Intelligent Completion in Extended Well Test

Abstract

This paper describes the wells completion design, operational performance and use of intelligent completion by Libra Consortium for EWT wells. Additionally, it will describe new technologies that will support the full field development. The paper presents the de-risking plan EWT Program implementation to help full field development, which consists up to four ultra-deepwater mega projects. The EWT wells were assumed as keepers, thus designed as convertible, with metallurgy requirements for both oil production and Water Alternating Gas injection. The intelligent completion, with multi-position valves for each production zone, was selected to allow choking-back gas coning, early gas breakthrough or water production in one zone, while another remains opened. These valves were useful to determine vertical communication between different reservoir zones, making it possible to have buildup in one zone while producing another. Four appraisal wells were completed, for the EWT program up to now, using a full-dual rig. Three of the completions were in sequence, providing a sound learning curve with a significant time reduction, and no installation problems. It was noticeable a correlation between improvement in operational efficiency and a decrease in HSE incidents. The use of intelligent completion made possible an efficient well stimulation, avoiding inter-zonal communication during the acid job. A production rate higher than 60 kboe/day was reached and 100 MM scf/day gas was re-injected. This injection rate implied risk of control lines fatigue due to induced vibration, therefore a Computational Fluid Dynamics (CFD) study was required to determine the maximum injection rate. The Operator implemented mitigation measures for intelligent completion valves actuation since some operational difficulties were observed during the EWT. These situations did not affect the EWT information acquisition plan, but represented significant operational experience for Mero Field future development projects, where multiplexed intelligent completions and open-hole intelligent completion are being also considered. The approach taken by Libra Consortium helps to gain early experience about well design for carbonate reservoirs and intelligent completion behavior, with high CO2 and GOR, where gas re-injection is a necessity and the use of intelligent completion is a mandatory strategy. The performance of the completion design fitted the field evaluation purpose and the wells will be successfully used as keepers.