Abstract: A well casing is insonified with a first acoustic wave in a first mode that may be any mode of a set including: extensional mode, thickness mode, flexural mode. A first echo is received at a first acoustic transducer for receiving, a first signal is produced and a first measurement is extracted from the first signal. The casing is then insonified with a second acoustic wave in a second mode that may be any mode of the set of modes but is distinct from the first mode. A second echo is received at a selected second acoustic transducer for receiving and a second signal is produced. A second measurement is extracted from the second signal. The zone behind the casing of the well is evaluated from a combination of the first measurement and the second measurement.

Abstract: A method for estimating an impedance of a material behind a casing wall in a borehole, the method comprises exciting (602) the casing wall with an acoustic pulse, and measuring (603) an experimental acoustic waveform (W) reflected from the casing wall. The method further comprises initializing (600) an impedance parameter (Zin), computing (601) an inverse casing response (Rcas?1) as function of the impedance parameter, and deconvoluting (604) the experimental acoustic waveform with the inverse casing response to obtain a transducer (T). An iterative loop (605, 606, 607) is performed, comprising the computing of an inverse casing response and the deconvoluting of the experimental acoustic waveform by varying (607) the impedance parameter until the transducer response becomes compact (605, 606) in the time domain. The estimated impedance (Zcem) is obtained (606) from the impedance parameter when the transducer response is compact.

Abstract: A surface mud pipeline system is described with a mechanical acoustic filter (1245) tuned to a predetermined frequency band so as to attenuate pump noise (132) within this band. The filter can be combined with a Venturi constriction to provide enhanced attenuation and is used to improve signal transmission of a mud pulse telemetry system (113-2).

Abstract: The invention provides a method for estimating an impedance of a material behind a casing wall, wherein the casing is disposed in a borehole drilled in a geological formation, and wherein a borehole fluid is filling said casing, the material being disposed in an annulus between said casing and said geological formation, said method using a logging tool positionable inside the casing and said method comprising: exciting a first acoustic wave in said casing by insonifying said casing with a first pulse, the first acoustic wave having a first mode that may be one of flexural mode or extensional mode; receiving one or more echoes from said first acoustic wave, and producing a first signal; extracting from said first signal a first equation with two acoustic properties unknowns for respectively said material and said borehole fluid; exciting a second acoustic wave in said casing by insonifying said casing with a second pulse, the second acoustic wave having a thickness mode; receiving one or more echoes from said

Abstract: A well casing is insonified with a first acoustic wave in a first mode that may be any mode of a set including: extensional mode, thickness mode, flexural mode. A first echo is received at a first acoustic transducer for receiving, a first signal is produced and a first measurement is extracted from the first signal. The casing is then insonified with a second acoustic wave in a second mode that may be any mode of the set of modes but is distinct from the first mode. A second echo is received at a selected second acoustic transducer for receiving and a second signal is produced. A second measurement is extracted from the second signal. The zone behind the casing of the well is evaluated from a combination of the first measurement and the second measurement.

Abstract: The invention provides a method for measuring and locating a fluid communication pathway in a material behind a casing wall, wherein said material is disposed in an annulus between said casing and a geological formation, and said method comprising: measuring a set of parameters of the material behind the casing within a range of radius, depths and azimuthal angles; defining sections comprising a sub-set of parameters wherein said sub-set of parameters is taken in said set of parameter for a given range of radius, depths and azimuthal angles included in said range of radius, depths and azimuthal angles; defining for each section a first limit zone and a second limit zone in frontier of said given range; determining among said sections the ones that comprise a continuous fluid communication pathway from said first limit zone to said second limit zone, said sections being renamed in retained sections; determining from said continuous fluid communication pathway an area or a width of pathway versus depth for each

Abstract: The invention provides a method for estimating an impedance of a material behind a casing wall, wherein the casing is disposed in a borehole drilled in a geological formation, and wherein a borehole fluid is filling said casing, the material being disposed in an annulus between said casing and said geological formation, said method using a logging tool positionable inside the casing and said method comprising: exciting a first acoustic wave in said casing by insonifying said casing with a first pulse, the first acoustic wave having a first mode that may be one of flexural mode or extensional mode; receiving one or more echoes from said first acoustic wave, and producing a first signal; extracting from said first signal a first equation with two acoustic properties unknowns for respectively said material and said borehole fluid; exciting a second acoustic wave in said casing by insonifying said casing with a second pulse, the second acoustic wave having a thickness mode; receiving one or more echoes from said

Abstract: A surface mud pipeline system is described with a mechanical acoustic filter (1245) tuned to a predetermined frequency band so as to attenuate pump noise (132) within this band. The filter can be combined with a Venturi constriction to provide enhanced attenuation and is used to improve signal transmission of a mud pulse telemetry system (113-2).

