The effectiveness of thermal control systems for gas hydrates formation prevention for optimal production activation

Abstract

Our study is about the effectiveness of heat exchanger on eliminating Hydrates on gas lift lines and maintaining the well on optimum production. And aims to enhance the exchanger performance to overcome Hydrates problem completely leading to minimal Downtime due to Hydrates and maximum well availability. The heat exchanger in Hassi Messaoud was tested on 15 wells, one well out of the 15 wells failed, two wells had 100% success rate which means Hydrates did not occur on these wells anymore. The rest of the wells had a variant success rate. Among these wells, a candidate well MDZ717, where Hydrates formation decreased but not entirely eliminated, was selected to investigate the performance of the heat exchanger by using Kern method and HYSYS tools, Exchanger Design and Rating is used to create a model of the exchanger in order to integrate it in HYSYS simulation. Kern method results indicated that the exchanger is sufficient to eliminate Hydrates completely, however, it’s not the case with MDZ717. HYSYS simulation, with a very similar model of the exchanger used in Hassi Messaoud designed with Exchanger Design and Rating, estimated the temperature of gas after exiting the exchanger at 13 C° (60 bar), which falls in the range of metastable Hydrates formation, which explains the reason why Hydrates is not totally eliminated. HYSYS showed very accurate results compared to Kern method, and using the same simulation we designed another exchanger and tested it on the MDZ717 simulation, the model gave a very satisfying result by increase the temperature of the gas to 21C°, making the well operating on the free Hydrates area.