Application of Thru Tubing Technologies in the Caspian Sea Uphole Recompletion

Abstract

Thru-tubing uphole re-completion is a workover technique aiming to re-complete the existing wellbore by temporary abandoning the lower producing zone and subsequently perforate upper layer. There are various techniques used to temporarily abandon the lower zone worldwide. Specific to Caspian Sea development, the temporarily abandonment will only be required to set an isolation plug. However, statistically speaking, success ratio of lower zone temporary abandonment, is quite low using current plugs set in different condition of completion. In addition, the risk of deploying balance cement plug also presents significant challenge due to interval limitation between top of the cement and new perforation interval. It is deemed necessary to find a fit-for purpose solution that provides a solution to the Caspian Sea environment plug and temporary abandonment strategy. A new plug technology, metal to metal system, was introduced to provide assurance isolating the lower zone prior to perforating new upper zone. Subsequently, a wireline deployed or pipe (tubing) conveyed perforation is not an attractive solution to thru-tubing up-hole recompletion technique. A new technology to perforate lively is selected from safety and economic point of view for this specific well. The perforation was done in underbalance condition with intelligent coiled tubing. The uphole re-completion (well delivery) performance was more attractive than other conventional uphole re-completion techniques. This paper will elaborate the success of recompletion techniques by deploying multiple new technologies in the Caspian Sea.