Patent ID: 8424377

Claim:
An apparatus for monitoring changes in a level of a fluid in a formation, there being a borehole extending into the formation from a formation surface, the apparatus having at least one tubing system comprising: a transducer tube extending in the borehole and having a top end above the formation surface and a bottom end below the fluid level in the formation; a transducer above the formation surface and in closed fluid communication with the top end of the transducer tube, for measuring a gas pressure within an upper portion of the transducer tube; and a port tube in fluid communication with the fluid in the formation and with the bottom end of the transducer tube, via which port tube the fluid flows between the formation and a lower portion of the transducer tube, whereby a level of the fluid in the transducer tube tends to equilibrate with the level of the fluid in the formation; wherein the level of fluid in the transducer tube affects the gas pressure within the upper portion of the transducer tube, and wherein further a change in gas pressure measured by the transducer indicates a change in the level of the fluid in the formation.