through the well fluid

Full Title

Survey of boreholes or wells (monitoring pressure or flow of drilling fluid E21B21/08) > Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling > using acoustic waves > through the well fluid

Child Classifications

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• E21B 47/20 by modulation of mud waves, e.g. by continuous modulation
• E21B 47/22 by negative mud pulses using a pressure relieve valve between drill pipe and annulus
• E21B 47/24 by positive mud pulses using a flow restricting valve within the drill pipe