Field development of a mature, highly fractured carbonate field presents several challenges. Most of the horizontal wells drilled in such fractured reservoirs suffer from early gas or water breakthrough because conductive fractures dominate the influx from the reservoir and cause an unbalanced flux profile along the wellbore. Premature gas or water breakthrough can result in poor sweep efficiency and reduced oil recovery for the well.

To address the aformentioned challenges, passive inflow control devices (ICDs) can be used to equalize influx from the reservoir to the wellbore, thereby delaying gas or water breakthrough. However, during the life of the well, as water or gas breakthrough occurs, a passive ICD can be less effective in preventing water or gas production. This can effect well productivity and reduce the production life of the well, especially for a naturally flowing well.

This paper describes how adjustable ICD technology with a sliding sleeve can be used as an effective reservoir management tool in mitigating challenges faced in a naturally fractured Middle Eastern carbonate field. Various examples from the subject field are presented to describe production challenges faced by barefoot and passive ICD-completed horizontal wells. The field cases suggest the need for adjustable ICD with sliding sleeve technology which provides a zonal shut-off option in case of water or gas breakthrough. A detailed workflow for usage of adjustable ICDs is described, and which includes well candidate selection, well monitoring and pre and post shifting well performance evaluation to determine which ICD unit must be shifted to a closed or open position. A dynamic simulation using a single-well model was also conducted to establish the benefits of a sliding sleeve on well production performance.

An adjustable ICD with a sliding sleeve was chosen as the preferred completion technology over the passive ICD for horizontal wells for the subject field with a naturally fractured carbonate reservoir. A sliding sleeve integrated in an ICD is a simple and cost-effective tool for zonal water or gas shut off compared to conventional intervention technology available for horizontal wells. Sliding sleeves maximize the value of ICD technology by adding an adjustability feature to ICD to overcome the challenges faced by unexpected changes in well behavior and premature water or gas breakthrough. Dynamic simulation results also confirm the sliding sleeves can prolong the life of the well by reducing high water and free gas production, thereby increasing cumulative oil production.

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