Patent ID: 9194225
Filing Date: 2015-11-24
Classification: E21B,G01F

Abstract:
1. A system for measuring a fluid surface level of a fluid in a pipe, comprising: a drill pipe positioned within a wellbore, the drill pipe having an internal diameter, the wellbore being defined by a casing; a fluid disposed within the drill pipe, the upper portion of the fluid being defined by a surface level, wherein wire transmission lines are not present in the region of the surface level of the fluid; a pulse generator operable to generate a pulse of electromagnetic wave energy to propagate along the drill pipe towards the surface level of the fluid in the drill pipe, the pulse of electromagnetic wave energy being transmitted along the drill pipe, the length of the wave being preselected and tuned to correlate to the internal diameter of the drill pipe, wherein the lower (minimum) cut-off wavelength (λ) is calculated to be about λ=0.59 (ID), wherein ID represents the internal diameter of the drill pipe, further wherein the wavelength of the wave energy deployed to propagate along the drill pipe is between about 1.1 and about 1.5 times the lower cut-off wavelength, and wherein the drill pipe and casing, together, act as a coaxial waveguide for transmission of the signal along the wellbore; a detector operable to detect a portion of the electromagnetic pulse that is reflected from the surface level of the fluid in the drill pipe and propagated along the wellbore towards the detector; a processor, configured and arranged to receive a signal from the detector representative of the detected portion of the electromagnetic pulse and to analyze the detected portion of the electromagnetic pulse to determine the position of the surface level of the fluid; a delay defining a detection time window for detecting the portion of the electromagnetic pulse reflected from the surface level of the fluid; and a pump controller, configured and arranged to receive distance information from the processor and to use the distance information to control the operation of a pump located in the wellbore, further wherein the magnitude and direction of change of the fluid level in the drill pipe is employed to control the pump operation speed or stroke to adjust the fluid level in the drill pipe.