AE12.pdf

Different techniques of calibration there are three

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Different Techniques of Calibration There are three alternative approaches to calibration. 1. For in-house calibration, when installing the sand monitor and using only the in-house calibration, a deviation in the range of 25 to 50 percent can be expected. System repeatability is ±1 percent. 2. For in-house calibration plus adjustment for flow, when the monitor is installed, the reading for the actual flow conditions is adjusted for that particular well. This will provide an accuracy in the range of ±15 to 25 percent. Repeatability still remains at ±1 percent. 3. For field calibration using a sand injector, the monitor and the sand injector are installed upstream of the monitor. Then sand is injected into the flow line to adjust or verify the performance of the particle monitor. Accuracy in the range of ±5 to 15 percent can now be expected. In other words, a repeatability of ±1 percent can be expected and does not depend on the calibration technique. When the operator installs a monitor on a well, it should usually be allowed to run for some time to find the zero level. This adjustment of the system for background noise usually takes around 30 to 60 min. The operation is easy but slightly time consuming. If sand is already being produced and is in the flow line already, it will be detected and shown immediately on the computer screen. The repeatability is still ±1 percent and the trend will be good but the accuracy will suffer. In practice, sand is never produced continuously. To establish the zero level, the trend should be measured until a sand free period comes up. All the factors mentioned above are valuable for using an acoustic emission particle monitor to minimize sand in oil and gas production. Maximizing of Sand Free Production An operator worried about sand production will sometimes reduce production unnecessarily. A cutback in production in the range of 20 to 75 percent is fairly common in oil and gas wells. Because of the values such production limitations represent, it is well worth evaluating sand monitoring systems as a way of increasing production without high investment costs. It is important to have a system that responds rapidly and accurately to improve the sand detection. Figure 24 shows a flow chart with generic steps for analysis of sand production. Usually, the operator reduces production immediately after sand is discovered or suspected. The discussion below explains how to maximize production while maintaining a well consolidated reservoir. Figure 25a shows a producing well in which sand production is declining. The curve represents what is called a good pattern. As the figure shows, sand is being produced because of the increase in production (opening the choke valve). A reliable sand monitoring system, however, lets the operator monitor the development of the sand production. The 411 Special Applications of Acoustic Emission Testing
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figure shows how sand production is being reduced over time because of consolidation of the producing reservoir.
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  • Fall '19
  • The Land, Nondestructive testing, Acoustic Emission, Acoustic Emission Testing

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