, the temperature of extracted crude oil drops from 39.5 °C to 26.8 °C, demonstrating the effectiveness of this approach for oil cooling. Sensitivity analysis indicates that the season is the primary determining factor for the cooling efficacy of crude oil. Even worse, cooling will be useless when the ambient temperature exceeds 35 °C. However, increasing brine temperature will reduce the surface pumping pressure from 7.60 MPa to 5.17 MPa, with a decrease of up to 31.97%. A special focus was given to the brine injection rate, which seemed to have less impact on the cooling efficiency but became more significant in the pressure profile. In addition to providing further insights into the flow and thermal performance of strategic petroleum reserves in the salt cavern, this study could also be a powerful tool for determining the best process parameters to ensure the delivery temperature of crude oil and the stability of the salt cavern.