Abstract: A well passing through a geological formation is fitted with a tube, open at its bottom end, that is filled with a fluid. Another fluid is in the annular space between the tube and the wall of the well, the two fluids exhibiting an interface situated in the annular space. A hydraulic balance of the fluids of the well is disturbed and the trend of certain quantities is measured. These measurements are moreover simulated by computer by using different sets of values for the physical parameters, and efforts are made to estimate the geological formation. A comparison of the measurements with the simulation results makes it possible to identify an optimum set of values for the parameters.

Abstract: A well passing through a geological formation is fitted with a tube, open at its bottom end, that is filled with a fluid. Another fluid is in the annular space between the tube and the wall of the well, the two fluids exhibiting an interface situated in the annular space. A hydraulic balance of the fluids of the well is disturbed and the trend of certain quantities is measured. These measurements are moreover simulated by computer by using different sets of values for the physical parameters, and efforts are made to estimate the geological formation. A comparison of the measurements with the simulation results makes it possible to identify an optimum set of values for the parameters.

Abstract: The method comprising measuring the rate at which working fluid is expelled from a cavity through a central tubing to a well head under atmospheric pressure at the well head; determining the shape of a zone of the well selected for positioning an interface between a test fluid and the working fluid; performing temperature measurements and pressure measurements over the full height of a cavity under atmospheric pressure at the well head; injecting additional working fluid into the central tubing or into the annular space until a predetermined test pressure is reached; measuring the compressibility of a cavity during the preceding step; injecting test fluid into the annular; measuring the depth of the interface between the test fluid and the working fluid for a first time at the end of injecting test fluid; measuring the test fluid and the working fluid pressures at the well head; measuring the level of the interface between the test fluid and the working fluid for a second time; and evaluating the real leakage