Deepwater production is challenged by well underperformance problems that are hard to diagnose early on and expensive to deal with later. Problems are amplified by reliance on few complex wells with sophisticated sand control media. New downhole data is required for better understanding and prevention of completion and formation damage. We introduce Real-Time Completion Monitoring (RTCM), a new non-intrusive surveillance method for identifying impairment in sand-screened completions that utilizes acoustic signals sent via the fluid column. These signals are carried by tube waves that move borehole fluid back and forth radially across the completion layers. Such tube waves are capable of "instant" testing of the presence or absence of fluid communication across the completion and are sensitive to changes occurring in sand screens, gravel sand, perforations, and possibly reservoir. The part of the completion that has different impairment from its neighbors will carry tube waves with modified signatures (velocity, attenuation) and also would produce a reflection from the boundary where impairment changes. The method relies on permanent acoustic sensors performing acoustic soundings at the start of production and then repeating these measurements during the life of the well. Thus, it could be thought of as "miniaturized" 4D seismic and "permanent log" in an individual wellbore. In the meantime repeated conventional wireline measurements can be performed to assess the completion permeability.

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