Schlumberger Technology Corporation

Demid Valeryevich Demidov

Artem Valeryevich Kabannik

Roman Vladimirovich Korkin

Andrey Vladimirovich Fedorov

Roman Korkin

Methods for locating fluid interfaces in a cased wellbore include generating vibrations in the casing, thereby forming oscillations in the wellbore fluids and the casing. The oscillations are detected by a vibration detector. The oscillations are recorded by a data acquisition system. Mathematical processing of the oscillations by cepstrum analysis is performed to determine the depths of interfaces between fluids in the annulus. The methods may also be employed to determine the time at which a cement slurry begins to set and harden. The methods may be performed in real time.

Methods for determining positions of fluid interfaces and detecting cement setting in a subterranean wellbore

The position of a droppable object (e.g., a cementing plug or drillpipe dart) in a cased wellbore may be determined in real time during a cementing operation. A pressure data acquisition system is installed at a wellsite and a pressure transducer is installed at the wellhead. As the droppable object travels through casing it encounters regions with a positive or a negative change of inner cross-sectional dimension. The droppable object generates a pressure pulse as it passes through the regions. The pressure pulse and associated reflections are detected by the pressure transducer, and the signals are processed mathematically to determine the current position of the droppable object.

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Novosibirsk, Russia

Demid Valeryevich Demidov