A Successful Implementation of a Cost-Effective Well Intervention Using Gas Injection Technique in Producing Wells to Increase Oil Production in Mature Fields

Abstract

Abstract The objective of this paper is to present a successful and cost-effective technique applied in a producing well located in a Mature Field offshore Brazil. The Gas Injection technique increased the productivity index and rates temporarily in sandstones reservoirs suffering from compaction and fines migration, causing solids to deposit and build up in completion screens. It also increases temperature profile from the well, assisting in flow assurance issues and minimizing possibility of dynamic hydrate formation. The gas injection operation is performed periodically, shutting the well and injecting gas - through gas lift lines - into the wellbore passing by the completion screens. Due to the risk of hydrate formation, an inhibitor is injected to avoid this issue in both wellbore and jumper flowlines. The operation comprises of an injection target at controlled rate of 4 MMSCFD. Once performed, the well is brought back online. It is then evaluated the well performance aligned to a test separator, comparing current production figures to reference values prior to the gas injection operation. The mechanism of gas being injected into the wellbore will push the fines away from the completion screens, restoring the flow area. The results have shown an average increase of 21% of oil production with a lasting effect of ten days until it reaches same production figures as pre-injection reference figures. It has also been observed an increase of the well temperature profile (bottom hole and wellhead temperature transmitters), assisting in preventing dynamic hydrate formation and minimizing operational costs reducing continuous hydrate inhibitor injection rates for this well. Integrity risks have been considered and assessed with regards to reservoir, well completion and subsea system, with no major risks being identified. This technique presents a way to obtain production increase with no major intervention or downtime, at a low cost, extending the life cycle of producing wells in mature fields using means already available (in fields that use gas lift as artificial lift system). Secondarily, it will also assist in flow assurance issues with temperature increase and preventing dynamic hydrate formation.