Abstract: Various disclosed distributed acoustic sensing (DAS) based systems and methods include embodiments that process the DAS measurements to detect one or more contrasts in acoustic signatures associated with one or more fluids flowing along a tubing string, and determine positions of the one or more contrasts as a function of time. The detected contrasts may be changes in acoustic signatures arising from one or more of: turbulence, frictional noise, acoustic attenuation, acoustic coupling, resonance frequency, resonance damping, and active noise generation by entrained materials. At least some of the contrasts correspond to interfaces between different fluids such as those that might be pumped during a cementing operation.

Abstract: Various disclosed distributed acoustic sensing (DAS) based systems and methods include embodiments that process the DAS measurements to detect one or more contrasts in acoustic signatures associated with one or more fluids flowing along a tubing string, and determine positions of the one or more contrasts as a function of time. The detected contrasts may be changes in acoustic signatures arising from one or more of: turbulence, frictional noise, acoustic attenuation, acoustic coupling, resonance frequency, resonance damping, and active noise generation by entrained materials. At least some of the contrasts correspond to interfaces between different fluids such as those that might be pumped during a cementing operation.

Abstract: Various disclosed cement slurry monitoring methods include monitoring one or more parameter of the cement slurry at various positions along the borehole during the curing process and responsively identifying a span over which the slurry extends and whether there are any gaps or voids in that span. At least some system embodiments include a distributed sensing arrangement to provide parameter measurements as a function of position and time during the curing process. A computer analyzes the measurements to determine the span of the cement slurry and whether any gaps exist. Contemplated measurement parameters include temperature, pressure, strain, acoustic spectrum, acoustic coupling, and chemical concentration. Individually or in combination, these measurements can reveal in real time the state of the cement slurry and can enable remedial actions to be taken during or after the curing process if needed to address deficiencies in the annular seal being provided by the cement.

Abstract: Various disclosed cement slurry monitoring methods include monitoring one or more parameter of the cement slurry at various positions along the borehole during the curing process and responsively identifying a span over which the slurry extends and whether there are any gaps or voids in that span. At least some system embodiments include a distributed sensing arrangement to provide parameter measurements as a function of position and time during the curing process. A computer analyzes the measurements to determine the span of the cement slurry and whether any gaps exist. Contemplated measurement parameters include temperature, pressure, strain, acoustic spectrum, acoustic coupling, and chemical concentration. Individually or in combination, these measurements can reveal in real time the state of the cement slurry and can enable remedial actions to be taken during or after the curing process if needed to address deficiencies in the annular seal being provided by the cement.