The Margham Dubai Establishment (MDE) asset is a mature gas-condensate field that was put on production in 1985. As the energy demands of Dubai are ever increasing, MDE has been releasing (net) gas resulting in rapid dwindling of remaining reserves. In order to reduce the amount of alternate fuels required to meet the Dubai energy demands, MDE initiated a drastic field intervention campaign prior to June 1, 2006. Preliminary feasibility studies concluded that the only identified practical option of increasing drainage capacity was to re-enter existing wells drilling high deviation multi-laterals with coiled-tubing, underbalanced drilling (CTUBD) techniques. After approximately three months of rigorous project planning and engineering, the well sequence of Phase I was initiated (4 wells). Upon completion, a 73% net increase (including average field decline) of gas from the Margham field was observed equating to a gas lift cost of less than $2/Mscf (25% less cost than alternate fuels). Due to the success of Phase I, an additional four wells were approved. Upon Phase II completion, a 125% increase (over nonintervention predicted field production rate) resulted, equating to a gas lift cost of less than $1.33/Mscf. The reduction in lift cost in Phase II was attributed to the cost of front-end engineering, mobilization, retention of equipment and additional start-up costs all being absorbed in Phase I. Also, the technical limit (rig move, milling time, drilling time, etc.) for the CTUBD operation was not reached until the drilling of the third well. Thereafter a third and final phase was approved consisting of three additional wells. The total number of wells rejuvenated was eleven.

This paper addresses the conceptualization of the project, the well selection criteria, identified risk and uncertainties, the risk management methods employed, environmental impact, implementation practices, key achievements, production improvement, ultimate recovery enhancement and a cost versus value summary. Overall the CTUBD intervention campaign as a mature field rejuvenation technique has been a great technical and economic achievement. In addition to the apparent increase in production, the rejuvenation of the Margham field will allow for more efficient gas storage methods in the future (if required) due to the increased injectivity index and the ability to use fewer wells for gas cycling.

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