Abstract: The invention concerns a device (10) for measuring calorific energy contained in a fuel gas transported in a pipe (16) comprising a gas meter (12) measuring a volume V in pressure conditions P and temperature conditions T of a gas circulating in said pipe and an apparatus (14;52;63) to determine the gas calorific power H. The invention is characterized in that said apparatus for determining calorific power measures at least one physical variable proportional to the number of molecules of the gas different constituents in a given volume and is placed as near as possible to the gas meter so as to determine the calorific power H(P,T) in similar pressure P and temperature T conditions as those wherein the gas volume V(P,T) is measured, said device then determining the calorific energy H(P,T) V(P,T) contained in the gas.

Abstract: The invention provides a fluid meter comprising ultrasound transducers, attenuation means for attenuating parasitic ultrasound waves of wavelength &lgr;, and constituted by at least one passage in which said waves propagate along a main direction corresponding to a longitudinal dimension a of said passage, said passage having a transverse dimension b perpendicular to a and much smaller than the wavelength &lgr; of the parasitic waves in the propagation medium, said passage comprising a plurality of consecutive passage portions each having a part presenting a reduction in transverse propagation section along the dimension b of the passage, the longitudinal dimension of each passage portion being substantially equal to &lgr;/2.

Abstract: A logging tool having a tool body, which can be positioned in a fluid-filled borehole, including a receiver section and a dipole transmitter; wherein the dipole transmitter includes a transducer with a shell having a reaction mass and a motor located therein, the motor operatively connecting the shell and the reaction mass such that only an outer surface of the shell is in contact with the fluid in the borehole. This new type of dipole source for well logging involves shaking all or part (axially) of a dipole tool body to produce a pure, broadband acoustic dipole signal while at the same time coupling as little energy as possible into the tool body. Important variations on this idea include a linear phased array of shaker sources, and active cancellation of tool borne noise.

Abstract: A method for measuring a fluid flow rate between two points of a fluid flow according to which a measurement of the respective propagation times of two acoustic signals transmitted in opposite directions is combined with a measurement of acoustic phase shifts respectively induced in each signal. Each received signal is sampled and digitized and the corresponding acoustic phase shift is determined by synchronous detection. During successive iterations, a programmable phase shift dependent on the value of the acoustic phase shift obtained by synchronous detection in the previous iteration is determined for each iteration, so that the result of the synchronous detection step in the current iteration is as close as possible to zero, and the acoustic phase shift is therefore substantially the same as the last programmable phase shift.

Abstract: The invention concerns an ultrasonic fluid counter including at least two ultrasonic transducers collectively defining an ultrasonic measuring path and emitting and receiving ultrasonic waves in the fluid along said ultrasonic measuring path according to at least one ultrasonic frequency, wherein attenuation means for attenuating parasitic ultrasonic waves generated outside said fluid counter and transmitted by the fluid according to the ultrasonic frequency or frequencies are associated with the fluid counter.

Abstract: A geophysical prospecting method comprises injecting signal energy in the form of at least two pseudo-random pulse sequences of the complementary sequence type into an underground formation. Next, the signal energy is detected after it has been attenuated by passing through the underground formations in the form of response signals. The response signals are correlated with reference signals comprising at least two pseudo-random binary sequences to yield correlations. The correlations are summed so that the resultant signal which corresponds to the subsurface response signal does not have secondary lobes. The method is applicable to seismic prospecting and more particularly to cross-well seismic surveying. It is also applicable to acoustic prospecting for logging measurements. In a preferred embodiment, the pseudo-random sequences comprise a pair of Golay sequences.