This paper describes the use of fiber-optic distributed temperature systems to monitor production from BP's Azeri field in Azerbaijan and highlights the benefits and issues encountered during the start-up of the first production wells. Production from BP's Azeri field in the Caspian Sea commenced in February 2005. These offshore wells are completed across multiple sand intervals using sand screens with gravel packs. Each fiber-optic monitoring system was installed with the completion in a purpose-built groove in the side of the gravel-pack screen. The screen is connected to the upper completion string via a hydraulic wet-connect enabling fiber passage from surface to total depth. The primary Azeri reservoir consists of multiple sand bodies in the Pereriv formation. Commingled completions across these sand bodies are providing wells capable of producing more than 40,000bopd. The issues that dictate the requirement for regular distributed temperature (DTS) monitoring are long, high-angle well bores and the need to understand well and reservoir performance by sand body. Additionally, the requirement for minimal production interruptions during the early years of field life does not favor conventional production logging, which would also cause interruptions to the drilling program. A thermal model is used to analyze the producing well temperature profiles and calculate the flow contribution from each of the producing zones. The results demonstrate that, once deployed, permanently installed fiber-optic distributed temperature monitoring is a cost-effective and low-risk method of monitoring multiple-pay sand screen completions without having to reduce production rates to allow conventional production logging to be carried out. The Azeri Reservoir The Azeri, Chirag and Ganashly reservoirs are located offshore Azerbijan Fig 1 and are being developed by a consortium of oil companies with BP as operator. The reservoirs are part of a multilayered sandstone anticline with approximately 5 billion barrels of reserves in place. The Azeri field is located at the south end of the anticline and it's north flank dips steeply at about 35 degrees and has a 1,000 meter oil column between the gas/oil and water/oil contacts. The south flank dips less steeply (20 degrees) and is suspected having perched oil/water contacts. Voidage support will be achieved by both water and gas injection and effective voidage replacement is considered critical to optimum reservoir drainage. The high deviation producing wells will be mostly completed with sand screens and are capable of up to 50,000bopd flow rates Fig 2. The main Azeri producing reservoir is the Pereriv formation that consists of interbedded layers of soft sand and shale. The main technical challenges being addressed by BP are:Sand control issues in the soft sands - requiring sand screens and gravel packs.Well performance and management issues in the high angle long well bores.Reservoir uncertainty, gas-oil and water-oil contact location and movement over time. Studies show that more than 100 million barrels of the secondary reserves are at risk because of poor voidage, thus a comprehensive reservoir surveillance program is required in order to minimize this risk.
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